From time immemorial the Coeur d’Alene Tribe depended on runs of anadromous salmon and steelhead and centered their fishing activities along the upper reaches of the Spokane River and in Hangman Creek (Scholz et. al. 1985).  Several estimates have been made of the amount of the anadromous fish resource that was consumed by the Coeur d’Alene People.  These estimated annual per capita consumption rates for the Coeur d’Alenes ranged from 100 pounds per year to 700 pounds per year, with the average per capita for Plateau Tribes in general ranging from 300-365 pounds per year (Scholz et al. 1985).  It is generally acknowledged that the Coeur d’Alenes shared Spokane Falls with the Spokane People, but Hangman Creek at the confluence with the Spokane River and the fishing site near what is now Tekoa, Washington are recorded as being primarily used by the Coeur d’Alene People (Scholz et. al. 1985).  Chinook are acknowledged to prefer riverine habitat (Healey 1991), and the reference to their harvest in the Hangman Watershed near the western boundaries of the current Coeur d’Alene Reservation (Scholz et al. 1985) indicates conditions prior to the 20^th century were substantially different than the current Hangman Watershed.

Construction and operation of the Federal and non-Federal hydropower system during the 20^th century directly led to the complete extirpation of all anadromous and some resident fish populations as well as the permanent destruction of thousands of acres of critical fish and wildlife habitat throughout portions of the Upper Columbia River and its tributaries.  Such is the case with Chief Joseph, Grand Coulee, and Albeni Falls dams as well as additional hydro facilities constructed along the Spokane River.  Simultaneously, rapid changes in land management practices further altered the fish species composition in Hangman Creek and the availability of native terrestrial wildlife habitat (Edelen and Allen 1998).  From the World War II era to the present, streams were straightened and channelized to provide more arable lands, with the greatest modifications occurring during the 1950s and 1960s.  By 1996, the predominant use of the land within the Hangman Watershed on the Coeur d'Alene Reservation was agriculture (65.1%), followed by forest (37.9%), grassland (0.2%), developed (0.3%) and wetland (0.006%) (Redmond and Prather 1996).  Because of the land modifications to Hangman Creek, the watershed was listed in the Environmental Protection Agency’s 303d list in 1998 for habitat alteration, sediment, nutrients, and bacteria.  Moreover, tributaries to Hangman Creek within Idaho were also listed in 2002 for elevated temperature.

The Pacific Northwest Electric Power Planning and Conservation Act (Act) of 1980 explicitly gives the Bonneville Power Administration (BPA) the authority and responsibility “to protect, mitigate, and enhance fish and wildlife to the extent affected by the development and operation of any hydroelectric project of the Columbia River and its tributaries in a manner consistent with the program adopted by the Northwest Power Planning Council (NWPPC).”  The Coeur d’Alene Tribe has engaged in restoration of the resident redband populations in the Hangman Creek watershed through provisions of the Act as part of the Substitution for Anadromous Fish Losses defined in the NPCC’s 2009 Fish and Wildlife Program Amendments (i.e. Restore and increase the abundance of native resident fish species throughout their historic ranges when original habitat conditions exist or can be feasibly restored or improved. {Page 12}).  The companion projects entitled, Coeur d’Alene Fisheries Enhancement- Hangman Creek (BPA Project #2001-032-00) and Hangman Creek Wildlife Restoration (BPA Project #2001-033-00), were initially submitted during 2000 for inclusion in the FY2001 – FY2003 budget cycle for the Spokane Subbasin, and the Coeur d’Alene Tribe proposes to continue the process of Resident Fish Substitution by resubmitting these projects in the current solicitation process.

Environmental Conditions in Hangman Creek

The study area consists of the portion of Hangman Creek watershed that lies within the Coeur d’Alene Reservation and extending east to the headwaters.  The Washington-Idaho State border, which corresponds to the border of the Coeur d’Alene Indian Reservation, marks the western boundary of the project area.  Watershed area is 870 sq. km with elevations ranging from 754 meters at the Washington/Idaho border to 1,505 meters at the top of the Hangman/Coeur d'Alene Basin divide.  The named tributaries within the basin include NF Rock, Rose, and Rock Little Hangman, Moctilimne (a tributary of Little Hangman), Mission, Lolo, Tensed, Sheep, Smith, Mineral, Nehchen, Indian, the SF Hangman and its’ tributaries Conrad, Martin, Tenas, and Papoose, and the upper part of Hangman Creek east of the Reservation along with its’ named tributaries Hill and Bunnel.  All of these tributaries except Little Hangman were thought to be home to trout in the 1940’s (Aripa 2003).  By 2005, the study area was focused to include just the 638 sq. km that comprise the southern part of the watershed to be addressed by this project.

The climate is sub-humid temperate with cool, wet winters and warm, dry summers.  Annual precipitation at DeSmet, Idaho for the years 1963-1983 was estimated to range from 70 to 90 cm (WRCC 2008).  A distinct precipitation season typically began in October or November and continued through March.  Approximately two-thirds of annual precipitation occurred during this period and rain-on-snow events generated by moisture laden Pacific air masses were common in late winter months (Bauer and Wilson 1983).  Temperatures in the watershed are mild overall.  The average daily maximum for August of the 1963-1983 reporting period was 82.2°F.  The average daily minimum for January, which was the coldest month of the year, was 20.9°F.  Snows in the lower elevations of the study area do not persist throughout the winter and in the higher elevations the snowpack is typically depleted by April or May.  The geology of the Project Area consists of a Precambrian basement complex (the Belt Series) overlain in most areas by alternating strata of the Latah Sands and Clays and Columbia River Basalts that are highly variable in extent and depth (Ko et al., 1974).  Terrain above roughly 850 meters is composed mainly of Precambrian quartzites and argillites.  Terrain below 850 meters is capped almost exclusively by the Palouse loess uplands and Holocene alluvium along current stream channels, and exhibits characteristic rolling, hilly topography.  The Project Area is perched 150 to 300 feet above its aquifers that are confined to Latah Sands and Clays and the Columbia River Basalts (Ko et al. 1974).  The Project Area is on the eastern edge of what Bailey (1995) referred to as the Dry Steppe portion of the Temperate Steppe Division.  The higher elevation quartzite and argillite formations are largely covered by coniferous forests.  The lower-elevational Palouse formation, with its deep loess soils, is managed for the cultivation of non-irrigated crops (e.g. wheat, oats, and lentils).

Natural disturbance and succession regimes in the target watersheds have been severely altered during the last 100 years and are consistent with commodity-induced patterns described for much of the Interior Columbia Basin (USDA Forest Service 1996).  The historical vegetation communities characterized by mesic mountain forests, open woodland transition forests, and wetland/riparian habitats have been replaced by agricultural crops in much of the watershed and the remaining native habitats have been greatly altered to channel water off the landscape to facilitate agricultural production (Redmond and Prother 1996; Black et al. 1998, Jankovsky-Jones 1999).  Currently, 65% of lands in Hangman Creek have been converted to agricultural and other uses.  Bottomland wetlands have largely disappeared due to ditching and draining of fields, entrenched stream beds, and cultivation - more than 80% of historic wetlands demonstrate some loss of functional value (CDA Tribe 2000).  Riparian vegetation is likewise sparse over much of the basin.  In the valley bottom along the mainstem, fields are typically plowed to the channel margins.  Where riparian vegetation does exist in the open bottomlands, it is dominated by invasive reed canary grass (Phalaris arundinacea).  Old (160+years), unmanaged forests had been reduced to a fraction (~10%) of their historic extent by 1933 (Wyckoff 1937), although forest conversion has been minimal since the 1960’s.  In much of the remaining forested habitats, the old single- and multi-story forests resulting from more or less frequent disturbance by fire have largely been replaced by younger forests resulting from frequent harvest.  The current communities often are denser and have higher mortality, higher fuel loadings, and higher susceptibility to crown fire than historical communities.  Geomorphic instability associated with channel incision, alteration of riparian vegetation, and increases in peak flow and sediment loading affect much of the mainstem Hangman Creek as well as the lower portion of tributaries reaches.

Status of Interior Redband Trout in the Upper Hangman Watershed

Interior redband trout are native to the watersheds of the Spokane Subbasin.  However, because of a paucity of available records and documents, many information gaps exist regarding their historical distribution and abundance for comparison with contemporary data.  In addition, the current carrying capacity and potential productivity for redband trout within the Spokane Subbasin have not yet been determined.  Recent surveys suggest that redband trout are present, or suspected to exist, in the Spokane Arm, Spokane River, Little Spokane River drainage, and Hangman Creek drainage of the Spokane Subbasin.

In order to manage, conserve, and protect native redband trout, a better understanding was needed of their current status and distribution within watersheds of the Spokane Subbasin.  To address this concern, assessments were conducted during the early years of this project from 2002 to 2004 to examine the distribution, abundance, and genetic status of redband trout in the upper Hangman watershed.  Results from these surveys indicated that redband were not found within lands managed for agricultural production, but were found in headwater streams where forest overstory and steep topography provided suitable in-stream habitats for fish (Peters et al. 2003).  Briefly, redband trout were sampled in the Mission, Sheep, Nehchen, Indian, and South Fork of Hangman sub-watersheds, and in upper reaches of Hangman creek (Figure 1).  In contrast, redband trout have not been found in tributaries in the north section of the assessment area where agriculture predominates (e.g., Tensed, Moctilemne, Lolo, Rock, North Fork Rock, Rose, and Little Hangman creeks).

Results from the genetic analysis conducted in 2003-2004 indicated that sampled subpopulations in tributary reaches in the upper Hangman Creek watershed formed a cohesive group, and were more associated with each other than with fish from lower Hangman and from other reaches in the Spokane River (Small and Von Bargen 2005).  However, results also indicated that population fragmentation indicative of reproduction isolation may be occurring at the tributary scale in the upper Hangman watershed (i.e., significant genotypic differences among sampled sub-populations).  Furthermore, significant departures from Hardy-Weinberg equilibrium expectations for most of the upper Hangman collections suggest that either substantial inbreeding may be occurring within each sub-population, likely the result of small effective population sizes, or that subpopulations each experienced a recent genetic bottleneck.  Collectively, these results suggest that increasing the connectivity of tributary subpopulations would promote a more robust and resilient population structure and would minimize the adverse consequences that arise from isolated, small populations (Gilpin and Soule 1986).  Further, given that the genetic signature from redband trout in California Creek, a tributary in the lower reach of the Hangman watershed, aligned more with fish from upper Hangman than with those downstream in the Spokane Subbasin, there is evidence that movement and sub-population connectivity throughout the drainage likely existed in the past and may have been an important mechanism that promoted metapopulation persistence.

Results from the genetic analysis also indicated that redband trout in the upper Hangman watershed were relatively pure with a lack of detectable introgression with coastal strains of rainbow trout.  Thus, even though the non-native coastal subspecies of rainbow trout have been repeatedly introduced into the Spokane River by WDFW from 1933 to 2002, apparently conditions in upper Hangman have prevented successful colonization by these fish and a resulting lack of genetic introgression.  Another finding from the genetic analyses that confirmed our visual observations was that fish sampled from upper Nehchen Creek were genetically more similar to cutthroat trout, a salmonid not native to the Hangman watershed, than to redband trout.  However, given the low allelic richness detected in these fish and the lack of detectable cutthroat genes in other sampled tributary subpopulations, it is likely that the fish from Nehchen creek were the result of a localized introduction of a small number of fish and, as a result, were relatively isolated and not widespread throughout the upper Hangman watershed.  Indeed, this was corroborated by a landowner who claims to have transplanted cutthroat trout from Benewah Creek, a tributary of Coeur d’Alene Lake, into Nehchen Creek in 1985.

Figure 1.  Contemporary distribution of interior redband trout in the upper Hangman watershed.

Established Limiting Factors

There are a number of limiting factors that have contributed to a decline in productivity for native fish stocks within the watershed, as reflected in the QHA analysis completed for the Subbasin Plan.  Habitat factors include alteration of stream flow patterns, increased sediment production and delivery to streams, widespread channel instability, elevated summer water temperatures in some mainstem reaches, and reduction in overall habitat diversity/complexity (Intermountain Province Subbasin Plan 2004).  The magnitude and severity of impacts have been ranked with the greatest deviation from the reference habitat conditions for redband trout in the subbasin (Intermountain Province Subbasin Plan 2004).  Many of these major limiting factors are addressed by this project and are discussed below.

Hydrologic and Geomorphologic Factors

The prevailing climate and topography when coupled with land management practices such as tilling, tiling, grazing, riparian vegetation removal, stream channelization, logging, and road building have all contributed to a flashy hydrologic cycle and increased stream sediment pollution (Spokane County Conservation District 1994, Isaacson 1998).  Rain-on-snow events in particular swell streams, contribute to the erosion of lands and cause a pulse of stream sediment pollutants (Bauer and Wilson 1983).  Conversion of forestlands and other native vegetation communities has enhanced the rain-on-snow phenomenon and accelerated the rate of snow pack depletion to varying extents.  Estimates of peak stream flow increases in the watershed range from 55-93%, although site specific rates of change are unknown (Coeur d’Alene Tribe 2000).  Discharge regimes during high flow events are flashier in the Hangman mainstem and in Mission and Sheep creeks compared with tributaries that are less disturbed such as Indian and Nehchen creeks (Figure 2).  In addition to Mission and Sheep creeks, other heavily impacted sub-watersheds, such as Smith and Tensed creeks, exhibited severe flooding during moderate rain storms.  

Figure 2. Comparisons of discharge in Hangman Creek and four fish bearing tributaries, 2004-2007.

In much of the mainstem Hangman Creek and lower tributary reaches of the upper watershed, stream flow alteration and removal of native riparian vegetation has greatly reduced the resistance of stream banks and the channel bed to erosion.  Stream channel morphology and landform within the valley bottoms are consistent with the entrenchment and development of a new, lower elevational flood plain that occurs following major disturbance (Leopold 1994; Rosgen 1996; Shields et al. 1995).  Channel morphology has been altered in this manner through approximately 26.6 miles (51%) of the project area (Figure 3).  Stream cross sectional data gathered through watershed assessments (Inter-Fluve 2006; 2008) are representative of conditions in the upper mainstem and indicate that these reaches are entrenched 3 to 8 feet below the valley floors (Figure 4).  The high sediment loads and low base flows are indicative of this transition phase in stream morphologic development (Hardin-Davis, Inc. 2005, Idaho Department of Environmental Quality 2007, Washington Department of Ecology 2009).

Figure 3. Spatial distribution of incised reaches in the upper Hangman watershed.  Channel incision was determined from Rosgen channel typing surveys. 

Figure 4. Sample cross section of the Hangman Creek mainstem within the hnt'k'wipn Management Area.  The red horizontal line represents the approximate elevation of the abandoned flood plain at two times the bankfull flood elevation (blue line).

Over time, this process has affected the hydraulic linkages between channels and floodplains through reduction in floodplain recharge and hyporheic exchange (Darby and Simon 1999).  These linkages are particularly important in maintaining floodplain wetlands and their wet meadow, scrub-shrub and forested plant communities in systems like Hangman Creek, where soil characteristics restrict water infiltration and retention for spring plant growth (Westbrook et al. 2006; Westbrook et al 2011).  The resulting reduction in floodplain storage capacity within the watershed is evident in both the responses of stream channels to storm events and in the low base flows observed during the warmest part of the year (Idaho Department of Environmental Quality 2007; Washington Department of Ecology 2009; Kinkead and Firehammer 2011).  Additional modeling completed in the Hangman Creek watershed (Hardin-Davis 2005; Uhlman 2007; Callery 2007) has helped to identify hydrologic priority areas for addressing these limiting factors (Figure 5).  The overlap between these hydrologic priorities and the stream reaches that connect critical spawning and rearing habitats currently sustaining fish define the focal areas for restoration efforts to reconnect streams/floodplains addressed by this project.

Figure 5. Priority habitats for restoration of channel/floodplain linkages in relation to the distribution of redband trout in Upper Hangman Creek.

Water Quality

Low flows and inadequate dissolved oxygen levels during summer base flow periods have presented suboptimal rearing conditions for redband trout in specific locales in the upper Hangman Creek watershed (Table 1).  Tributaries in the northern part of the Hangman Creek watershed that are heavily impacted by agriculture (e.g., Andrew Springs, Lolo, Tensed, and Rock creeks) either lack water during base flow periods or display dissolved oxygen profiles that would be insufficient to support salmonids.  Low flows (e.g., standing pools or dewatered reaches) and attendant low levels of dissolved oxygen (i.e., < 6 mg/L) have also been repeatedly documented in reaches of Mission, Sheep, and South Fork of Hangman sub-watersheds.  Lower reaches of Nehchen Creek have also been found to be consistently dewatered during summer periods.  Low levels of dissolved oxygen have also been documented in main-stem reaches of Hangman creek in some years (e.g., 2007).

Table 1.  Discharge (DS; cfs) and dissolved oxygen (D.O.; mg/L) measured during base flow conditions at sites in sub-watersheds of the upper Hangman watershed, 2004-2007.  Sites are ordered relative to their longitudinal position downstream to upstream within each sub-watershed.

The legacy of land-use activities in the upper Hangman watershed has also contributed to elevated stream temperatures through various mechanisms.  Agricultural conversion of native vegetation communities in riparian habitats, notably in low gradient floodplain reaches, has reduced streamside canopy closure. Channel incision, in part due to the loss of riparian and floodplain vegetation, also has contributed to elevated summer water temperatures due to a reduction in overbank flooding and concomitant loss of groundwater recharge from floodplain storage during summer base flows (Brunke and Gonser 1997).  As a result of these impaired processes, temperature profiles exhibit distinct differences between agriculturally dominant reaches and forested reaches in the upper Hangman watershed.  Generally, stream temperatures during critical spawning/incubation and summer rearing periods exceed established thresholds (14^oC, a threshold selected by the Idaho Department of Environmental Quality, identified suitable spawning and incubation temperatures from May 1 to June 30, and 20^oC, a threshold selected internally, identified suitable summer rearing temperatures from July 1 to August 31) a high percentage of the time in main-stem reaches of Hangman Creek and in lower non-forested reaches of Mission, Sheep, Nehchen, and Indian sub-watersheds (Figure 6).  In comparison, stream temperatures in forested, upstream reaches within these sub-watersheds typically remain below these established thresholds.  Moreover, when considering stream reaches in aggregate, temperatures are more favorable in Indian Creek and in tributaries in upper Hangman Creek (e.g., Martin Creek) than other sub-watersheds (Figure 6).  Given the relationships between stream temperature and redband trout distribution and abundance that have been documented in other systems (Li et al. 1994; Zoellick 2004; Meyer et al. 2010), the marked differences in temperature profiles that are evident across stream reaches in the upper Hangman watershed likely explain in part the distributional patterns that have been reported for redband trout in our study area.

Figure 6.  Spatial pattern of temperature exceedances above established thresholds during critical periods for redband trout in the upper Hangman watershed.  Thresholds included a value of 14^o C during the spawning/incubation period from May 1 to June 31, and a value of 20^o C during the summer rearing period from July 1 to August 31.

Habitat Diversity/Complexity 

The documented disparity in the distribution of redband trout within the upper Hangman watershed may not only be explained by temperature but may also be a result of differences in physical attributes among reaches that constitute habitat suitability.  Forested reaches in Indian Creek and in upper Sheep and Mission creeks, where redband trout are commonly found, have a lower percentage of fines in riffle substrates, greater canopy cover, and more in-stream wood than in other agriculturally-dominant reaches, such as downriver reaches of Sheep and Mission creeks and main-stem reaches in Hangman creek (Table 2, Figure 7).  This is consistent with other studies that have found redband trout occurrence and abundance to be positively related to the percent of silt-free substrate and canopy cover (Li et al. 1994; Zoellick and Cade 2006; Meyer et al. 2010).  Macro-invertebrate metrics (e.g., percent plecopterans), which were highly correlated with percent fines and stream temperatures, also describe a trend of decreasing habitat quality for salmonid species from upstream to downstream for all fish-bearing tributaries in the upper Hangman watershed (Table 2).

Only discrete stream reaches within upper, forested portions of some tributaries (e.g., Indian Creek and Mission Creek) have wood volumes that are comparable to the median values gathered from other studies of managed and unmanaged sites in forest types similar to our study area (Miller et al 2008; Young et al. 2006; Fox and Bolton 2007); the vast majority of stream segments have much lower wood volumes than the criteria we have established for these areas (6.0 m³/100m).  However, even in these select few forested reaches, these comparable wood volumes comprise relatively small individual pieces (e.g., lack of pieces > 1.0 m³) that do not necessarily contribute to channel-forming processes.  Consequently, the general lack of large woody debris, both within the stream channel and the adjacent floodplain, within the upper Hangman Creek watershed has been identified as a contributor to poor habitat quantity and quality.  Researchers have attributed wood volume and/or frequency as influential in processes operating at the channel reach, valley bottom, and landscape scales.  Not surprisingly, our habitat data indicate that the frequency, depth and longitudinal percentage of pool habitats were generally much lower than that reported in the 7-year PACFISH/INFISH status review for long-term monitoring sites with similar channel geometry (Henderson et al. 2005).  Pools greater than 1 ft in residual depth are generally scarce throughout tributary reaches (Table 2).  In fact, much of the deep pool habitat (e.g., mean residual pool depth greater than 1.5 ft) in the study area is found in the main-stem of Hangman Creek and in lower reaches of Mission and Sheep creeks where water quality and other physical features (e.g., low canopy cover and LWD volume, excessive fine sediments) are currently inadequate to support suitable rearing habitat for redband trout (Table 2).  Our surveys of tributary habitats in adjacent watersheds indicated that only a small proportion (about 3% overall) of in-stream wood pieces form pools, while larger pieces are more likely to provide habitat function (Miller et al. 2008).  One implication of this research was that any reduction in wood abundance translates directly to a reduction in the number and quality of pools.  We hypothesize much of these deficiencies could be corrected through a combination of management actions, including large wood additions to streams and improved management of riparian areas with the objective of increasing canopy cover and wood loading over time.  The moderate gradient, gravel-bed streams within the project area may be the most responsive to these treatments as suggested by other researchers (Andrus et al. 1988; Robison and Beschta 1990; Abbe and Montgomery 1996).

Table 2. Summary of habitat data collected from select sites in the upper Hangman watershed during 2004-2009.  Site data are representative of lower, more agriculturally-dominant and upper, more forested reaches in each of the four fish-bearing tributaries in the watershed, and of representative mainstem Hangman reaches that are targeted for restoration actions.

Figure 7.  Spatial distribution of percent fines calculated from pebble count surveys conducted at 75 sites distributed across reaches in the upper Hangman watershed. 

Historically beaver were particularly abundant in the lower gradient reaches of these watersheds - their dams and impoundments controlled the composition and density of riparian and wetland plants, quality and quantity of fish habitat, and fluvial geomorphic processes of erosion and sedimentation (Ruedemann and Schoonmaker 1938; Naiman et al. 1988; Gurnell 1998; Rosell et al. 2005; Pollock et al. 2007; Westbrook et al. 2011).  A self-reinforcing, positive feedback cycle may exist where historic beaver trapping and removal of trees and shrubs used by beaver has resulted in extirpation or significant reduction in beaver populations in the basin, and both beaver population and beaver-generated fish habitat recovery may not occur substantively until riparian vegetation is restored (Pollock et al. 2004).  This positive feedback cycle in many cases may represent a roadblock to successful riparian and fish habitat restoration over a human lifetime.  Recovery of beaver-generated floodplain wetlands and their wet meadow, scrub-shrub and forested plant communities depends upon restoring lost hydraulic linkages between the channel and its floodplain (Westbrook et al. 2006).  Characteristic riparian floodplain vegetation depends on annual flood-pulses and a locally high water table.  Importantly, water availability may not be sufficient under certain settings such as an arid or semi-arid climate, entrenched and incised channels, and where soil characteristics restrict infiltration and water retention for spring growth.  In the Hangman watershed, we believe that beaver were the historic mechanism that supplied riparian vegetation with sufficient water to establish and maintain trees and shrubs, and that this co-dependent mechanism has not been recognized or represented sufficiently in the stream restoration tool box (Pollock et al. 2011).  Where we have surveyed beaver dams and their backwater habitats, we find much deeper pools, lower ambient water temperatures and increased thermal heterogeneity that are more conducive to providing rearing habitats for redband trout (Firehammer et al 2011). We propose to accelerate the trajectory for recovering habitat by utilizing restoration approaches that emulate the ecosystem engineering effects of beaver and enhancing the stability of natural dams where they exist in the watershed.