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SUMMARY OF BOTANICAL RESOURCES SECTION
EXHIBIT E, CHAPTER 3 OF THE
SUSITNA HYDROELECTRIC PROJECT
FERC LICENSE APPLICATION
BASELINE DESCRI~
Threatened or Endangered Plants
The Susitna River watershed upstream from Gold C~eek was surveyed at
selected habitat sites for plant taxa under consideration for threatened or
endangered status. Access routes, borrow areas, and the intertie corridor
were also surveyed for the presence of these taxa. No candidate threatened
or endangered plants were found. Further endangered pl~nt surveys will be
made in the Healy-to-Fairbanks and Willow-to-Anchorage tt"ansmission
corridors during the detailed design phase of project development.
Plant Communities
A diversity of plant communities occurs within the areas potentially
affected by the project. The types of plant communities encountered and
their areal coverage within a 20 mile (32km) wide area spanning the Susitna
River between Gold Creek and the Maclaren River, include: Coniferous fo.rest
_(351, 640 a.c), .consisting of woodland, open and closed spruce (black and
white spruce); mixed open and closed conifer-deciduous (56,500 ac);
deciduous .forest (10, 860 ac), consisting of open an4 closed birch, and
""" closed balsam poplar vegetation types; tundra (283,490 ac), consisting of
wet sedge-grass, sedge scrub, herbaceous alpine, and mat and cushion
vegetation types; shrubland (438,020 ac) consisting of open and closed tall
shrub, and birch, willow, and mixed low shrub vegetation types; herbaceous
(44 e.c), and grassland (2, 670 ac) communities.
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Wetlands
Wetlands within the Susitna project area primarily include locations within
riparian zones, ponds and lakes and adjacent areas on upland plateaus, wet
black spruce woodland, and wet tundra. Concentrations of wetlands occur in
the vicinity of upper Brushkana Creek and Tsusena Creek, the area between
lower Deadman Creek and Tsusena Creek, the Fog Lakes are~ the Stephan Lake
area, Swimming Bear Lake, Jack Long Creek, in and near the many lakes of the
Watan& watershed, and along the transmission line corridors betw;tt Willow
and Knik Arm and in the Tanana Flats area. e
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IMPACTS
This section summarizes botanical resource impacts that are of sufficient
magnitude to influence mitigation planning. Imp~cts are grouped into one of
three categories (direct loss; indirect loss; and alteration of
communities}, based on resource vulnerability, the probability of the impact
occurring; and the duration of the impact. Direct losses of vegetation are
judged most important because of the certainty and permanence of the impact.
Plant community alterations are judged to be less important than vegetation
losses. These impacts are less predictable and often of shorter duration
than vegetation losses.
Direct Loss of Vegetation
Direct losses for the Watana project include 31,300 acres (12,667 ha) of
vegetation for the dam, impoundment, and spillway. An additional 4300 acres
(1742 ha) have been designated for use as camp, village, airstrip, and
borrow areas. These potential losses account for 1 percent of all
vegetation in the middle Susitna basin, and 3 .. 6 percent of the vegetation
present in a 20 mile (32 km) wide area spanning the Susitna River from the
mouth of the Maclaren River to Gold Creek. M~re importantly, substantial
losses of certain vegetation types will be sustained during construction of
the Watana Dam. Losses of forested areas may total 8.3 percent of the 20
mile (32 km) wide area. Losses of open and closed birch forest will be
greater than 20 percent for the 20 mile (32 km) wide area.
Direct losses for the Devil Canyon project will include 5871 acres (2376 ha)
of forests, tundra and shrubland. Negligible amounts of tundra and
shrubland (less than .05 percent) will be lost, but 0.7 percent of all
forested lands in the middle basin (1.8 percent of the 20 mile (32 km) wide
area) will be affected.. Because of the steepness of Devil Canyon, these
losses are 1:elatively smal~compared to the Watana site and are
comparatively less. importanf for wildlife. However, 18.6 percent of the
closed birch forest within the 20 mile (32 km) area will be eliminated.
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The ~atana access road will result in a loss of approximately 568 acres (230
ha) of ~ixe1rtundra vegetation types. Additional losses of about 494 acres
(200 ha) for access roads and 193 acres (78 ha) for rail will be produced by
the Devil Canyon facility. Direct losses within transmission corridors will
occur from construction of access tails, tower sites, and substations.
Indirect Loss of Vegetation
Additional losses of vegetation may 9Bcur due to erosion 3 permafrost melting
and subsequent land slides and slumpage, ORV use, blowdown of trees, and
other causes. While some of these losses will be short-term with typical
vegetation succession ensuing, or with shifts to new vegetation types for
that area, long-term vegetational losses enduring for 30 to more than 100
years may occur on sites of continual erosion, land slumpage, or ORV use.
The amounts that will be lost because of these factors are small compared to
amounts inundated by the reservoirs.
Indirect losses of vegetation are projected to be greatest at the Watana
site, where large areas on the south side of the impoundment are underlain
by 200 to 300 feet (60 to 90 m) of permafrost at near melting temperature.
Also, because of the large size of the reservoir, other erosional processes
such as wind erosion 1, together with effects of dust, may cause very
localized vegetation loss, especially in wind-exposed areas. The smaller,
steeper nature of Devil Canyon will limit indirect losses of vegetation.
Except for the possibility of one massive flow near River Mile 175, rock
slides occurring above the impoundment represent the greatest threats
and these will result in only small scale loases.
Some indirect loss of vegetation is expected due to erosion caused by
changes in drainaage pat.terns and dust deposition along the access road
edges. Increased utlilization by ORVs along access roads and road
maintenance may damage adjacent are~ Little indirect loss in transmission
line corridors is likely as a result of clearing or construction, but
uncontrolled ORV access could affect vegetation on and adjacent to
corridors.
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Alteration of Vegetation Types
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Alteration of.vegetation types will be caused by changes in drainage
patterns, altered river flows, and fires In many instances, nat~ral
succession of cleared or disturbed areas not subject to inunde,;.:ion, will
result in vegetation type cl~anges. For example, primary he{aceous and weedy
vegetation and secondary shrub growth may follow clearing of sites. There
may be development of algal species and aquatic vegetation in shallow areas
of the impoundments.
The most important change to existing conditions that will result from the
Watana and Devil Canyon dams will be in the downstream floodplain between
Gold Creek and Talkeetna, where annual spring and summer flooding and scour
by ice jams will be reduced. As a result, some of the previously pulse-
stabilized communities will matureo The willow and balsam poplar shrub will
eventually change to mature balsam poplar and then to spruce. Within the
license period, new vegetation on the newly exposed banks and island will
develop into medium and tall Slhurubs.
Potentially ~ignificant impacts may occur to the vegetation surrounding the
Watana Reservoir. Disturbance may cause warming of the soil, melting of the
permafrost, and deepening of the active layer. In well-drained areas, this
may result in increased growth. and productivity by the existing ~lant
community, but in waterlogged areas a shift to bog vegetation is likely. If
the organic layer is lost during disturbance, long term losses of
vegetation may result. Most forest and shrub areas disturbed near the
reservoir will recover naturally. The ensuing patterns of vegetational
succession will be enhanced if the organic layer is retained, and if root
suckers or seed of vegetation remain.
Outside the actual impoundment and dam site, very few alterations of
vegetation types are anticipated at Devil Canyon. Forest types will be
subject to minor alterations, primarily near borrow sites G and K, and near
camp and village sites. Likewise, changes in drainage, waterlogging of soil
60751/SUM 5
• or permafrost melting, will be highly localized because the soil is
general~y vtry rocky and well drained, with only sporadic occurrences of
permafrost.. The smaller., steeper character of Devil Canyon will also act to
limit microclimatic and meeoclimatic alterations.
The access roads between the Devil Canyon and Watana sites, and between
Watana and the Denali Highway, as well as rail construction between Devil
Canyon and Gold Creek, will alter surface drainage patterns and may induce
dust-related alterations in vegetation at roadsides. Selective clearing or
top-cutting of tall vegetation for transmission line corridors will result
in loc.al shifts in plant: types from trees to shrubs. Wet and moist tundra
areas and their periphari~s will be more susceptible to water logging due to
vehicular traffic, with s~tsequent development of bog species and/or black
spruce in place of cottongrass and shrub species.
Mitigation Summarx
Mitigation plans for botanical ~esources have been developed primarily to
support the wildlife mitigation program. Listed below is a brief synopsis
of the mitigation plan elements:
1. Minimize facility dimensions.
2. Consolidate stru~tures.
3. Site facilities in areas of low biomass.
4. Site facilities to ~inimize clearing 9f less abundant vegetation
types~
5. Site facilities to minimize clearing of vegetation types
productive as wildlife habitat components.
6. Minimize volume requirements for borrow extraction.
7. Dispose of spoil within the impoundments or previously excavated
8.
607~1/SUM
areas.
Design transmission corridors to allow selective cutting of trees
and to accomodate uncleared low shrub and tundra vegetation within
rights-of-way.
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9. Dismantle nonessential structures as soon as they are vacated.
lOo ~elop a comprehensive site rehabilitation plan.
11. Monitor progress of rehabilitation to identify locations requiring
further attention.
12. Acquire replacement lands for implementation of ha~itat
enhancement measures.
13. Plan and develop an environmental bt.iefings program for all field
personnel.
14. Avoid the Prairie Creek, Stephan Lake, Fog l,akes, and Indian River
areas by access routing.
15. Restrict public access du·ring construction by gating the access
road.
16. Use signs and possibly establish regulatory designation and
measures to discourage use of ORVs and ATVs.
17. Phase implementation of the project Recreation Plan with
interagency review and concurrence.
18. Site and align all facilities to avoid wetlands to the maximum
extent feasible.
19. Involve agency coordination and participation in detailed
engineering design and construction planning of civil engineering
measures to minimize potential wetlands impacts.
20. Conduct high-resolution mapping of wetland vegetation within the
project area, in coordination with COE and USFWS representatives
(scheduled for 1983) •
60751/SUM 7