Appendix 5. Habitat Characteristics Important to Bull Trout (Temperature, Habitat, Complexity, Connectivity, Substrate Composition and Stability), and Management Issues (Roads, Floodplain and Riparian Protection) That Affect These Habitat Characteristics

The organization of each “Habitat and Management issue” is as follows:

· Problem Assessment--current habitat and management conditions relative to bull trout.

· Biological Needs--bull trout biological requirements relative to the issue.

· Objectives--specific to the issue type.

· Caution Zone--areas where land management activities have the greatest potential to adversely affect bull trout. We have adopted the “caution zone” from the Montana Bull Trout Scientific Group’s report “The Relationship between Land Management Activities and Habitat Requirements of Bull Trout” (MBTSG 1998). We have identified caution zones for each issue, often using the 100-year floodplain plus one site-potential tree height distance on both sides of the stream. For some issues, such as roads, the entire watershed is identified as the caution zone. One site-potential tree is approximately 150' on the west side of the Cascade Mountains; 90' to 150' on the east side dependent on forest Potential Vegetation Type (PVG = cold, moist, or dry).

The 100-year floodplain was chosen based on the need to fully incorporate the channel migration zone (CMZ) on low gradient alluvial streams. These stream channels provide critical spawning and rearing habitat for bull trout. An additional 150 feet on either side of the 100-year floodplain is required for the following reasons: 1) it encompasses one site-potential tree height at most locations; 2) provides sufficient width to filter most sediment from non-channeled surface runoff from most slope classes; 3) provides some microclimate and shallow groundwater thermal buffering to protect aquatic habitats inside the channel and the channel migration zone; and 4) provides an appropriate margin of error for unanticipated channel movement, hillslope and soil stability, blowdown, wildfire, operator error, disease, and certain other events that may be difficult or impossible to foresee on a site specific basis” (MBTSG 1998).

The caution zone may include non-fish bearing tributaries, seeps, springs, and wetlands in order to capture the linkages in a watershed critical to aquatic system function: stream, riparian, and sub-surface networks (Stanford and Ward 1992). In the caution zone the site-potential tree distance is measured horizontally from the edge of the floodplain.

TEMPERATURE

Problem Assessment

Bull trout distribution is strongly influenced by water temperature (Ratliff 1992; Rieman and McIntyre 1993, 1995; Bonneau and Scarnechia 1996; Buchanan and Gregory 1997; Lee et al. 1997), and they are found to be associated with the coldest stream reaches in basins (Lee et al. 1997). Researchers recognize temperature more consistently than any other factor influencing bull trout distribution (Rieman and McIntyre 1993). Thermal barriers have contributed to the disruption and fragmentation of bull trout habitat (Buchanan et al. 1997; EPA 1997; WDFW 1997; MBTSG 1998). Increases in stream temperatures can cause direct mortality, displacement by avoidance (Bonneau and Scarnechia 1996), or increased competition with species more tolerant of warm stream temperatures (Rieman and McIntyre 1993; Craig and Wissmar 1993 cited in 62 FR114 Proposed Rule; MBTSG 1998). Brook trout, which can interbreed with bull trout, may be more competitive than bull trout and displace bull trout in drainages containing more fine sediment and higher temperatures (Clancy 1993; Leary et al. 1993).

Many areas within the species range have temperature standards that exceed levels identified as necessary to support various life stages of bull trout (Montana Dept. of Health and Environmental Sciences 1994; Oregon Dept. of Environmental Quality 1996; EPA 1997; Washington Dept. of Ecology 1998). For example, in Washington, the current State temperature criteria are inadequate to protect bull trout (WDOE 1998); in 1996, EPA disapproved Idaho’s standards after concluding they were inconsistent with the Clean Water Act (EPA 1997); and in Oregon, as recently as 1995, bull trout and other cold water species were not protected by Oregon’s threshold temperature standards (Buchanan and Gregory 1997

Biological Needs

Bull trout and other char often thrive in waters too cold for other salmonid species (Balon 1980). Although preferred water temperatures vary by life history stage, consistently cold water is required at all critical life history stages (spawning, incubation, rearing, overwintering).

· Spawning is initiated in the fall as temperatures drop to 9-10°C (McPhail and Murray 1979; Fraley and Shepard 1989; Riehle, 1993), although the threshold for char spawning in north Puget Sound is believed to be 8°C (Kraemer 1994).

· Survival of incubating eggs has been found to be optimal at constant exposure to 2-4°C water, with mortality increasing markedly above 8°C (McPhail and Murray 1979; Weaver and White 1985). From egg deposition to emergence, juvenile bull trout may reside 220 or more days in the gravel.

· Optimal juvenile rearing temperatures range between 4-10EC (Buchanan and Gregory 1997).

· For migratory corridors, bull trout require water temperatures ranging between 10-12°C (McPhail and Murray 1979; Buchanan and Gregory 1997

Temperature criteria are based on the consecutive 7-day average daily maximum temperature standards consistent with EPA water quality standards for Idaho (EPA 1997).

Objectives

· Maintain or restore temperature regimes that are optimal to support bull trout at all life-history stages, including historic migratory corridors that will be necessary for reconnecting fragmented subpopulations

· Maintain or restore cold water temperature contributions of intermittent and non-fish bearing tributaries to bull trout streams.

· Decrease the risk of invasion and displacement by introduced species by preventing increases in water temperature.

· Provide or maintain sufficient thermal refugia (deep pools, tributary confluences, groundwater influences) to support residence throughout summer months.

· Protect all ground water sources (seeps, springs, wetlands, hyporheic zone) that may influence stream temperatures.

· Maintain or restore water quality within a range that maintains the biological, physical, and chemical integrity of bull trout watersheds.

Caution Zone

100-year floodplain plus one site potential tree distance, including tributaries that provide or have potential to provide thermal refugia, wetlands, and groundwater (seeps and springs) sources that provide cool water (USDA et al. 1993). USDA et al. (1993) indicated that stream buffers may need to be wider for maintaining microclimate than for other riparian functions. The contribution of microclimate to stream temperature is an area needing further research.

HABITAT COMPLEXITY

Problem Assessment

Land management activities can alter processes that create and maintain riparian and aquatic habitats, often resulting in reductions of habitat complexity and the diversity of aquatic species (Elmore and Beschta 1987; USDA et al. 1993). In watersheds containing bull trout, changes in habitat features associated with reductions in habitat complexity include decreases in: large woody debris, pool quality, channel stability, substrate quality, groundwater inflows, and suitable habitat serving as corridors between habitat patches (e.g., resulting from increases in water temperature [MBTSG 1998.

Large pools, consisting of a wide range of water depths, velocities, substrates, and cover, are characteristic of high quality aquatic habitat and an important component of channel complexity. Moreover, bull trout are associated with large, deep pools (Watson and Hillman 1997). Large pools have been lost in many tributaries of the Columbia River in the past 50 years (Sedell and Everest 1991; McIntosh et al. 1994; USFS 1996). Overall, there has been a 58 percent reduction in the number of large, deep pools in resurveyed streams in National Forests within the range of the Northern spotted owl in western and eastern Washington (USDA et al. 1993). A similar trend is apparent on private lands in coastal Oregon where large, deep pools decreased by 80 percent (USDA et al. 1993). In western Washington, Bisson and Sedell (1984), reported a similar loss of pools in basins with moderate to intensive levels of timber harvest has been reported. Historical grazing practices in eastern Oregon have contributed to degraded riparian zones with reduced summer flows, unstable and eroding stream banks, and reduced productivity of fish and wildlife (Elmore and Beschta 1987). Reduction of wood in stream channels, either from present or past activities, generally reduces pool frequency, quality, and channel complexity (Bisson et al. 1987; House and Boehne 1987; Spence et al. 1996). Road construction and timber harvest on unstable slopes can result in the loss of pools due to mass wasting and sedimentation (Janda et al. 1975; Morrison 1975; Swanson and Dyrness 1975; Ziemer and Swanston 1977; Betcha 1978; Ketcheson and Froehlich 1978; Marion 1981; Swanson et al.1981; Coats 1987; Kelsey et al. 1981; Madej 1984; Nolan and Marron 1985; Grant and Wolff 1991).

Large woody debris (LWD) in streams enhances the quality of habitat for salmonids and contributes to channel stability (Bisson et al. 1987). It creates pools and undercut banks, deflects streamflow, retains sediment, stabilizes the stream channel, increases hydraulic complexity, and improves feeding opportunities (Murphy 1995). By forming pools and retaining sediment, LWD also helps maintain water levels in small streams during periods of low stream flow (Lisle 1986 cited in Murphy 1995).

Cover is another important component of habitat complexity that is utilized by bull trout at all life-history stages. Cover can include woody debris, overhanging vegetation, undercut banks, cobble and boulder substrate, water depth and turbulence, and aquatic vegetation (Graham et al. 1981; Pratt 1984; Hoelscher and Bjornn 1989; Goetz 1991; Pratt 1992; Murphy 1995). Past land management activities have reduced cover through reductions in riparian vegetation and associated decreases in woody debris recruitment, declines in pool size and frequency, stream clean-up activities that removed woody debris, splash dams, and declines in shrub lands (Narver 1971; Sedell and Luchessa 1982; Bisson and Sedell 1984; NMFS 1991; Sedell et al. 1991; Lee et al. 1997).

Biological Needs

Complex aquatic habitats are necessary to accommodate the diverse needs of various salmonid species (Murphy 1995; Spence et al. 1996). Complex habitats not only provide salmonids with critical habitat for all life-history stages in freshwater, but provide refuges from environmental variability (e.g., extreme flows) and stochastic events (e.g., catastrophic fires), buffering populations from the effects of environmental perturbations (Sedell et al. 1990; Rieman and McIntyre 1993). Because most bull trout spend their entire life in freshwater, they are more sensitive to habitat disturbance than anadromous salmonids (Balon 1980; Rieman and McIntyre 1993). Bull trout are strongly associated with various components of habitat complexity, including cover, large woody debris, side channels, undercut banks, boulders, pools, and interstitial spaces in coarse substrate (Rieman and McIntyre 1993; Jakober 1995; MBTSG 1998).

Several life history features of bull trout make them particularly sensitive to activities directly or indirectly affecting stream channel integrity and natural flow patterns (MBTSG 1998). Examples of these life history features and their association with habitat complexity are:

· An extremely long period from egg deposition to fry emergence from the gravel (220 days or more during winter and early spring);

· Strong association of juvenile bull trout with streambed cobble and substrates low in fine sediments;

· Extensive spawning and overwintering migrations of adult bull trout, which require a large network of suitable freshwater habitat with migratory corridors;

· Use of deep pools by both adults and juveniles for cover and thermal refuge;

· Selection of redd sites by adults in low gradient reaches and in areas of ground water influence (C. Baxter, University of Montana, pers. comm. 1998).

· Use by both adults and juveniles of areas with reduced water velocity, such as side channels, stream margins, and pools (Watson and Hillman 1997; MBTSG 1998).

Objective

· Maintain and restore floodplain, riparian, and channel processes, including hydrologic regime, sediment inputs and transport, channel configurations, and bank characteristics, to resemble watershed-specific historic or expected conditions to the greatest extent possible.

Caution Zone

In streams, channel morphology is largely influenced by geomorphic setting and riparian vegetation (Sullivan et al. 1987 cited in Murphy 1995), and by climate (Leopold 1994) such as the frequency of rain and snow. Other factors influencing channel morphology are discharge, sediment load, bank characteristics, and solid structures, such as LWD,(large woody debris), bedrock, and boulders (Murphy 1995). The upstream head of steep channels and other steep hill slope areas are common initiation sites of debris slides and debris flows (Dietrich and Dunne 1978). Headwater riparian areas need to be protected, so that adequate materials contributing to complex habitat downstream would be available when debris slides and flows occur (USDA et al. 1993).

Because the natural processes (erosion, fire, flood, mass wasting, wind, avalanches) in a watershed produce the components that maintain complex aquatic habitat, the whole watershed may be the caution zone. At the very least, the caution zone is the 100-year floodplain plus 150 feet, plus all unstable or potentially unstable slopes. This applies to all streams, fish bearing, non-fish bearing, and intermittent in bull trout watersheds.

CONNECTIVITY

Problem Assessment

The Service’s bull trout listing team identified 141 isolated bull trout subpopulations in the Columbia River distinct population segment (DPS) and 7 subpopulations in the Klamath River DPS (Service 1998). Overall, there is a lack of connectivity among subpopulations. Isolating mechanisms that have resulted in the loss of migratory (anadromous, adfluvial, and fluvial) bull trout (Rieman and McIntyre 1993) include, physical passage blockages at mainstem impoundments that have isolated whole subbasins (Brown 1992; Pratt and Huston 1993; Rieman and McIntyre 1995), water diversions preventing spawners access to formerly suitable habitat, and thermal passage barriers at both tributary and mainstem scales.

Currently, fish passage research, management, and facility modification efforts at mainstem projects are focused on salmon and steelhead. Most projects provide upstream adult passage facilities (designed to pass steelhead and salmon), but the development of downstream passage of migrating steelhead kelts (or adult bull trout) have not been developed, and efficiency of passing these individuals through juvenile passage facilities or via spill has not been thoroughly examined (NMFS 1998). Other natural and artificial barriers may prevent upstream or downstream movement of juveniles or adults at some locations or at certain times of the year. Intervening areas of poor habitat quality may also limit dispersal of resident forms. Conversely, some man-made barriers may have unintentionally benefited bull trout by preventing invasion of non-native species such as introduced brook trout or lake trout. Habitat fragmentation and the subsequent isolation of bull trout subpopulations is a key factor in the current threatened status of bull trout in the Klamath River and Columbia River basins (Lee et al. 1997; Rieman et al. 1997). Historically current bull trout subpopulations were well connected throughout the basins (Lee et al. 1997). Many bull trout subpopulations are currently confined to smaller headwater streams that have been minimally affected by human caused habitat alterations. First and second-order streams in steep headwaters tend to be hydrologically and geomorphologically more unstable than larger, low gradient streams (Spence et al. 1996).

Small, isolated subpopulations are more likely than larger subpopulations to go extinct over long time scales due to stochastic events (e.g., landslides, catastrophic fires, and floods). Further isolation of subpopulations in shrinking habitat will probably lead to increasing rates of extirpation not proportional to the simple loss of habitat area (Lee et al. 1997). Even with no further habitat loss, extirpation may be likely for many remaining isolated subpopulations (Lee et al. 1997; Rieman et al. 1997). As subpopulations become fragmented and isolated, local extinctions become permanent, making the extirpation of other subpopulations more likely (Rieman and McIntyre 1993). Meffe et al. (1994) cautioned against managing for unnaturally small populations, and urge that gene flow among historically connected populations should continue at historical rates.

Irrigation diversions, culverts, and degraded mainstem habitats have eliminated or seriously depressed migratory bull trout, effectively isolating resident subpopulations in headwater tributaries (Brown 1992; Ratliff and Howell 1992; Rieman and McIntyre 1993; Thurow et al. 1997). Loss of suitable habitat through watershed disturbance may also increase the distance between suitable or refuge habitats and strong subpopulations, thus reducing the likelihood of effective dispersal (Frissell et al. 1993).

Biological Needs

Bull trout is a wide-ranging species with different habitat requirements at specific life history stages (MBTSG 1998). Migratory corridors provide the necessary connection between bull trout spawning, juvenile rearing, sub-adult rearing, and adult over-wintering and foraging areas (Rieman and McIntyre 1993). Disruption of migratory corridors can increase stress, reduce growth and survival, and potentially lead to the loss of the migratory life-history types (Rieman and McIntyre 1993). In general, it is necessary to provide bull trout access to a large, connected, high quality, freshwater habitat that includes cool temperature, deep pools, large wood, low substrate embeddedness, unimpaired flow regime and channel floodplain interactions.

Movement is also believed to be important to the persistence and interaction of local populations within the larger subpopulations (Rieman and McIntyre 1993). Furthermore, within the Columbia River basin, bull trout persistence will require improved connectivity among the 141 subpopulations that are not historically isolated by natural barriers or that are not currently at risk of invasion by non-native species. Enhanced connectivity for migratory life forms within bull trout subpopulations is needed to encourage population refounding and to allow gene transfer at historical rates.

Objectives

· Protect current bull trout refugia. Avoid activities or their negative effects that would further fragment habitat, reduce habitat patch size, or further isolate remaining bull trout subpopulations.

· Maintain or improve connectivity among occupied habitats and refugia by removing human-caused physical, thermal, and chemical barriers within and among isolated subpopulations in areas not at risk of invasion by non-native species (e.g., introduced brook trout, lake trout).

· Improve connectivity among occupied habitats and refugia by providing for passage of both upstream and downstream bull trout migrants at mainstem hydroelectric and flood control projects.

· Restore occupiable habitat, particularly in low gradient unconstrained channels that often serve as migratory corridors or seasonal habitats for specific life-history stages of bull trout. Historically, alluvial floodplain reaches were highly productive for salmonids, and bull trout occur significantly more often in streams of alluviated lowlands and valleys than in other areas.

Caution Zone

The area of concern for improved connectivity is the watershed, basin, or largest hydrologic unit that matches bull trout distribution within a distinct population segment (DPS) or historical subpopulation. Further research into interactions among bull trout subpopulations may help refine the appropriate scale for understanding connectivity issues.

SUBSTRATE COMPOSITION AND STABILITY

Problem Assessment

Bull trout show strong affinity for stream bottoms and a preference for deep pools of cold water streams, lakes and reservoirs (Goetz 1989). Because of this strong association with the stream bottom throughout their life history, they can be adversely affected by human activities that directly or indirectly change substrate composition and stability.

Sedimentation reduces pool depth, alters substrate composition, reduces interstitial space, and causes channels to braid (Rieman and McIntyre 1993 citing others). For example, in National Forests within the range of the northern spotted owl in western and eastern Washington, there has been a 58 percent reduction in large, deep pools as a result of sedimentation and loss of pool-forming structures such as boulders and large wood (USDA et al. 1993). In the Oregon and Washington portions of the Columbia Basin outside the range of the northern spotted owl, preliminary results indicate that the frequency of large pools within managed watersheds have decreased by 28 percent over the past 50 years (McIntosh et al. 1994). Sedimentation from extensive and intensive land use activities (timber harvest, road building, livestock grazing, agriculture, and urbanization) is recognized as a primary cause of habitat degradation in the range of west coast steelhead and west coast chinook salmon (NMFS proposed rules: 62FR43937, 63FR11798, and 63FR11482). Impoundments and diversions have altered natural sediment transport processes, causing deposition of fine sediments in slackwater areas, reducing flushing of sediments through moderation of extreme flows, and decreasing recruitment of coarse material (including spawning gravels) downstream of the obstruction (Spence et al. 1996).

According to Rieman and McIntyre (1993), “Some substrates are more likely to accumulate fine sediments than others, and some bull trout populations probably are more sensitive than others. In the absence of detailed local information on population and habitat dynamics, any increase in the proportion of fines in substrates should be considered a risk to productivity of an environment and to the persistence of associated bull trout populations”

Biological Needs

For spawning, bull trout prefer loose, clean, gravel (McPhail and Murrey 1979; Fraley and Shepard 1989). Spawning occurs primarily in gravels and cobbles (Baxter and McPhail 1996). Due to the bull trout’s extended residency in the gravel (220+ days from egg deposition to emergence), eggs, alevins, and fry are highly vulnerable to bedload movements and deposition of fine sediments. Because juvenile bull trout are closely associated with the stream substrate, they are also sensitive to bedload movements. Unembedded substrate is an important cover element for juvenile bull trout, especially in areas lacking other forms of cover (Goetz 1989; Pratt 1992; Baxter and McPhail 1996; Thurow 1997). Juvenile bull trout densities decrease with increasing embeddedness of substrate (Shepard et al. 1984; Enk 1985; Pratt 1992).

Objectives

· Maintain or restore the sediment regimes under which aquatic ecosystems evolved.

· No increase of sediment delivery from management activities to stream channels in sensitive reaches (spawning and rearing areas, less than 3% gradient) including no measurable increase in percent inter-gravel fine sediment in spawning areas.

· Where land management induces sediment delivery is occurring, achieve a net decrease in sediment delivery.

· No measurable detrimental change in channel stability (MBTSG 1998).

· No measurable loss of pocket water and pools.

Caution Zone

Because coarse and fine substrate may come from any part of the watershed, and its delivery is influenced by basin hydrology, the entire watershed is the caution zone.

ROADS

Problem Assessment

Roads are a prevalent feature on managed forested and rangeland landscapes, and can have numerous negative effects to bull trout. The aquatic assessment portion of the Interior Columbia Basin Ecosystem Management Project (ICBEMP) provides a detailed analysis of the relationship between road densities and bull trout status and distribution (Quigley et al. 1997). The following problem assessment draws on information contained in that report. Bull trout are less likely to use streams in highly roaded areas for spawning and rearing, and where found in highly roaded areas are less likely to be at strong population levels. Bull trout strongholds in the Interior Columbia River Basin showed a very strong (P=0.0001) negative correlation with road densities. The average road density in bull trout strongholds was 0.45 miles/square mile, which is considerably less than the standard of 2 - 3 miles/square mile reported as adequate for populations of other, anadromous salmonids. Bull trout populations classified as “depressed” had an average watershed road density of 1.4 mile/square miles and bull trout typically were absent at an average road density of 1.7 miles/square miles. Although some variability in these patterns was apparent (correlation coefficients were not reported) the association was strong, suggesting that bull trout are exceptionally sensitive to the direct, indirect, or cumulative effects of roads.

Quigley et al. (1997) state that,

“the effects associated with roads reach beyond their direct contribution to disruption of hydrologic function and increased sediment delivery to streams. Roads provide access, and the activities which accompany access magnify the negative effects on aquatic systems beyond those due solely to roads themselves. Activities associated with roads include, but are not limited to, fishing, recreation, timber harvest, livestock grazing, and agriculture. Roads also provide avenues for stocking non-native fishes. Unfortunately, we do not have adequate broad-scale information on many of these attendant effects to identify their component contributions accurately. Thus we are forced to use roads as a catch-all indicator of human disturbance.”

Biological Needs

Bull trout need streams and lakes that are cold, clean, complex and connected (MBTSG 1998). Roads have the potential to adversely affect all of the habitat components discussed in this Guidance: water temperature, substrate composition and stability, habitat complexity, and connectivity. Roads may also isolate streams from riparian areas, causing a loss in floodplain and riparian function. Furniss et al. (1991) state that,

“Roads may have unavoidable harmful effects on streams, no matter how well they are located, designed or maintained...Roads modify natural hillslope networks and accelerate erosion processes. These changes can alter physical processes in streams, leading to changes in stream flow regimes, sediment transport and storage, channel bank and bed configurations, substrate composition, and stability of slopes adjacent to streams. These changes can have significant biological consequences that affect virtually all components of stream ecosystems.”

Increased sediment transport to streams is one of the most frequently cited effects of roads (Gibbons and Salo 1973; Reid and Dunne 1984; Everest et al. 1987; Swanston 1991). Increased levels of sedimentation often have adverse effects on fish habitats and riparian ecosystems, and fine sediment deposited in spawning gravels of bull trout can reduce survival of eggs and developing alevins (Weaver and White, 1985; Weaver and Fraley 1991; Cross and Everest1995). Important habitat components for juvenile bull trout such as benthic invertebrate abundance, food availability, interstitial spaces in the substrate, and pools may be reduced or lost due to increased levels of sediment (Megahan et al. 1980; Shepard et al. 1984; Everest et al. 1987; USDA and USDI 1993)

Various effects of roads may combine to alter the hydrologic response to characteristics of streams. Roads and roadside ditches may substantially increase the stream drainage network. Roads also intercept groundwater and significantly compact forest soils, resulting in increased surface runoff. Any of these changes may contribute to increased stream peak flows. During normal high flow events, the added stream power may help mobilize coarse bedload (boulders, cobble, gravel). Depending on magnitude and timing, this has the potential to cause physical displacement and direct mortality of bull trout eggs and juveniles.

Bull trout are highly vulnerable to extinction when they exist as small, isolated subpopulations above man-made barriers. Widespread degradation of bull trout habitats resulting from direct and indirect effects of roads provide barriers to bull trout movement. Barriers to movement can result in fragmentation and isolation, resulting in subpopulations being more vulnerable to all other stressors. Other stressors include hybridization with brook trout, angling and poaching, as well as degradation of spawning and rearing habitats (MBTSG 1998).

Objectives

· Manage or reduce negative road effects to habitat in bull trout watersheds by repairing and relocating roads, and by decreasing current road densities.

· Restore floodplain and habitat connectivity by removing physical barriers to migration caused by roads, culverts, fords and crossings, and maintain or restore hydrologic processes and floodplain functions. However, in specific cases where barriers block non-native species access to bull trout habitat, retaining the barrier may be more desirable than removing it.

· Implement integrated road management strategies across public and private lands for bull trout.

· Control road access, avoid road placement, and prioritize road removal to eliminate access for non-native species introductions in areas of high native species integrity.

· Control road access, avoid road placement, and prioritize road removal to eliminate access for poaching in bull trout staging and spawning areas.

· Avoid road placement and prioritize road removal to eliminate impacts that increase peak flows and physical disturbance causing mortality of eggs that may be in the gravel or displacement of juveniles using the substrate for cover.

Caution Zone

Because impacts from roads in both upland and riparian forests potentially affect bull trout habitat, the entire watershed is the caution zone. Although findings from ICBEMP have not been analyzed for watersheds west of the Cascades (i.e., where the Northwest Forest Plan applies), it is very likely that these patterns will apply equally to those steeper, wetter coastal forests.

FLOODPLAIN AND RIPARIAN PROTECTION

Problem Assessment

Both east and west of the Cascades, current riparian vegetation patterns are fragmented and early seral vegetation has frequently replaced mature riparian forests. For example, basinwide analysis of the Interior Columbia Basin indicates that riparian tree composition and age and size class have changed largely as a result of land management activities, while riparian stand density has increased (USDA and USDI 1997). In many areas, including eastern Washington, fire control in addition to other land management practices has contributed to shifts in species composition away from native, shade intolerant species (e.g., ponderosa pine) towards higher stand densities of native and non-native shade tolerant species.

Similarly, riparian habitat conditions on federal lands within the range of the northern spotted owl have been degraded by road construction and land management activities (USDA and USDI 1994). This has resulted in many riparian areas being currently dominated by red alder or bigleaf maple and containing fewer conifers than the historic condition (USDA et al. 1993). These changes in species composition and size of riparian conifers can affect the amount of shading provided to streams and the potential large woody debris component needed to maintain channel complexity, as well as other riparian and floodplain functions.

Biological Needs

Floodplain and riparian forest functions important to bull trout include: storing and slowing floodwaters; absorbing pollutants from runoff; reducing sediment delivery to streams; providing a forage base to fish and habitat to some aquatic invertebrates; maintaining habitat and channel complexity; supplying shade, nutrients, and large woody debris; providing hydrologic connectivity for seeps, springs, and groundwater upwellings; and providing connectivity to off-channel habitats.

Caution Zone

Each specific riparian function primarily operates within an area of variable size relative to the stream channel. For example, the USDA et al. (1993) and Montana Bull Trout Scientific Group (1998), identified the following functions of riparian zones and widths of riparian area associated with maintaining each function: