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Home My WebLink AboutIce Form and Streamflow on Salmon Incubation Habitat Bradley River 1996-tf:?~ Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 96-4202 Prepared in cooperation with the ALASKA ENERGY AUTHORITY Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska By Ronald L. Rickman U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 96-4202 Prepared in cooperation with the "<> ALASKA ENERGY AUTHORITY - - .... --• • .. ... - - Anchorage, Alaska 1996 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY GORDON P. EATON, Director For additional information write to: District Chief U.S. Geological Survey 4230 University Drive, Suite 201 Anchorage, AK 99508-4664 Copies of this report may be purchased from: U.S. Geological Survey Branch of Information Services Box 25286 Denver, CO 80225-0286 .- .. • ,, • • • • -.. • I ,. - - - .... -- -• • • • CONTENTS Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Location of Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Bradley Lake Hydroelectric Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Winter Flow Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Purpose and Scope............................................ . . . . . . . . . . 3 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Description of Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Bear Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Tidewater ........................................................... . Tree Bar Reach ....................................................... . Below Fish Camp ..................................................... . Upper Riffle Reach .................................................... . Lower Riffle Reach ................................................... . Middle Fork Bradley River Below North Fork Bradley River ................... . 4 5 5 7 7 7 Methods and Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Measurements of Surface Water ......................................... . Measurement of lntragravel Water ........................................ . Observation Methods of Spawning Area Locations and Population Estimates ...... . Ice Formation and Streamflow ............................................... . 7 8 9 10 Hydraulic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Surface-Water Velocity ................................................. . 10 Surface-Water Depth.................................................... 12 Wetted Perimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Field Water-Quality Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Dissolved Oxygen...................................................... 21 Specific Conductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Streambed Stability and Permeability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Fine Sediment Deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Stranding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Discharge from the North and Lower Middle Forks of the Bradley River. . . . . . . . . . . 29 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Suggested Future Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Contents Ill Appendix 1: Cross section and velocity distribution at selected sites in the lower Bradley River, November 1994 through April 1995............................ A-1 Appendix 2: Selected hydraulic properties, water-quality data, and site characteristics for the lower Bradley River, November 1994 through April 1995 .......... A-25 FIGURES 1. Map showing location of the Bradley Lake Hydroelectric Project area. . . . . . . . . . . VI 2. Photograph showing aerial view of the study area on the lower Bradley River from Bear Island to Lower Riffle Reach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Map showing Lower Bradley River study transect locations. . . . . . . . . . . . . . . . . . . 6 4. Photograph showing sample tube used to collect intragravel water samples. . . . . . . 9 5. Graph showing daily mean discharges for Bradley River near Tidewater. . . . . . . . . 11 6-11. Graphs showing physical properties of Bradley River: 6. At Bear Island transect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7. Near Tidewater transect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 8. At Tree Bar Reach transect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9. Below Fish Camp transect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 10. At Upper Riffle Reach transect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 11. At Lower Riffle Reach transect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 ~"I lilt 12-17. Graphs showing: .1 12. Selected surface-water velocity distributions for the six transects in the lower Bradley River . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 13. Daily mean surface and intragravel water temperature of the Bradley River near Tidewater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 14. Dissolved oxygen concentrations at the six study transects . . . . . . . . . . . . . . . . 24 15. Dissolved oxygen percent interchange at the six study transects . . . . . . . . . . . . 27 16. Instantaneous discharge measurements of the Middle Fork Bradley River below North Fork Bradley River . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 17. Results of periodic specific conductance measurements in the Middle Fork Bradley River below North Fork Bradley River. . . . . . . . . . . . . . . . . . . . . . . . . . 31 TABLES 1. Types of data collected and frequency of collection in the lower Bradley River, March 1993 through April1995 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Gravel bar slopes at the six study transects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 IV Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska .. • .... ---... - -• -- • CONVERSION FACTORS, VERTICAL DATUM, AND WATER-QUALITY INFORMATION Multiply by To obtain inch (in.) 25.4 millimeter foot (ft) 0.3048 meter mile (mi) 1.609 kilometer square foot (ft2) 0.0929 square meter foot per second (ft/s) 0.3048 meter per second cubic foot per second (ft3/s) 0.02832 cubic meter per second In this report, water temperature is reported in degrees Celsius (0 C), which can be converted to degrees Fahrenheit (°F) by the following equation: °F = 1.8 (0 C) + 32 ABBREVIATED WATER-QUALITY UNITS mL, milliliter mg/L, milligrams per liter ~S/cm, microsiemens per centimeter at 25 degrees Celsius VERTICAL DATUM Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929-A geodetic datum derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum of 1929 . Contents V 151°00' 15~'" s9"51'r-__;-r;.;;._----~r;r;r:rr-.:.:;-;:;.;;....--------;:===========·:I:::·.-==::::1 KACHEMAK BAY I 5 Kn..OMETERS Figure 1. Location of the Bradley Lake Hydroelectric Project area. EXPLANAnON A USGS Stream-gaging station .& AEA Stream-gaging station -Dam VI Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska •.. I "' • • • • Ill • M • .. .. - - -----• - • • .. • • Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska by Ronald L. Rickman Abstract A minimum flow of 40 cubic feet per second is required in the lower Bradley River, near Homer, Alaska, from November 2 to April 30 to ensure adequate salmon egg incubation habitat. The study that determined this minimum flow did not account for the effects of ice formation on habitat. An investigation was made during periods of ice formation. Hydraulic properties and field water-quality data were measured in winter only from March 1993 to April 1995 at six transects in the lower Bradley River. Discharge in the lower Bradley River ranged from 42.6 to 73.0 cubic feet per second (average 57 cubic feet per second) with ice conditions ranging from near ice free to 100 percent ice cover. Stream water velocity and depth were adequate for habitat protection for all ice conditions and discharges. No relation was found between percent ice cover and mean velocity and depth for any given discharge and no trends were found with changes in discharge for a given ice condition. Velocity distribution within each transect varied significantly from one sampling period to the next. Mean depth and velocity at flows of 40 cubic feet per second or less could not be pre- dicted. No consistent relation was found between the amount of wetted perimeter and percent ice cover. lntragravel-water temperature was slightly warmer than surface-water temperature. Surface and intragravel-water dissolved-oxygen levels were adequate for all flows and ice conditions. No apparent relation was found between dissolved-oxygen levels and streamflow or ice conditions. Excellent oxygen exchange was indicated throughout the study reach. Stranding potential of salmon fry was found to be low throughout the study reach. The limiting factors for determining the minimal acceptable flow limit appear to be stream-water velocity and depth, although specific limits could not be estimated because of the high flows that occurred during this study. INTRODUCTION Location of Study Area The Bradley River originates in the Kenai Mountains east of Homer and flows into Bradley Lake (fig. 1), then flows northward from Bradley Lake for about 5 mi to Kachemak Bay. The Mid- dle and North Forks of the Bradley River flow into the main stem of the Bradley River 3.3 mi downstream from the Bradley Lake outlet. Flow from the upper basin of the Middle Fork is diverted into Bradley Lake. The most downstream mile-long reach of the Bradley River provides habitat for five species of Pacific salmon and Dolly Varden char (Rundquist and others, 1985, p. 78) . Bradley Lake Hydroelectric Project The Alaska Energy Authority (AEA) began operation of the Bradley Lake Hydroelectric Project near Homer, Alaska in 1991 (fig. 1). The dam, which was constructed at the Bradley Lake outlet, incorporated a fish-water bypass system to maintain flows required for fish habitat enhance- INTRODUCTION 1 ment in the lower Bradley River. Project operation has resulted in reduced streamflow in the lower Bradley River during the summer, and increased flow above natural conditions during the winter (Rickman, 1993), thus improving salmon spawning and rearing habitat (Morsell and Howard, 1995). Federal Energy Regulatory Commission (FERC) licensing requirements for the Bradley Lake Hydroelectric Project require maintenance of a minimum flow of 40 ft31s from November 2 to April30, measured at the U.S. Geological Survey (USGS) stream-gaging station Bradley River near Tidewater (station No. 15239070). This discharge of 40 ft 31s is based on an open-water instream flow study (Woodward-Clyde Consultants, 1983). The instream flow study was based pri- marily on egg incubation requirements of pink salmon (Oncorhynchus gorbuscha), but other salmon species and Dolly Varden char habitat requirements were also addressed. The study found little difference in usable egg incubation habitat between flows of 30 and 40 ft3 Is, but did not account for the effects of river ice formation, which is common in the lower Bradley River during the winter months. Many stqdies have developed suitability criteria for salmon spawning habitats, but few have addressed salmon egg incubation habitats in ice-covered streams (Morsell, 1994). The embryos and alevins are essentially immobile, so it is important that the egg incubation habitat remain healthy throughout the winter (Rundquist and Baldrige, 1990, p. 591). Hydraulic and phys- ical characteristics important to the incubation process are stream velocity, depth of surface water, wetted perimeter, intragravel water temperature, intragravel dissolved oxygen, specific conduc- tance, and streambed stability and permeability. Winter Flow Conditions Ice formation in the lower Bradley River may cause backwater conditions leading to an increase in wetted perimeter and depth of surface water. Stream velocity may decrease, which can adversely affect dissolved-oxygen levels in surface and intragravel waters. Anchor ice may retard water and dissolved-oxygen interchange between surface and intragravel environments. Periodic temporary dewatering of the lower Bradley River could potentially occur because of ice jamming upstream, or because of problems with the fish-water bypass system. Rapid dewa- tering of the stream channel may leave juvenile salmon stranded, thus killing them. Stranding fre- quency is inversely proportional to the slope of the dewatered gravel bars (Prewitt and Whitmus, 1986). Expansive, flat bars are associated with higher stranding rates than steeper bars, because fish may not be able to swim fast enough to remain in the water during rapid declines in stage. Maintenance of 40 ft3 Is flow is difficult in the lower Bradley River during the winter months because ice formation makes it difficult to measure flow accurately. It is not practical to obtain a record of continuous river discharge directly. Instead, river stage is continuously monitored with instruments and discharges are measured at various stages to define the correlation between stage and discharge (Rantz and others, 1982). The correlation between river stage and discharge remains valid as long as the hydraulic properties do not change. Ice formation in the lower Bradley River channel causes rapid and highly variable changes in channel geometry, rendering the stage-dis- charge relation useless. Operators of the Bradley hydroelectric project have released flows of 40 ft3 Is at the fish-water bypass (measured at the USGS gaging station Bradley River below dam, which generally remains ice free) to ensure maintenance of a flow of 40 ft31s in the lower Bradley River. However, actual 2 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska "'I ~, I .. , A> I ., .. ., .. ., .. • • " • • • • • • • • .. • I j --- - - ... • • .. -• -• • flows in the lower Bradley River have been significantly higher than the required minimum because of inflow from the Middle and North Fork Bradley Rivers. In March 1993, under a cooperative agreement with the Alaska Energy Authority, the USGS began a study of winter flow conditions in the lower Bradley River. Northern Ecological Services, under contract with the Alaska Energy Authority, has monitored salmon escapement in the lower Bradley River (Morsell and others, 1993; Morsell, 1994) throughout this study. Purpose and Scope The objectives of this study were to: (1) determine whether a flow of 40 ft3/s from November 2 to April30 provides adequate salmon egg incubation habitat protection and whether a lesser flow provides adequate protection; (2) gain insight into the minimum limits of flow that would provide some assurance of egg protection in the event of unexpected decreases in flow below the allowable minimum; and (3) determine the discharges that must be released at the fish- water bypass to maintain 40 ft' /s in the lower Bradley River. The objectives could not be met because target flow conditions were not reached between March 1993 andApril1995. The project has been extended through 1998 in order to observe target flow conditions. This interim report describes activities through April1995. The report discusses critical habitat needs of pink salmon from egg incubation to the juvenile stage. It also describes hydraulic properties and water-quality characteristics with respect to stream discharge and ice conditions, and their potential impact on the habitat at six transects in the lower Bradley River for the periods March 1993 through April1994, and November 1994 through April 1995. Fine-sediment deposition and dissolved-oxygen interchange between surface water and intragravel water are discussed. Stranding potential at each of the six transects, and flow contribu- tions from the Middle Fork Bradley River below the North Fork Bradley River are presented. This report also summarizes data collected from November 1994 through Aprill995 at selected sites in the lower Bradley River (appendixes 1 and 2). A previous report summarizes hydraulic and water- quality data collected from March 1993 through April 1994 (Rickman, 1995). The types of data collected and the frequency of collection are shown in table 1 . Acknowledgments The author gratefully acknowledge the assistance of John Morsell, of Northern Ecological Services (under contract with the Alaska Energy Authority), for assisting with field studies and providing salmon escapement information . DESCRIPTION OF STUDY AREA An aerial view of the study area is shown in figure 2. Six transects were selected at known spawning areas of pink salmon (Morsell and others, 1993) in the lower Bradley River between Bear Island and Lower Riffle Reach (fig. 3). Stream-water discharge measurements were made on the Middle Fork Bradley River below North Fork Bradley River. Site characteristics of each transect and the Middle Fork Bradley River below North Fork Bradley River are described below. DESCRIPTION OF STUDY AREA 3 Table 1. Types of data collected and the frequency of collection in the lower Bradley River, March 1993 through April 1995. 1993 Water year 1994 Water year 1995 Water year Type of data collected MAMJJAS ONDJFMAMJJAS ONDJFMA Daily mean discharge at stream-gaging station Bradley River near Tidewater xxxxxxx xxxxxxxxxxxx xxxxxxx Instantaneous discharge measurements 1 Hydraulic measurements (wetted perimeter, depth, and velocity distribution) 2 Surface and intragravel water temperature3 Surface and intragravel water dissolved oxygen at the six transects 3 Surface-water specific conductance 1 Estimate percent ice cover 2 Substrate siz.e classification 2 Photographs to document ice conditions at time of field measurements 2 X X X X X X X X X X X X X X X X X X X X X 1Measured at the six transects and at Middle Fork Bradley River below North Fork Bradley River 2Measured at the six transects XXX XXX XX XX XX XX X XX 3Field surface-water temperature measured at all transects; hourly recording of surface-water and intragravel water temperature measured at sensor sites near the Tidewater and Tree Bar Reach transects, respectively, throughout the entire study period. Field intragravel-water temperature measured only when calibrating intragravel temperature probe. Bear Island XX XX XX XX XX XX XX This transect, located near the mid-point of Bear Island, is near the upstream boundary of the usable spawning habitat (fig. 3). A waterfall approximately 500ft upstream from this transect pre- vents salmon from moving farther upstream. The transect is at a transition from pool to riffle and is characterized by shallow sloped gravel bars on both right and left banks (fig. A, appendix 1). A small narrow gravel bar near the right bank splits the river into two channels; only a small portion of the total flow passes through the right channel. The river channel is wider at the Bear Island transect than at the other five transects. Substrate is composed of large cobbles to medium-sized gravels, with a median diameter of 0.22 ft. This transect is not affected by high tides. Tidewater The Tidewater transect is located approximately 100 ft below Bear Island, and 35 ft below the .. .. Ill .. • • • • • • • - USGS stream-gaging station Bradley River near Tidewater (fig. 3). The transect is located at a pool-• to-riffle transition area, and is characterized by a steep root mass and soil on the right bank and a 11111 steep gravel bar on the left bank (fig. B, appendix 1). The channel at this transect is narrower than at the other five transects. Substrate ranges from large cobbles to medium gravel with a median diam-• eter of 0.26 ft. This transect is affected by extreme high tides, which occur on three to five days each • month. A surface-water temperature sensor located near the gaging station records the temperature every hour. • 4 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska -• • I Figure 2. Aerial view of the study area on the lqwer Bradley River from Bear Island (upper left) to Lower Riffle Reach (bottom center). Tree Bar Reach Tree Bar Reach (fig. 3), located 280 ft downstream from the Tidewater transect, is character- ized by a moderately wide channel with a flat bottom. The transect is located in the midpoint of a long riffle. The right bank consists of steep sloped gravel overlain with roots and soil. The left bank is a relatively steep gravel bar. A small abandoned overflow channel is located along a bedrock wall on the far left side of the canyon (fig. C, appendix 1). Substrate ranges from medium cobbles to medium gravel with a median diameter of 0.10 ft. This transect is affected by extreme high tides on five to seven days each month. An intragravel temperature sensor, buried to a depth of 1 ft below the streambed, is located 10 ft downstream from this transect. Below Fish Camp Below Fish Camp transect (fig. 3) is approximately 150ft downstream from the fish camp and 500ft downstream from the Tree Bar Reach transect. The transect is in a riffle-to-pool transi- tion area and is characterized by moderately sloped gravel bars on both the right and left banks. A small slough on the extreme right edge of the channel remained dry during the study period (fig. D, appendix 1). The channel is moderately wide. Substrate consists mostly of gravel with some cobbles. The median diameter of the substrate is 0.07 ft. This transect is affected by medium and extreme high tides on approximately 10 to 14 days each month. DESCRIPTION OF STUDY AREA 5 en m = ID a 0 -n ID "II 0 ... 3 I» J\ I ,I v· N C!: 0 ::s I» ::s CL VJ .. iil I» 3 -0 :e 0 ::s VJ I» 3 .... '• r-= ~ 0 ::s S' n c D" I» .. o· ::s :I: I» D" TIDEWATER BEAR ISLAND s= .. :;· .. :T ID r 0 :e ID ... UPPER RIFFLE 11slo~yPJ 'S[f ('<'1Afp m ii1 CL ii '< :u <" 0 SOOFEET ID !' ,.. I iii I I I I I I I Ill 0 ~ lOOMETERS Figure 3. Lower Bradley River study cross section transects (modified from Morsel!, 1994, fig.1 ). Upper Riffle Reach The Upper Riffle Reach transect is located approximately 850ft downstream from the Below Fish Camp transect, in a deep riffle (fig. 3). The river is split by a gravel bar into two channels of approximately equal width. The right channel is deeper than the left channel (fig. E, appendix 1). The right bank of the right channel is vertical and composed of tree roots and soil. The left bank of the right channel and the right bank of the left channel are formed by moderately steep sloped gravel bars which are covered sparsely with grass. The left bank of the left channel is steep sloped and composed of tree roots and soil. The median diameter of the substrate is 0.17 ft in the right channel and 0.23 ft in the left channel. During much of the winter, mud covers the substrate of approximately 25 percent of both channels, usually near the gravel bar. The mud is carried in from Kachemak Bay during extreme high tide. This transect is affected by backwater from high tide on most days during the winter. Lower Riffle Reach The Lower Riffle Reach transect is located 350 ft downstream from the Upper Riffle Reach transect, in a deep riffle, and defines the lower boundary of the study area (fig. 3). The river forms two channels separated by a gravel bar. The right channel is narrower and deeper than the left chan- nel (fig. F, appendix 1). The right bank of the right channel is vertical and is composed of tree roots and soil. The left bank of the right channel and the right bank of the left channel are formed by moderately steep sloped gravel bars which are covered sparsely with grass. The left bank of the left channel is steep sloped and is composed of tree roots and soil. The median diameter of the substrate is 0.10 ft in the right channel and 0.13 ft in the left channel. During much of the winter, mud covers the substrate in approximately 25 percent of both channels, usually near the gravel bar. Mud is car- ried in from Kachemak Bay during extreme high tide. This transect is affected by backwater from high tide on most days during the winter. Middle Fork Bradley River Below North Fork Bradley River A discharge measuring section was established at the Alaska Energy Authority (AEA) stream-gaging site (fig. 1). The river flows through a deep narrow canyon. The river channel con- sists of deep pools and small waterfalls. Both riverbanks consist of bedrock, and the channel bot- tom is composed of medium gravels and small boulders. No fish are in this drainage basin because obstructions downstream from the confluence with the main stem of the Bradley River prevent fish from moving upstream. Ice forms in the river in early November and remains through mid-April. METHODS AND MATERIALS Measurements of Surface Water Measurements of streamflow were made using standard methods (Rantz and others, 1982). Photographic points were established for each transect in the lower Bradley River, and photographs were taken to document ice conditions at the time streamflow measurements were made. Transects were tied to a common vertical datum for determination of water-surface elevation (Rickman, 1995). Gravel bar slopes were measured at each transect using standard surveying techniques to estimate stranding potential. Rates of gage-height change-important to the understanding of METHODS AND MATERIALS 7 stranding potential-were calculated from the stage hydrographs obtained from the USGS stream- gaging station Bradley River near Tidewater (station No. 15239070). Hydraulic properties of water velocity and depth were obtained from streamflow measurements, and wetted perimeter was cal- culated using the Slope-Area Computation (SAC) program (Fulford, 1994). Wetted perimeter, as used in this report, refers to the length of interface of the water/streambed boundary, and does not include the ice/water boundary. Water temperature was recorded at 1-hour intervals near the Tidewater transect, and water temperatures were measured periodically at all transects and at the Middle Fork Bradley River below North Fork Bradley River, using standard methods (Stevens and others, 1975). Specific con- ductance was measured according to methods described by Hem (1985) at all six transects to gain insight into ground-water contributions (Riggs, 1972, p. 12; Miller and others, 1988) and possible salt-water intrusion from high tides. Dissolved-oxygen concentration was determined using the modified Winkler method (American Public Health Association and others, 1989, p. 4-152). Baro- metric pressure was also measured concurrently to calculate the percent oxygen saturation. Dupli- cate measurements of water temperature, dissolved oxygen, and specific conductance were made on 16 percent of the measurements. Measurements of water temperature, dissolved oxygen, and specific conductance were made at several points across each transect, one time only, to determine variability within the transect. Measurement of lntragravel Water Intragravel water is defined as the fluid occupying the porous interior of the streambed. For this study, it was the interstitial water collected from 8 to 12 in. below the streambed surface-the depth of buried eggs-for physical and chemical analysis. Water-temperature data were collected at 1-hour intervals throughout the study near the Tree Bar Reach transect, using standard methods (Stevens and others, 1975). The temperature probe was buried to a depth of 12 in., but this depth varied slightly during the study period because of scour and fill of the streambed. Dissolved-oxygen samples were collected using special equipment and procedures that differ from those commonly used for fisheries studies. This was necessary to collect representative sam- ples. The samples were collected by inserting a stainless-steel tube with an inside diameter of 3/16 in. through a hole drilled in the ice and into the streambed to a depth of 12 in. The lower 4 in. of the sample tube was perforated with 1116 inch diameter holes, enabling water samples to be col- lected between 8 and 12 in. below the streambed (fig. 4). Water was pumped at a rate of 10to 15 mL per minute into a 60-mL biochemical oxygen demand (BOD) bottle. The slow pump rate was nec- essary to prevent surface-water intrusion (Hoffman, 1986, p. 446). A total of three sample volumes were pumped through the bottles, and the samples were fixed and analyzed using the azide modi- fication of the Winkler method. The pump, tubing, and BOD bottle were placed in a 2 °C waterbath to keep from freezing whenever the air temperature was below 0 °C. Silt content in dissolved-oxy- gen samples was recorded; depth and velocity of surface water at the sample sites were also recorded. Water temperature was measured at the Tree Bar Reach transect using the intragravel temperature probe. This transect is the only one where intragravel water percent oxygen saturation was calculated. The percent dissolved-oxygen interchange between surface and intragravel water was calculated (Woods, 1980). 8 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska . . ~-. < ·:..: •• Figure 4. Sample tube used to collect intragravel- water samples (height of tube from ring to bottom is 1 foot}. Observation Methods of Spawning Area Locations and Population Estimates Active spawning areas were located and monitored by Northern Ecological Services of Anchorage, Alaska, under contract to the Alaska Energy Authority, from mid-July through early September 1993-95. Seine nets and trap nets were positioned in active spawning areas to sample fish populations. Salmon population and escapement were estimated and compared with pre- project data (Morsell and others, 1993; Morsell, 1994). METHODS AND MATERIALS 9 ICE FORMATION AND STREAMFLOW Pink salmon (Oncorhynchus gorbuscha) move into the lower Bradley River to spawn from mid-July to early September with the highest concentration about mid-August (Morsell and others, 1993). The female digs a nest (redd) in the stream gravels, lays the eggs at an average depth of approximately 12 in., and covers them with gravel. The alevins emerge sometime in January and remain in the gravel through the winter (John Morsell, Northern Ecological Services, oral. com- mun., 1995). The exact time of emergence in the lower Bradley River is unknown, but is suspected to be in late March and early April. The lower Bradley River has ice formation during much of the egg incubation, hatching, and alevin development stages. Ice formation in the lower Bradley River, measured at the stream-gaging station Bradley River near Tidewater (station No. 15239070), was intermittent during the study period (fig. 5). The period of March 1 to April 30, 1993 was mostly ice free, with a few days of shore ice formation (Linn and others, 1994). The November 1, 1993 through April 30, 1994 period was ice affected approximately 50 percent of the time (Bigelow and others, 1995). Ice formation during this period was usually shore ice, with short periods of complete ice cover in mid-January and late February. Ice formed in the lower Bradley River approximately 70 percent of the time between November 1, 1994 and April30, 1995 (Schellekens and others, 1996). The river was completely ice covered dur- ing much of this period. Discharge in the lower Bradley River ranged from 42.7 to 73 ft31s (7 to 83 percent higher than the target flow of 40 ft3 Is) during the study period. The average discharge was 57 ft3 Is throughout the study. Estimation of the effects of a discharge of 40 ft31s or less on the fish habitat was difficult because of the high flows that occurred during the study period. The remainder of this report will highlight the knowledge obtained from the higher flow data. HYDRAUUCPROPERTIES Selected hydraulic properties of the transects in the lower Bradley River from March 1993 to April 1994 have been previously reported (Rickman, 1995). Selected hydraulic properties from November 1994 to April 1995 are presented in appendix 2 (table A1). Surface-Water Velocity Adequate surface-water velocity is necessary during the winter to prevent freezing of the streambed gravels and to assure adequate incubation success. Surface-water velocity has a direct relation to intragravel water velocity, which is important for supplying dissolved oxygen to the eggs and removing metabolic wastes (Wickett, 1954, p. 945; Coble, 1961, p. 469; Vaux, 1968, p. 479; Johnson, 1980, p. 156). Winter surface-water velocities needed for pink salmon egg incu- bation and fry development have been reported as 0.5 to 8 ft/s (Woodward-Clyde, 1983, p. 47) and greater than 1 ftls (Reiser and White, 1981 ). The instream flow model used by Woodward-Clyde (1983, p. a5) chose 0.5 to 8.0 ft/s as the optimum velocities for embryo development. Mean surface-water velocities measured in the lower Bradley River ranged from 0.33 ft/s at Upper Riffle Reach on January 12, 1995 (discharge 50.5 ft 31s) to 1.48 ft/s at the near Tidewater transect on December 3, 1993 (discharge 65 ft31s; Rickman, 1995, p. 6). The average mean velocity for all transects during this study was 0.92 ft/s (n = 36). 1 0 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 0 z 0 0 w CJ) a: w a.. 1--w w u.. 0 iii :::> 0 z u.i C} a: <{ r 0 CJ) 6 z <{ w ~ ~ <( 0 200 100 ... -· ----- 300 200 100 1993 MARCH 1 TO APRIL 30, 1993 . ' ............ ......... -.................... ... 0~--------~-----------+----------~--------~----------~--------~ 300 200 100 Nov Dec 1993 Jan Feb 1994 NOVEMBER 1, 1993 TO APRIL 30, 1994 ,~ . ,.. ./............ , .. ,, .......... , .... _ ........ ______ ,...,., .. _ ............ ___ , Nov Dec 1994 Jan Feb 1995 NOVEMBER 1, 1994 TO APRIL 30, 1995 EXPLANATION Dashed line indicates estimated discharge due to ice formation Mar Apr Mar Apr Figure 5. Daily mean discharges for Bradley River near Tidewater (station number 15239070). HYDRAULIC PROPERTIES 11 The relations between discharge, percent ice cover, and mean velocity were not always obvi- ous. Mean velocities plotted against discharge for varying ice conditions (figs. 6A-11A) highlight this ambiguous relation. Mean velocity was expected to decrease with increased ice cover for any given discharge, but this was not always the case. Mean velocities for ice cover of 80 to 100 percent were smaller than those for ice cover of 30 percent or less, at both Bear Island and Tidewater transects, but this pattern does not hold for the other transects. Mean velocity did decrease signif- icantly during periods of rapid ice formation, such as that measured on January 11-12, 1995 (table Al, appendix 2). At this time, formation of anchor ice, as well as surface ice, significantly increased channel friction and resulted in lower mean velocities. The January 11-12, 1995 episode is typical of early stages of ice development. Eventually, the river reaches a steady-state condition where no additional ice is formed. The soft anchor ice is then eroded away leaving only the harder surface ice. Such were the conditions at all six transects during February and December 1994, and from February to March 1995. Mean velocity was expected to decrease with decreasing discharge for a given percent ice cover, but no consistent relation is apparent for any of the cross sections. Surface-water velocities typically increased with increasing total water-column depth (mea- sured from streambed to water surface) within each transect, except during periods of rapid ice for- mation (figs. A-F, appendix 1; Rickman, 1995). Velocity distribution within each transect also varied significantly with changing ice conditions. Selected surface-water velocity distributions for the six transects in the lower Bradley River are shown in figure 12. Each episode of ice formation causes different and unique velocity distributions. This is most apparent at the Bear Island and Tree Bar Reach transects (figs. 12A and 12C). None of the observed velocities were high enough to cause channel scour, but higher velocities may have occurred between observations. Surface-water velocities within each transect appear to be adequate for the discharges noted during this study, regardless of ice conditions. However, velocity predictions at discharges of 40 ft 3/s or less cannot be made because the discharges during this study were too high to allow rea- sonable extrapolation to lesser discharges. Surface-Water Depth Adequate surface-water depth is necessary to ensure that enough hydrostatic pressure exists to force movement of intragravel water needed to supply dissolved oxygen to the eggs and alevins, and to remove metabolic waste (Reiser and White, 1981). Reported depths required for pink salmon incubation range from greater than 0.2 ft (Woodward-Clyde, 1983, p. A5) to greater than 0.5 ft (Reiser and White, 1981; Morsell, 1994, p. 3). Woodward-Clyde used 0.2 ft as the minimum allowable depth for adequate embryo development for their instream flow model. Data of surface- water depth for March 1993 to April 1994 have been previously reported (Rickman, 1995). Data for November 1994 through April1995 are presented in appendixes 1 (figs. A-F) and 2 (table AI). Mean depths ranged from 0.55 ft at the Lower Riffle Reach transect (November 30, 1994, discharge 46.8 ft 3/s) to 1.95 ft at the below Fish Camp transect (January 12, 1995, discharge 42.6 tt3/s) and were usually smallest at the Lower Riffle Reach transect (fig. 11B). Within each transect, depths were less than 0.2 ft near the streambanks. Mean depths at all the transects were slightly larger than those predicted using the instream flow model for flows between 40 and 50 ft3/s. This may be due to channel changes resulting from the floods of October and December 1986. 12 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 1.6 2.0 1.8 1.4 f-A B 0 z 1.6 0 () -w 1.2 r 1.4 UJ a: ..._ 80 w w <10 w 0.. IJ.. 1.2 • ..._ .30 • ;!!:; w 1.0 f-- w <10 :i IJ.. • ..._ 1.0 100 ;!!:; 0.. <20 w 100 • ~ 0.8 1-• -0 u z 0.8 • <10 <( • <20 • 0 w 30 ...J • 100 100 :! •• w • > o.6 r -0.6 <10 z <( w :! • 80 0.4 o.4 r - 0.2 0.2 0 40 50 60 70 80 40 50 60 70 80 DISCHARGE, IN CUBIC FEET PEA SECOND DISCHARGE, IN CUBIC FEET PEA SECOND 120 a: 15 w ..._ ::; a: 115 w .30 c 0.. D (/) 14 100 :! <( ..._ 110 • a: 100 C!l w ::; • w IJ.. .80 ...J 13 ~ ;!!:; 105 ;!!:; <10 <10 a: <20 ;;i so • w • ..._ • w • w C!l • :! 100 >-12 a: X 100 w 0 0.. 0 0 95 100 w w > I= • • <10 ...I 11 0 w (/) :;= (/) 90 Ci <10 ...I w • ~ 10 - 85 a: 0 30 <( a: • ..._ 80 ;!!:; 9 40 50 60 70 80 40 50 60 70 80 DISCHARGE, IN CUBIC FEET PEA SECOND DISCHARGE, IN CUBIC FEET PEA SECOND EXPLANATION • 1 OO data point and percent ice cover at time of measurement Figure 6. Physical properties of Bradley River at Bear Island transect. HYDRAULIC PROPERTIES 13 1.6 2.0 <10 • • <20 1.8 100 1.4 • 0 100 A B z 1.6 0 (.) w 1.2 0 1.4 (/) a: 100 • • 1-100 0 w w c.. w • • 100 IJ.. 1.2 1-• w 1.0 ~ w :i <10 • IJ.. ~ 1-1.0 • c.. <20 ~ 100 w 0.8 0 5 • z 0.8 0 <( w --' ::;: w > 0.6 0.6 z <( IJ.I ::;: 0.4 r 0.4 j 0: t 1 I 0.2 I I I I . ' I I I ' I I I I I I I I I I I I I I I . I I I I 40 50 60 70 80 40 50 60 70 80 DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND 46 a: 15 w 1- ::J a: 20 w c c.. D 44 100 .. (/) 14 ::;: • 100 <( a: 1-C!) w 100 w ::J <20 • IJ.. 42 ---' 13 1-::li • • ~ 100 a: ~ 0 w 0 z 1-• w w C!) ::;: 40 r->-12 1- if X 100 w 0 c.. 100 0 0 • w • w > I= 38 1---' 11 0 w (/) 3: f/) 0 --' w 36 1-<10 > 10 <( • a: C!) <( a: 1- 34 ~ 9 40 50 60 70 80 40 50 60 70 80 DISCHARGE. IN CUBIC FEET PEA SECOND DISCHARGE, IN CUBIC FEET PER SECOND EXPLANATION 100 data point and percent ice cover at time of measurement • Figure 7. Physical properties of Bradley River near Tidewater transect. 14 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 1.6 2.0 A <25 1.8 B • 1.4 - 0 1.6 z <10 0 100 • (.) UJ 1.2 1-• -1.4 Cl) a: • <20 ..... UJ UJ UJ 0.. LL 1.2 r-..... 100 ~ 100 UJ 1.0 1-- UJ • I. • LL ~ ..... 1.0 1-100 0.. UJ • 100 > 0.8 -0 • ..... z (3 0.8 1- 100 <( • <20 • <25 g UJ UJ ::!' •<10 > 0.6 0.6 z <( w 0.4 r-::!' 0.4 1- 0.2 0.2 0 40 50 60 70 80 40 50 60 70 80 DISCHARGE, IN CUBIC FEET PEA SECOND DISCHARGE, IN CUBIC FEET PER SECOND 110 a: 15 w ..... :J 100 a: D UJ 100 c • 0.. 100 Cl) 14 • ::!' 100 <( a: ..... Cl • w :::; w LL 90 ..J 13 • 100 ~ :E a: ~ ,f z • UJ <10 ..... w UJ Cl ::!' 80 -> a: X LU 0 0.. 0 0 100 w w > 1: 70 <10 •• • <25 ..J 11 -0 w Cl) 3: Cl) • <20 a ..J w 60 • > 10 100 <( a: Cl <( a: ..... 50 ~ 9 40 50 60 70 80 40 50 60 70 80 DISCHARGE, IN CUBIC FEET PEA SECOND DISCHARGE, IN CUBIC FEET PER SECOND EXPLANATION 100 data point and percent ice cover at lime of measurement . Figure 8. Physical properties of Bradley River at Tree Bar Reach transect. HYDRAULIC PROPERTIES 15 1.6 2.0 • 1.8 100 1.4 A B 0 z 1.6 0 (.) w 1.2 1.4 <20 (/) a: ..... 100 <10 100 • w w a.. 100 w • u. 1.2 •• ..... <10 UJ 1.0 • ~ w • .<20 :i <10 u. ~ ..... 1.0 • 100 a.. > 100 <10 UJ ..... 0.8 • • 0 13 z 0.8 0 <( UJ ....) • 100 :::E w > o.6 r-0.6 z <( UJ :::E 0.4 - 0.4 • 100 0.2 - 0.2 0 I ' 40 50 60 70 80 40 50 60 70 80 DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND 66 a: "I 1 w 100 ..... • ::J 64 a: UJ c a.. D Ul 14 62 100 ~ 100 • ..... a: 100 <20 (!l IJJ 100 ::J • IJJ • u. 60 • ....) 13 100 ~ ~ • a: <10 <20 ~ <10 • • • w 58 z ..... IJJ IJJ 0 :::E >-12 a: X IJJ 56 r-0 a.. 0 0 UJ IJJ > I= 54 ....) 11 0 IJJ (/) 3: Ul l5 52 100 -....) w • > 10 <( 50 <10 -a: . (!l <( a: ..... 48 I ~ 9 40 50 60 70 80 40 50 60 70 80 DISCHARGE. IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND EXPLANATION .too data point and percent ice cover at time of measurement Figure 9. Physical properties of Bradley River below Fish Camp transect. 16 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 1.6 2.0 1.8 - 1.4 A -8 Cl z 1.6 r-- 0 100 () w 1.2 -1.4 r-• en 1-c: w w w c.. u. 1.2 1-~ <15 w 1.0 - w 100 r." <15 • u. ~ • 1-1.0 r-• -c.. • • 100 w • 100 ~ 0.8 r--Cl <10 u • <10 z 0.8 r-1oo· • -. 1oo· <( 0 . w -' <15 • :::!: w <15 o.6 r-100 > 0.6 -z <( w 0.4 :::!: o.4 r--100 0.2 0.2 0 I 40 50 60 70 80 40 50 60 70 80 DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND 120 c: 15 w • 1- 100 ::::; c: w 100 c c.. D en 14 • 100 110 r-:::!: <( c: 1-(!) w ::::; w u. -' 13 ~ ~ ci 100 r-~ w z-<15 1-w • w (!) :::!: >-12 a: X 100 w 0 c.. 90 r-Cl <15 Cl w • • w 100 > I= <10 -' 11 100 -• 0 w <15 • en • :;: en • . i5 80 r-• <15 <10 -' 1oo· w > 10 -<( c: (!) <( c: 1- 70 ~ 9 40 50 60 70 80 40 50 60 70 80 DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND EXPLANATION 100 data point and percent ice cover at time of measurement • Figure 10. Physical properties of Bradley River at Upper Riffle Reach transect. HYDRAULIC PROPERTIES 17 1.6 2.0 1.8 1.4 f-A -100 8 • 0 z 1.6 0 (.) <10 w 1.2 f-100 0 . 100 (Jl 1.4 a: • • • f- w w c.. 0 w u. 1.2 f-~ w 1.0 r-w 100" :I u. ~ f-1.0 c.. ~ w 0.8 r--0 t3 z 0.8 100 <{ 0 w 0 <10 • ...J ~ 100 • w • > 0.6 r--0.6 r-• z 100". 0 <{ w 100 0.4 r-~ 0.4 r-• - 0.2 f-. - 0.2 0 40 50 60 70 80 40 50 60 70 80 DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND 90 a: 15 w 100 f-. ::::; 88 f-a: w 100" c c.. (Jl 14 0 D 86 ~ <{ 100 a: • f-C!l 100 w w 84 0 ::::; u. • ...J 13 ~ ~ cr: 82 • ~ 100 0 • w z f-UJ w C!l ~ 80 >-12 a: X UJ 0 c.. 78 0 0 UJ UJ > ~ ...J 11 f-0 0 w 76 • 100 -(J) ~ (Jl i5 74 f--...J 100 UJ . 100 > 10 f- <{ • <10 a: 72 r-C!l • <{ a: f- 70 ~ 9 40 50 60 70 80 40 50 60 70 80 DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND EXPLANATION 100 data point and percent ice cover at time of measurement • Figure 11. Physical properties of Bradley River at Lower Riffle Reach transect. 18 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska A. BEAR ISLAND B. TIDEWATER 3 3 ""I I I I 1 I I I I I I 2 . : I 2 'I I "I I .. . UJ I I "'•" l 1\ 'I I ' .. ' ~· I ~· I 4' I ~' I ~ ' .. ~ ••• I I . .. I ~--• • I _I I • I I 0 0 40 60 80 100 120 140 160 180 20 40 60 80 100 120 C. TREE BAR D.BELOW FISH CAMP 3 3 0 z 0 (.) w CIJ a: 2 ., 2 w l I a.. 1-w ,:. \ w u. ~ ;.: 1 1- (3 0 1: -' w > ,: 0 0 0 50 100 150 200 20 40 60 80 100 E. UPPER RIFFLE F. LOWER RIFFLE 3 3 left channel right channel 2 2 left channel right channel A A .. 0 L-~~~~~~~~~~~~~~-L~~~~ 0 L-~-A~~-L~~~~--~~--~~~--~~ 0 50 100 150 200 20 40 60 80 100 120 DISTANCE FROM LEFT BANK, IN FEET DISTANCE FROM LEFT BANK, IN FEET EXPLANATION MARCH 1993, ice cover <1 0 percent, discharge 57 tt3/s FEBRUARY 1994, 100 percent ice cover, discharge 66 tt3ts FEBRUARY-MARCH 1995, 100 percent ice cover, discharge 52 tt3ts Figure 12. Selected surface-water velocity distributions for the six transects in the lower Bradley River. (Graphs are displayed in downstream order from A to F. See figure 3 for locations of transects.) 140 HYDRAULIC PROPERTIES 19 160 Mean depths were higher when ice cover exceeded 80 percent than when ice cover was less than 30 percent for the Bear Island, Tidewater, and Tree Bar Reach transects (figs. 6B-8B). No apparent relation exists between ice cover and mean depth at the Below Fish Camp, Upper Riffle Reach, and Lower Riffle Reach transects (figs. 9B-11B). Mean depths did decrease with decreasing discharge, for similar ice conditions, for the Bear Island and Lower Riffle Reach transects. The relation between depth and discharge for similar ice conditions is ambiguous at the remaining transects, where each episode of ice formation caused a different and unique velocity distribution. Depth in the lower Bradley River does not appear to be a significant factor affecting salmon egg and alevin habitat, except possibly at Lower Riffle Reach. Shallow depths at Lower Riffle Reach may explain why pink salmon spawning has decreased in this area, but a more likely explanation is silt deposition (Morsell and Howard, 1995). Wetted Perimeter Wetted perimeter is defined for this report as the part of streambed within a transect that is wetted by surface water, and does not include the ice/water boundary. Prior to flow regulation in the lower Bradley River, wetted perimeter during summer spawning was much larger than that dur- ing egg and alevin development during the winter. As a result, most of the eggs deposited in the summer were dewatered and frozen during the winter, resulting in a high mortality rate (Wood- ward-Clyde, 1983, p. 47; Rickman, 1993, p. 12). The Woodward-Clyde instream flow study showed little difference in wetted perimeter (less than 15 percent) for flows between 30 and 50 ft3/s, but did not account for the expected increase caused by ice formation. Rundquist and Baldrige (1990, p. 82) suggested that incubation habitat would encompass 98.6 percent of the usable spawning habitat (assuming a discharge of 100 ft 3/s during spawning) at 40 ft3/s and 97.2 percent at 30 ft3/s. Wetted perimeter data for March 1993 to April 1994 have been reported previously (Rick- man, 1995). Data for November 1994 through April1995 are presented in appendixes 1 and 2. Wet- ted perimeter ranged from 35.6 ft for the Tidewater transect (March 11, 1993, discharge 56 ft3/s, ice cover less than 10 percent; Rickman, 1995) to 118ft for the Upper Riffle Reach transect (Jan- uary 12, 1995, discharge 50.5 ft 3/s, 100 percent ice cover). From March 1993 to April 1995, the Tidewater transect had the least wetted perimeter variability (range 35.6 to 43.8 ft), probably because the channel is narrow and deep, with steep streamban.ks. Tree Bar and Upper Riffle reach transects had the greatest variability. No apparent relation exists between percent ice cover and wetted perimeter for similar dis- charges (figs. 6C -11C). Ice sometimes freezes to the stream bottom along the streamban.ks, result- ing in dry, frozen stream gravels. Other times, the ice may not freeze to the bottom, but instead it may cause a backwater condition to increase wetted perimeter, as was expected. Ice may also be bridged and have no effect on wetted perimeter. Wetted perimeter does not appear to be a function of discharge for any given percent ice cover. Graphs of discharge plotted against wetted perimeter (figs. 6C-11 C) show a wide scatter in the data with few or no trends. Discharges of 40 ft3/s or less will probably have little effect on wet- ted perimeter as shown by the data presented here and the Woodward-Clyde open-water instream flow study. 20 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska FIELD WATER-QUALITY DATA Temperature Development rate, survival, size of hatched alevins, and the percentage of deformities are related to water temperature during incubation (Groot and Margolis, 1991, p. 156). Cold water is able to hold a higher concentration of dissolved oxygen than warm water, which is beneficial to salmon embryo development. Water that is too cold retards development. Severe icing of the streambed can cut off oxygen supplies to the intragravel water. The effect of temperature on the rate of development in salmonids has been well documented (Groot and Margolis, 1991, p. 159). Warmer temperatures result in faster development. Development rate is proportional to thermal input and expressed in degree-days Celsius, and varies widely among fish stocks. Hatching has been found to occur roughly 100 to 600 degree-days after fertilization, depending on stock. Stock differences between and within pink salmon populations permit adaptive adjustments in hatching and emergence timing to thermal characteristics of individual streams (Groot and Margolis, 1991, p. 159). The degree-days required for the lower Bradley River stock has not been investigated. In the lower Bradley River, eggs hatch in January, and the alevins remain in the gravel throughout the winter (John Morsell, Northern Ecological Services, oral commun., 1995). The exact time of emer- gence in the lower Bradley River is not known, but is suspected to be late March or early April. Analysis of intragravel-water temperature data for Bradley River near Tidewater from January 1 to April 1 gives 80, 106, and 99 degree-days for 1993, 1994, and 1995 water years, respectively. This is much lower than the 450 to 640 degree-days from hatching to emergence reported by Godin (1980, p. 741). Intragravel-water temperature is generally warmer than surface-water temperature during the winter months in glaciated streams (Baldrige and Trihey, 1982). This is true for the lower Bradley River where the intragravel-water temperature is generally 0.5 to 1.0 °C warmer than surface water (fig. 13). Surface-water temperatures measured at all the transects were within 0.5 °C of each other on any given date (Rickman, 1995; appendix 2, table A2). Surface-water temperature was usually 0 °C during periods of ice formation, regardless of discharge. Changes in surface and intragravel- water temperature were mostly a function of periodic warm rains and do not seem to be related to stream discharge. Neither surface-nor intragravel-water temperatures are expected to change at lesser discharges of 30 to 40 ft 3 /s in the lower Bradley River. Dissolved Oxygen Adequate intragravel-water dissolved oxygen is necessary for salmon incubation success. The U.S. Environmental Protection Agency (USEPA, 1977) recommends a minimum of 5 mg/L dissolved oxygen to protect early life stages of cold water biota. Exchange of surface water with intragravel water is largely responsible for the maintenance of intragravel dissolved oxygen (Vaux, 1968). This exchange is controlled by depth and velocity of surface water, channel morphology, and streambed permeability (Wickett, 1954; Coble, 1961; Shumway and others, 1964; Chapman and McLeod, 1987). Dissolved-oxygen data for the lower Bradley River, March 1993 to April1994 have been pre- viously reported (Rickman, 1995). Data for November 1994 to April 1995 are presented in appen- dix 2 (table A2). Concentrations of surface-water dissolved oxygen ranged from 13.0 mg/L at the FIELD WATER-QUALITY DATA 21 March April 1993 MARCH 1 TO APRIL 30, 1993 1993 1994 NOVEMBER 1, 1993 TO APRIL30, 1994 Nov Dec Jan Feb Mar Apr 1994 1995 NOVEMBER 1, 1994 TO APRIL 30, 1995 EXPLANATION Surface water lntragravel water Figure 13. Daily mean surface and intragravel water temperature of Bradley River near Tidewater. 22 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska Upper Riffle Reach transect on AprilS, 1995 (discharge 56.9 ft3/s, less than 10 percent ice cover, water temperature 1.0 °C) to 15.0 mg/L at the Below Fish Camp transect on December 1, 1994 (dis- charge approximately 48 ft3/s, 100 percent ice cover, water temperature 0.0 °C). Dissolved oxygen in surface water, expressed as percent saturation, ranged from 95 to 104 percent from March 1993 to April1995. The high saturation is expected because water discharged from the fish-water bypass and tributary streams flows over numerous waterfalls before entering the lower Bradley River. Concentrations of intragravel dissolved oxygen ranged from 10.1 mg/L at the Lower Riffle Reach transect on November 30, 1994 (discharge 46.8 ft3/s, 100 percent ice cover, 0.90 ft depth of water above streambed, surface-water velocity 1.2 ft/s, intragravel-water temperature unknown) to 14.1 mg/L at the Bear Island transect on March 1, 1995 (discharge 53 ft3/s, 30 percent ice cover, 0.45 ft depth of water above streambed, surface-water velocity 0.3 ft/s, intragravel-water temper- ature unknown). All dissolved-oxygen concentrations were well above the concentration recom- mended by the USEPA. Concentrations of surface-water and intragravel dissolved oxygen are plotted against dis- tance downstream throughout the study area (fig. 14). Variance in the intragravel concentrations is much greater than in the surface-water concentrations. The reason for this is unknown. No clear relations exist between percent ice cover, discharge, and intragravel dissolved- oxygen concentrations (figs. 6D-11D). In many cases, concentrations of intragravel dissolved oxy- gen were proportional to the percent ice cover, and inversely proportional to discharge. The reason for this is not clear, but may be a function of intragravel-water temperature. Observed intragravel and surface-water dissolved-oxygen concentrations were excellent for salmon egg, alevin, and fry development for stream-water discharges greater than 45 ft3 Is at all six transects. The data indicate that adequate dissolved-oxygen concentrations will occur at lesser flows, and that oxygen content is not the limiting factor for determining the minimum acceptable flow limit. Specific Conductance Intrusion of seawater into the lower Bradley River during periods of high tides is a function of river discharge (Woodward-Clyde, 1983, p. 48). Seawater intrusion is most likely to occur dur- ing the winter months when river discharge is lowest. Pink salmon often spawn in intertidal zones. Pink salmon eggs and alevins are tolerant to short exposures to seawater (Groot and Margolis, 1991, p. 156). The Woodward-Clyde study (1983, p. 55) showed that seawater intrusion would not be a factor within the study reach. Specific conductance may also be an indicator of ground-water contribution to stream discharge (Riggs, 1972, p. 12). Specific conductance data for the lower Bradley River, March 1983 to April1994 have been previously reported (Rickman, 1995). Data for November 1994 to April 1995 are presented in appendix 2 (table A2). From March 1993 to April 1995, specific conductance ranged from 60 to 76 J.1Sicm and did not vary significantly spatially or temporally. There was no indication of seawater intrusion from measurements taken immediately following high tides (March 1993, November to December 1994) which caused river water to back up in the study reach. Ground- water contributions to total river discharge cannot be determined from the specific conductance data. Specific conductance is not a factor for determining the effects of lesser flows on salmon incu- bation habitat in the lower Bradley River. FIELD WATER-QUAUTY DATA 23 14 12 A. December 1993 500 1,000 B. February 1994 500 1,000 14 Q' / td 12 '' / ' / e C. December 1994 500 1,000 o ...... ...... -...... -...... 1,500 1,500 e_ ----- 1,500 --/ -e 2,000 2,000 ...... <25 percent ice cover / / 0 / 2,500 100 percent ice cover - 2,500 100 percent ice cover 2,000 2,500 DISTANCE DOWNSTREAM, IN FEET EXPLANATION surface water 3,000 - - 3,000 3,000 Q 0 intragravel water Figure 14. Dissolved oxygen concentrations at the six study transects, December 1993 to April 1995. (Graphs are displayed in chronological order from A to F. See figure 3 for location of study sites.) 24 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 90 to 1 00 percent ice cover -14 1-- 12 0 - D. January 1995 10L-~~--~~~~~~~~--~~~--~~~--~~~--~J-~--~~~~J--.~~~--._~ 0 30 percent ice cover at Bear Island 1 00 percent ice cover at other five transects· ---e--e----e --------- - E. March 1995 10 ~~~--~~~~~~--~~~--~~--~~~--~~~--~~~--~~--~~~--~~~~ 0 <15 percent ice cover 14p-----------------~------------------ G----e--e----e----- 12 ----e ' - F. April1995 ' 0 10~~~--~~--~~~--~~~--~~--~~~--~~~--~~~~~~--~~~--~~~~ 0 500 1,000 1,500 2,000 2,500 3,000 DISTANCE DOWNSTREAM, IN FEET EXPLANATION surface water G E) intragravel water Figure 14. Continued. FIELD WATER-QUALITY DATA 25 STREAMBED STABILITY AND PERMEABILITY Fine Sediment Deposition Measurement of fine sediment deposition in the lower Bradley River was beyond the scope of this study. However, field observations, stream discharge, and water-quality data have provided insight concerning the effects of sedimentation on Bradley River salmon incubation habitat. There are many definitions of particle size that constitutes "fine sediment" (Chapman and McLeod, 1987), but because particle size determination was not within the scope of this study, "fine sedi- ment" will be used in a qualitative sense for purposes of discussion. Large quantities of fine sedi- ment in salmon spawning beds can have severe adverse impacts on incubating salmon (Chapman and McLeod, 1987; Groot and Margolis, 1991 ). The largest effect of sediment deposition is reduced gravel permeability, which can reduce intragravel flow and decrease intragravel dissolved oxygen (Vaux, 1968; Wickett, 1954; Woods, 1980). Wickett found good survival in the presence of much surface sediment if adequate intragravel-water upwelling occurred. Large quantities of sediment can also hamper alevin movement and fry emergence. Rundquist and others (1985, p. 86) noted deposition of fine sediment up to 0.3 ft thick in dewatered areas during winter flows. Field observations at the Upper and Lower Riffle Reaches showed similar deposits in low-velocity areas within the wetted perimeter of the river following high tide cycles. Morsell and others (1993) noted that the Lower Riffle Reach had, at that time, been abandoned as a spawning area, while new spawning areas have opened up above Bear Island. This may be due to sediment deposition during high tides. Reduction of peak discharges following dam construction has lessened the ability of the river to flush fine sediment. Conversely, fine sedi- ment load to the lower river from the upper Bradley River basin has probably decreased as a result of flow regulation. The North Fork and lower Middle Fork Bradley Rivers are clear-water non-gla- cial streams. They contribute a significant portion of the flow into the lower Bradley River, and this portion increases as the total flow decreases. Fine sediment reduces gravel permeability, which reduces the interchange between surface and intragravel waters. A method to quantify this is to look at the percentage of dissolved-oxygen interchange between surface and intragravel-waters (Woods, 1980). Percentage of dissolved-oxy- gen interchange is defined using the equation: p =/IS X 100 where P is interchange percentage, I is intragravel dissolved-oxygen concentration, and S is dis- solved-oxygen concentration of surface water. The interchange percentages at all six transects for each field visit are shown in figure 15. Interchange percentages ranged from 68 at the Lower Riffle Reach transect (December 1, 1994) to 98 at Bear Island and Upper Riffle Reach transects (March 1, 1995). No consistent patterns of inter- change percentage change from upstream to downstream are apparent within the study reach. Inter- change percentages are high for all ice conditions and flows noted during this study, but additional data are needed to determine the effects of lesser flows. 26 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 100 90 80 <25 percent ice cover 70 A. December 1993 60 1-0 500 1,000 1,500 2,000 2,500 3,000 z w (.) a: w c.. 100 ~ u.i (!) 90 z < J: (.) a: w 80 1 00 percent ice cover 1- ~ z UJ (!) 70 B. February 1994 >-X 0 Cl w > 60 _J 0 0 500 1,000 1,500 2,000 2,500 3,000 CIJ CIJ i5 100 1 00 percent ice cover 80 60 C. December 1994 50~~~~~--L-~~~~--~~~~~~~~~~--~~~~~--~~~~~~~ 0 500 1,000 1,500 2,000 2,500 DISTANCE DOWNSTREAM, IN FEET ~0 &..o ~~ ~ 6'~ ~ "',), ~~ <a 1> ~,(-~'$> s..., ~,(- ~ ~ ~(I "11,..0 Figure 15. Dissolved oxygen percent interchange at the six study transects, December 1993 to April 1995. ~ ~ <o ~~ 1> ~,(-~ ~ (Graphs are displayed in chronological order from A to F. See figure 3 for location of study sites.) 3,000 STREAMBED STABILITY AND PERMEABILITY 27 80 D. January 1995 90 to 100 percent ice cover 60 501 1-0 500 1,000 1,500 2,000 2,500 3,000 z UJ (.) a: 100 UJ 0.. ~ u.i (.!) z <( I 0 80 a: UJ 1-30 percent ice cover at Bear Island ~ 1 00 percent ice cover at other live transects z UJ :t 1 (.!) >-X E. March 1995 0 0 UJ > -' 0 0 500 1,000 1,500 2,000 2,500 3,000 (/) (/) i5 100 ,.... ,... ..... rr. ..... r-' ...., ..., ""' ~ 80 <:15 percent ice cover 60 F. April 1995 50 0 500 1,000 1,500 2.000 2,500 3,000 DISTANCE DOWNSTREAM, IN FEET 6>~ Qo ~ 6>~ v..o (o -'1-9 ~tv ~~ (o :;o~ 7t-~ ~ -"1/l ~ 7t-k ')> ')> ~~ ~-9 ')> ~ '$,(-. '$,(-. ~ ~c X( X( '14:-..o ~ ~ Figure 15. Continued. 28 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the lower Bradley River, Alaska Stranding Salmon fry occupying pools or gravels that are isolated from the active river flow are said to be stranded. Pink salmon fry emerge from the spawning gravels sometime in late March and early April (Morrow, 1980, p. 65; John Morsell, Northern Ecological Services, oral commun., 1995). Salmon fry emerge through the gravel at up to 2 in. per minute under favorable conditions (Groot and Margolis, 1991, p. 162). Rapid changes in river stage can leave emerging fry stranded along gravel bars, resulting in mortality. Rapid dewatering of gravel bars can result from temporary dam- ming of the river during ice breakup, or from rapid decreases in flow downstream from reservoirs (Becker and others, 1982). Rapid decreases in stage during tide cycles may cause stranding in the lower Bradley River. Stranding potential is increased as the gravel-bar slope decreases. Slope is measured from mid-channel, perpendicular to the direction of flow. Slopes of less than 4 percent are likely to cause stranding, whereas slopes greater than 9 percent are not (Prewitt and Whitmus, 1986). Streambank and gravel bar slopes measured at the six study transects are presented in table 2. Slopes of non- gravel banks were not reported because emerging fry do not occupy these areas. The smallest slopes were found to be 4 percent on the left side of the Bear Island and Lower Riffle Reach transects. Most of the slopes were greater than 9 percent. Table 2. Gravel bar slopes at the six study transects [See figure 3 for location of the study transects; --, transect has a single channel; NA, bank is not usable salmon habitat] Percent slope Transect Lett bank main Right bank main Lett bank, right (lett) channel (lett) channel channel Bear Island 4 6 Tidewater 9 17 Tree Bar 28 NA Fish Camp 18 7 Upper Riffle NA 10 10 Lower Riffle 4 7 13 Right bank, right channel NA NA Examination of stage data from the USGS stream-gaging station Bradley River near Tidewa- ter showed a maximum of 0.6 in. per minute change in stage, which occurred with an outgoing tide. The largest rate of stage change from ice breakup was 0.1 in. per minute. Neither rate is considered fast enough to cause significant stranding of juvenile salmon. Discharge from the North and Lower Middle Forks of the Bradley River Natural discharge from the lower Middle Fork and North Fork Bradley Rivers (fig. 1) is not adequate to meet minimum flow requirements in the lower Bradley River during the winter months, so additional flow is released from the dam through the fish-water bypass. The Alaska STREAMBED STABILITY AND PERMEABILITY 29 Energy Authority has operated a stage gage on the Middle Fork Bradley River below North Fork Bradley River for several years. Ice formation on the river during the winter months prevents use of a stage-discharge rating curve (Rantz and others, 1982). Because winter flow from the Middle Fork Bradley River below North Fork Bradley River is not well understood, additional water has been released from the fish-water bypass to ensure adequate flow at the regulatory gaging station, Bradley River near Tidewater. Discharge measurements made during a previous study (Rickman, 1995) and during this study were plotted against time (fig. 16). Discharge is lowest during March and early April and did not drop below 7 ft 3/s. This plot shows a consistent trend in the flow through the winter months. Data are insufficient for statistical analysis to determine the expected lower limits of flow. Specific conductance measurements were also made along with the discharge measurements to determine if a relation existed between river discharge and specific conductance (Riggs, 1972; Miller and others, 1988). Specific conductance is plotted against discharge in figure 17. No discern- ible relation was apparent between discharge and specific conductance at this site. SUMMARY AND CONCLUSIONS The lower Bradley River between Bear Island and Lower Riffle Reach provides most of the spawning habitat for five species of Pacific salmon and Dolly Varden char. FERC licensing requires maintenance of a minimum flow of 40 ft 3/s from November 2 to April 30 to ensure adequate flow for incubation habitat. The 40 ft3/s minimum is based on an open-water instream flow study, and does not account for ice formation, which is common in the winter months. Stream discharge aver- aged 57 ft 3/s during this study, which is significantly higher than the target flow of 40 ft 3/s. Ice con- ditions ranged from nearly ice free to 100 percent ice cover. Hydraulic and physical characteristics important to the incubation process are stream velocity, depth of surface water, wetted perimeter, intragravel water temperature, intragravel dissolved oxygen, specific conductance, and streambed stability and permeability. Surface-water velocities within each transect appear to be adequate for the discharges noted during this study. However, velocity predictions at discharges of 40 ft 3/s or less cannot be made because the discharges during this study were too high to allow reasonable extrapolation to lesser discharges. Water depth in the lower Bradley River does not appear to be a significant factor affecting salmon egg and alevin habitat, except possibly at Lower Riffle Reach. Shallow depths at Lower Riffle Reach may be a factor why the use of this area by pink salmon has decreased; a more likely factor is silt deposition. No apparent relation exists between percent ice cover and wetted perimeter for similar discharges (Woodward-Clyde, 1983). Intragravel-water temperatures were generally 0.5 to 1.0 °C warmer than those of surface water during the winter months. Changes in surface-and intragravel-water temperature were mostly a function of periodic warm rains and do not seem to be related stream discharge. No clear relations were noted between percent ice cover, discharge, and intragravel dis- solved-oxygen concentrations. Observed intragravel-and surface-water dissolved-oxygen concen- trations were excellent for salmon egg, alevin, and fry development for stream-water discharges greater than 45 ft 3/s at all six transects. No indication of seawater intrusion was evident from specific conductance measurements made immediately following high tides. Ground-water contributions to total river discharge could 30 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 30 0 z WATER YEAR 0 () 0 w D 1993 (/) 25 f-a: w 6. 1994 a. f-0 1995 w w u._ 20 r-() iii :::> () ~ u.i 15 0 <!l 0 a: <( :I: () (/) 0 D 0 10 f- (/) l:l.o :::> 0 w z <( 5 f-z <( f- (/) I I I I I ~ 0 NOVEMBER DECEMBER JANUARY FEBRUARY MARCH APRIL Figure 16. Instantaneous discharge measurements of the Middle Fork Bradley River below North Fork Bradley River. 93 a: w f-92 w 0 :::;; f= z w () 91 a: 0 w a. (/)(/) Z:::J W-90 :::;;(/) w-' _w 0 (/)() 0"' a:w Uw 89 ~§ Zw -:o w"' ()('l 88 Zr- ;::<( 0 - () :::> 0 z 87 0 - () () u:: 0 86 w 0 a. (/) 85 I L 6 8 10 12 14 16 18 20 22 24 26 28 DISCHARGE, IN CUBIC FEET PER SECOND Figure 17. Results of periodic specific conductance measurements in the Middle Fork Bradley River below North Fork Bradley River, March 1994 through March 1995. SUMMARY AND CONCLUSIONS 31 not be determined from the specific conductance data. Specific conductance is not a factor for determining the effects of lesser flows on salmon incubation habitat in the lower Bradley River. Measurement of fine sediment deposition in the lower Bradley River was beyond the scope of this study. However, field observations, stream discharge, and water-quality data have provided important insight concerning the effects of sedimentation on Bradley River salmon incubation hab- itat. Because fine sediment reduces gravel permeability, which reduces the interchange between surface and intragravel waters, a method to quantify this is to look at the dissolved-oxygen inter- change percentage between surface and intragravel-waters. Interchange percentages are high for all ice conditions and flows noted during this study, but additional data are needed to determine the effects of lesser flows. Pink salmon fry emerge from the spawning gravels in late March and early April. Rapid changes in river stage can leave emerging fry stranded along gravel bars, resulting in mortality. Rapid dewatering of gravel bars can occur from temporary damming of the river during ice breakup, or from rapid changes in flow downstream from reservoir. Stranding potential is increased as the gravel-bar slope decreases. Rate of stage change due to outgoing tide or ice breakup was found to be slow enough to not cause significant stranding of juvenile salmon. Discharge contributions from the North and Middle Forks of the Bradley River show a sea- sonal trend, but not enough data are available for statistical analysis of the trend. Measured dis- charge did not drop below 7 ft 3/s. SUGGESTED FUTURE STUDIES In order to determine the effect of flows of 40 ft3/s or less on salmon incubation habitat, the following could be done: 1. Collect and analyze stream velocity, depth, and wetted perimeter, as well as surface-and intra- gravel-water dissolved oxygen at discharges close to the allowable minimum flow of 40 ft3/s. 2. Study siltation of the spawning bed using approved methods. 3. Measure additional discharge at the Middle Fork Bradley River below North Fork Bradley River to allow valid statistical interpretation of the flow contribution to the lower Bradley River. REFERENCES CITED American Public Health Association, American Water Works Association, and Water Pollution Control Federation, 1989, Standard methods for the examination of water and wastewater (17th ed.): Washington D.C., 1451 p. Baldrige, J.E., and Trihey, E.W., 1982, Potential effects of two alternative hydroelectric developments on the fishery resource of the lower Tazimina River, Alaska: Anchorage, Alaska, Arctic Environmental Information and Data Center, Report for Alaska Power Authority. Becker, C.D., Neitzel, D.A., and Fickeisen, D.H., 1982, Effects of dewatering on Chinook salmon redds-Tolerance of four developmental phases to daily dewatering: Transactions of the American Fisheries Society, v. 111, p. 624-637. Bigelow, B.B., Bailey, B.J., Hiner, M.M., Schellekens, M.F., and Linn, K.R., 1995, Water resources data for Alaska, water year 1994: U.S. Geological Survey Water-Data Report AK-94-1, 289 p. Chapman, D.W., and McLeod, K.P., 1987, Development of criteria for fine sediment in the Northern Rockies ecore- gion: Final report for the U.S. Environmental Protection Agency, Contract No. 68-01-6986, 279 p. 32 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska Coble, D.W., 1961, Influence of water exchange and dissolved oxygen in redds on survival of Steelhead Trout embryos: Transactions of the American Fisheries Society, v. 90, p. 469-474. Fulford, J.M., 1994, User's guide to SAC-A computer program for computing discharge by slope-area method: U.S. Geological Survey Open-File Report 94-360, 30 p. Godin, J.G.J., 1980, Temporal aspects of juvenile pink salmon (Oncorhynchus gorbuscha Walbaum) emergence from simulated gravel redd: Canadian Journal of Zoology, v. 58, p. 735-744. Groot, C., and Margolis, L.,1991, Pacific salmon life history: Vancouver, Canada, UBC Press, 564 p. Hem, J.D., 1985, Study and interpretation of chemical characteristics of natural water (3d ed.): U.S. Geological Survey Water-Supply Paper 2254, 263 p. Hoffman, R.J.,1986, A horizontal intragravel pipe for sampling water quality in salmonid spawning gravel: North American Journal of Fisheries Management, v. 6, p. 445-448. Johnson, R.A., 1980, Oxygen transport in spawning gravels: Canadian Journal of Fisheries and Aquatic Science, v. 37, no. 2, p. 155-162. Linn, K.R., Kemnitz, R.T., Bailey, BJ., Rickman, R.L., and Swanner, W.C., 1994, Water resources data for Alaska, water year 1993: U.S. Geological Survey Water-Data Report AK-93-1, 373 p. Miller, R.L., Bradford, W.L., and Peters, N.E., 1988, Specific conductance-Theoretical considerations, and applica- tions to analytical quality control: U.S. Geological Survey Water-Supply Paper 2311, 16 p. Morrow, J.E., 1980, The freshwater fishes of Alaska: Anchorage, Alaska, Alaska Northwest Publishing Company, 248 p. Morsell, John, 1994, Bradley Lake Hydroelectric Project investigation of winter flow conditions required to support salmon egg incubation: Anchorage, Alaska, Northern Ecological Services, 10 p. Morsell, John, and Howard, R.L., 1995, Final report-Bradley River salmon study program: Anchorage, Alaska, Northern Ecological Services, 59 p. Morsell, John, Howard, R.L., and Bingham, M.M., 1993, Bradley River salmon escapement monitoring and tailrace attraction studies 1993-Final report: Anchorage, Alaska, Northern Ecological Services, prepared for the Alaska Energy Authority, 71 p. Prewitt, C.M., and Whitmus, C., 1986, A technique for quantifying effects of daily flow fluctuations on stranding of juvenile salmonids: Colorado State University Instream Flow Chronicle, v. II, no. 4, 8 p. Rantz, S.E., and others, 1982, Measurement and computation of streamflow-Volume 2. Computation of discharge: U.S. Geological Survey Water-Supply Paper 2175,631 p. Reiser, D.W., and White, R.G., 1981, Influence of streamflow reductions on salmonid embryo development and fry quality: Idaho Water and Energy Resources Research Institute, Report for Office of Water Research and Technol- ogy, Washington, D.C., 154 p. Rickman, R.L., 1993, Hydrologic conditions and low-flow investigations of the Lower Bradley River near Homer, Alaska, October 1991 to February 1992: U.S. Geological Survey Open-File Report 93-95, 17 p. __ 1995, Hydrologic and water-quality data for the lower Bradley River, Alaska, March 1993 to April1994: U.S. Geological Survey Open-File Report 95-338, 30 p. Riggs, H.C., 1972, Low-flow investigations: U.S. Geological Survey Techniques of Water-Resources Investigations, book4, chap. Bl, 18 p. Rundquist, L.A., and Baldrige, J.E., 1990, Fish habitat considerations, in Ryan, W.L., and Crissman, R.D., eds., Cold regions hydrology and hydraulics: American Society of Civil Engineers Monograph, p. 579-613. Rundquist, L.A., Baldrige, J.E., and Joyce, M.R., 1985, Lower Bradley River flow regime and its relation to fish, in Resolving Alaska's water resources conflicts, Proceedings, Alaska Section, American Water Resources Associa- tion: Fairbanks, University of Alaska, Institute of Water Resources Report IWR-1 08, p. 77-88. Schellekens, M.F., Linn, K.R., Bigelow, B.B., Shaw, S.K., and Hiner, M.M., 1996, Water resources data for Alaska, water year 1995: U.S. Geological Survey Water-Data Report AK-95-1, 278 p. REFERENCES CITED 33 Shumway, D.L., Warren, C.E., and Doudoroff, P., 1964, Influence of oxygen concentrations and water movement on the growth of steelhead trout and coho salmon embryos: Transactions of the American Fisheries Society v. 93, p. 342-356. Stevens, H.H., Jr., Ficke, J.F., and Smoot, G.F., 1975, Water temperature-Influential factors, field measurements, and data presentation: U.S. Geological Survey Techniques of Water-Resources Investigations, book 1, chap. Dl, 65 p. U.S. Environmental Protection Agency, 1977, Quality criteria for water, 1976: Washington, D.C., U.S. Government Printing Office, 256 p. Vaux, W.G., 1968, Intragravel flow and interchange of water in a streambed: Fishery Bulletin, v. 66, no. 3, p. 479-489. Wickett, W.P., 1954, The oxygen supply to salmon eggs in spawning beds: Journal of the Fisheries Research Board of Canada,~ ll,no.6,p.933-953. Woods, P.F., 1980, Dissolved oxygen in intragravel water of three tributaries to Redwood Creek, Humboldt County, California: American Water Resources Association, Water Resources Bulletin, v. I 6, no. 1, p. 105-111. Woodward-Clyde Consultants, 1983, Bradley River instream flow studies: Anchorage, Alaska, 75 p. 34 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska APPENDIX 1 Cross-section and velocity distribution of the lower Bradley River: A. At Bear Island B. Near Tidewater C. At Tree Bar Reach D. Below Fish Camp E. At Upper Riffle Reach F. At Lower Riffle Reach APPENDIX 1 A-1 20 1-:::E w:::l WI-1.1..<( 18 ~0 ·>-Za:: Q<( 1-0:: 16 <(f->-wal _,a: w<C 14 0 20 40 0 z 0 3 () w (/) a: w 2 a.. 1-w w 1.1.. ~ > 1- (3 0 0 _, 0 20 40 w > BRADLEY RIVER AT BEAR ISLAND 60 60 CROSS SECTION 80 100 120 140 160 180 200 220 240 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline December 1, 1994, 100 percent ice cover Discharge, 45.5 cubic feet per second VELOCITY DISTRIBUTION 80 100 120 140 160 180 200 220 240 DISTANCE FROM LEFT BANK. IN FEET Date of survey, ice conditions, and discharge December 1, 1994, 100 percent ice cover Discharge 45.5 cubic feet per second Figure A. Cross-section and velocity distribution of the lower Bradley River at Bear Island (see figure 3 for transect location) A-2 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 1-::::E UJ:::> UJI-u..<( ~0 -> Za: Q..c 1-r:I: <CI->-wm _Jr:I: w<C 0 z 20 18 16 14 0 20 40 BRADLEY RIVER AT BEAR ISLAND 60 CROSS SECTION Water surface 17.0 It 'Y 80 100 120 140 160 180 200 220 240 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline January 11 , 1995, 80 percent ice cover Discharge= 62.7 cubic feet per second VELOCITY DISTRIBUTION 8 3.-~-.--~-,--~.-~--.--r-:r-~-.--~-.~--.-~--.-~-.--~-.--~~ w (J) a: ~ 2 1-UJ UJ u.. ~ 1 ~ § oL-~~--~_L~~~~--~~--L-~~~~~--~~~--~~~L_~~--~~ ~ 0 20 40 60 Figure A. Continued. 80 100 120 140 160 180 200 220 240 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge -~ January 11, 1995, 80 percent ice cover Discharge= 62.7 cubic feet per second APPENDIX 1 A-3 20 1-::E UJ:::> WI- L1..<( 18 ~Cl ·>-Za: Q<e 1-0: <(f-16 aJco ...Ja: w<e 14 0 20 40 Cl z 3 0 u w (/) a: w 2 a. 1-w w u.. ~ ~ u g 0 w > 0 20 40 Figure A. Continued. BRADLEY RIVER AT BEAR ISLAND 60 60 CROSS SECTION 80 100 120 140 160 180 200 220 240 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline March 1, 1995, 30 percent ice cover ·Discharge, 53.3 cubic feet per second VELOCITY DISTRIBUTION 80 100 120 140 160 180 200 220 240 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge March 1, 1995, 30 percent ice cover Discharge, 53.3 cubic feet per second A-4 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 20 1-:::;; UJ:::> UJI- u..<( 18 ~0 ->-Za: Q<( 1-CI: <1:1-16 >-UJCD _,a: UJ<I: 14 0 20 40 0 BRADLEY RIVER AT BEAR ISLAND 60 CROSS SECTION 80 100 120 140 160 180 200 220 240 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline April 5, 1995, minor shore ice Discharge, 56.7 cubic feet per second VELOCITY DISTRIBUTION 6 3r-~-.--~-,--~-.--~~--~-r--~-.~~.-~--.--,--~~--r--r--r-~-, () UJ rJ) a: ~ 2 1- UJ UJ u.. z ~ 1- 0 0 -' oL_~_J--~~--~~--~~--~~--~-L~~~~~~~--~~--~~--L-~--' ~ 0 20 40 60 Figure A. Continued. 80 100 120 140 160 180 200 220 240 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge April 5, 1995, minor shore ice Discharge, 56.7 cubic feet per second APPENDIX 1 A-5 22 20 1--:2 w::::> WI- u...<( 18 ~0 .,... Za:; 9< 1--C:: <I-16 ::.-wt:D ....~a: w< 14 12 0 10 20 30 BRADLEY RIVER NEAR TIDEWATER CROSS SECTION Water surface 15.6 It 40 50 60 70 80 90 100 110 DISTANCE FROM LEFT BANK, IN FEET Date of swvey, ice conditions, and discharge June 29, 1993, open-water baseline December 1, 1994, 100 percent ice cover Discharge, 55.2 cubic feet per second o VELOCITY DISTRIBUTION ~ 3~~~~~~~~~~~~~~~rr~~rr~~~~~~~~~~~~~~ () w en a: ~ 2 1--w w u. ~1 > 1--u go~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~ 0 10 20 30 40 50 60 70 80 90 100 110 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge December 1, 1994, 1 OOpercent ice cover Discharge, 55.2 cubic feet per second Figure B. Cross section and velocity distribution of the lower Bradley River near Tidewater (see figure 3 for transect location) A~ Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 22 20 1-:; w:::> WI-LL<( 18 ~Cl ·>-Za: Q<e 1-a: <CI-16 >-wiD _,a: w<C 14 12 0 10 20 30 10 20 30 Figure B. Continued. BRADLEY RIVER NEAR TIDEWATER CROSS SECTION 40 50 60 70 80 90 100 110 DISTANCE FROM LEFT BANK, IN FEET 40 Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline March 1 , 1995, 40 percent ice cover Discharge, 52.5 cubic feet per second VELOCITY DISTRIBUTION 50 60 70 80 90 100 110 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge March 1, 1995, 40 percent ice cover Discharge, 52.5 cubic feet per second APPENDIX 1 A-7 20 14 Figure B. Continued. BRADLEY RIVER NEAR TIDEWATER CROSS SECTION DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline April 5, 1995, no ice Discharge, 57.1 cubic feet per second VELOCITY DISTRIBUTION 90 100 110 Date of survey, ice conditions, and discharge AprilS, 1995, no ice Discharge, 57.1 cubic feet per second A-8 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 22 12 20 40 0 BRADLEY RIVER AT TREE BAR REACH CROSS SECTION 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline November 30, 1994, 100 percent ice cover Discharge, 51.8 cubic feet per second VELOCITY DISTRIBUTION 5 2.0.-~---r--~--,---~--r-~--~--~--~--~~r-~--~--~--~--~~ (.) w (J) a: 1.5 w a. 1- tjj 1.0 u.. ~ ~ 0.5 ~ w oL-~--~--~--~--~--~----~--~--~--~--~~--~--~~~--~~ > 0 20 40 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge November 30, 1994, 1 00 percent ice cover Discharge, 51.8 cubic feet per second Figure C. Cross section and velocity distribution of the lower Bradley River at Tree Bar Reach (see figure 3 for transect location) APPENDIX 1 A-9 BRADLEY RIVER AT TREE BAR REACH CROSS SECTION 22 Water surface 13.20 ft. 12 10~--~~--~--~--~--~--~--~--~---L--~---L--~---L--~--~--~~ 0 20 40 0 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline February 28, 1995, 1 00 percent ice cover Discharge, 56.5 cubic feet per second VELOCITY DISTRIBUTION 53.------,,---,--,--~---.--~--~-------.---.--~--~--~------------~ u UJ (/) a: ~ 2 ..... UJ w u.. ~ 1 ~ i3 0 m oL---~--~--~~L-~--~--~--~-L~---L~~L_-L~~--~--~~~--~--- > 0 20 40 60 80 100 120 140 160 180 Figure C. Continued. DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge February 28, 1995, 1 00 percent ice cover Discharge, 56.5 cubic feet per second A-10 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska BRADLEY RIVER AT TREE BAR REACH CROSS SECTION 22 Water surface 13.21 ft. 12 1oL-~---L--~--~--~--L---~~--~---L--~--~--~--L-~--~--~--~ 0 20 40 20 40 Figure C. Continued. 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET 60 Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline April 4, 1995, minor shore ice Discharge, 55.3 cubic feet per second VELOCITY DISTRIBUTION 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge April 4, 1995, minor shore ice Discharge, 55.3 cubic feet per second APPENDIX 1 A·11 BRADLEY RIVER BELOW FISH CAMP CROSS SECTION Water surface 12.80 ft. 10L---~--L---~--~--~--~--~--~--~---L--~---L--~--~--~--~ Cl z 0 (.) w UJ a: w "- 1-w w IJ.. ~ ~ 0 0 2 0 20 40 60 80 100 120 140 160 DISTANCE FROM LEFT BANK. IN FEET Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline November 29, 1994, 100 percent ice cover Discharge, 48.4 cubic feet per second VELOCITY DISTRIBUTION ~ OL---~--L---~--~--~--~--~--~--~---L--~---L--~--~--~--~ > 0 20 40 60 80 100 120 140 160 DISTANCE FROM LEFT BANK. IN FEET Date of survey, ice conditions, and discharge November 29, 1994, 1 00 percent ice cover Discharge, 48.4 cubic feet per second Figure D. Cross section and velocity distribution of the lower Bradley River below Fish Camp (see figure 3 for transect location) A·12 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska BRADLEY RIVER BELOW FISH CAMP CROSS SECTION Water surface 13.9 fl. 10~--~--~--~---L--~--~--~--~~--~--L---._--~--~---L--~--~ 0 20 40 Figure D. Continued. 60 80 100 120 140 160 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline January 12, 1995, 100 percent ice cover Discharge, 42.6 cubic feet per second VELOCITY OISTRIBUTION 100 120 160 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge January 12, 1995, 100 percent ice cover Discharge, 42.6 cubic teet per second APPENDIX 1 A-13 20 0 BRADLEY RIVER BELOW FISH CAMP 40 CROSS SECTION 60 80 100 120 140 160 DISTANCE FROM LEFT BANK. IN FEET Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline March 1 , 1995, 100 percent ice cover Discharge, 47.5 cubic feet per second VELOCITY DISTRIBUTION 5 3,---~--~--~---.--~---.-------,--~----r---~--~--~--,----.--~ frl I/) a: !!: 2 1- I.Ll UJ lJ._ z >-" 1-u 0 ~ 0~--~--~~U----L--~--~--~--~~--~--L---~--~--~---L--~--_j > 0 20 40 Figure D. Continued. 60 80 100 120 140 160 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge March 1, 1995, 100 percent ice cover Discharge, 47.5 cubic feet per second A-14 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 20 I-::;; 18 w::> WI- LL-<( ;!;c 16 ·> Za: Q<( 1-a: 14 <(j->-weD _,a: w<C 12 10 0 20 20 Figure D. Continued. BRADLEY RIVER BELOW FISH CAMP 40 40 CROSS SECTION 60 80 100 120 140 160 DISTANCE FROM LEFT BANK, IN FEET 60 Date of survey, ice conditions, and discharge June 29, 1993, open-water baseline April 5, 1995, minor shore ice Discharge, 57.9 cubic feet per second VELOCITY DISTRIBUTION 80 100 120 140 160 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge April 5, 1995, minor shore ice Discharge, 57.9 cubic feet per second APPENDIX 1 A-15 1-::::; UJ::> UJI-u..<( ~Cl ">-Zc:: Q<( 1-C:: <(I->-UJCD _,c:: UJ<( Cl 18 16 14 12 BRADLEY RIVER AT UPPER RIFFLE REACH CROSS SECTION DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 30, 1993, open-water baseline December 1, 1994, 1 00 percent ice cover Discharge, 47.1 cubic feet per second VELOCITY DISTRIBUTION ~ 3.-~---,--~---,--~--,---~--.-~---,--~--,---~--.---~--.-~---. (.) UJ (/) c:: lf 2 1- UJ UJ u.. ~ 1 ~ 0 0 ~ oL-~--~--~---L--~--~--~--L-~--~--~---L~W---~--~--u_~--~ > 0 20 40 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge December 1 , 1994, 1 00 percent ice cover Discharge, 47.1 cubic feet per second Figure E. Cross section and velocity distribution of the lower Bradley River at Upper Riffle Reach (see figure 3 for transect location) A-16 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska BRADLEY RIVER AT UPPER RIFFLE REACH CROSS SECTION 20 1-:::;;; LU::> LUI- IJ..<( ~0 15 Water surface 13.0 ft. -> Zc:: Q.:r: 1-C:: <(I-10 [ijffi ....Jc:: w< 5 0 20 0 40 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 30, 1993, open-water baseline January 12, 1995, 100 percent ice cover Discharge, 50.5 cubic feet per second VELOCITY DISTRIBUTION 5 3,-~-----,----~--.---~--.---r--,,-~-----.--~--.---.---r---~-,---,--. (.) w (/) c:: ~ 2 1-w LU IJ.. ~ 1 ~ § t_--~==~~~~L-~~~--~---L--~--~--~~--~--~--~~~--~_j w 0 > 0 20 40 Figure E. Continued. 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge January 12, 1995, 100 percent ice cover Discharge, 50.5 cubic feet per second APPENDIX 1 A-17 18 t-:::= w:::> wt-16 LL.<( ~0 ·>-Za: 14 g<( t-a: <(t->-wiD 12 -'a: w<( 10 0 20 40 0 BRADLEY RIVER AT UPPER RIFFLE REACH CROSS SECTION 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 30, 1993, open-water baseline VELOCITY DISTRIBUTION March 1, 1995, 1 00 percent ice cover Discharge, 47.5 cubic feet per second 6 3 r---r--,---,---,--~---.--~--~--~---.--~--~--~--~--~--~--~~ (.) w (/) a: ~ 2 t-w w LL. ~ ~ l5 9 w oL---~--'L-~--~--~--~~~--~--~--~--~--~-L~---'---~---'L--~~ > 0 20 40 Figure E. Continued. 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge March 1, 1995, 100 percent ice cover Discharge, 47.5 cubic feet per second A-18 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska 18 t-:: w::::> 16 WI-u..<( ~0 ·>-Za:: 14 Q<( t-a:: <(!->-12 wa:l _,a: w<( 10 0 20 40 20 40 Figure E. Continued. BRADLEY RIVER AT UPPER RIFFLE REACH CROSS SECTION 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 30, 1993, open-water baseline April 5,1995, some ice debris in left channel Discharge, 56.9 cubic feet per second VELOCITY DISTRIBUTION 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge AprilS, 1995, some ice debris in left channel Discharge, 56.9 cubic feet per second APPENDIX 1 A-19 BRADLEY RIVER AT LOWER RIFFLE REACH CROSS SECTION 14 ( Water surface 11.9 ft. 10 8~~---L--~--~----~--~--~--~~--~---L--~--L-~---L--~~ 0 20 40 Cl 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 30, 1993, open-water baseline November 30, 1994, 100 percent ice cover Discharge, 46.8 cubic feet per second VELOCITY DISTRIBUTION 53~~--~--~--~----~--~--~--~~--~--~--~--------~--~~ u w (/) a: ~ 2 f-w w lL ~ 1 ~ l3 0 m oL-~---L--~--~--~~--~---L--~~~~---L-L~--L-~-L-L--~~ > 0 20 40 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge November 30, 1994, 1 00 percent ice cover Discharge, 46.8 cubic feet per second Figure F. Cross section and velocity distribution of the Lower Bradley River at Lower Riffle Reach (see figure 3 for transect location) A-20 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska BRADLEY RIVER AT LOWER RIFFLE REACH CROSS SECTION 14 Warer surface 12.8 ft. 10 8L_~~~--~---L--~--~--~--L-~--~--~--~--~--~--~~--~--~ 0 20 40 20 40 Figure F. Continued. 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET 60 Date of survey, ice conditions, and discharge June 30, 1993, open-water baseline January 12, 1995, 100 percent ice cover Discharge, 61.4 cubic feet per second VELOCITY DISTRIBUTION 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge January 12, 1995, 100 percent ice cover Discharge, 61.4 cubic feet per second APPENDIX 1 A-21 BRADLEY RIVER AT LOWER RIFFLE REACH CROSS SECTION 14 1-:::E UJ::::> UJI-LL<( ~Cl ( ·>-Za:: 12 Q<( t-0:: <(t->-UJ!Xl ..Ja:: w< 10 8~--~~--~--~--~--..J_--~--L---~~--~---L--~--~--~--L_~ __ _j 0 20 40 Figure F. Continued. 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 30, 1993, open-water baseline March 1, 1995, 100 percent ice cover Discharge, 47.8 cubic feet per second VELOCITY DISTRIBUTION DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge March 1, 1995, 100 percent ice cover Discharge, 47.8 cubic feet per second A-22 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska BRADLEY RIVER AT LOWER RIFFLE REACH CROSS SECTION 16 ( 14 1-:::i: w::l WI-u..< ~Cl -> Za:: 12 Q< 1-C:: <I->-will _.a: w< 10 a~~--~--~--~--~--~--~~--~--~--~--~--~--~~~~--~--~ 0 20 40 60 80 100 120 140 160 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge June 30, 1993, open-water baseline AprilS, 1995, no ice Discharge, 53.8 cubic feet per second VELOCITY DISTRIBUTION Cl 53.-~---.--~--,---~--.---~-.--~---.--~--~--~--.-~---.--~--. (.) w {/) a: ~ 2 1- I.U w u._ 20 Figure F. Continued. 40 60 80 100 120 140 16() 180 DISTANCE FROM LEFT BANK, IN FEET Date of survey, ice conditions, and discharge April 5, 1995, no ice. Discharge, 53.8 cubic feet per second APPENDIX 1 A-23 A-24 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska APPENDIX 2 Table AI. Selected hydraulic properties for the lower Bradley River, November 1994 to April1995 Table A2. Selected water-quality data and site characteristics for the lower Bradley River, November 1994 to April1995 APPENDIX 2 A·25 A-26 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska Table A 1. Selected hydraulic properties for the lower Bradley River, November 1994 to April 1995. [ft. foot; ft2, square foot; ft/s; foot per second; ft 3/s, cubic foot per second;<, less than;>, more than] Ice Discharge Mean Mean Wetted Hydraulic Transect site Date cover Discharge velocity depth Top width Area perimeter radius (fig. 3) (per-(tt3/s) accuracy (ft) (tt2) cent) (percent) (ftls) (ft) (ft) (ft) Bear Island 12-01-94 100 45.5 >8 0.66 0.80 93.0 74.6 93.9 0.79 01-11-95 80 62.7 8 0.49 1.22 105 129 106 1.23 03-01-95 30 53.0 8 0.98 0.67 81.0 54.3 81.3 0.70 04-05-95 <10 56.7 5 0.91 0.72 85.8 62.2 86.5 0.70 Tidewater 12-01-94 100 55.2 >8 0.76 1.74 41.5 72.2 43.3 1.67 01-12-95 90 (a) 03-01-95 100 52.5 8 1.11 1.25 38.0 47.4 38.6 1.23 04-05-95 0 57.1 8 1.13 1.26 40.0 50.4 40.5 1.24 Tree Bar 11-30-94 100 51.8 >8 1.19 0.93 59.0 55.0 60.1 0.92 Reach 01-12-95 90 (a) 02-28-95 100 56.5 8 0.97 0.84 69.0 58.0 69.9 0.85 04-04-95 <10 55.3 5 1.24 0.65 69.0 44.5 69.2 0.64 Below Fish 11-29-94 100 48.4 >8 0.67 1.22 59.7 72.7 60.1 1.21 Camp 01-12-95 100 42.6 >8 0.34 1.95 64.0 125 64.5 1.94 03-01-95 100 47.5 b>8 0.79 0.98 61.0 60.1 61.3 0.99 04-04-95 <10 57.9 8 0.81 1.23 58.0 71.5 58.3 1.23 Upper Riffle 12-01-94 100 47.1 b>8 0.72 0.79 77.6 61.4 80.3 0.76 Reach 01-12-95 100 50.5 >8 0.33 1.43 116 166 118 1.41 03-01-95 100 47.5 8 0.81 0.69 84.5 58.3 85.9 0.69 04-05-95 <15 56.9 5 0.70 1.00 82.0 81.8 82.8 0.99 Lower Riffle 11-30-94 100 46.8 >8 1.00 0.55 84.0 46.9 86.4 0.55 Reach 01-12-95 100 61.4 8 0.42 1.69 86.0 145 88.7 1.63 03-01-95 100 47.8 8 1.14 0.59 71.0 42.0 72.5 0.59 04-05-95 0 53.8 5 1.14 0.57 82.0 47.0 82.3 0.57 aunable to measure all properties because of thin ice and deep water. bMeasurements may be tide affected. APPENDIX 2 A-27 A-28 Effect of Ice Formation and Streamflow on Salmon Incubation Habitat in the Lower Bradley River, Alaska Table A2. Selected water-quality data and site characteristics for the lower Bradley River, November 1994 to April1995. [rrun Hg, millimeter of mercury; °C, degree Celsius; mgll.., milligram per liter; j.lS/cm, microsiemen per centimeter; ft, foot: ft/s, foot per second; --no data] Transect site Date (fig. 3) Bear Island 12-01-94 01-11-95 03-01-95 04-05-95 Tidewater 12-01-94 01-12-95 03-01-95 04-05-95 Tree Bar 11-30-94 Reach 01-12-95 03-01-95 04-05-95 Below Fish 12-01-94 Camp 01-12-95 03-01-95 04-05-95 Upper Riffle 12-01-94 Reach 01-12-95 03-01-95 04-05-95 Lower Riffle 11-30-94 Reach 01-12-95 03-01-95 04-05-95 Baro· metric pressure (mm Hg) 775 759 780 752 775 762 778 754 770 762 780 754 774 762 781 754 776 762 782 752 767 762 782 752 Surface water Temper· Dissolved ature (OC) 0.0 0.0 0.5 1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.5 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0 oxygen (mg/l) 14.8 14.4 14.4 14.1 14.8 14.3 14.4 14.0 14.7 14.8 14.4 13.9 15.0 14.8 14.5 14.0 14.6 14.7 14.2 13.0 14.7 14.5 14.4 13.8 Dissolved oxygen percent saturation 100 99 98 100 100 98 96 99 99 101 96 99 101 101 97 100 98 101 95 99 100 99 96 98 Specific conduct- ance (j.tS/cm) 70 75 62 64 69 68 62 74 69 62 63 70 69 62 70 71 64 65 76 71 64 64 lntragravel water Temper- ature (OC) 1.0 1.0 1.5 Dissol- ved oxygen (mg/L) 13.3 12.1 14.1 12.4 11.4 13.0 12.4 13.4 13.0 12.5 12.8 13.2 12.5 10.7 11.4 13.9 12.2 10.1 12.5 13.3 10.8 Dissolved oxygen percent saturation 90 87 89 lntragravel sample location Depth of water above streambed (ft) 0.80 0.80 0.45 1.10 0.4 1.6 <1.2 0.96 0.4 0.4 1.22 0.80 0.70 0.65 1.00 0.90 0.80 0.15 <1.2 Surface- water velocity (ftls) 0.6 0.0 0.3 0.6 0.2 1.0 1.2 0.6 0.5 0.9 0.4 0.2 0.1 0.1 1.2 <0.6 0.5 <2.0 APPENDIX 2 A·29