E. Limiting Watershed Processes and Habitat Features
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This section includes descriptions of:
- NOPLE Watershed Pages
- general salmon needs
- priority watershed processes
- priority limiting habitat features.
Watershed Pages
Whereas determining the priority
stocks and prioritizing the watersheds
into tiers are accomplished by the NOPLE
LEG and TRG, determining
a restoration strategy within each watershed is accomplished by the relevant Watershed
Stakeholders as only they have
the watershed-specific expertise. These stakeholders use the latest and
most relevant Documentation
(Appendix E) available on the watershed and its stocks, and the prioritization
process described in the SRFB
Guide to Strategy Development to determine
the priority watershed processes and habitat
factors that limit the priority stocks within that watershed, and to
devise a watershed-specific
list of priority actions and areas to recover them. This process is
reflected in each respective "Watershed
Page" (Appendix D).
NOPLE-general Salmon
Needs
Although there remains some debate on specific habitat thresholds necessary
for productive salmon habitat, there is broad consensus that salmon require:
- cool, clean, well-oxygenated
water,
- instream flows that mimic the
natural hydrology of the watershed, maintaining adequate flows during
low flow periods and minimizing the frequency and magnitude of peak
flows (stormwater),
- clean spawning gravels not clogged
with fine sediment or toxic materials,
- presence of instream pools that
will support juvenile rearing and resting areas for returning adults,
- abundance of instream large
woody debris, particularly large key pieces, that provide cover,
create pools, and provide habitat diversity,
- free, unobstructed migration
for juveniles and adults to and from the stream of origin,
- broad, dense riparian stands
of mature conifer that provides cover, shade, LWD recruitment, etc.,
and
- estuarine conditions that support
production of prey organisms for juvenile outmigrants as well as
for rearing and returning adults.
Priority habitat processes
The NOPLE-wide priority watershed processes that affect salmon habitat
include
- hydrologic regime,
- sediment supply,
- riparian processes,
- organic matter flow,
- heat and light inputs,
- nutrient and chemical inputs.
Over the past 150 years, hatchery, harvest, agricultural and forestry
practices, urbanization, dams (hydroelectric and diversion), and various
port and shipping activities have impacted salmon, their habitat and
the associated watershed processes to varying degrees. While specific
habitat concerns differ between the 90 independent watersheds within
the NOPLE area, there are some common habitat/watershed processes themes,
including:
- Loss of functioning floodplain results in loss of sediment sink and narrowed flood width, resulting in Increased main channel sediment transport, accelerated incision and bank erosion, increased downstream sedimentation, loss of dynamic geomorphic processes that sustain dynamic riparian succession, complexity and diversity.
- Excessive sediment inputs occurring from roads, land management practices, old railroad grades and mass wasting sites results in increased downstream sedimentation resulting in increased mortality (from eggs to adults), reduced reproductive success, induced physiological stress, reduced feeding rates (increased weight loss), reduced ability to detect prey, reduced availability of prey, increased parasitism, simplification of community structure, and hypertrophy/necrosis of gill epitheliums.
- Substrate instability has resulted
in decrease of fine sediment (<0.85 mm) levels in the stream gravels
to less than the 12% level identified as representing suitable spawning
habitat.
- Historic removal of large woody
debris as well as loss of old growth riparian vegetation has resulted
in lack of adequate large woody debris in streams, particularly larger
key pieces that are critical to developing pools, log jams, and other
habitat components important to salmonids.
- Lack of large woody debris has
resulted in loss of deep pools, needed by rearing juvenile salmonids
and adult salmonids on their upstream migration.
- Loss of riparian function due
to removal/alteration of natural riparian vegetation (including infestations
of noxious weeds), has resulted in reduced water quality, increased
lateral erosion, streambank instability, loss of instream habitat
conditions, and the like.
- The placement of a significant
number of culverts/screens/dams/etc. has restricted upstream and
downstream access to juvenile and adult salmonids.
- Upland rain on snow as exacerbated
by deforestation
- Permitted and perfected water
withdrawals have resulted in loss of in-channel, and access to off-channel
habitat
- Removal of natural riparian
vegetation has resulted in increased temperatures due to loss of
shade.
- Decreased numbers of spawned
out salmon have reduced nutrient loading
- Physical alterations and armoring
of estuaries and shoreline have
The NOPLE-wide Priority Limiting Habitat Featuers include:
Geographic Area |
Priority Processes and Limiting Factors |
WRIA 18 watersheds
|
Priority Processes and Limiting Factors include Elwha River
Dungeness River
Other WRIA 18 streams
|
Neashore WRIA 18 and 19 nearshore (Strait Coast) |
From Agate Bay to Clallam County line (WRIA 18) Priority Nearshore Processes include
Priority Limiting Factors include
From Cape Flattery to Agate Bay (WRIA 19), Priority Nearshore Processes include
Priority Limiting Factors include
|
WRIA 19 watersheds |
Priority Processes and Limiting Factors include
|
WRIA 20 watersheds |
Priority Processes and Limiting Factors include
|
Nearshore WRIA 20 (Pacific Coast) |
Priority Nearshore Processes include
Priority Limiting Factors include
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