Study No. 18. Mystic Lake, Montana. PPL Montana 45 Basin Creek Road Butte, Montana 59701

Transcription

1 Study No. 18 Evaluation of the Current Fish Population and Habitat in West Rosebud Creek Downstream from Emerald Lake Mystic Lake Hydroelectric Project FERC No Mystic Lake, Montana PPL Montana 45 Basin Creek Road Butte, Montana Prepared by: 127 E. Front Street Ste 216 Missoula, Montana October 3, 2005

2 Table of Contents Executive Summary ii 1.0 Introduction Modified R1/R4 Habitat Inventory of West Rosebud Creek MFWP West Rosebud Creek Fish Population Sampling West Rosebud Creek Sediment and Macroinvertebrate Inventory Methods Modified R1/R4 Habitat Inventory of West Rosebud Creek MFWP West Rosebud Creek Fish Population Sampling West Rosebud Creek Population Estimate Fall Redd Survey West Rosebud Creek Sediment and Macroinvertebrate Inventory Results Modified R1/R4 Habitat Inventory Lower Reach Upper Reach Comparison of Lower and Upper Reaches MFWP West Rosebud Creek Fish Population Sampling West Rosebud Creek Population Estimate Fall Redd Survey West Rosebud Creek Sediment and Macroinvertebrate Inventory Discussion Modified R1/R4 Habitat Inventory MFWP West Rosebud Creek Fish Population Sampling West Rosebud Creek Sediment and Macroinvertebrate Inventory Tables Figures Photographs References 37

3 Executive Summary This report summarizes all studies pertaining to Study 18, Mystic Project Effects on Fish Populations and Habitat in West Rosebud Creek downstream from Emerald Lake. During 2005 PPL Montana with collaboration from the USFS and MFWP sampled stream habitat during both the spring and fall in West Rosebud Creek downstream of Emerald Lake. Prior to 2005 no habitat data was available for this section of West Rosebud Creek. Studies included using a modified USFS R1/R4 habitat survey, sediment core sampling, and aquatic macroinvertebrate sampling. In addition, MFWP provided both fish sampling data and brown trout redd survey data for PPL Montana to analyze. Those data are also contained within this report. Data from the August 29 and , substrate core and aquatic macroinvertebrate sampling are not yet available due to the limited timeline between field sampling and the scheduled deadline of this document. However, once those data have been analyzed the results will be added to this report and the report will then again be distributed to all stakeholders and the FERC. All work done in West Rosebud Creek during 2005 was done in a collaborative manner with PPL Montana, the US Forest Service and Montana Fish, Wildlife, and Parks. All members of the aquatic resource group had a voice in what studies would be conducted and what protocols would be used. Instream habitat data suggest that instream habitat in upper and lower West Rosebud Creek differ. The upper section just downstream of the Emerald Lake campground has higher quality fish habitat than the lower section, which is situated entirely within private land. Although these differences were present in the data, it is not fully understood what mechanisms are controlling these differences. Land management practices, differences in stream channel type, and the location of each reach along the longitudinal stream gradient may all be factors affecting the two sections in different ways. The size frequency histograms of fishes captured during the fall 2004 sampling indicate that various age classes of trout are present within West Rosebud Creek. This suggests that trout are using this section of stream for both juvenile and adult rearing habitat. In addition, the presence of large brown trout redds during the fall and rainbow trout redds during the spring indicate that suitable spawning habitat is available. However, it is unclear if these redds are being created by migratory fish moving into West Rosebud Creek from further downstream in the drainage, or if these are resident fish that spend their entire life cycle in West Rosebud Creek, or a combination of the two.. ii

4 1.0 Introduction This report contains all portions of Study 18, Mystic Project Effects on Fish Populations and Habitat in West Rosebud Creek downstream from Emerald Lake. Although all of the data for Study 18 have been collected, certain portions are still being analyzed and are not currently included within this report. Data that have not yet been analyzed include sediment core sampling and aquatic invertebrate sampling, both of which occurred on August 29 and 30, Those samples are currently in laboratories being analyzed. As soon as the results are available they will be added to this report, at which time PPL Montana will deliver a final all inclusive copy to the stakeholders and the FERC. 1.1 Modified R1/R4 Habitat Inventory of West Rosebud Creek During the spring of 2005 PPL Montana in collaboration with the U.S. Forest Service (USFS) and Montana Fish, Wildlife and Parks (MFWP) surveyed the aquatic habitat in two sections of West Rosebud Creek downstream of Emerald Lake. The habitat survey was conducted to assess the quality of the instream habitat and to develop a baseline for future habitat evaluations. Two sections of stream were chosen to represent conditions in West Rosebud Creek. The upper section is located on both private and US Forest Service (USFS) system lands, while the downstream section is entirely contained within private land. Historically the two sections have been influenced by different land management practices, mainly due to their ownership. For example, the USFS system land has had limited amounts of cattle grazing on it throughout the years, while heavier grazing is known to occur on the private land on an annual basis. Consequently, differences in the current habitat condition of the two sections may exist for a variety of reasons, including differing land use practices and natural differences in the physical nature of the two stream reaches (e.g. gradient, valley form, substrate composition). However, effects from the Mystic Project would likely be observed in both the upper and lower sections sampled if the Mystic Project is deteriorating the aquatic habitat downstream of Emerald Lake. For a detailed description of the West Rosebud Creek drainage and the historical operations of PPL Montana s Mystic Lake Project see the Mystic Lake Project Pre-Application Document (2004). 1.2 MFWP West Rosebud Creek Fish Population Sampling Montana Fish, Wildlife, and Parks (MFWP) collected fish population data for West Rosebud Creek downstream of Emerald Lake in the fall of The effort consisted of a mark/recapture population estimate via electrofishing and the collection of other population 1

5 statistics. Furthermore, MFWP also conducted a visual brown trout (Salmo trutta) redd survey during the fall of 2004 on West Rosebud Creek, downstream of West Rosebud Lake. Data from both the population estimate and the redd survey are presented within this report. 1.3 West Rosebud Creek Sediment and Macroinvertebrate Inventory To specifically assess the quality of important salmonid spawning habitats in West Rosebud Creek, PPL Montana with consultation from MFWP and the USFS performed a stream channel sediment and an aquatic macroinvertebrate inventory for both the upper and lower reaches on August 29 and 30, The overall goal was to assess the amount of fine sediment deposition in areas within both the upper and lower sections where salmonid spawning is most likely to occur. It is well known that excess fine sediment deposition in spawning gravels can limit trout production by suffocating redds and impairing juvenile emergence from the gravel matrix. By evaluating the quality of spawning gravels in both sections of West Rosebud Creek, we can gain a further insight into how the modified flow regime in West Rosebud Creek might be impacting these important salmonid habitats. Typically flows near bankfull discharge clean gravels of finer sized sediments, which is important in maintaining high quality spawning habitat. Therefore, by evaluating the amount of fine sediment deposition in areas where gravels are dominant, we can get a better understanding if gravels are being flushed by the current flow regime. Furthermore, it is also well known that poor land use practices such as grazing can greatly increase the overall input of fine sediments into streams. Thus, by evaluating both the upper and lower sections of West Rosebud Creek we can gain additional perspective as to the source of any excessive fine sediment deposition since both the upper and lower sections are subjected to different pressures from land management. In addition, macroinvertebrate sampling in the same habitats that are evaluated for substrate composition was conducted. This will permit analyses of the correlation between sediment and macroinvertebrate metrics. 2

6 2.0 Methods 2.1 Modified R1/R4 Habitat Inventory of West Rosebud Creek On May 2 and 3, 2005 a team of fisheries professionals lead by Darin Watschke (USFS Custer National Forest, Fisheries Biologist), Jim Olsen (MFWP, Fisheries Biologist), and Brent Mabbott (Senior Fisheries Biologist, PPL Montana) inventoried aquatic habitat in two sections of West Rosebud Creek downstream of Emerald Lake. The upper section surveyed was approximately 1.35 miles in length beginning on private land and ending on the Custer National Forest. The downstream site was entirely on private land and was approximately 0.9 miles in length. The locations of the two sites are shown in Figures 1 and 2. Global Positioning Satellite (GPS) coordinates of the upstream and downstream boundaries of the two sites can be found in Table 1. A modified USFS R1/R4 habitat inventory methodology was used. At the beginning and end of the sampling a GPS coordinate was taken to aid in repeating the sampling in the future. Sampling was conducted by beginning at the downstream boundary of the designated reach and surveying in an upstream manner, therefore river right was designated as the right bank looking upstream and river left was determined in the same manner. Both mainstem and side channel habitat was quantified. The sampling consisted of breaking the two surveyed reaches of West Rosebud Creek into habitat units (pools, riffles, runs, glides, etc.). For data analysis purposes, glides and runs were combined into a Flat Fast Water category. Alcoves were enumerated and the area estimated by taking a length and average width using a surveyors tape. In addition, maximum depth was recorded for alcoves by probing for the deepest portion of the habitat unit. Pool length was measured by using a laser rangefinder, which consisted of shooting the length between the head crest (upstream break in slope) and the tail crest (downstream break in slope). Maximum depth was recorded in pools by probing until the deepest spot was located. Pool crest depth was recorded and was defined as the maximum depth in the pool tail crest. Residual pool depth was then calculated by taking the difference between the maximum depth and the pool crest depth. Average wetted width (portion of stream that has water) of pools was recorded by taking one to three measurements perpendicular to the flow using a surveyors tape in a representative area across the stream channel. Habitat unit length was measured for all fast water habitats using a laser rangefinder by shooting the length from the units downstream to upstream boundary. Average wetted depth was measured by taking depth measurements at one-fourth, one-half, and three-fourths across a representative cross-sectional transect. Bankfull width was measured for all fast water habitat types using a surveyors tape. 3

7 In addition, bank stability was visually estimated on both the right (looking upstream) and left banks at most habitat units and recorded as the percent of the bank within the habitat unit that is stable. Bank height was also visually estimated for some habitat units. Available salmonid spawning habitat area was visually estimated throughout the reaches by visually estimating the lengths and widths of unconsolidated gravel patches, which were then converted into area (ft 2 ). Large woody debris located within the wetted width of the stream was quantified and categorized into single or aggregate. For a single piece of wood to be considered large woody debris, it needed to be at least 3 m in length or must have a length equal to or greater than two-thirds the wetted width of the stream. In addition, a single piece of large woody debris must be at least 0.1 m in diameter one-third of the way up from the base. An aggregate represents two or more pieces of large woody debris clumped together. Photographs were taken of many of the habitat units throughout the survey, especially where bank instability was high. Additionally, comments were made for habitat units where unique features were identified, such as rainbow trout (Oncorhynchus mykiss) redds, beaver complexes, head gates, etc. Due to changes in aquatic habitat parameters such as depth and wetted width with varying stream flows, the results of this report would likely be different if conducted at different flows. The most useful interpretation of the data presented within this report may be to compare the upstream and downstream reaches, which we can assume change in a similar manner with changing flow regimes. 2.2 MFWP West Rosebud Creek Fish Population Sampling West Rosebud Creek Population Estimate On September 30 and October 8, 2004 MFWP sampled the fish populations in West Rosebud Creek downstream of Emerald Lake using electrofishing techniques. The boundaries of the electrofished section are shown in Figure 3. A mark/recapture technique was used where each fish captured on the initial electrofishing pass was marked and released into the sampling reach. The reach was subsequently electrofished and the number of marked and unmarked fish were enumerated. Additionally, fish total length (inches) and wet weight (pounds) were recorded for all fish captured. Data collected by MFWP were given to GEI Consultants, Inc. and used to estimate the size of the brown trout and rainbow trout populations using the Chapman-Petersen method (Ricker 1975). Fish abundance was subsequently calculated by dividing the population estimate by the length of the stream reach sampled. 4

8 Population estimates were made for brown trout and rainbow trout. No population estimate was made for brook trout (Salvelinus fontinalis) due to the small sample size collected. It is known that fish size effects electrofishing efficiency, thus it is common to separate population estimates by size class. However, when using mark recapture methodology it is recommended that at least three fish are recaptured for a valuable estimate (Ricker 1975). Therefore, the population estimate for brown trout was broken into only two size classes, less than 8 inches in total length and greater than eight inches in total length due to the size distribution of recaptures. In addition, a population estimate was made for rainbow trout even though only one rainbow trout was recaptured. Thus, some caution should be used in making inferences from the results of the rainbow trout population estimate Fall Redd Survey On October 27, 2004 MFWP personnel conducted a redd survey in West Rosebud Creek from the outlet of West Rosebud Lake downstream to the second bridge crossing on private land located at N, W. The locations of observed redds were recorded using a handheld GPS unit and recorded. Based on past sampling of the stream and the limited number of small brook trout present, all redds were assumed to be constructed by brown trout. 2.3 West Rosebud Creek Sediment and Macroinvertebrate Inventory West Rosebud Creek was broken into an upper and lower section in the same manner as the spring modified R1/R4 sampling. All sampling was conducted using equal effort in both sections. Sampling occurred on the 29 th and 30 th of August, The sampling crew included Brent Mabbott and Frank Pickett (PPL Montana), Dan McGuire (McGuire Consulting), Darin Watschke (USFS, Custer National Forest) and Kristi Overberg and Tyler Haddix (GEI Consultants). All were present on both sampling days except for Darin Watschke, who as present during the upper section sampling. Core samples, using a 12-inch diameter McNeil Sampler were taken in individually selected salmonid spawning habitats. Five samples were taken in both the upper and lower sections. The depth of the core and the depth of the water (either below or above the rim of the sampler) was recorded for each sample. All sediments within the core were then removed and placed in five gallon buckets. A sample of the water within the core was taken using a 2 liter bottle. The position of each sample was fixed with a handheld GPS unit and recorded. A narrative description of the location of the sample site in relation to other obvious landmarks was also recorded. The sediment and the water samples from each core were labeled and sent to Piedmont Engineering in Belgrade, MT for particle size analysis. 5

9 Macroinvertebrate samples were conducted by Dan McGuire (McGuire Consulting). Macroinvertebrate samples were taken adjacent (< 1 m) to all core samples using a Hess Sampler with mesh sizes of 725 µm and a diameter of 33 cm. The samples were taken in the same type of substrate as the core samples. All macroinvertebrates were placed in an alcohol preservative and sealed for laboratory analysis. Invertebrate species identification and counts will be conducted by McGuire Consulting. The location of each sample was taken using a handheld GPS unit and recorded. Other parameters measured at macroinvertebrate sample sites were depth, velocity, and substrate composition. Velocity was taken directly upstream of the Hess sample using a digital current meter. Substrate composition was visually quantified and was recorded as percent class (cobble, gravel, sand, etc.). In addition, estimates of bed material embededness was determined along three horizontal transects within both the upper and lower reaches. Rebar pins were set at both margins of the stream channel and their locations were taken using a handheld GPS unit. A measuring tape was then strung between the pins and visual estimates of embededness were determined in equal intervals across each transect by percent embedded. Photographs were taken within the upstream and downstream sections, within the area sampled and looking upstream and downstream of the sampling sites. 6

10 3.0 Results 3.1 Modified R1/R4 Habitat Inventory A total of 11,896 ft of mainstem habitat were inventoried over the two day survey in West Rosebud Creek downstream of Emerald Lake (Table 1.) Lower Reach The lower reach consists of 4,785 linear ft of mainstem habitat and 2,585 ft of side channel habitat. Low gradient riffles dominate both mainstem (75.5%) and side channel (100%) habitat types in the lower reach Mainstem Habitat Riffles average ft in length, 54.1 ft wetted width, and 0.6 ft in depth. Pools average 134 ft in length, 44.4 ft wetted width, and 2.8 ft in maximum depth. Residual pool depth averaged 1.75 ft for the pools within the lower reach. Pool to riffle ratio for the lower mainstem reach is 0.19:1, which is consistent with both the number of pools (5) to riffles (9) and the overall length of pools (670 ft) to riffles (3,614 ft) (Table 2). The frequency of pools per length of channel is 0.1 pools per 100 ft of stream channel. Fast flat-water habitats consisting of runs and glides account for 10.5 % of the lower mainstem reach. Four of these habitat units are present in the lower reach and have an average depth of 0.9 ft. The lower reach has one alcove with a maximum depth of 0.9 ft and a total area of 572 ft 2. A total of 12 units of large woody debris were found in the lower reach, 3 aggregates and 9 single pieces. Eleven of the 12 units of large woody debris were found in riffles, with the other 1 located in fast flat-water habitat. The reach contains a total of 1,541 ft 2 salmonid spawning gravels. Five assumed rainbow trout redds were identified within the lower reach, all occurring in the downstream third of the reach. No beaver ponds are present within the lower reach. Bank stability in the lower reach ranged from a high of 100% stable to a low of 0% stable. The variety in bank stability is shown in photographs 1 through 5. The highest bank height was recorded at 15 ft, along the left bank (looking upstream) at the eastern side of the valley in habitat unit Side Channel Habitat 7

11 A total of 919 ft of side channel habitat exists in the lower reach, all of which is riffle habitat. Riffles average ft in length, 23.4 ft wetted width, and 0.4 ft in depth. Due to the absence of pools, the pool to riffle ratio is 0:1 for side channels in the lower reach. No alcoves or beaver complexes were observed within side channel habitats within the lower reach. A total of two single pieces of large woody debris and two aggregates of large woody debris were observed in side channel habitat. A total of 216 ft 2 of suitable spawning gravel occurs within the side channel habitats of the lower reach, although no salmonid redds were observed Upper Reach The upper reach contains a total of 7,111 ft of mainstem and 2,585 ft of side channel habitat. The length of mainstem (74%) and side channel (81%) habitats are dominated riffles, although pools, and other fast flat-water habitats are present Mainstem Habitat Riffles average ft in length, 39.7 ft in wetted width, and 0.6 ft in depth. Pools average ft long, 35.6 ft in wetted width, and have an average maximum depth of 3.3 ft. Residual pool depth averaged 2.15 ft for the pools in the upper reach. Riffles comprise 74% of the mainstem habitat, while pools and fast flat water habitats comprise 17% and 9%, respectively. The pool to riffle ratio for the upper mainstem is 0.23:1, with a frequency of 0.15 pools per 100 ft of stream channel. Three adjacent pools and 11 alcoves are situated within upper reach. A total of 38,112 ft 2 of alcove habitat is estimated to be present within the reach. Eleven single pieces of large woody debris and one aggregate were observed in the mainstem reach. One large beaver complex exists in the lower portion of the reach that includes two connected ponds and five intact beaver dams. Two other smaller beaver dams are located in the upper portion of the reach. A total of 2,079 ft 2 of suitable salmonid spawning habitat occurs within the upper mainstem reach. Thirteen salmonid redds were identified during the survey. Bank stability in the upper reach ranges from a low of 10% stable to a high of 100% stable. Photographs 6 through 12 show habitat units within the upper reach and give a clearer picture of how bank stability varies throughout the reach Side Channel Habitat A total of 2,585 ft of side channel habitat exists in the upper reach, with 81% comprised of riffle habitat, 10% pools, and 9% fast flat-water habitats. Riffles average ft in length, 18.5 ft in wetted width, and 0.4 ft in depth. Riffles are more numerous (12) than pools (4). Pools average 64.8 ft in length, 17.6 ft in wetted width, and have an average maximum depth 8

12 of 2.2 ft. The pool to riffle ratio for side channels is 0.12:1 and there are 0.15 pools per 100 ft of side channel habitat. A total of 26 single pieces of large woody debris and 8 aggregates were observed in the side channel habitat. No salmonid redds were observed, although 1,142 ft 2 of suitable spawning gravel exists within the side channel habitats Comparison of Lower and Upper Reaches When comparing the upper to lower reach, the upper reach is composed of a larger proportion of pool habitat, has a higher pool to riffle ratio, has a wider distribution in pool maximum depth, and has a higher frequency of pools per stream length. The upper reach is composed of 17.3% pools, 73.9% riffles, and 8.8% fast flat water habitats, while the lower reach consists of 14.0% pools, 75.5% riffles, and 10.5% fast flat water habitats (Figure 4 and Table 2). The maximum depth of pools for the upper reach range from 1.65 ft to 5.25 ft, whereas the lower reach ranges from 2.6 ft to 3.27 ft (Figure 5). The median and mean for the average maximum depth of pools is larger for the upper reach than for the lower reach (Figure 6). Residual pool depth is deeper on average for pools in the upper reach (2.15 ft) than for pools in the lower reach (1.75 ft). Although the upper reach was 1.49 times longer than the lower reach (Table 2), the upper reach contains 2.8 times more side channel habitat by length than the lower reach. Surprisingly, the upper reach contains 27 times the amount of alcove habitat by length than the lower reach. Conversely, the upper reach only contained 1.35 times more spawning habitat, which is actually less in proportion to the total length of the upper reach when compared to the lower reach. Stream stability seems to be higher in the upper reach than in the lower reach. Although no robust quantitative study comparing the two reaches was conducted, it was evident that the lower reach had more grazing impacts than the upper reach. In particular the upstream area of the upper reach, which is situated on USFS system lands, had relatively stable banks and minimal signs of bank sloughing or compaction due to cattle. Conversely, the lower reach had many areas where bank stability was very low and signs of cattle compaction and bank sloughing were present. Visual observations of the riparian areas in both areas indicated that willow regeneration is occurring throughout a large proportion of the floodplain, although heavy grazing by ungulates have kept most willows from reaching maturity. 3.2 MFWP West Rosebud Creek Fish Population Sampling West Rosebud Creek Population Estimate 9

13 A total of 382 individual (not including recaptures) brown trout, 34 rainbow trout, and 3 brook trout were captured during the September - October 2004 electrofishing effort conducted by MFWP. Brown trout were on average the largest species captured, averaging 9.5 inches in total length and 0.54 lbs, while rainbow trout and brook trout averaged 5.7 and 4.1 inches in total length and 0.19 and 0.04 lbs in weight, respectively (Table 3). The largest trout captured was a brown trout that measured 23.1 inches in total length and weighed 4.58 lbs. Although all of the largest fish captured were brown trout, both brown trout and rainbow trout have similar length-weight relationships (Figure 7). Although no aging of fish occurred, size frequency histograms for brown trout and rainbow trout clearly indicate that a variety of age classes are present for both species within the sampled reach (Figure 8). The brown trout population is most likely composed of at least 6 age classes, while at least four age classes make up the rainbow trout population. Too few brook trout were captured to make any inferences on how many age classes are present within the sampled reach. Due to the size distribution of recaptured brown trout (Figure 9), brown trout population estimates were divided into fish less than, and fish larger than, 8 inches in total length. The population estimate indicates a total brown trout population of 2,408 inhabiting the sampled reach, with the 95% confidence intervals ranging from 1,142 to 4,494 (Table 4). The population of brown trout less than 8 inches in total length was estimated at 1,785, while brown trout larger than 8 inches was estimated at 623. These population estimates yield an abundance of 1,504 brown trout per mile with lower and upper 95% confidence intervals at 714 and 2,810 brown trout per mile. The population estimate for rainbow trout was calculated at 161, with 95% confidence intervals of 48 and 282 rainbow trout. The abundance of rainbow trout was calculated at 100 fish per mile, with lower and upper 95% confidence intervals at 30 and 176 fish per mile. Only three brook trout were captured in the initial pass and none in the recapture pass, therefore no population or abundance estimates were made for brook trout Fall Redd Survey A total of 31 brown trout redds were observed during the October 27, 2004 survey. The majority of redds (16) were observed in a 1.8 mile stretch of stream beginning at the Pine Grove Campground going downstream (Figure 10). Another congregation of redds (7) occurred within 0.3 miles of the downstream boundary of the sampled section. The remaining 8 redds were found between these two areas of West Rosebud Creek. No brown trout redds were observed between West Rosebud and Emerald Lakes, nor were any redds observed between Emerald Lake and the Pine Grove Campground. 10

14 3.3 West Rosebud Creek Sediment and Macroinvertebrate Inventory Results from the August 2005 sediment and macroinvertebrate sampling are not presently available due to the limited time between sampling and the production of this report. Core samples are currently being analyzed by Piedmont Engineering and macroinvertebrate samples are being analyzed by McGuire Consulting. As soon as the results are available those data or written reports will be integrated into this report and will be distributed to all relevant stakeholders. However, photographs of the sites were taken and are presented in Photographs

15 4.0 Discussion 4.1 Modified R1/R4 Habitat Inventory The upper reach has a higher pool to riffle ratio, more side channel habitat, deeper average maximum depth for pools, less average wetted width for pools and riffles, and more large woody debris. From visual observations of the two reaches, bank stability in the upper reach was in general higher than that of the lower reach. A total of nineteen rainbow trout redds were observed during the two days of habitat sampling; fourteen in the upper reach and five in the lower reach. Alcove habitat, which is important for rearing of juvenile salmonids, is more abundant in the upper reach than the lower reach. Overall fish habitat in the upper reach is of a higher quality than that of the lower reach. Unfortunately no fish sampling has occurred in the lower reach to verify this observation. To test this hypothesis, fish sampling would need to occur in both the upper and lower reaches within the same time of year to verify if habitat quality is actually different enough to translate to differences in fish production. 4.2 MFWP West Rosebud Creek Fish Population Sampling Brown trout dominate the fishery of West Rosebud Creek downstream of Emerald Lake. Rainbow trout are present in lower numbers and brook trout are relatively scarce. No Yellowstone cutthroat trout were captured during the sampling. Abundance estimates were relatively low for catchable sized trout. This section of stream has an estimated 389 brown trout larger than 8 inches in total length per mile. Although limited recaptures precluded the analysis of catchable sized rainbow trout, the abundance of all size rainbows was estimated at 100 rainbow trout per stream mile. These estimates are somewhat low when compared to popular stream fisheries in Montana. However, the habitat in the upper reach was quite diverse and other environmental factors such as climate and geology may play an important role in trout production, especially in a high elevation stream such as West Rosebud Creek. Understanding how fish population metrics differ between the upper and lower reach would allow inferences to be drawn between how the quality of habitat in West Rosebud Creek may be influencing fish production. It is apparent from the size distributions of fishes sampled that many age classes of fish are present within West Rosebud Creek. West Rosebud Creek is being used as both juvenile and adult rearing habitat. The presence of brown trout redds in the fall, and rainbow trout in the spring, lend evidence that spawning habitat is present within the stream. However, it is unclear what proportion of the observed redds, if any, are from migratory fishes that originate from lower portions of the drainage. The very limited presence of brook trout in the sampling combined with previous MFWP data from Emerald Lake suggests that the few brook trout found may be from Emerald Lake. 12

16 4.3 West Rosebud Creek Sediment and Macroinvertebrate Inventory Because no data has yet been analyzed from the core or macroinvertebrate sampling, no discussion is provided at this time. 13

17 5.0 Tables Table 1.0 GPS coordinates of habitat sections. GPS Locations of the Two Surveyed Habitat Sections of West Rosebud Creek Downstream Boundary Upstream Boundary Upper Section N W N W Lower Section N W N W

18 Table 2. Measured stream habitat parameters for the modified R1/R4 habitat survey of West Rosebud Creek. Av. Reach Habitat Type Unit Type Av. Length (ft) Total Length (ft) Wetted Width (ft) n % of total Av. Depth (ft) Av. Max Depth Total # LWD Spawning Gravel ft2 Pools * Riffles * Mainstem Flat Water * 2 60 Upper Side Channels Total * * 35 * * Alcoves * * Pools * Riffles * Flat Water * Total * * 18 * Alcoves * * * 0 * * * * * Lower Mainstem Side Channels Pools * Riffles Flat Water Total * * 18 * * Alcoves * * Pools * 0.0 * * * * Riffles * Flat Water * 0.0 * * * * * Total * * 6 * * * Alcoves * 0.0 * 0 * * * * * 15

19 Table 3. Biological statistics for trout captured during the September 30, 2004 and October 8, 2004 mark/recapture electrofishing effort conducted by MFWP on West Rosebud Creek, downstream of Emerald Lake. Species Mean Length (in) Max (in) Min (in) SE Mean Weight (lbs) Max (lbs) Min (lbs) Brown Trout Rainbow Trout Eastern Brook Trout SE n Table 4. Fish population estimates for trout sampled in West Rosebud Creek, downstream of Emerald Lake on September 30, 2004 and October 8, 2004 by MFWP. Population estimates are based on mark/recapture methodology. The electrofishing section was 1.6 miles in length. Species Brown Trout Rainbow Trout Brook Trout Length (inches) Pop. Estimate Lower 95 % Confidence Upper 95 % Confidence Fish/Mile Lower 95% Fish/Mile Upper 95% Fish/Mile < > Total All Lengths Only 3 brook trout were captured in first pass, none on the recapture pass 16

20 6.0 Figures Figure 1. Location of the two surveyed habitat sections in West Rosebud Creek, May 2005, small scale view. 17

21 Figure 2. Location of habitat survey section of West Rosebud Creek, May 2004, large scale view. 18

22 Figure 3. Location of MFWP s September October 2004 fish sampling on West Rosebud Creek. 19

23 West Rosebud Creek Habitat Inventory May 2 and 3, Upper Reach Lower Reach Pools Riffles Flat Water % of Total Mainstem Habitat Figure 4. Proportion of habitat units in both the upper and lower surveyed reaches of West Rosebud Creek, downstream of Emerald Lake. 20

24 West Rosebud Creek May 2 and 3, 2005 Depth of Pools 50 Upper Reach Lower Reach 40 Percent of Pools Depth (ft) Figure 5. Distribution of pool depths for both the upper and lower surveyed reaches of West Rosebud Creek, downstream of Emerald Lake. 21

25 West Rosebud Creek, May 2 and 3, 2005 Pool Maximum Depth n = Depth (ft) 3.5 n = Lower Reach Upper Reach Figure 6. Distribution of pool depths for both reaches sampled in West Rosebud Creek, downstream of Emerald Lake. Box plots represent median (solid line), mean (dashed line), 10, 25, 75, and 90 percentiles, and any outliers. Sample size is given. 22

26 Brown Trout W = * L Adj r 2 = 0.98 n = Weight (lbs) Rainbow Trout W = * L Adj r 2 = 0.99 n = Length (inches) Figure 7. Weight-length relationships for brown trout and rainbow trout captured by MFWP during the Fall 2004 mark/recapture population estimate for West Rosebud Creek, downstream of Emerald Lake. 23

27 80 Eastern Brook Trout n = Frequency (%) Rainbow Trout n = Brown Trout n = Total Length (inches) Figure 8. Size frequency histogram of fish captured by MFWP during the Fall 2004 mark/recapture population estimate for West Rosebud Creek, downstream of Emerald Lake. 24

28 Size Distribution of Recaptured Brown Trout 7 6 n = 25 # of Brown Trout Recaptures Total Length (inches) Figure 9. Size distribution of recaptured brown trout during the mark/recapture electrofishing effort conducted on West Rosebud Creek, downstream of Emerald Lake on September 30, 2004 and October 8,

29 Figure 10. Location of brown trout redds observed by MFWP on October 27, 2004 in West Rosebud Creek, Montana. Red flags represent the location a redd was observed, the number adjacent to the flag indicates the number of redds in that location. 26

30 7.0 Photographs Photograph 1. Lower reach, habitat unit # 10 looking upstream. Left bank stability was estimated at 60% stable, while the right bank was estimated at 70% stable. Photograph 2. Lower reach, habitat unit #15, left bank. Bank stability was estimated at 35% stable for the left bank and 92.5% stable for the right bank. 27

31 Photograph 3. Lower reach, habitat unit #17. Scour pool with suitable spawning gravel in the tail out. Bank stability was estimated at 90% stable for the left bank and 40% stable for the right bank. Photograph 4. Lower reach, habitat unit #25 side channel, eroding right bank. Bank stability was estimated at 0 % stable for right bank and 100% stable for the left bank. 28

32 Photograph 5. Lower reach, habitat unit #27, natural bank erosion. Bank stability was estimated at 0 % stable for the left bank and 80% stable for the right bank. Left bank height was estimated at 15 ft. Photograph 6. Upper reach, habitat unit # 2 looking upstream. Bank stability was estimated at 75% stable for the left bank and 90% stable for the right bank. 29

33 Photograph 7. Upper reach, aerial photograph of the lower section including the adjacent beaver complex. Note the bridge in the upper right hand corner was the beginning of the survey for the upper reach. Photograph 8. Upper reach, habitat unit # 14, right bank. Bank stability was estimated at 10% stable for the right bank and 90% stable for left bank. Note the short grasses in the background, a sign of heavy cattle grazing. 30

34 Photograph 9. Upper reach, habitat unit #18 looking upstream. Bank stability was estimated at 60% stable for the left bank and 40% stable for the right bank. Photograph 10. Upper reach, habitat unit #18 is in the upper right hand corner where the two pronounced side channels meet. This aerial photograph was taken in October of

35 Photograph 11. Upper reach, habitat unit 33 looking downstream. Photograph 12. Upper reach, habitat unit 36. Bank stability was estimated at 20% stable for the left bank and 100% stable for the right bank. Bank height for the left bank was estimated at 5.5 ft. 32

36 Photograph 13. Upper reach, habitat unit #41 looking downstream. This unit is a glide with a total length of 174 ft, an average wetted width of 48.5 ft, and an average depth of 0.69 ft. Photograph 14. Upper reach, near upstream end of survey. 33

37 Photograph 15. Lower section core and macroinvertebrate sampling site, West Rosebud Creek. Note the suitable salmonid spawning gravels where core and macroinvertebrate samples were taken. Photograph 16. Upstream view of the lower section of West Rosebud Creek core and macroinvertebrate sampling site. 34

38 Photograph 17. Core sample being taken using a McNeil Core Sampler in the lower section of West Rosebud Creek. Photograph 18. Upper section of West Rosebud Creek core and macroinvertebrate sampling site. Note: Sampling of upper section occurred on August 30,

39 Photograph 19. Downstream view of the upper section of West Rosebud Creek core and macroinvertebrate sampling site. Note: Photograph was taken on August 30, Photograph 20. Upstream view of the upper section of West Rosebud Creek core and macroinvertebrate sampling site. 36

40 8.0 References Ricker, W. E Computation and interpretation of biological statistics of fish populations. Bull. Fish. Res. Board Can. 191: 382 p. PPL Montana Mystic Lake Project Pre-Application Document (2004). 37