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Watershed AssessmentLower Snake River Compensation Plan 1976. Describes fish populations and their distributions and sets mitigation levels for fish and fishery losses caused by the four lower Snake River dams. Bennett et al. 1983 - UI reservoir fishery evaluations describe fish distribution, abundance, and harvest levels for fish in the Snake River mainstem. COE Draft Environmental Impact Statement (DEIS) Lower Snake River Juvenile Salmon Migration Feasibility Report. 1999. Describes four alternatives to try and improve juvenile survival for salmon and steelhead passing the Snake River dams. For more information about the environment see EISs for construction of Snake River dams and Biological Assessments for projects at those dams. A cursory assessment of fish distribution, relative abundance and stream habitat conditions was conducted in Alpowa Creek in 1981 (Mendel and Taylor) and in 1998 (Mendel 1999). None of the other small tributaries have been surveyed in the past several decades. Parkhurst, Z. Survey of the Columbia River and its tributaries. 1950. Part 6. Fish and Wildlife Service (FWS), Spec. Sci. Rep. Fish. 39p. Assessed the fish value of tributaries of the Snake River. Fulton, L. 1970. Compiled the available information on spawning and rearing distribution and abundance of steelhead and salmon in the Columbia R. Basin. Fishery Steering Committee of the Columbia Basin Interagency Committee. 1957. Inventory of streams and proposed improvements of the fishery resources of the upper Columbia River Basin. Mains and Smith. 1955. Determination of the normal stream distribution, size, time and current preferences of downstream migrating salmon and steelhead trout in the Columbia and Snake Rivers. Pirtle, R. 1957. Final Report to the US Army Corps of Engineers (USACE). Enumeration Study upper Columbia and Snake Rivers. IDFG. This report describes timing and size of adult runs of salmon and steelhead in the Snake River. There have been no official watershed assessments completed in the Alpowa or Deadman watersheds or any of the other minor watersheds. A draft watershed characterization was completed by the Center for Environmental Education of WSU in 1999 and much of that information is contained in this summary for the Alpowa Watershed to be included in the Lower Snake Subbasin Summary. Limiting FactorsResident FishReservoirs (Corps 1999)Water TemperatureOne of the key environmental variables that will serve as a limiting factor in the ability of the members of the resident fish community to successfully adapt to new riverine or impoundment conditions is water temperature. The seasonal Snake River hydrograph typically experiences peak flows in May and/or June from spring rains and snowmelt. Dry or wet springs or accelerated or delayed snow melt create highly variable inter-annual spring runoff, which in turn plays a major role in the overall timing of the water temperature regime and the summer thermal maxima experienced by lower Snake River fish. High temporal variability in water temperature may have a profound effect on the spawning success of lower Snake River resident fish. The ranges of spawning temperatures and time frames for the resident are summarized in Table 43. Site-specific Snake River spawning temperatures are provided for 13 species, largely from the work of Bennett et al. (1983). White sturgeon spawning temperatures were those reported for the Lower Columbia River by Parsley et al. (1993). Spawning temperatures for the remaining species were derived from several literature sources. Sculpins, white sturgeon, and bridgelip sucker are the earliest spawning native species. Yellow perch generally spawn earliest among the introduced fish, in very early spring at 7 to 8°C (44 to 46°F). However, most non-native Snake River fish such as bass, sunfish, crappie, and, particularly, catfish spawn much later, usually at least after water temperatures have attained 15 to 18°C (59 to 64°F). Water temperatures were monitored in Lower Granite Reservoir by recording thermographs for several years (Bennett et al. 1997; Connor et al. 1998). These data represent at least the lower two-thirds of the reservoir (Connor et al. 1998). For the 3 years depicted, 1994 represents a dry or low flow year, 1995 an "average" flow year, and 1997 a wet or high flow year. These data show typical seasonal water temperatures and trends experienced by lower Snake River resident fish. A major source of variability imposed on the spring-summer temperature regime experienced by resident fish in reproductive mode is the apparent cooling effect of augmentation flows released from upstream reservoirs (e.g., Dworshak Reservoir) to enhance juvenile salmonid smolt outmigration. Three episodes of rapidly declining water temperatures are evident in mid-May, mid-June, and nearly the entire month of July into August. Two similar episodes occurred in June 1995. The release of upstream storage for flow augmentation, primarily to speed passage of salmonid smolts through reservoirs, can affect the spawning and growth of resident fish in several ways. The attainment of a suitable temperature to initiate spawning can be delayed substantially. If the delay were prolonged, as may have occurred in 1994, the effect on year-class production and/or growth due to persistent, lower-than-optimal temperatures can be severe (Bennett et al. 1991). Delayed spawning followed by a short growing season may yield young-of-the-year too small to survive over-wintering. Spawning also can be interrupted, potentially several, by the steep temperature declines that can accompany release of augmentation flows, particularly during releases from Dworshak Reservoir. Such releases pose an additional stress on introduced resident fish that may already be exposed to sub-optimal thermal regimes in the Pacific Northwest (e.g., smallmouth bass-Bennett et al. 1991). The delay attaining certain critical spawning temperatures in some years can be substantial. For example, 18°C (64.4°F) is a critical temperature for initiation or continuation of spawning activities for many of the introduced sunfish and catfish. However, the date when 18°C (64.4°F) is attained can vary as much as 50 days from late May (1992) to mid-July (1993; Bennett et al. 1998). In addition, the attainment of peak summer temperatures may vary by a comparable time period. For example, the highest summer water temperature reached in Lower Granite Reservoir in 1995 was 20.4°C (68.8°F) on July 23, compared to a peak of 22.2°C (72°F) on September 5 in 1997, a difference of 44 days. Table 43. Spawning temperatures of Snake River fish.
The effects of accelerated, delayed, or depressed spawning temperatures may be dramatic, but very difficult to isolate. Successful early spawning of some species may create a year-class with greater than average first-year growth, a recruitment advantage that may remain with that year class throughout its life. Conversely, delayed spawning may limit the growth of first-year fish, possibly to the extent that over-winter survival is poor, and the year-class may be virtually absent from the population as advanced juveniles or adults. While the above implications were evaluated for Snake River smallmouth bass (Bennett et al. 1991), similar effects on other resident, introduced fish not studied in such detail are likely. Further, for some species with relatively high spawning temperature requirements such as catfish, late warming may preclude attainment of optimum temperatures, seriously impacting reproductive success in that year. Inundated HabitatAvailable historical data does not suggest bull trout spawning/early-rearing habitat was inundated when the Lower Snake River dams were completed; all evidence suggests that the impounded areas were historically used as adult/subadult foraging and overwintering areas. This use continues today for these age groups. The transition from a riverine environment to a reservoir would likely eventually force the historic fluvial local populations to adapt to an adfluvial type life history. Provided the local populations adapt to the altered environment and sufficient forage is available throughout time in the reservoirs, the change to a reservoir system could have some positive effects on the bull trout as well. For example, adfluvial fish typically grow to larger sizes than fluvial migrants, and as a result can be more fecund (Goetz 1989). If sufficient spawning and early rearing habitat is available, a potential increase in individual fecundity may result in a larger, more robust local population. However, the available data does not indicate whether the reservoirs on the Lower Snake River have resulted in larger, more fecund bull trout. The data indicates some individuals use the reservoirs for adult and subadult rearing, so we assume that at least a portion of the local populations have adapted to the adfluvial migratory behavior. As a result, adverse effects associated with inundated habitat appear to be minimal, and may be offset by associated increased growth and fecundity. Gas SupersaturationElevated levels of TDG are a common problem below dams during periods of high runoff and spill. High TDG can result in gas bubble disease (GBD) in fish. Bull trout that may be present in the tailraces below the Lower Snake River dams are subjected to high TDG levels, and as a result, could be adversely affected by GBD. Shrank et al. (1997) found that resident fish experienced a higher mortality rate from GBD than migratory fish moving through areas with high TDG concentrations. For comparison purposes, we are including some data associated with Dworshak Dam on the Clearwater River. GBD was observed in 90 out of 8,842 individual fish sampled downstream of Dworshak Dam in the spring and summer of 1997 (Cochnauer and Putnam 1997). The occurrence of GBD in sampled fish ranged from 0.9 to 16.5%, and was most prominent following periods when TDG levels approached 120% saturation. The highest rate of incidence occurred in resident salmonid species sampled in the 1.5 miles long section immediately below the dam, but none of the 12 bull trout sampled in this section showed signs of GBD. Total dissolved gas levels in the tailraces below the Lower Snake River dams are typically higher than those observed at Dworshak (Fish Passage Center 1997). During high spring runoff in 1997, TDG levels below these facilities were commonly at or above 130% saturation, and occasionally approached 140%. During late summer and early fall, when discharge was low, TDG levels were typically around 100%. Data collected near the Lower Snake facilities indicated occurrence of GBD in fishes in the Lower Snake River was less than the values Cochnauer and Putnam (1997) identified in the Dworshak Dam Tailrace. The data presented, however, appeared to focus on emigrating anadromous species. There are no documented GBD effects to bull trout in association with the Lower Snake River dams, but the potential for adverse effects is higher than that below Dworshak Dam as a result of higher TDG levels. Passage/EntrainmentBased on fish counting schedules outlined in Corps reports (Corps 1997), adult fish enumerations are not conducted at the Lower Monumental, Little Goose, or Ice Harbor fish counting windows from November 1 - March 31. Unfortunately, this period coincides with adult bull trout movements into larger mainstem systems. In the U.S Fish and Wildlife Service’s (USFWS or Service) Federal Columbia River Power System (FCRPS) Biological Opinion, the Service anticipated that the operation of the Lower Snake River dams is likely to result in variable levels of incidental take of bull trout. However, the Service is at this time unable to quantify the numbers of bull trout to be taken. Incidental take of bull trout will be difficult to quantify or detect for the following reasons:
The Service anticipates indeterminate levels of harassment, harm or killing of bull trout to occur in the Lower Snake River as described below: Harm and harassment to bull trout resulting from impediments to both upstream and downstream passage, potential entrainment of both adult and juvenile bull trout into turbine intakes, potential entrainment of adult bull trout into juvenile bypass systems, changes in pool water level elevations affecting food and habitat availability, elevated water temperatures resulting from impoundment, and gas supersaturation resulting from both voluntary and involuntary spill events are likely to continue to occur under the current water management scenario . In the biological opinion, the Service determined that this level of anticipated take is not likely to result in jeopardy to the species. Critical habitat has not been designated for bull trout, therefore, none will be affected. The effects of entrainment can include physical injury, direct mortality, migration delays, and isolation from spawning areas. All these effects are likely to occur at all the Lower Snake River facilities at some unknown rate, but without appropriate monitoring and research it is impossible to estimate impacts to the population resulting from entrainment. Operations that increase uncontrolled or controlled spill are likely to increase adverse affects from entrainment. System improvements that are focused on more effective diversion of juvenile fish away from the turbines may also effectively divert bull trout away from the turbines and thereby potentially decrease take below existing levels. However, short term disturbances from improvement construction may also adversely affect bull trout by preventing or discouraging use in the construction area, further impeding migration. Since the extent and timing of bull trout use of the four dam facilities is unknown, we cannot quantify the impacts to bull trout at this time. Anadromous FishThe maximum water temperature criteria established by Washington for the main-stem Snake River is 20C, which is often exceeded during the warmest parts of the summer. The upper incipient lethal temperature for juvenile chinook salmon is 24C (Brett 1952). Temperature affects swimming performance (Brett 1967), growth and energetics (Brett 1952; Elliott 1982), movement behavior (Bjornn 1971), physiological development (Ewing et al. 1979), disease susceptibility (Fryer and Pilcher 1974), and vulnerability of fish to predation (Sylvester 1972; Coutant 1973; Yocom and Edsall 1974; Deacutis 1978). The long-term consequences to fall chinook salmon of chronic exposures to sublethal temperatures that exist in the Snake River during the summer is unknown, but may manifest itself in high mortality at dams due to increased physical stress during passage. Studies have also shown that late-migrating juvenile Snake River fall chinook salmon exposed to high water temperatures have poorer survival than earlier migrants (Connor et al. 1998; Muir et al. 1998). Considering the life history of fall chinook salmon along with the environmental conditions that exist during their freshwater life cycle, high water temperatures may limit this population by reducing fish performance and long-term survival. Flow and Migratory ConditionsThe Snake River hydrosystem has increased the travel times of emigrating juvenile salmonids from those experienced historically. Spring and summer flows are currently augmented to reduce the travel times of in-river migrants to subsequently reduce exposure to such risks as predators, disease, and high summer temperatures. Although juvenile fall chinook travel time has been shown to be weakly related to river flow (Berggren and Filardo 1993; Giorgi et al. 1997; Tiffan et al. 2000), a clear flow-survival relationship has yet to be demonstrated and is the subject of considerable debate. The effects of flow on salmonid travel time and survival are often confounded with other behavioral, biological, and environmental factors. River flows is one of few variables that can be managed for juvenile salmonids, but much remains to be learned of its role as a limiting factor. PassageUsing radio telemetry, Venditti et al. (2000) showed that most summer-migrating juvenile fall chinook salmon traveled fairly rapid through the upper and middle sections of Little Goose Reservoir, but 10-20% of the fish were delayed in the forebay for a week or more. This delay and inability to pass the dam quickly likely increases fall chinook salmon risk of predation and exposure to high summer water temperatures, which may decrease their survival. Habitat LossesHydroelectric development has transformed most fast-moving main-stem riverine habitats into slow-moving reservoir impoundments. Construction of Ice Harbor, Lower Monumental, Little Goose, and Lower Granite dams from 1961 to 1975 inundated virtually all fall chinook salmon spawning habitat in the main-stem Lower Snake River. Recently, a very limited amount of fall chinook salmon spawning was documented in the tailraces of Lower Granite, Little Goose, Lower Monumental, and Ice Harbor dams, but did not contribute significantly to the production of fall chinook salmon in the Snake River (Dauble et al. 1999). Juvenile fall chinook salmon use main-stem shorelines for rearing, but the amount of available rearing habitat has not been quantified to date. The shoreline habitats available in lower Snake River reservoirs are predominantly rip-rapped, which juvenile fall chinook salmon avoid, and are often preferred by predators (USGS, unpublished data). These habitat-related limitations in main-stem reservoirs further reduce the production potential and survival of fall chinook salmon. Food WebsThe transformation of the main-stem Snake River into a series of reservoirs has altered the food webs that support juvenile salmonids and resident fish (Bennett et al. 1988, 1990, 1991; Dorband 1980). Before impoundment, the benthic community of the now inundated Lower Granite Reservoir consisted of mainly ephemeropterans and thrichopterans (Edwards and Funk 1974). Today, the food of juvenile fall chinook salmon consists primarily of midges (Diptera), mayflies (Ephemeroptera), zooplankton (Cladocera), and larval fish in the upper portion of Lower Granite Reservoir (Curet 1993). However, Curet also observed an increase in terrestrial insects further downstream in Little Goose Reservoir. Similarly, Rondorf et al. (1990) found juvenile fall chinook salmon in McNary Reservoir consumed primarily midges, terrestrially-derived insects, and zooplankton. The limitation that altered reservoir food bases present is lower in-reservoir food production and an increased foraging cost to consume smaller, less energetically profitable zooplankton. The effect of this on the growth and survival of salmonids rearing and migrating in the Lower Snake River is unknown, but should be cause for concern. DiseaseThe bacterium Flexibacter columnaris has been shown to be a significant pathogen to steelhead, and coho and chinook salmon (Holt et al. 1975; Becker and Fujihara 1978). The incidence of Flexibacter columnaris in the main-stem Snake River has not been rigorously monitored in recent history, but has been documented at Lower Granite and Lower Monumental dams (USGS, unpublished data). Its occurrence in juvenile fall chinook salmon has also been documented at Columbia River dams and may have contributed to the thermal-related mortalities observed at McNary Dam in 1994 and 1998. Little is known about the environmental and biological conditions that contribute to large-scale infections that could ultimately decrease fish performance and survival. TributariesAlpowa and Deadman creeksA limiting factors report will be completed by the Washington State Conservation Commission in 2001 for the Snake river basin from the mouth of the Tucannon River upstream in WRIA 35 within Washington. The following information was gathered by the Center for Environmental Education at WSU. Sediment sources should also be considered in terms of the frequency of their impacts, as eventscale (short time-frame) vs. geoclimatic scale (long time-frame) affect aquatic habitat differently. Infrequent events such as landslides associated with major storms and flooding have obvious and recognizable impacts. Large storm events can totally restructure the stream channel by removing riparian vegetation and redistributing pools and riffles. Short interval events such as daily changes in flow and small amounts of precipitation can cause minor siltation or changes in the width and depth of the wetted channel. The seasonal increases associated with snowmelt and winter rains are not as dramatic, but still important contributors to the sediment load. Seasonal fluctuations can cause changes in the diversity of habitat units such as pools and riffles or increased instances of siltation during spring run-off (Swanston 1991). Spatial and temporal sediment sources control the distribution of sediment in the channel, which potentially impacts other important functions such as water quality, channel stability, and aquatic habitat in the Alpowa Creek watershed. Once sediment enters the channel, much of it settles there until a large flood event moves it in the form of a sediment pulse. Low flows rework the deposited pulses during the times between flood events. The frequency of flooding partially determines the rate sediment moves through the stream system. For example, when intermittent creeks in the Alpowa watershed rapidly rise to flood stage, they can deliver large amounts of sediment to the larger channels in a short time period. However, no data currently exist specific enough to the Alpowa drainage to gage the contribution of individual tributaries to this process. Water TemperatureHigh water temperatures occur mainly from June through September. This is not likely to affect adult steelhead that enter Alpowa Creek or Deadman Creek in late winter and early spring. However, it indirectly affects the success of spawning steelhead by reducing survival of juveniles that emerge from the substrate during the summer when temperatures are excessively high. High stream temperatures throughout the summer and sometimes into the early fall probably leave Alpowa Creek as marginal conditions for steelhead rearing and unsuitable for spawning adult chinook salmon and bull trout. High water temperatures and sedimentation are directly related to the degraded condition of the riparian zone. In small streams, vegetative cover of the channel provides shade and can maintain cool water temperatures suitable for salmonids and other native fish species. A healthy vegetative community in the riparian zone also stabilizes streambanks and intercepts some upland sediments before they reach the channel, both of these function to reduce sediment delivery to the stream. Mature woody riparian vegetation also provides a source of woody debris to the stream channel, which is important in forming pools and creating complexity in stream habitats. Rearing Habitat ConditionsJuvenile salmonid rearing is limited mainly to reaches upstream of Highway 12, although in 1998, salmonids were found as far downstream as the mouth late in the summer. A late summer rainfall may have allowed some fish to move that far downstream. Rearing conditions are marginally adequate in areas upstream of Highway 12 because the water is generally cooler, but conditions could be improved by improvement of the riparian vegetation and increases in channel complexity and cover. Further downstream, water temperature and the lack of pools makes these areas less tolerable to young fish. Sediment LevelsElevated sediment levels are one of the potential limiting factors to salmonid use in Alpowa Creek. Sediment is limiting for several reasons, including channel instability and habitat impairment. Brief field investigations in the spring of 1999 showed extensive areas of aggradation and channel incision in Alpowa Creek, both indicators of an altered sediment regime. The altered regime is of particular importance above the confluence of Stember Creek, where the only likely spawning habitat in the watershed occurs. Elevated sediment levels are one of the potential limiting factors to salmonid use in Deadman Creek. Sediment is limiting for several reasons, including channel instability and habitat impairment. Brief field investigations in the spring of 1999 showed extensive areas of aggradation and channel incision in Deadman Creek, both indicators of an altered sediment regime. Elevated sediment levels negatively impact aquatic habitat in many ways. Fine sediment and organic matter suspended in the water column impact the salmonid life cycle at several points, primarily in the first year of life. Fine sediment makes it difficult for adults to clean gravel nests (redds) for spawning, covers and suffocates eggs, and fills the interstitial space between larger gravel and cobbles where juveniles seek cover. Coarse sediment inputs can alter the morphology of channels that have evolved under specific sediment conditions, leading to pool filling, aggradation, and bed instability. A highly mobile streambed can scour and fill active redds. Land use practices, topography, soils, geology, and climatic conditions in the watershed combine to produce sediment in streams. Sediment sources are areas or activities prone to producing sediment above natural levels. Sediment production can be broken into two phases: detachment and transport. Sediment detachment occurs from different sources and at different magnitudes throughout the Alpowa Creek watershed. For example, mass wasting rapidly contributes large amounts of both coarse and fine sediment, while surface erosion from overgrazing may contribute fine sediment at a slower rate to the creek. Wind and water constantly redistribute this sediment across the landscape. When sediment is deposited in areas sensitive to sedimentation such as spawning redds, then sediment becomes a problem. The spatial distribution of sediment sources, their transport mechanisms, and ways in which they contribute sediment to the channel are important factors in understanding the appropriate sediment regime for the watershed. Sediment sources should also be considered in terms of the frequency of their impacts, as eventscale (short time-frame) vs. geoclimatic scale (long time-frame) affect aquatic habitat differently. Infrequent events such as landslides associated with major storms and flooding have obvious and recognizable impacts. Large storm events can totally restructure the stream channel by removing riparian vegetation and redistributing pools and riffles. Short interval events such as daily changes in flow and small amounts of precipitation can cause minor siltation or changes in the width and depth of the wetted channel. The seasonal increases associated with snowmelt and winter rains are not as dramatic, but still important contributors to the sediment load. Seasonal fluctuations can cause changes in the diversity of habitat units such as pools and riffles or increased instances of siltation during spring run-off (Swanston 1991). Spatial and temporal sediment sources control the distribution of sediment in the channel, which potentially impacts other important functions such as water quality, channel stability, and aquatic habitat in the Alpowa Creek watershed. Once sediment enters the channel, much of it settles there until a large flood event moves it in the form of a sediment pulse. Low flows rework the deposited pulses during the times between flood events. The frequency of flooding partially determines the rate sediment moves through the stream system. For example, when intermittent creeks in the Alpowa watershed rapidly rise to flood stage, they can deliver large amounts of sediment to the larger channels in a short time period. However, no data currently exist specific enough to the Alpowa drainage to gage the contribution of individual tributaries to this process. Reference conditions help in the understanding of how the sediment regime changes as a result of different land use impacts. The reference conditions for Alpowa Creek were determined from historic descriptions of the density and species diversity of the vegetation; current observations of basin morphology, geology, and soils; current and historic climate data; and current and historic hydrologic data. Historically, the major sediment sources in the Alpowa watershed included mass wasting, bank erosion, and surface erosion. All of these are naturally occurring phenomena. The primary factor involved in the distribution was probably slope, with higher slope areas being more likely to fail than lower slope areas. Although natural sediment sources fluctuated historically both in time and space, the watershed was able to return to a stable balance following disturbance events and adapt to climatic and geologic changes. Natural sediment production increased most dramatically during large precipitation events that triggered landslides and caused floods that scoured the riverbanks, eroded fluvial terraces, and moved sediment pulses through the stream system. After these events, the stream reworked the sediment, and the channel morphology adapted to the new sediment distribution. In steep terrain where the hillslopes have weakened to the point at which they can no longer -resist gravity, catastrophic mass movements such as landslides result. Large precipitation events that saturate soils and increase interstitial pore pressure reduce resistance to gravity and contribute to shallow landslides on steep terrain. If the slide enters a flood-swollen stream, the flow becomes a slurry of sediment and water or a debris flow, which moves rapidly downstream and entrains material stored in the channel. Debris flow deposits were seen through9ut the -Alpowa watershed during the 1999 field reconnaissance and probably played an important role in channel development. Many of the larger tributaries to Alpowa Creek are lined with debris flow deposits, and first-order draws are often filled with stored colluvial material brought down from the steep hillsides. These types of mass wasting events probably dominated the reference sediment regime, with surface erosion providing comparatively little sediment to the aquatic ecosystem. Surface erosion is limited when a watershed is in an undisturbed state. Accordingly, historic sources of surface erosion were most likely secondary to wide-scale disturbances such as fire or landslides that removed large portions of the vegetation from the soil surface. In places where soil was left exposed to the forces of wind, rain, and gravity, the soil was detached from its original position on the slope and transported to a new position down-slope. In places where no large-scale disturbance occurred, surface erosion was minimal. What erosion did occur was probably the result of the winnowing of fine-grained material from between the clumps of bunchgrass by wind and rainfall. Surface erosion probably did not deliver concentrated enough amounts of fine sediment to the stream to negatively impact the aquatic habitat until after the land use impacts from grazing and cultivation became prevalent in the region. Agriculture practices over the last 135 years in the region are responsible for changes to vegetative cover that have increased surface erosion rates. These and other human land uses result in a loss of topsoil, reduced infiltration, lowered water retention, and escalated run-off (Bureau of Reclamation 1997). Soil erosion is most severe in winter and early spring when melting snow and rain occur at their maximum rates. Highway 12 occupies Megginson Gulch for its entire length and the fill and rip-rap from the highway constrict the channel for much of the channel length. Megginson Creek has undercut the hillslope opposite Highway 12 and it is actively eroding in many places. Area on northside of Snake River in Whitman County and the Small Area North of Tucannon and Pataha Creek in Columbia CountySediment deposition and water temperature are assumed to be limiting factors in streams located in this combined watershed. Lack of riparian cover and sedimentation from cropland is presumed to be the main cause for these limiting factors. Small Area North of Tucannon and Pataha Creek in Columbia CountyThe Columbia County Weed Board (Weed Board) visually surveyed approximately 48 miles of the Tucannon River, including private and public lands. Approximately 20% of the riparian areas are infested with yellow starthistle, Centaurea solstitialis, and knapweeds (Centaurea diffusa, Centaurea biebesteinii, Acroptilon repens). Eighty percent of rangelands are infested with yellow starthistle. The Weed Board found limited amounts of rush skeletonweed, Chondrilla juncea, and is attempting to contain leafy spurge, Euphorbia esula. Yellow starthistle is a member of the Asteraceae family. It is a winter annual with yellow flowers. About 60% of the seeds produced by yellow starthistle survive dispersal (Sheley and Larson 1994) . Birds, wildlife, humans, domestic animals, whirlwinds, and vehicles may transport the seeds. A single plant may produce up to 150,000 seeds. Studies show that 90% of the seed falls within 2 feet of the parent plant (Roche 1991). Of these seeds, 95% are viable, and 10% can remain viable for 10 years (Callihan et al. 1993). Yellow starthistle can grow more rapidly than most perennial grasses. It is deep-rooted and will grow twice as fast as annual grasses (Sheley and Larson 1995) . Yellow starthistle displaces native plant communities and reduces plant diversity. It can accelerate soil erosion and surface runoff (Lacey et al. 1989). Yellow starthistle forms solid stands that drastically reduce forage production for wildlife. Knapweeds are also members of the Asteraceae family. Spotted knapweed is a deep taprooted perennial that lives up to nine years (Boggs and Story 1987). Seed production ranges from 5,000 to 40,000/m2 (Shirman 1981). Seeds can germinate in the spring and fall when moisture and temperature are suitable (Watson and Renney 1974). Spotted knapweed is able to extend lateral shoots below the soil surface that can form rosettes next to the parent plant (Watson and Renney 1974). Diffuse knapweed is a biennial that grows from a deep taproot. Seed production ranges from 11,200 to 48,000/m2 (Shirman 1981). Knapweeds are spread by wind, animals, and vehicles. Diffuse knapweed reduces the biodiversity of plant population, increases soil erosion (Sheley et al. 1997), threatens Natural Area Preserves (Schuller 1992) and replaces wildlife forage on range and pasture. Spotted knapweed also reduces wildlife forage. Watson and Renney (1974) found that spotted knapweed infestations decreased bluebunch wheatgrass by 88%. Elk use was reduced by 98% on range dominated with spotted knapweed compared to bluebunch-dominated sites (Hakim 1979). Spotted knapweed also increases surface runoff and stream sediment (Lacey et al. 1989). Rush skeletonweed is in the Asteraceae family. It can be a perennial, a biennial, or a short-lived perennial, depending on its location. Seed production ranges from 15,000 to 20,000 seeds. The seeds are adapted to wind dispersal but are also spread by water and animals. Rush skeletonweed can also spread by its roots. Rush skeletonweed reduces forage for wildlife. Its extensive root system enables it to compete for the moisture and nutrients that grasses need to flourish. Leafy spurge is a perennial belonging to the Spurge family. The root system can penetrate the soil 8 to 10 feet. The plants will also produce horizontal roots that enable colonies to enlarge. The seeds are in a capsule and, when dry, the plant can project the seeds as far as 15 feet. Seeds may be viable in the soil up to 8 years. Leafy spurge is spread by vehicles, mammals, and birds. Leafy spurge root sap gives off a substance that inhibits the growth of grasses and reduces forage for wildlife. It also spreads by seed and root, which crowd out desirable forages. WildlifeWildlife populations within the subbasin have been impacted by habitat loss due to agricultural development, hydropower development, livestock grazing, and the invasion of noxious weeds. Noxious weeds threaten mule deer winter range by decreasing both the volume and availability of palatable forage species. Agricultural development has altered or destroyed vast amounts of native shrub steppe habitat in the uplands, and increased herbicide/pesticide and sediment loads into streams. Construction of Lower Granite Dam, the fourth and final of a series on the Lower Snake River, was completed in 1975 (Lewke 1975). The resulting reservoir caused a backup of waters flowing into the Snake from Alpowa Creek and flooded its lower reaches, inundating the surrounding riparian vegetation. Lewke (1975) estimated that the loss of riparian habitat caused by the impoundment of Lower Granite Dam resulted in a loss of habitat for 11,000 summer and 17,000 winter birds. There has of course been some recovery, but the carrying capacity for wildlife in the area has been undeniably lowered. Since impoundment, the recovery of riparian habitat has been slowed due to shallow soils along the current banks of the reservoir in comparison to soils formed in a natural riparian area. The Lower Snake River, from the confluence of the Clearwater River to the confluence of the Snake River and the Columbia, provides a major transportation route by land and water. The railroad runs along the entire length of the Lower Snake corridor. The railroad presents a number of issues, which are limiting factors to wildlife. Direct loss of wildlife along the rail system is not avoidable. Fires set by the operation of the rail system is a common problem along the rail line. This can also lead to direct loss of wildlife. Indirect losses to wildlife due to the rail system is the permanent loss of riparian habitat due to rock rip rap along much of the rail system to reduce erosion from wave action along the reservoir, both man-made and natural. Barge traffic on the Lower Snake produces wave action throughout the length of the system. Along with barge traffic comes the continuous maintenance of the channel due to sedimentation deposit. Dredging is a continuous issue. Dredging activity and sediment deposit will always be a problem. Alpowa and Deadman CreeksClean" farming practices (field burning, herbicide use, and roadbed-to-roadbed farming) have increased crop yields but negatively impacted habitat quality in the Alpowa Creek and Deadman Creek ecosystems. Wheat production in Garfield County increased from 20-30 bushels/acre in 1929 to 40-50 bushels/acre in 1992 (Black et al. 1997), but wildlife populations have declined. Cultivation is the main factor causing the disappearance of the Columbian sharp-tailed grouse (Lewke 1975). Even species well adapted to life on agricultural lands such as ring-necked pheasant have experienced recent population declines. Pheasant harvest in Washington fell from over 500,000 birds in 1981 to 70,000 in 1995, most likely due to reductions in cover for nesting and protection and the effect of pesticides on breeding success. Ring-neck pheasants are currently the focus of a major habitat restoration program and the Alpowa and Deadman creek watersheds have been designated part of the high priority area (Ware and Tirhi 1999). Erosion is also a major problem associated with agriculture in the area since much is practiced on the ridgetops. Soils in the watershed are fine and easily erodable. Runoff from storm events easily disturbs the soil particles, carrying them through the rangeland and into the streams. The -degraded quality of the vegetation in the ranges and riparian zone reduces the ability of these areas to trap sediments and prevent them from reaching the stream. The Southeast Washington Cooperative River Basin Study found that the croplands in the Alpowa Creek basin contributed more than 16,000 tons per year to the stream system (Soil Conservation Service et al. 1984). Fertilizers and pesticides used to increase crop yields can be introduced to Alpowa Creek attached to sediment particles. Once in the stream, fertilizers encourage algal blooms and -aquatic plant growth due to their high nitrogen and phosphorus content (Bauer and Burton 1993). Pesticides can be toxic to wildlife, particularly amphibians and fish. Pesticides have been blamed for the drastic decline of many bat populations. Exposure to pesticides kills bats either directly through exposure or indirectly through ingestion of sprayed insects (Washington -Department of Fish and Wildlife 1998). Pesticides can also reduce reproductive success in birds, having been shown to lower chick production, chick viability, and cause degeneration of the nervous system in ring-necked pheasants (Ware and Tirhi 1999). In addition to the cheatgrasses described above, a reconnaissance of the Alpowa Creek watershed in March of 1999 showed that yellow star thistle is among the most established introduced plant species in the drainage. This noxious weed reduces the diversity of the ecosystem by forming a canopy so dense that it shades out grasses and small herbs. Yellow star thistle can be fatal to cattle and wildlife if ingested (Stubbendieck et al. 1992). Its invasion of the watershed reduces available food, further increasing grazing pressures on the remaining forage and thus causing greater problems with erosion. These effects serve to limit the habitat and reduce essential requirements for aquatic species. Precious Lands ProjectCurrently, the main limiting factors for wildlife populations within the Precious Lands project area are noxious weed infestations, effects of fire suppression, trespass livestock grazing, and altered hydrologic regimes. A wide variety of invasive, non-native plant species currently occupy portions of the Precious Lands Wildlife Area. Species of particular concern are yellow starthistle and cheatgrass. Yellow starthistle is a very aggressive annual weed that invades after disturbance but once established can encroach upon seemingly pristine native bunchgrass communities. Cheatgrass is also a disturbance-adapted annual that can significantly alter plant community composition once it becomes established. In addition, cheatgrass can alter the fire regime of infested communities by providing fine, highly volatile fuels during the height of fire season. The long-term result of noxious weed invasion is a loss of biodiversity as exotic species out compete natives and replace diverse communities with monocultures or highly depauperate stands. Indirect affects to wildlife species can be a loss of food, cover, or nesting habitat. Fire suppression efforts over the last 100 years have significantly altered natural fire return intervals within the canyon grassland systems of the Lower Snake River Basin. The result has been less frequent but more severe fires. Within the Precious Lands Area, old burn patterns are evident in the extent and composition of plant communities. The most recent natural fire event occurred in 1988 when part of the Teepee Butte Fire burned through the eastern portion of the project area. This was an intense stand-replacing fire event that resulted in conversion of several hundred acres of conifer forest to shrub fields. Under a more “natural” fire cycle perhaps this event may have been an underburn that maintained an open forest structure more common 100 years ago. Regardless of any speculation about this one fire event, it seems clear that current vegetation patterns are the result of lowered fire frequency. This has resulted in multi-layered conifer stands, high litter build-up, decadent bunchgrasses with poor forage values, and, in some areas, lower snag recruitment. The existence of noxious weeds like cheatgrass only acerbates concerns of altered fire regimes. Livestock grazing is currently not permitted on the Precious Lands Wildlife Area, but some trespass grazing does occur from cattle moving into the area from adjoining ranches. Efforts are underway to establish fences where needed to limit livestock access to the property. The most noticeable impacts to wildlife habitat occur in the riparian corridors favored by grazing livestock. In these areas, herbaceous and shrub vegetation is directly removed through eating or trampling. Loss of understory vegetation can limit food, cover and nesting opportunities for riparian-dependant wildlife species. It can also mean a loss of shade to the stream, which may result in elevated water temperatures. In addition, cattle can transport noxious weed seeds in their feces, fur, or on their hooves, which can have long-term impacts to wildlife habitat even after livestock are removed from the area. The Precious Lands Area is a low elevation site that largely encompasses the lower end of most streams crossing its boundaries. This lower elevation position means that area streams are impacted by upstream factors outside the management area and outside any management control of the Nez Perce Tribe (NPT). As such, the Wildlife Area is impacted by erosion, timber harvesting, livestock grazing, road construction, irrigation, and a host of other factors occurring in headwater areas. Sometimes these factors act to limit habitat values by direct degradation of habitat like increased water temperatures or turbidity. Other influences are more subtle and may act to alter in-stream flow patterns or acerbate the severity of flood events. Flood events in particular may impact wildlife habitat by removing overstory trees or otherwise impacting streamside vegetative structure. Such was the case of the 1996-97 flood events along Cottonwood, Buford, and Joseph Creeks which resulted in altered stream channels, and loss of overstory trees. Riparian systems are naturally dynamic but up-stream events may alter an areas ability to recover following a disturbance event. Artificial ProductionArtificial production occurs in the Lower Snake River (Figure 17) through the Lower Snake River Compensation Plan (LSRCP) and at Lyons Ferry Hatchery near the mouth of the Palouse River, and upriver mitigation programs funded by Idaho Power and others. Large numbers of hatchery steelhead and salmon from upriver in Idaho, Oregon or eastern Washington migrate through the area as adults or juveniles. The LSRCP developed in 1976 to mitigate for fish and fishery losses caused by the four lower Snake River dams. Lyons Ferry Hatchery, funded by the USFWS and operated by WDGW, was built near the mouth of the Palouse River as part of the LSRCP. It is currently the only fall chinook hatchery program in the Snake River basin. The hatchery goal was to return 18,300 adult fall Chinook to the Snake River each year to mitigate as harvest augumentation and as an eggbank for the native Snake River stock of fall chinook (Bugert et al 1995, Mendel 1998). Snake River fall Chinook were trapped at Snake River dams to develop the broodstock for the Lyons Ferry Hatchery program. Juvenile fall chinook produced by Lyons Ferry Hatchery were barged downstream of Ice Harbor dam or released directly into the Snake River for several years (Bugert et al 1997) and are now released directly into the river at Lyons Ferry Hatchery (Table 44) or at three acclimation sites upstream of Lower Granite Dam (Mendel 1998). The priority for release is yearling fall chinook because of survival rates that are 4-10 times better than survivals of subyearling hatchery chinook (Bugert et al. 1997, Mendel 1998). Any production beyond 900,000 yearlings is released as subyearlings because of limited space at Lyons Ferry Hatchery. 
Figure 17. Location of LSRCP Hatcheries and Satellite Facilities Lyons Ferry Hatchery also releases steelhead (Table 45) at the hatchery site for harvest mitigation and to return Lyons Ferry broodstock for the hatchery program. Releases have been reduced in recent years. This stock of fish may be phased out in the future. U.S. v Oregon agreements exist to try and minimize or stabilize the downriver harvest of naturally produced steelhead and fall chinook from the Snake River. The fisheries are currently controlled to protect these weak ESA listed stocks. Prior to ESA listings, Snake River hatchery and wild fall chinook were harvested at high rates in downriver fisheries. Resident trout fisheries occur in many of the small impoundments along the Snake River that are stocked by Lyons Ferry Hatchery as mitigation for lost fishing opportunities along the Snake River due to the construction and operation of the Snake River dams. Several small tributaries were stocked until the 1990’s however concerns for ESA listed steelhead resulted in the termination all stream stocking by the WDFW. Table 44. Fall Chinook releases at Lyons Ferry Hatchery, 1990-2000. Release Year Age Number of fish Pounds of fish 2000 Yearling 456,401 48,699 Subyearling 196,643 4,326 1999 Yearling 432,166 51,881 Subyearling 204,194 4,171 1998 Yearling 418,992 41,484 1997 Yearling 456,776 49,168 1996 Yearling 407,503 38,996 Subyearling(fry) 83,183 186 1995 Yearling 349,124 44,905 1994 Yearling 603,661 54,818 1993 Yearling 760,018 67,387 Subyearling 206,775 3,390 1992 Yearling 689,601 81,677 1991 Subyearling 224,439 4,581 1990 Yearling 436,354 45,326 Subyearling 3,812,068 54,658 Table 45. Steelhead releases near Lyons Ferry Hatchery from 1990-2000. Year Number released Pounds released 2000 1999 87,992 24,004 1998 93,842 19,059 1997 81,162 17,996 1996 71,942 13,833 1995 66,972 17,730 1994 119,039 31,087 1993 247,950 43,450 1992 66,688 18,460 1991 93,075 16,715 1990 43,479 7,730 | |||||||||||||||