USE OF DIVE COUNTS TO

ESTIMATE FISH POPULATION ABUNDANCE

IN THE ROCK CREEK – CRESTA REACHES

OF THE NORTH FORK FEATHER RIVER,

CALIFORNIA.

Prepared For:

Technical & Ecological Services Pacific Gas & Electric Company 3400 Crow Canyon Road San Ramon, CA 94583

Prepared By:

Thomas R. Payne & Associates 890 L Street Arcata, CA 95521 707-822-8478

Contributors:

Mark Allen, Thomas Gast

February 7, 2007 ABSTRACT

Direct observation dive counts were conducted by a team of divers in individual habitat units in the Cresta Reach and Rock Creek Reach of the North Fork Feather River in 2002 (a pilot study), 2004, 2005, and 2006, under base flow conditions elevated from historical levels. Habitat units were selected for diving using a stratified random design that allowed estimation of indexes of fish abundance within species, size class, habitat type, and reach strata. Annual comparisons of index abundance were possible due to consistency in sampling designs and field methodologies, and because stream conditions (e.g., streamflow, water temperature, and water visibility) remained relatively similar in each year of study. Statistically significant differences between annual estimates of abundance were determined through assessment of index confidence intervals or by explicitly estimating the difference in abundance between occasions (2005-2006 only).

Differences in fish index densities between reaches were minor for rainbow trout, but were consistently higher in the Rock Creek Reach for adult-sized (>10 inches) hardhead, pikeminnows, and suckers. Smallmouth bass, in contrast, were consistently more abundant in the Cresta Reach. Index densities of fry (<5 inches) were not consistently different between reaches, but juvenile (5-10 inches) non-trout species were notably absent from the Cresta Reach in each year of study. Differences in index abundance between habitat types are difficult to assess due to expected differences in fish detectability, but abundance trends clearly showed higher densities of rainbow trout (especially fry and juveniles) in run and riffle habitats, whereas all size classes of hardhead and bass were more common in pool habitats. Pikeminnows and suckers occurred more evenly among habitat types, but few large adults were observed in riffles. Annual trends were dominated by strong increases in fry of all species in 2005 and 2006 (bass only in 2005). Juvenile adult trout showed a general decline in abundance from 2004 to 2006, with 2006 densities less than 50% of the 2004 maxima. Juvenile and adult size classes of all non-salmonid species showed little consistency in annual trends, but densities in 2006 were typically higher than in 2004.

The temporal effects of changes in base flows and annual differences in high winter and spring flows, and the spatial effects of reach and habitat location on observed indexes of abundance are discussed. High spring flows during 2005 and 2006 may be associated with high recruitment of trout and non-salmonid species during those years, but the mechanisms by which recruitment appeared enhanced remain unknown. The absence of juvenile hardhead, pikeminnows, and suckers in the Cresta Reach is considered in relation to potential predation by bass and differential recruitment from above the study area. The observed index densities of trout in the study area were compared to data from other California locations. Index densities in the North Fork Feather River were similar to estimated densities in other large, low elevation mainstem rivers in the Sierra Nevada, but densities in higher elevation or “blue ribbon” trout streams (including upper reaches of the North Fork) were typically five to ten times higher than densities in the Cresta and Rock Creek reaches. Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

INTRODUCTION

Thomas R. Payne and Associates (TRPA) was contracted by Pacific Gas & Electric Company (PG&E) to assess trends of fish populations in the Rock Creek Reach and Cresta Reach of the North Fork Feather River, California using direct observation methodologies. PG&E has entered into an agreement with the Ecological Resources Committee (ERC) to conduct staged increases in flows released into the Rock Creek and Cresta reaches over a fifteen year period. PG&E and the ERC are interested in determining what effect the staged increases in flows will have on the fish populations resident within the affected reaches. Part of the assessment of effects on fish populations involves conducting electrofishing surveys in shallow portions of the study area following short-term periods of significantly reduced flows (Salamunovich 2005a, 2005b, 2007). A previous component of the assessment involved electrofishing deeper water pool habitats using boat electrofishing equipment (Stillwater Sciences 2005). Because conventional bank electrofishing is only effective in shallower areas after a significant reduction in flow, and because boat electrofishing is also highly restricted in the depths and habitat types that can be sampled, PG&E and the ERC wanted to also use direct observation methodologies to assess fish population characteristics.

STUDY OBJECTIVES

This study was conducted with the following principal objective:

To produce quantitative estimates of fish abundance and density that will contribute to an assessment of population changes over the period of this study (2004-2006) and with future snorkeling efforts to be conducted during the second and third test flow periods through Year 15 of the License (2016).

STUDY AREA

This study was conducted in the Rock Creek Reach and Cresta Reach of the North Fork Feather River in Plumas and Butte Counties, California (Figure 1). The Rock Creek Reach is approximately 8.5 mi long, and extends from the Rock Creek Diversion Dam downstream to the Rock Creek Powerhouse. The Rock Figure 1. Area map of North Fork Feather River, California.

1 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Creek Reach includes a 1.0 mi area between Bucks Powerhouse and Rock Creek Powerhouse that is subject to higher flows and greater daily fluctuations in flows than the rest of study area. Dive counts were not conducted in the one mile portion affected by Bucks Powerhouse. The Cresta Reach is approximately 4.7 mi long and extends from the Cresta Diversion Dam to the Cresta Powerhouse. In general, both reaches have areas with relatively steep gradient (1.2-2.2%) and confined channel, as well as relatively low gradient (0.4%) areas with less-confined channel. Boulder and cobble are the dominant substrates in both reaches, with many bedrock-formed deep pools. Finer substrate particles, including spawning-sized gravels, are relatively rare in both reaches. The Rock Creek Reach has more riparian vegetation, consisting of willows and alder, than the Cresta Reach.

SAMPLING DESIGN

Use of Direct Observation to Assess Fish Population Abundance

Direct observation methodologies, including snorkeling and SCUBA diving, have been used to study riverine fish populations for many years, particularly in regards to fish distribution, species composition, relative abundance, and microhabitat requirements. Data based on direct observation surveys have frequently been misunderstood in a variety of ways, however. For example, it must be clearly understood that most direct observation surveys produce an index of abundance, but do not actually provide an estimate of total abundance. Except under the most ideal of situations (e.g., sculpin counts in precisely defined quadrats, TRPA 2005a), divers can only be expected to see and count a fraction of the total number of fish that are actually present in a habitat area. Restrictions due to poor underwater visibility, the abundance of instream cover, deep water or swift currents, and the rapid swimming speed and avoidance behavior of most fish species all combine to constrain dive counts to a proportion less than the total abundance. Consequently, dive counts should typically be viewed as a conservative (e.g., minimum) estimate of abundance.

In small streams, dive counts can be successfully calibrated to estimate true abundance using a more exhaustive methodology such as intensive electrofishing (Hankin and Reeves 1988) or, in extreme cases, poisoning or explosives (Northcote and Wilkie 1963). Such methods for converting index estimates of abundance to estimates of true abundance can only be applied where the exhaustive methodology is highly efficient (such as in smaller streams) or highly destructive (such as poisoning). The use of less accurate and less efficient estimators to calibrate dive counts have been attempted and even proposed to be transferable to other systems (Hillman et al. 1992, Hagen and Baxter 2005), but the validity of such practices is highly questionable (Dave Hankin, personal communication).

For a stream the size of the North Fork Feather River, it is highly untenable that any capture methodology, aside from poisoning with intensive collection, would be capable of producing a sufficiently accurate estimate of total abundance to adequately calibrate a dive count, or to accurately represent total fish abundance throughout the entire range of

2 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

stream habitats (i.e. shallow and deep, fast and slow areas). For example, divers counted 49 adult trout in a pool near Rogers Flat in October 2004, but the total abundance was likely greater due to the large trout’s ability to avoid divers. Two weeks later, the flows were dropped substantially and a boat electrofishing survey estimated the abundance of adult trout at only 26 fish, with a 95% confidence interval of 19-33 fish (Stillwater Sciences 2005). Because the second survey was conducted at a different time and a different flow, this is not a rigorous comparison. However one would expect the reduction in flows to cause a movement of adult trout into pool habitats and thus the disparity between the higher dive count and the lower electrofishing estimate is more striking.

Although both methods have limitations and likely only represent indexes of abundance, dive counts can provide reach-wide index estimates that can detect trends in fish abundance in a highly quantitative and statistically rigorous manner. For example, dive counts conducted over a ten-year period in the upper Sacramento River were capable of detecting statistically significant changes in trout index densities in many years (TRPA 2005a). Dive counts in the upper reaches of the North Fork Feather River also detected statistically significant differences in index densities of trout among reaches and habitat types (TRPA 2002).

Assessing statistical differences based on index estimates of abundance must be made with caution, however. To make such comparisons one must have a reasonable assurance that the proportion of the total abundance that can be counted by divers (i.e., the observation probability or fish detectability) is relatively constant. Numerous factors can easily affect the observation probability, such as fish species or size (e.g., brown trout are harder to see than rainbows, fry are harder to see than adults, etc.), water visibility (due to differences in depth, turbulence, or water clarity), water temperature (due to many fishes hiding behavior at lower temperatures), or even current velocities (as it affects a divers ability to scan for fish). With a careful sampling design, standardized diving methodologies, and relatively stable environmental conditions, many of these factors can be controlled or accounted for to help ensure statistically valid comparisons of fish population estimates.

For example, in the upper Sacramento River Cantara Spill studies, statistical comparisons of trout densities were not made between fry and adults, or between pools versus riffles, or between the larger, warmer lower reaches and the smaller, colder upper reaches (TRPA 2005a). However, statistically valid comparisons were made for assessing annual trends within each species, size class, habitat type, and reach strata, as well as combined reach population trends. Such direct observation data and associated analyses can thus be applied to the evaluation of staged flow changes in the Rock Creek-Cresta reaches and the subsequent effects on the resident fish populations.

General Background and Basic Stratifications

Extrapolating dive counts in individual habitat units to represent reach-wide abundance requires a careful and statistically valid sampling design. The power to detect actual

3 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

changes in abundance between years is dependent upon numerous factors, including the sample size, the natural variability in the fish populations, the sampling design used to estimate population abundance and variances, and the methods used to compare annual changes. The dive count study conducted in 2004 (TRPA 2005b) utilized a statistically valid but relatively simple sampling design (stratified random sampling) at a modest sampling rate (approximately 20% of the available habitat units). In order to increase precision of estimates in 2005 and to better distinguish changes in abundance in future years, an alternative sampling design was initiated in 2005 that utilized an increased level of effort (to approximately 36% of available habitat units) with a more sophisticated, unequal-probability sampling design. Data from the 2004 survey was also used to optimize allocation of sampling effort among the two reaches and four habitat types in order to further increase precision of abundance estimates. See the 2004 final report (TRPA 2005b) for details regarding the design used in that year.

The 2005 sampling design retained the same species, size class, reach, and habitat type stratifications employed in 2004 (TRPA 2006). Independent samples were drawn for each habitat type and each reach, thus estimates could be combined across reaches to represent project area totals for each species, size class, and habitat type strata. These strata-specific estimates could be directly compared between years to evaluate annual trends. Although 2005 estimates were sometimes combined across habitat type or size class strata to represent overall totals, such estimates were not statistically compared between reaches or years due to expected, but unmeasured, differences in diver observation probabilities that could bias such comparisons. Quantitative comparisons between reaches and years were thus only made within each species, size class, and habitat type strata.

The 2006 sampling design was identical to the 2005 design and utilized the same set of sampling units (e.g., the same runs, riffles, and pools). Thus, the 2006 sampling employed the concept of “sampling on repeated occasions”, which uses correlations between counts in "index" habitats to increase the precision of estimates of change over time (see Cochran 1977, Des Raj 1968). Given positive correlations between years (e.g., units that tend to have high abundance in year 1 also contain high abundance in year 2, etc.), “difference estimators” can yield greater precision in determining the statistical significance of differences in annual index estimates, in comparison to simply evaluating overlap in 95% confidence intervals, which is also employed in this study.

Stratification by reach and habitat type was intended to improve precision of index estimates by reducing variation in average fish densities between strata. For example, the variation in fish species/life stage density among shallow pools (for example) was expected to be less than the variation in fish density between shallow pools and other habitat types. The ratio of fish observed by divers to the actual number of fish present (the observation probability) was also expected to differ between habitat types. For example, the dive count of trout in run habitats would probably be closer to the total number present than would dive counts in riffle habitats, where large boulders and areas of whitewater may obscure vision.

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These basic elements of the survey design produced the sampling frames. Given a feasible sampling frame, the next step in survey design was the determination of methods for: (a) allocation of effort from the sampling frame, (b) selection of individual habitat units from the sampling frame, and (c) estimation based on survey data collected from those selected units.

Allocation of Effort Among Reach and Habitat Type Strata

Optimum allocation formulas were applied to the 2004 dive count estimates for juvenile, small adult, and large adult trout to reallocate sampling effort among reaches and habitat types (Cochran 1978, equation 5.26). Optimum allocation will result in larger sample sizes for a stratum if 1) the stratum is larger, 2) the stratum is more variable, or 3) the stratum is less expensive to sample (fixed coasts were assumed for this analysis). For an anticipated total sample size (n) of 70 habitat units (n based on projected costs and budget allowance), the allocation formula suggested a sample of approximately 30 habitat units in the Cresta Reach and 40 units in the Rock Creek Reach (Table 1). Among habitat types, optimum allocation suggested increasing effort in run habitats and decreasing effort in pools. In order to ensure that estimates for hardhead, pikeminnows, and other pool-dwelling species were not excessively degraded due to inadequate sample sizes in pool habitats, a minimum sample sizes of n=6 units per habitat type was selected.

Table 1. Comparison of sampling effort by reach and habitat type using ~equal allocation in 2004 and optimum allocation in 2005/2006.

Habitat Number of Habitat Units % Sampled Total Length (ft) % Sampled Year Reach Type Available Sampled by Number Available Sampled by Length 2004 Cresta Deep Pools 14 4 29% 8,596 1,674 19% Shallow Pools 11 5 45% 3,859 2,257 58% ~equal allocation Runs 39 5 13% 7,136 1,150 16% Riffles 15 5 33% 1,624 516 32% sums: 79 19 24% 21,215 5,597 26%

Rock Creek Deep Pools 14 5 36% 7,543 2,731 36% Shallow Pools 23 5 22% 7,133 1,180 17% Runs 47 6 13% 10,902 1,808 17% Riffles 27 6 22% 3,498 763 22% sums: 111 22 20% 29,076 6,482 22%

2005-06 Cresta Deep Pools 14 6 43% 8,596 4,642 54% Shallow Pools 11 6 55% 3,859 2,694 70% optimum allocation Runs 39 12 31% 7,136 2,909 41% Riffles 13 6 46% 1,579 852 54% sums: 77 30 39% 21,170 11,097 52%

Rock Creek Deep Pools 14 6 43% 7,543 3,267 43% Shallow Pools 22 8 36% 7,045 2,649 38% Runs 47 16 34% 10,902 5,508 51% Riffles 27 10 37% 3,498 1,519 43% sums: 110 40 36% 28,988 12,943 45%

5 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Optimum allocation for rainbow trout with the above sample size constraints produced changes in effort allocation from 2004 to 2005 as shown in Table 1. The minor reduction in the availability of habitat units in 2005 was due to the re-classification of three habitat units as non-sampleable (see habitat mapping section below). As stated above, the 2006 sample utilized the same habitat units that were selected in 2005. The approximate locations of the habitat units sampled in 2005 and 2006 are shown in Figures 2 and 3.

Selection of Survey Units

The equal-probability, stratified random design used to select habitat units in 2004 was replaced in 2005 with a more sophisticated, unequal-probability design, that was expected to produce more accurate estimates with greater precision. The 2006 sampling utilized the same set of habitat units selected in 2005. Within each of the four habitat types that could be sampled (run, riffle, shallow pool, deep pool) in each of the two reaches an independent sample of size n survey units was drawn from the total N units of that type within that stratum (Table 1). Each of these n units was selected by Probability Proportional to Size With-Out Replacement (PPSWOR) using the procedure by Chao (1982). The measure of habitat unit size was the length of each habitat unit (xi) that was measured during habitat mapping (Appendix A). An extremely long unit (e.g. 1,000 feet) therefore had a relatively large chance of selection, whereas a very short unit (e.g. 20 feet) had a relatively small chance of being selected. When compared to equal probability selection, where each unit has an equal probability of being selected on a given draw, PPSWOR will on average select longer units.

One benefit of PPSWOR and the selection of longer average units is a reduction in the amount of field time required to locate and sample enough habitat units to achieve a desired river length coverage. PPSWOR also provides unbiased estimation of sampling variance, which should improve precision over equal-probability designs when the number of fish counted in units is positively correlated with habitat unit length. This assumption is biologically reasonable for resident species of fish, where larger units would be expected to contain more fish than would smaller units. Count data from 2004 and 2005 frequently produced correlations that exceeded 0.5 for most size classes of rainbow trout in runs and riffles (TRPA 2006). Correlations between counts of non- salmonid species and unit lengths were also typically over 0.5 in pools and runs. Given these results, a PPSWOR design should outperform either equal probability or unequal probability (with-replacement) designs (Hankin 1984).

Calculation of Index Estimates and Variances

Within selected survey units, a sufficient number of divers were deployed in the river to achieve full observation coverage over the width of the unit. The following definitions apply to estimation of abundance and sampling variance for a particular habitat type stratum within a particular reach:

6 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Figure 2. Map of Rock Creek Reach showing location of 2005/2006 sampling units and other landmarks.

7 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Figure 3. Map of Cresta Reach showing location of 2005/2006 sampling units and other landmarks.

8 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

yi (or yj ) = the total count of fish in habitat unit i (or unit j)

xi = the size (length) of unit i

st πi = the probability that unit i appears in a PPSWOR sample of size n (= 1 order inclusion probability)

πij = the probability that unit i and unit j are in a PPSWOR sample of size n (= 2nd order inclusion probability), i ≠ j

N Yy=∑i =the total number of fish present in all units of a given habitat type stratum within a particular reach

"Fish" in the above context refers to a single species/size class category (e.g. rainbow trout juveniles or pikeminnow adults). For estimation of the total number of fish that can be counted within a given habitat type stratum within a reach, based on selection of a PPSWOR sample of size n, we used the Horvitz-Thompson estimator (see Cochran 1977; Sarndal et al. 1992):

^ n y Y =∑ i (1) π i

To estimate the sampling variance for the Horvitz-Thompson estimator, for fixed sample size n, we used the Sen-Yates-Grundy variance estimator (see Cochran 1977; Sarndal et al. 1992):

2 ^^ n−1 n ()ππij− π ij⎡ y y j ⎤ VY()=∑∑ ⎢ i − ⎥ (2) i ji> πππij ⎣⎢ i j ⎦⎥

Upper and lower 95% confidence bounds about the estimated total (Yˆ ) was calculated by multiplying the appropriate Student's t value for n-1 degrees of freedom by the square root of the estimated sampling variance (Thompson 1992):

^^ .. ±= n− )1( YVtIC )( (3)

The conversion of index estimates of abundance to index estimates of fish density Dˆ (number/ mile) for a given species and size class was based on the total length of all units within a given habitat stratum within a particular reach:

9 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

^ ^ Y D = where M =length of all units in miles (4) M

Corresponding estimated sampling variances for the estimated densities were calculated as:

^^ 1 ^^ DV )( = YV )( (5) M 2

The 95% confidence intervals around these density estimates were calculated by multiplying the square root of the estimated sampling variance (for density) by the appropriate Student's t value for degrees of freedom.

To evaluate the relationship between unit length (x) and the number of fish counted (y), we estimated linear correlations, r$xy, , accounting for unequal probability of selection of habitat units. The correlation coefficient was derived to evaluate the efficiency of the PPSWOR survey design, and to evaluate changes in variability of fish densities over time. A perfect correlation of 1.0 would indicate that variability of dive counts among habitat units was fully explained by differences in habitat unit length.

For a PPSWOR design, the linear correlation coefficient is estimated using (Sarndal et al. 1992): xy ∑∑i i xy ππ ∑−ii i i π 1 i ∑ ^ π = i (6) r xy, 2 2 ⎛ ⎛ x ⎞ ⎞⎛ ⎛ y ⎞ ⎞ ⎜ ∑ i ⎟⎜ ∑ i ⎟ 2 ⎜ ⎟ 2 ⎜ ⎟ ⎜ xi ⎝ π i ⎠ ⎟⎜ yi ⎝ π i ⎠ ⎟ ⎜∑− ⎟⎜∑− ⎟ π 11π ⎜ i ∑ ⎟⎜ i ∑ ⎟ ⎜ π ⎟⎜ π ⎟ ⎝ i ⎠⎝ i ⎠ where all sums are over the i = 1 through n units in the PPSWOR sample.

Estimation of Differences Between Occasions

Difference estimators (Cochran 1977, Des Raj 1968) were used to assess the statistical significance in annual changes of abundance within study strata between 2005 and 2006 (the 2004 survey utilized a different set of sampling units, therefore changes from 2004 estimates were assessed using the more conservative method of overlap in confidence intervals). Difference estimators utilize the expected correlation in dive counts within

10 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______specific habitat units between years to increase the precision of the estimated change in abundance.

The estimated difference in abundance between 2005 and 2006 for a given study strata (e.g., juvenile rainbow trout in Cresta run habitats) is calculated as: ˆˆˆ −= YYFID 0506 (7) with a variance of: ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ( ) ( 05 ) ( 06 −+= 2) ( ,YYVOCYVYVFIDV 0605 ) (8) where the covariance term is:

ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ( , 0605 = () , 0605 ) ( 05 ) (YVYVYYrYYVOC 06 ) (9) and the correlation between years (r), ˆ yxROC ),( = A , where x is count from year 1 and y is count from year 2, is estimated by: B

yx i i xi 2 yi 2 ∑∑ 2 ∑ )( 2 ∑ )( yx ii i ππ i x π y π A −= and B [ i −= i ][ i − i ] (10) ∑ π 1 ∑ 1 ∑ 1 i π i π i ∑ π ∑ ∑ i π i π i

The 95% confidence interval for the estimated difference between years is:

ˆ ˆ (11) %95 = n−1 ( FIDVtCI ) A statistically significant difference in abundance between years is indicated if the 95% confidence intervals for the difference does not encompass zero.

Estimation of Pooled Index Estimates

To present the resulting indexes of abundance in a more simplified and understandable manner, data were pooled within habitat type across both reaches. The pooled estimates represent the index of abundance for fish of a particular species/size class within a specific habitat type in the entire study area. Pooling was justified by the similar water visibility and water temperatures between the two reaches (Figure 4). Although water clarity decreased near the top of each reach, lane widths were intentionally narrowed to maintain consistency in index counts.

The pooled estimates of abundance or variance for specific species/size class/habitat type strata were simply the sums of the two independent reach-specific estimates. The upper

11 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

15 Water Visibility vs. Location 14 Cresta

13 Rock

12

11

10

9 Water Visibility (ft) Water Visibility 8

7

6 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5,000 0 Distance Below Dam (ft) 69 Water Temperature vs. Time 68 Cresta

67 Rock 66 65 64 63 62

Water oF Temperature 61 60 59 8 9 10 11 12 13 14 15 16 17 18 Hour of Day

Figure 4. Eye-estimated water visibility (distance to recognize a 3-inch trout model) by reach and distance below dam (upper figure), and measured water temperature by reach and hour of day (lower figure), September 2006. and lower 95% confidence bounds about the pooled totals were calculated by multiplying the appropriate Student's t value for the pooled degrees of freedom (n Rock + n Cresta – 2) by the square root of the pooled variance. The statistical significance of differences between years for pooled reach estimates was conservatively evaluated by overlap in 95% confidence intervals. Data pooled among size classes or habitat types were not statistically compared between years due to large expected, but unknown, differences in diver observation probabilities that could severely bias such comparisons and lead to erroneous conclusions about annual trends.

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FIELD METHODS

Habitat Mapping

The aquatic habitat in the Rock Creek Reach was mapped on 28-29 September 2004, and the habitat in the Cresta Reach was mapped from 30 September through 03 October 2003, at flows of approximately 257 cfs and 275 cfs respectively (Appendix A). The type and length (measured by “hip-chain”) of each habitat unit was documented while walking along the stream margin in an upstream direction. Labeled flagging was hung at regular intervals (usually at unit boundaries) as reference stations to aid in relocating habitat units. The location of each flag was recorded for each reference points. Mapping notes also included locations and descriptions of prominent landmarks, (e.g. tributaries, bridges, overhead lines etc.). Waypoints were taken with a handheld GPS unit at the top boundaries of each pool habitat in the Cresta Reach, and at all habitat units in the Rock Creek Reach where satellite coverage permitted. The GPS coordinates were used with the habitat mapping database to relocate all units selected for diving in 2005. The location of the upper boundary markers for these selected habitat units were also recorded by GPS in 2005.

Four habitat types were identified in this study: deep pools, shallow pools, runs, and riffles. The 2003 mapping in the Cresta Reach also included a pocketwater category, but those habitat units were reclassified into one of the above types in 2004 prior to initiation of this study. Riffles were visually sub classified as high-gradient (>4% slope) or low- gradient, but all diveable riffles were treated together during sample selection and estimation of fish abundance. Most high-gradient riffles were cascades or were too hazardous to dive and were therefore excluded from fish sampling and abundance estimation. Some very short transverse riffles, steep runs, short pools with dangerous drops, or pools immediately below dams or ongoing construction (e.g. bridge pools) were also excluded from sampling. Three very wide pools (>150 ft in width) in the Rock Creek Reach were considered infeasible for sampling due to limited personnel and were therefore excluded from selection or estimation. Typical descriptions of sampleable habitat types are as follows:

Deep Pools: Deep pools were characterized by areas of still or slow moving water with a highly pronounced scour channel or pocket. Deep pools contained significant areas where the bottom could not be clearly seen from the water surface (and typically required SCUBA equipment to survey). Deep pools could be almost entirely still or they may have large areas of moderate or even rapid velocities. Pools that contained rapid water (typically at the head) also had slack areas beside or between the high velocity chutes, and generally contained low velocities in the deep areas beneath the swift water.

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Shallow Pools: Shallow pools were similar to deep pools except that all (or nearly all) of the stream bottom could be seen by surface divers. Areas of scour were typically not as pronounced as in deep pools, and small pocket-pools in the upper reaches were sometimes classified as shallow pools.

Runs: Runs were characterized by even or gradually changing velocities of moderate to rapid speeds. Surface character ranged from smooth (e.g. glides) to choppy with standing waves. Unlike riffles, runs generally lacked whitewater, and waves, if present, were typically formed by an upstream source or isolated boulders rather than by continuous interaction with the stream bottom immediately below. Runs were often formed by a constriction of stream width or by a change in gradient. The downstream end of pools sometimes exhibited run-like characteristics and may have been split into a run component. Runs could have very consistent depth profiles (across stream) or they may contain deep channels in midstream or along the bank.

Riffles: Riffles were habitats of increased gradient with considerable surface turbulence, much of which was white-water. Surface turbulence was typically maintained by features of the stream bottom. Riffles were relatively shallow with an even depth X Cresta Reach profile. Riffles visually estimated to have 15% steep slopes (>4%) were sub classified as RF DP high gradient, low gradient riffles had 6% 35% slopes <4%.

The final habitat mapping database (Appendix A) therefore contained four usable habitat types: deep RN 29% SP pools (DP), shallow pools (SP), runs (RN), and 15% riffles (RF, HR, or LR). Non-sampleable habitats Rock Creek Reach are indicated with an “X” in front of the normal DP habitat designation (e.g., XHR or XRN). 17% X The proportions of habitat types in the Rock Creek 35% SP 16% Reach were: deep pool (17% of total length), shallow pool (16%), run (24%), and riffle (8%) (Figure 5). The remaining 35% of the reach was made up of non-sampleable units (X) such as RN cascades and white water chutes. The proportions RF 24% of habitat types in the Cresta Reach were: deep 8% pool (35%), shallow pool (15%), run (29%) and Figure 5. Habitat type riffle (6%). Approximately 15% of the Cresta proportions in the Cresta Reach consisted of non-sampleable units. The and Rock Creek reaches.

14 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______most apparent difference in habitat proportions between the two reaches was the higher proportion of deep pools in the Cresta Reach and the higher proportion of non- sampleable units in the Rock Creek Reach.

It has been assumed throughout the course of this study that the high degree of flow regulation and the predominance of large substrate elements in both reaches would yield a highly stable sampling universe with relatively little change in the number, location, or character of individual habitat units. Instability in the physical habitat is significant in many rivers and can effectively prevent the use of index area sampling designs. For example, the use of sampling on repeated occasions was proved infeasible in the Upper Sacramento River due to annual changes in habitat units. In the NFFR, we observed very little change in habitat units between 2003 and 2005, but high flow events during April 2006 did cause channel changes in some habitat units. Most noticeable were changes in the depths of several pool habitats, some deep pools appeared to become shallower and some shallow pools appeared to have been scoured deeper. It is unknown to what degree these changes affect the comparability of index estimates between years.

Dive Count Methodology

The 2004 study used a combination of upstream dive counts, based on methodologies developed for the Cantara Spill fish recovery studies (TRPA 2005a), and cross-sectional dive counts, based on habitat suitability studies previously conducted in the Rock Creek-Cresta reaches (TRPA 2001). A comparison of the two dive count methodologies showed that the cross-sectional method produced much higher variation in index estimates than did the upstream method, largely due to the subsampling component of the former method (TRPA 2005). Conse- quently, all dive counts conducted in 2005 and 2006 utilized the upstream methodology.

After the upstream and downstream boundaries of the selected habitat unit were identified, the unit was partitioned into parallel dive lanes running from the upstream to the downstream boundaries (Figure 6). Unit width and water visibility dictated the number of dive lanes required for each survey site. Most units required five or six dive Figure 6. Examples of different lane-line lanes for complete coverage. The dive configurations.

15 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______lane boundaries were physically delineated with high visibility lane-lines to improve the accuracy of underwater counts and to expand the effective counting area of each diver.

Physical partitioning reduced the possibility of duplicating or missing observations between divers and improved confidence in each diver's count. The lane-lines also effectively reduced the number of required divers in comparison to conventional downstream protocols because each upstream diver could look to the left and to the right towards the physically delineated boundaries and thus was not required to look in a single direction to the neighboring diver. Effective full-width coverage using a one-directional methodology would have required significantly more divers given the width and visibility conditions of the Rock Creek and Cresta Reaches. Also, the use of lane-lines allowed each diver to move back and forth within his/her lane to take advantage of current eddies, optimal footholds, etc., without compromising the dive count of the adjacent divers (since the line boundaries remain fixed). This factor is especially important in large, swift rivers where upstream diving is inherently difficult.

Dive lanes were delineated with one-eighth inch diameter white solid-braid nylon cord held on plastic or metal spools that could be easily and safely operated by a diver while in the water. The lane-lines were typically fixed at the upstream boundary with a rock or lead weights and then unspooled as a diver walked or floated downstream along a pre-determined route. Divers attempted to space the lane- lines equally and to place them parallel to the streambanks. Habitat units having non-parallel streambanks were accommodated by varying the length of margin lanes (Figure 6) rather than by constricting or expanding lane widths, which proved to be impractical while floating downstream. Lane-lines were kept near the stream bottom by periodically placing rocks over the line (in shallow water) or by attaching lead weights to the line while drifting downstream (in deep water). Lane-lines were deployed one at a time or staggered to minimize "herding" of fish downstream (Figure 7, bottom). Figure 7. Positioning of divers during lane line deployment (bottom) and during dive Following each survey dive, rocks counts (top). or bottom weights were removed

16 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______and lines were re-wound onto the spools.

Each diver was equipped with a mask and snorkel (or SCUBA for deep pools), wet suit, and wading shoes (or swim fins for deep units). All divers carried a wrist-mounted ruler incremented at several lengths (at 5, 10, 15, and 20 inches) to calibrate eye-estimated fish lengths. Divers inspected their rulers immediately prior to each dive, and their size estimations were tested semi-daily using plastic fish silhouettes of known size. The number of observed fish of each species and size was recorded on a wrist-mounted plastic slate. Actual lengths were estimated for each observed trout, whereas all other species were counted according to the size classes formed by the above size increments.

After a 10 to 15 minute resting period following lane-line deployment, the survey divers carefully entered the water at the downstream boundary and moved to their assigned lanes. Divers then proceeded upstream in their lanes while maintaining a straight line perpendicular to flow (Figure 7, top). Divers counted all fish that were observed to pass downstream within their lanes. By maintaining a straight line and counting fish only as they passed downstream, the dive team minimized repeat counting of the same fish. In order to verify counts and avoid replication, adjacent divers communicated verbally or with hand signals whenever fish passed downstream over their mutual lane-line.

When approaching the upstream boundary of the survey unit, divers carefully monitored fish holding above their position and counted them if the fish swam upstream to the next unit. Following each dive, the slate data was transferred to field forms that included the beginning and ending dive times. Index estimates of abundance were calculated for each habitat unit by summing all diver counts within species and size class strata.

At units containing a wide channel of deep, fast water, it was sometimes necessary to hang a rope downstream on the water's surface to assist the diver upstream (Figure 7, top). The dive rope (typically one-half inch foam core polypropylene) was suspended downstream from the streambank or from an anchor rope (7/16 inch static climbing rope) stretched across stream above the water surface at the unit's top boundary (Li 1988).

Fry Lane Counts

In addition to the dive methodology described above, “fry-lane” counts were also conducted to estimate the numbers of small (<5 inches) fry occupying nearshore habitats. Fry lanes were sampled because the smaller, more cryptic fry are easily overlooked when conducting counts that include wider lanes and larger fish. Fry lanes were six ft wide strip transects that extended either the entire length of a habitat units or, for long units, from a random start for 200 feet upstream (see shaded bank areas in Figure 6).

Following the completion of the previously described dive counts, one diver returned to each fry lane and proceeded upstream within the strip while counting all trout and non- game fry less than five inches in length; larger fish were not counted. In general, fry lanes are most effective during spring and early summer sampling when young-of-year fish are very small and are largely restricted to nearshore margin habitats. By the time

17 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______this survey was conducted, most young-of-year trout were large enough to occupy locations away from the margin, however numerous small non-salmonid fry were still present within the fry lanes.

Fry lane counts were summed from both bank transects to represent the total fry lane count for that unit. Fry lane counts therefore only represent abundance of fish within the margin area of the river, not within the entire river channel. In very long units with subsampled fry lanes, the summed fry lane counts were expanded by the ratio of the total length of the unit to the length of the fry lanes.

Physical Measurements

A variety of physical habitat data was collected during the 2004 and 2005 surveys (Table 2) in order to characterize the dimensions and habitat characteristics of each sampled unit (TRPA 2005b, 2006). Because little change in streamflow or habitat was observed during those surveys, it was assumed that most habitat unit characteristics were similar during the 2006 survey, and only unit length, water visibility, and water temperature was remeasured. However, as noted previously, high flow events during April 2006 apparently caused channel changes in some habitat units. Most noticeable were changes in the depths of several pool habitats; some deep pools appeared to become shallower and some shallow pools appeared to have been scoured deeper. It is unknown to Table 2. Physical habitat parameters what degree these changes affect the measured or estimated at each sampling unit (shaded boxes) by year (refer to TRPA 2005, comparability of index estimates 2006 for variable descriptions). between years. Habitat Variable 2004 2005 2006 unit length New data collected in 2006 included unit width measured (rather than eye-estimated) unit surface area pool velocities in order to better unit volume characterize pool habitats for mean depth comparison with observed fish maximum depth abundance. Three surface velocities water temperature water visibility were measured with a “mini” current % canopy (entire unit) meter at pool heads, pool bodies, and % canopy (banks only) pool tails. Measurements were taken % escape cover at ¼, ½, and ¾ of the way across the % fines stream channel in pool heads % gravel approximately 50 ft below the upper % cobble boundary, and in pool tails 50 ft above % boulder (all) % boulder (small) the bottom boundary. Velocities were % boulder (large) also measured along one to three % bedrock transects spaced within pool bodies % turbulence (number of transects depending upon # shear zones pool length). Mean pool surface # large emergent boulders velocity was calculated by weighting pool surface velocity (eye est) the mean velocities from the pool head, pool surface velocity (measured)

18 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______body, and tail transects according to the proportion (by length) of each pool subtype (pool subtype lengths are recorded in the habitat mapping database (Appendix A).

QUALITY ASSURANCE / QUALITY CONTROL

The following QA/QC procedures were performed to ensure that fish count data were collected and recorded accurately and that results were representative of the population actually present.

General Procedures

All six divers were experienced with these methodologies from previous studies on the upper Sacramento River or the North Fork Feather River, however one-half day was allocated on-site prior to beginning this study to re-familiarize the personnel in species identification and survey techniques. Throughout the survey, an attempt was made to maintain consistency with respect to assigned tasks. Individual divers were repeatedly called on to perform specific tasks such as lane-line deployment, boundary monitoring, or diving within a specific lane. One of two crew supervisors acted as the data recorder and was responsible for ensuring that the dive team proceeded upstream at a suitable pace and in proper position.

The accuracy of dive count data was maximized by verbal communications between divers either during or immediately after a dive. If a school of fish passed downstream over a lane boundary the two adjacent divers compared counts to insure that all fish were observed and that only one diver recorded the data. Dive counts were continuously tallied on underwater dive slates to minimize loss of data. The divers were instructed to refer to a wrist-mounted underwater ruler incremented with each size class (5, 10, 15, and 20 inches) just prior to the initiation of each dive. The divers were also tested periodically with plastic fish models of differing lengths. These tests allowed individual divers to identify personal biases in size estimation and were intended to improve the accuracy of subsequent classifications.

The relative ability to see underwater was monitored during dive counts by estimating water visibility at each dive site. Minimum visibility was estimated by measuring the distance that a diver could clearly see an artificial trout approximately the size of a large fry. Water visibilities were measured perpendicular to flow and in the same lighting (sun or shade) that was predominant within the surveyed habitat unit. A comparison of visibilities measured with the small fish model with tests using an adult-sized fish model or a black and white Secchi disc in the upper Sacramento River indicated that adult trout could be identified at a distance approximately twice that of fry, and Secchi disc visibilities were approximately 2.5 times that of fry.

Several procedures were followed during preparation of dive count sites to minimize movement of fish into or out of survey units prior to diving. When crossing the stream channel divers crossed well upstream or downstream of unit boundaries or swam directly across the boundary line. Divers crossing the boundary line would locate all nearby fish

19 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______and carefully move around them. During deployment of lane-lines, only one diver proceeded downstream at a time to allow disturbed fish to swim around the diver rather than to exit the survey unit downstream. Subsequent divers deployed their lane-lines in turn; divers always maintained themselves a minimum of 100 feet upstream from the preceding diver to prevent herding the fish downstream (Figure 4, bottom). The exception to this rule was in deep pools where lane-lines were deployed together since the depth prevented adjacent divers from monitoring their locations by observing the previously deployed lines; divers then returned to staggered deployment near the units bottom boundary.

Because fish populations could potentially be altered by deployment of lane-lines, survey units were monitored to document the frequency and magnitude of disturbance. Prior to the deployment of the first lane-line, a monitoring diver carefully entered the water at the downstream boundary of the survey unit (Figure 7, bottom). The monitoring diver searched for a position that provided the best view of the boundary area where the lane- line diver would finish or where a disturbed fish would be expected to pass by (e.g. the channel thalweg). From this position (which could change for each deployed lane-line) the monitoring diver counted all fish that passed downstream out of the unit, or that re- entered the unit from below. Over a ten year period of diving in the upper Sacramento River, deployment of lane-lines displaced an average of one to two fish per habitat unit prior to the dive (TRPA 2005a). The survey unit's upstream boundary was also monitored for fish displaced upstream during the survey count if a deep, slow channel that provided an easy escape route for fish moving ahead of the dive team and if an extra diver was available (Figure 7, top). This monitor attempted to prohibit egress by blocking the escape route, and counted all fish that left the unit but were not included in the divers counts.

Replicate Counts

Replicate counts involving four consecutive dive counts were conducted in a subsample of habitat units during 2005 (3 units) and 2006 (7 units). Habitat units were chosen subjectively based on time constraints (e.g., not enough time to sample a new unit but too early to quit for the day); thus most replicate counts were conducted in the late afternoon hours. Each pass was conducted in like manner with divers remaining in their original lanes, with a waiting period of at least 20 minutes prior to beginning the next pass.

RESULTS

The 2006 dive counts were conducted from 6 to 20 September 2006, at streamflows of approximately 300 cfs in both reaches, which was similar to flows in 2005 but about 50 cfs higher than during the October 2004 survey (PG&E unpublished stream gage data). Water temperatures measured during dive counts ranged from 60oF to 68oF in both reaches, with a mean of 64.4oF in the Cresta Reach and 64.0 oF in the Rock Creek Reach (Figure 4). Estimated water visibilities ranged from a low of 6 ft (in morning hours) to a maximum of 14 ft (midday hours), with means of 9.2 ft and 9.5 ft in the Cresta and Rock

20 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Creek reaches, respectively. Water visibilities in both reaches were typically best in the middle and lower portions of each reach and worst closer to the diversion dams, presumably due to suspended algae entrained from the upstream diversion pools. There was no significant difference between reaches in water temperatures or water visibilities measured during the dive counts (t-test, P’s >0.40).

Characteristics of Sampled Habitat Units

The 2006 survey covered 11,097 ft of stream in the Cresta Reach and 12,943 ft of stream in the Rock Creek Reach, which represented 52% and 45% of the sampleable habitat in each reach, respectively (Table 1). In general, selected habitat units were well distributed longitudinally within each reach (Figures 2 and 3). A summary of unit dimensions (lengths, widths, and depths), % bank canopy, and metrics for describing habitat complexity (% turbulence, number of shear zones, density of emergent boulders, and pool velocities) according to reach and habitat type are available in the 2005 report (TRPA 2006). The units sampled in 2006 were the same as 2005 and the physical measurements were not repeated (Table 2). Photos of each sampled unit are presented in Appendix B (may only be available on CD).

Eye-Estimated Length-Frequency Distributions

The direct observation data can be used to estimate length-frequency distributions for each species, although actual validation of visual size estimates with captured and measured fish was not conducted. Consequently the following length-frequency distributions should be considered approximate. Fork lengths were visually estimated for rainbow trout to the nearest inch, although divers typically recorded lengths over 10 inches at even intervals (i.e., 12 or 14 inches versus 11 or 13 inches). Consequently the length frequency distributions for rainbow trout were plotted at intervals of two inches. The estimated lengths of all other species were recorded only within the following size classifications with the associated age-class descriptions: <5 inches (fry), 5-10 inches (juvenile), 11-15 inches (small adult), 16-20 inches (large adult), and >20 inches (very large adult). The age-class descriptions were not based on length at age data, but were used in this report to simplify text descriptions of the size classes.

Rainbow Trout

A total of 831 rainbow trout were counted in the Rock Creek and Cresta reaches during the 2006 survey, where each of the 70 units sampled contained between 1 and 36 trout (Table 3). The length-frequency histogram for rainbow trout in the Rock Creek Reach was unimodal at 3-4 inches, with equal counts between 5 and 12 inches and fewer fish larger than 12 inches (Figure 8). The length-frequency distribution for trout in the Cresta Reach was very similar with a prominent peak at 3-4 inches, then relatively flat from 5 to 12 inches (including a minor secondary mode at 12 inches), with decreasing counts to the maximum observed size of 19-20 inches.

21 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Table 3. Dive count data according to reach, habitat type, species, and size class. Fry counts for trout are from standard lanes, other species fry counts are expanded estimates from fry lanes. Rainbow Trout Sacramento Suckers Hardhead Pikeminnow Smallmouth Bass Hab Type Mile River Length ft <5 (incl PM) Reach Unit # <5 5-10 11-15 16-20 >20 <5 5-10 11-15 16-20 >20 5-10 11-15 16-20 >20 5-10 11-15 16-20 >20 <5 5-10 11-15 16-20 >20 CrestaRN10.00110161002802312890230000000100 CrestaDP80.131,5280330039014389022523853413910410 CrestaRN100.4514224800120010720000000000000 CrestaRF110.4717524570000000 410000000000000 CrestaRN120.5025972100638001029073281000100210 CrestaSP180.71973122007602006063 7 13 185100004810 CrestaSP321.3738901210121600107189 6 1330210002410 CrestaRN361.492162410060043 740010000001000 CrestaSP371.53225000108900017050241010101200 CrestaDP421.687300130033900201438 0 18 15 2 4 11 3 4 40 4 15 2 0 CrestaRN491.982171383101621040480000000030000 CrestaRN502.011880240010000102160010000010100 CrestaSP512.0446700050704001344236 1 13 181112024200 CrestaRN522.13187030007700001450010000000000 CrestaRF552.351151813100220000520000000000000 CrestaDP592.468050111020813911939 11 14 152000244900 CrestaRF622.75564100010320 50000000000000 CrestaRN632.775151100030600206309 0 1010000003320 CrestaDP753.2551318510868026150210231000000310 CrestaRN773.3718401031021604102930000000000100 CrestaDP793.4335501300618001128361300021003100 CrestaRN853.684111652058200204171260044000100 CrestaSP873.7952811100352022213131860122100000 CrestaRF903.931767800060160 70000000000000 CrestaRF923.97187215100212953170000000000000 CrestaRN934.00414111102023400502740200003000000 CrestaRF1014.1912517610012013000000000000000 CrestaDP1034.217240300019200007014440010000100 CrestaSP1074.36315000007100102470452010140110 CrestaRN1084.42160037109300101020010004100000 CRESTA TOTALS: 122 119 73 16 0 7288 4 30 100 19 42846 37 137 136 23 14 27 23 12 93 36 59 10 0

RockSP301.084862166006100530669012144020021210 RockRN341.29142032005400001540000100060100 RockRN401.4917012100135200021012000400000000 RockRN451.6018039300335053075611204400050000 RockRF461.61620100085000030700100100100000 RockRF511.83150842506714114300000000020000

22 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Table 3. (continued)

Rainbow Trout Sacramento Suckers Hardhead Pikeminnow Smallmouth Bass Hab Type River Mile Length ft <5 (incl PM) Reach Unit # <5 5-10 11-15 16-20 >20 <5 5-10 11-15 16-20 >20 5-10 11-15 16-20 >20 5-10 11-15 16-20 >20 <5 5-10 11-15 16-20 >20 RockSP561.9320637950 6503704750230042000110 RockRF591.998232000 51101 300000000000000 RockRN662.2242727720 541500329312010102120000 RockSP722.332020381016614005398418124011015600 RockRF752.3813175000 7600001510000000000000 RockDP943.062590130082502511340 87 2072930200000 Rock RN 102 3.33 469 9 5 3 2 0 1367 03302059 24 9 18 1 18 5 0 2 00000 RockSP1093.47162044001761449113833263901000000 RockRN1194.08420106610219003181000201100000000 Rock SP 120 4.13 318 1 4 3 3 0 270 0 18 91 21 2135 0 18 19 4 20 1 2 2 00000 RockRN1224.1921314600 95001043214000000000000 RockRF1234.22150117100 10120 130000000000000 RockRN1244.262285410046700106850300000000000 Rock RN 126 4.43 536 0 6 4 5 0 496 0 14 40 6 1803 26 37 30 2 38 1 3 0 00000 RockRF1274.461449550015408641740000000000000 RockSP1304.5615320100386004098500401030010000 Rock DP 139 5.02 494 3 3 3 2 0 607 0 2 29 0 3260 10 26 37 0 3 10 2 2 00000 Rock SP 144 5.37 523 5 2 4 2 0 3950 01504136 0 5 23 3 3 0 0 3 00000 Rock DP 146 5.60 1,140 0 1 0 0 0 1454 001121261103661114024200000 RockRN1536.023480230031502215384420100000000 RockRF1546.05169115000151041111110010100000000 Rock RN 155 6.16 577 2 4 5 2 0 1999 0 0 132 26 626 60 9 24 4 41 0 0 2 00000 RockRF1606.39234614000107191301320200000000000 RockRN1616.4214959310 5604721064130000000000 RockDP1646.5451910100 7800001817 87 20 23 4 75 18 0 0 00001 Rock RN 168 6.76 554 0 0 3 0 0 360 0 16 57 20 1288 70 9 30 5 32 5 5 0 00000 RockRF1696.8123614100 4900001061000100010000 RockRN1726.90296211510 550030 772200100000000 RockRF1787.21200149120 230370 150000000000000 RockSP1817.4868121400193189216118211026410135600 RockDP1857.92635032109300483630421886410160000 RockDP1878.033033131053700201148511111710001000 RockRN1958.296198731077318201101710841521300000 RockRN1978.351571211130 820113 30110000000000 ROCK CREEK TOTALS: 152 192 117 40 0 17825 10 139 508 105 49359 692 299 349 59 434 74 24 20 49 12 16 2 1

TOTALS BOTH REACHES: 274 311 190 56 0 25114 14 169 608 124 92204 729 436 485 82 448 101 47 32 142 48 75 12 1

23 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

The estimated proportions of 0.40 trout >17 inches in length was 0.35 2006 n=330 approximately 3% in both 0.30 mean L=7.7" reaches according to the raw 0.25 count data, however the true proportion of larger trout to 0.20 smaller trout cannot be assessed 0.15 with the uncalibrated count data. 0.10 Substantial differences in diver Relative Frequency Relative 0.05 observation probabilities for fish of different sizes are expected, 0.00 but are unknown, and will thus 1-2 5-6 9-10 13-14 17-18 >20 0.40 obscure that relationship.

0.35 2006 n=501 The similar water visibilities 0.30 mean L=8.1" between reaches and between 0.25 years (Figure 4) should, however, allow direct 0.20 comparisons of length- 0.15 frequency distributions. This 0.10 comparison assumes that diver Relative Frequency Relative 0.05 observation probabilities for a particular size class do not vary 0.00 between reaches (or, years). A 1-2 5-6 9-10 13-14 17-18 >20 Kolmogorov-Smirnov two- Fish Length (in) sample test indicated that the length frequency distributions Figure 8. Eye-estimated length-frequency between reaches in 2006 were distributions for rainbow trout according to reach. not significantly different (ks=0.07, P=0.32).

Hardhead

Because of species similarities, all hardhead and pikeminnow less than 5 inches were treated together and recorded as pikeminnow/hardhead. A total of 12,328 and 13,405 hardhead/pikeminnow less than five inches were observed during standard dive counts in the Cresta Reach and Rock Creek Reach, respectively. Higher counts occurred in the fry lanes that only extended six feet out from each bank, but where divers could concentrate solely on fry. Total expanded counts in fry lanes were 42,846 fry in the Cresta Reach and 49,359 fry in the Rock Creek Reach (Table 3). Of the larger size classes, a total of 333 juvenile and adult hardhead were observed in the Cresta Reach, most of which were in the 11-15 and 16-20 inch size classes (Figure 9). In the Rock Creek Reach, over four times as many juvenile and adult hardhead (1,399 fish) were counted than in the Cresta

24 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

CRESTA REACH ROCK CREEK REACH 0.8 0.8 Hardhead Hardhead 2006 n=333 2006 n=1399 0.6 0.6

0.4 0.4

0.2 0.2 Relative Frequency Relative

0.0 0.0 5-10 11-15 16-20 >20 5-10 11-15 16-20 >20 Fish Length (in) Fish Length (in) 1.0 1.0 Pikeminnow 2006 n=76 Pikeminnow s 2006 n=552 0.8 0.8

0.6 0.6

0.4 0.4

0.2 0.2 Relative Frequency Relative

0.0 0.0 5-10 11-15 16-20 >20 5-10 11-15 16-20 >20 Fish Length (in) Fish Length (in)

1.0 1.0 Suckers 2006 n=153 Suckers 2006 n=762 0.8 0.8

0.6 0.6

0.4 0.4

0.2 0.2 Relative Frequency Relative

0.0 0.0 5-10 11-15 16-20 >20 5-10 11-15 16-20 >20 Fish Length (in) Fish Length (in)

1.0 1.0

Smallmouth Bass 2006 n=105 Smallmouth Bass 2006 n=31 0.8 0.8

0.6 0.6

0.4 0.4

0.2 0.2 Relative Frequency Relative

0.0 0.0 5-10 11-15 16-20 >20 5-10 11-15 16-20 >20 Fish Length (in) Fish Length (in)

Figure 9. Eye-estimated length-frequency distributions for juvenile and adult size classes of non-trout species, according to reach (proportions exclude fry <5 inches).

25 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Reach. Juvenile hardhead 5-10 inches in length dominated the counts in the Rock Creek Reach, whereas juveniles were relatively rare in the Cresta Reach.

Sacramento Pikeminnow

The 2006 survey produced a total dive count of 552 juvenile and adult pikeminnow (>5 inches) in the Rock Creek Reach, but only 76 pikeminnow in the Cresta Reach (Table 3). As noted for hardhead, most of the pikeminnows observed in the Rock Creek Reach were juveniles, which comprised almost 80% of the total count (Figure 9). The length- frequency distribution of pikeminnow in the Cresta Reach was dominated by small adults and large adults (11-20 inches), with smaller but equal proportions of juveniles and very large adults.

Sacramento Suckers

A total of 2,931 and 6,671 suckers were observed in the Cresta Reach and the Rock Creek Reach in 2006, respectively. The vast majority of suckers counted (~90%) in both reaches were fry <5 inches in length. Total expanded counts in fry lanes were 7,288 fry in the Cresta Reach and 17,8259 fry in the Rock Creek Reach (Table 3). Unlike hardhead and pikeminnows, the length-frequency distributions for non-fry suckers were nearly identical in both reaches (Figure 9). Between 65% and 70% of all non-fry suckers were large adults (16-20 inches), with 10-20% of fish in the small adult and very large adult size classes.

Smallmouth Bass

Divers counted a total of 129 bass in the Cresta Reach but only 44 bass in the Rock Creek Reach. Although bass abundance differed between the reaches, the length-frequency distributions were very similar with a dominant mode for small adult bass 11-15 inches in length. Juvenile bass comprised about 35-40% of the count of non-fry bass, with about 10% over 15 inches in length (Figure 9). Counts of bass fry within fry lanes also favored the Cresta Reach over the Rock Creek Reach, with expanded counts of 93 fry versus 49 fry, respectively.

Index Estimates According to Reach and Habitat Type

Index estimates of abundance and density (# fish/mile) with associated variances and 95% confidence intervals are given for each species, size class, habitat type, and reach (see Appendix C for index estimates of abundance, variances, and associated confidence intervals). Comparison of abundance between reaches is influenced by the overall amount of sampleable habitat, which is greater in the Rock Creek Reach (at 5.5 mi) than in the Cresta Reach (4.0 mi) (Table 1). Note that the following estimates of abundance or density do not account for non-sampled habitat (i.e. “X”ed riffles, runs, and pools), which makes-up 15% and 35% of total stream length in the Cresta and Rock Creek reaches,

26 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______respectively (Figure 5). The abundance estimates are also affected by the relative availability of different habitat types, which also varies between reaches. Direct comparison of abundance between reaches is therefore best accomplished using estimates of fish densities (expressed as number/mile), which accounts for the differences in habitat availability. Estimates are also pooled across reaches to represent combined abundance and density in the study area according to each habitat type for each species and size class.

Quantitative, statistical comparisons are only made between index estimates within species, size class, and habitat type strata, by assessing the overlap of 95% confidence intervals (i.e. no overlap suggests a statistically significant difference). Qualitative comparisons of densities are also made between habitat types, however the reader should be cautioned that expected, but unknown, differences in diver observation probabilities between habitat types could produce misleading conclusions about relative densities in pools, runs, and riffles. For example, if estimated densities of juvenile trout are 20% higher in riffles than in runs, but the true (unknown in this study) observation probabilities are 50% higher in riffles than in runs, the true densities of juvenile trout would actually be higher in runs than in riffles. The same cautions apply to the qualitative comparisons of estimates between size classes, because large trout are generally much easier to observe than are small trout. Estimating diver observation probabilities in a large, swift river such as the North Fork Feather River would require numerous repeated dive counts in each habitat type, only a few of which (10 units in total) were conducted in 2005-06.

As a convention, life stages for each species will be referred to as fry (<5 inches), juvenile (5-10 inches), small adult (11-15 inches), large adult (16-20 inches), and very large adult (>20 inches), even though each species would be expected to transition from fry to juvenile to adult at different lengths. All rainbow trout fry estimates are based on standard lane counts encompassing the entire channel width because trout fry were commonly observed away from the stream margin and standard counts typically produced larger index estimates than did fry lane counts. The opposite relationship was true for non-salmonid species, which were more common along the streambanks and consequently fry lane estimates (only within 6 ft of the bank) were consistently greater than standard lane counts. Index estimates for hardhead/pikeminnow fry, sucker fry, and bass fry therefore use count data from fry lanes.

Rainbow Trout

Fry. The index estimates of abundance for rainbow trout fry were 258 in the Cresta Reach and 379 in the Rock Creek Reach (Figure 10). Index densities were also higher in the Rock Creek Reach than in the Cresta Reach for all habitats except riffles, where the index densities were significantly higher (Figure 11). Abundance estimates were higher in fast water habitats (runs and riffles) than in slower habitats (deep and shallow pools), largely due to the much higher index densities observed in riffles. Estimated fry abundance and density was particularly low in Cresta pool habitats, many of which were occupied by smallmouth bass. In the Rock Creek reach, where bass were much less

27 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

400 Cresta Reach 400 Rock Creek Reach RBT (<5") RBT (<5") 2006 Abundance 2006 Abundance std lane std lane 300 300

200 200 169 151 160 100 100

Index AbundanceIndex 84 AbundanceIndex 45 23 0 32 0 DP SP RN RF DP SP RN RF

400 400 RBT (5-10") RBT (5-10")

300 300

243 200 200 172 122 122 100 100 Index AbundanceIndex 73 AbundanceIndex 39 24 0 5 0 DP SP RN RF DP SP RN RF

400 400 RBT (11-15") RBT (11-15")

300 300

200 200 146 124 126 100 100 Index AbundanceIndex AbundanceIndex 36 40 18 22 0 6 0 DP SP RN RF DP SP RN RF

200 200 RBT (16-20") RBT (16-20")

150 150

100 100

50 50 Index AbundanceIndex AbundanceIndex 42 36 11 16 11 15 0 4 0 0 DP SP RN RF DP SP RN RF

100 100 RBT (>20") RBT (>20") 80 80

60 60

40 40

Index AbundanceIndex 20 Index AbundanceIndex 20

0 0000 0 0000 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 10. Index estimates of fish abundance for rainbow trout according to size class, habitat type, and reach. Vertical bars are 95% confidence intervals.

28 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

800 Cresta Reach 800 Rock Creek Reach RBT (<5") 2006 Density RBT (<5") 2006 Density std lane std lane 600 600 565

400 400

242 200 200 Index Density (#/mi) Density Index (#/mi) Density Index 62 73 34 0 2 3 0 16 DP SP RN RF DP SP RN RF 400 400 RBT (5-10") RBT (5-10")

300 300

244 200 200 184

127 118 100 100 91 Index Density (#/mi) Density Index (#/mi) Density Index

24 17 0 7 0 DP SP RN RF DP SP RN RF 200 200 RBT (11-15") RBT (11-15")

150 150

109 100 100 92

60 61 50 50 Index Density (#/mi) Density Index (#/mi) Density Index 28 33 22 9 0 0 DP SP RN RF DP SP RN RF 200 200 RBT (16-20") RBT (16-20")

150 150

100 100

50 50 Index Density (#/mi) Density Index (#/mi) Density Index 31 23 15 17 12 8 0 3 0 0 DP SP RN RF DP SP RN RF 200 200 RBT (>20") RBT (>20")

150 150

100 100

50 50 Index Density (#/mi) Density Index (#/mi) Density Index

0 0000 0 0000 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 11. Index estimates of fish density (#/mile) for rainbow trout according to size class, habitat type, and reach. Vertical bars are 95% confidence intervals.

29 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______common, fry densities were an order of magnitude higher in pools. In general, the estimated densities of fry were lower in pool habitats than were estimates for the larger trout, whereas densities of fry in riffles were greater than estimates for larger trout. When combined across reaches, the estimated abundance of fry ranged from a low of 26 fish in deep pools to 329 fish in riffles (Figure 12). The combined index density in riffles was 339 fish/mile, which was five times greater than the combined density in runs, and far greater than the estimates for pools. The importance of riffle habitats for trout fry in the study area is clearly evident. The combined index density for the entire study area (all habitat types combined) was 67 fish/mile.

Juvenile. Index estimates of abundance for juvenile trout in deep pools were similar in the Cresta and Rock Creek reaches, but in all other habitat types juveniles were more abundant in the Rock Creek Reach (Figure 10). Similar to fry, index densities for juveniles were mostly higher in runs and riffles than in pools, particularly in the Cresta Reach where juvenile densities in riffles were orders of magnitude higher than densities in pools (Figure 11). Combined estimates from the two reaches suggested that approximately 790 juvenile trout were observable (by divers) in the study area, with most fish occupying runs and fewest fish in deep pools (Figure 12). Combined density estimates also showed lowest densities for deep pools (21 fish/mile), but densities were higher in riffles (201 fish/mile) than in runs (121 fish/mile), with an overall index density of 83 fish/mile.

Small Adult. The index abundance (Figure 10) and density (Figure 11) of small adult trout were similar in the Rock Creek Reach and in the Cresta Reach in all habitat types except shallow pools, where fish density in the Rock Creek Reach (109 fish/mile) was significantly higher than in the Cresta Reach (9 fish/mile). In the Cresta Reach, small adult trout occurred, as did fry and juveniles, at higher densities in fast water habitats (e.g., runs and riffles) than in slow water pools, but this relationship was not as evident in the Rock Creek Reach. Unlike fry and juveniles, index densities of small adult trout were higher in runs than in riffles. Abundance estimates combined across reaches showed highest numbers in runs and lowest numbers in riffles, totaling 518 fish (Figure 12). Combined index densities were the same for shallow pools and runs, at 73 fish/mile, with lower densities (41 fish/mile) in riffles and deep pools (25 fish/mile). The overall index density for both reaches was less than the juvenile estimate at 55 fish/mile.

Large Adult. Large adult rainbow trout were more abundant in the Rock Creek Reach (with 104 fish) than in the Cresta Reach (with 31 fish). Although the difference in abundance in shallow pools was large with 42 fish in Rock Creek shallow pools versus only 11 fish estimated in Cresta shallow pools (Figure 10), it was not statistically significant. Differences in index densities were less apparent and were not statistically significant in any habitat type, but did illustrate higher densities in the Rock Creek Reach (Figure 11). No large adult trout were observed in riffles in the Cresta Reach; however, the index density for large adult trout in Rock Creek Reach riffles was intermediate to runs and shallow pools. When combined across reaches, identical numbers of large adult trout were observed in shallow pools and runs, and likewise for deep pools and riffles, for a total index estimate of 135 fish (Figure 12). Combined density estimates were highest

30 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

600 Combined Reaches 500 Combined Reaches RBT (<5") RBT (<5") 500 2006 Abundance 2006 Density std lane 400 std lane 400 339 300 329 300 235 200 200

Index AbundanceIndex 100 100 (#/mi) Density Index 69 47 26 23 0 0 8 DP SP RN RF DP SP RN RF

600 300 RBT (5-10") RBT (5-10") 500 250

400 415 200 201

300 150 121 200 195 100

Index AbundanceIndex 127 61 100 (#/mi) Density Index 50 53 21 0 0 DP SP RN RF DP SP RN RF

600 300 RBT (11-15") RBT (11-15") 500 250

400 200

300 150 250 200 100 152 73 73 Index AbundanceIndex 100 (#/mi) Density Index 50 76 41 40 25 0 0 DP SP RN RF DP SP RN RF

200 100 RBT (16-20") RBT (16-20") 80 150

60 100 40

50 53 52 25

Index AbundanceIndex 20 Index Density (#/mi) Density Index 15 15 15 15 5 0 0 DP SP RN RF DP SP RN RF

200 100 RBT (>20") RBT (>20") 80 150

60 100 40

50

Index AbundanceIndex 20 Index Density (#/mi) Density Index

0 0000 0 000 0 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 12. Index estimates of fish abundance (left column) and fish density (right column) for rainbow trout combined across reaches, according to size class and habitat type. Vertical bars are 95% confidence intervals.

31 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______in shallow pools, the same in runs and in riffles, and lowest in deep pools, with an overall index density of 14 fish/mile.

Very Large Adult. No very large adult trout were observed in either reach in 2006 (Table 3), thus all estimates of abundance and density for this size class were zero (Figures 10- 12).

Hardhead

Fry. As previously described, all hardhead and pikeminnow (HH/PM) fry were counted together due to difficulties in field identification (Table 3). The overall indexes of abundance for HH/PM fry were relatively similar in the two reaches at approximately 79,000 to 95,000 fish, according to expanded fry lane counts (Figures 13 and 14). Among habitat types, both abundance and density of fry was significantly lower in riffles in both reaches, with intermediate densities in runs. Unlike trout fry, HH/PM fry were consistently more abundant (by two to three times) in slow-water habitats than in fast- water habitats, with highest densities in deep pools and lowest densities in riffles. Combined estimates from both reaches reflected the reach-specific patterns, with a total index abundance of 173,367 fish, at approximately 18,000 fish/mile (Figure 15).

Juvenile. Juvenile hardhead were dramatically more abundant in the Rock Creek Reach than in the Cresta Reach, with an estimated 1977 fish and 60 fish, respectively (Figure 13). Despite high variability and wide confidence intervals, the differences in abundance and density (Figure 14) were statistically significant for deep pool and run estimates, but not for shallow pools or riffles (where only one juvenile was observed in both reaches). Like fry, juveniles were more abundant in slow water pools than in fast water runs and riffles. The combined index estimates were 2,037 juveniles at a density of 214 fish/mile (Figure 15).

Small Adult. Small adult hardhead were also more abundant in the Rock Creek Reach (686 fish) than in the Cresta Reach (214 fish); the differences in abundance and density were statistically significant for deep pools and runs (Figure 13). In both reaches, index densities were highest in pools, intermediate in runs, and near zero in riffles (Figure 14). Combined index estimates of abundance and density produced a total of 900 fish in both reaches, at a mean density of 95 fish/mile (Figure 15). Small adult hardhead were approximately three times more abundant than juveniles in the Cresta Reach, but showed the opposite relationship in the Rock Creek Reach were small adults were only about one-third as abundant as juveniles.

Large Adult. The abundance of large adult hardhead was similar to the abundance of small adult hardhead in both reaches, but abundance was approximately three times greater in the Rock Creek Reach as in the Cresta Reach (Figure 13) due both to the larger length of the Rock Creek Reach as well as higher index densities of hardhead (Figure 14). Only the density difference in deep pools was significant between reaches. Like the smaller size classes of hardhead, large adults also appeared to favor pool habitats over run habitats, where densities were typically less than one-half of pools. Index densities in

32 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

60000 Cresta Reach 60000 Rock Creek Reach 2006 Abundance HH/PM (<5") 64,924 2006 Abundance HH/PM (<5") 50000 50000 43,878 40000 40000 33,198 30000 30000 25,983 27,034 20000 19,327 20000 19,321 Index AbundanceIndex Index AbundanceIndex 10000 10000 4,389 0 237 0 DP SP RN RF DP SP RN RF

2000 2000 HH (5-10") HH (5-10")

1500 1500

1,109 1000 1000

500 500

Index AbundanceIndex 442 425 Index AbundanceIndex

0 33 19 8 0 0 1 DP SP RN RF DP SP RN RF

500 500 HH (11-15") HH (11-15") 400 400 331 300 300

221 200 200

131

Index AbundanceIndex 109

100 AbundanceIndex 100 74 31 0 0 0 3 DP SP RN RF DP SP RN RF

500 500 HH (16-20") HH (16-20") 400 400

300 300 314

200 200 210 172

Index AbundanceIndex 100 94 AbundanceIndex 100 75 55 0 0 0 8 DP SP RN RF DP SP RN RF

100 100 HH (>20") HH (>20") 80 80

60 60 54 50 40 40 Index AbundanceIndex Index AbundanceIndex 20 18 20 21 13 0 2 0 0 0 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 13. Index estimates of fish abundance for hardhead according to size class, habitat type, and reach. Vertical bars are 95% confidence intervals.

33 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

60000 Cresta Reach 60000 Rock Creek Reach HH/PM (<5") HH/PM (<5") 2006 Density 2006 Density 50000 fry lane 50000 fry lane 40000 40000 35,551 30000 30000 30,714

20000 20,392 20000 20,261 14,300 Index Density (#/mi) Density Index Index Density (#/mi) Density Index 10000 10000 9,357 6,625 0 793 0 DP SP RN RF DP SP RN RF

1400 1400 HH (5-10") 1200 1200 HH (5-10")

1000 1000

800 800 776 600 600

400 400 331 Index Density (#/mi) Density Index (#/mi) Density Index 200 200 206

0 20 26 6 0 0 2 DP SP RN RF DP SP RN RF 350 350 HH (11-15") 300 HH (11-15") 300

250 250 232 200 200 166 150 150

100 101 100

Index Density (#/mi) Density Index 67 (#/mi) Density Index 63 50 50 23 0 0 0 5 DP SP RN RF DP SP RN RF 350 350

300 HH (16-20") 300 HH (16-20")

250 250 220 200 200

150 150 157

100 103 100 83 Index Density (#/mi) Density Index Index Density (#/mi) Density Index 58 50 41 50 12 0 0 0 DP SP RN RF DP SP RN RF 100 100 HH (>20") HH (>20") 80 80

60 60

40 40 40 35

20 Index Density (#/mi) Density Index 18 (#/mi) Density Index 20 11 10 0 2 0 0 0 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 14. Index estimates of fish density (#/mile) for hardhead according to size class, habitat type, and reach. Vertical bars are 95% confidence intervals.

34 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

120000 Combined Reaches 50000 Combined Reaches 2006 Abundance HH/PM (<5") 2006 Density HH/PM (<5") 100000 fry lane 40000 fry lane

80000 77,076 30000 60000 25,216 25,467 53,017 20000 40000 38,648 10000 11,313 Index AbundanceIndex 20000 (#/mi) Density Index 4,769 4,626 0 0 DP SP RN RF DP SP RN RF

2000 700

HH (5-10") 600 HH (5-10") 1500 500

1,142 400 374 1000 300

200 221 500 461

Index AbundanceIndex 433

Index Density (#/mi) Density Index 127 100

0 1 0 1 DP SP RN RF DP SP RN RF

600 250 HH (11-15") HH (11-15") 500 200 440 400 150 144 142 300 295 100 200 162

Index AbundanceIndex 50 47 100 (#/mi) Density Index

0 3 0 3 DP SP RN RF DP SP RN RF

600 250 HH (16-20") HH (16-20") 500 200 400 408 150 133 137 300 285 227 100 200 66

Index AbundanceIndex 50 100 (#/mi) Density Index

0 8 0 8 DP SP RN RF DP SP RN RF

120 250 HH (>20") HH (>20") 100 200 80 150 68 67 60 100 40

Index AbundanceIndex 23 50 20 (#/mi) Density Index 32 22 0 0 0 7 0 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 15. Index estimates of fish abundance (left column) and fish density (right column) for hardhead combined across reaches, according to size class and habitat type. Vertical bars are 95% confidence intervals.

35 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______riffles were almost zero with only eight fish estimated to occupy riffles in the Rock Creek Reach and none in the Cresta Reach. Combined reach estimates were similar to that for small adult hardhead, with an estimated 928 large adults at a density of 98 fish/mile (Figure 15).

Very Large Adult. Very large adult hardhead were relatively uncommon with index estimates of abundance of only 33 fish in the Cresta Reach and 125 fish in the Rock Creek Reach (Figure 13). Only the difference in runs was statistically significant between reaches. Very large adults were almost always observed in pool habitats, with a few fish in runs, but no fish were observed in riffles. Index densities in pools were between 10 and 40 fish/mile, well below the estimates for small and large adult hardhead (Figure 14). The combined index estimates of abundance were 158 fish at a mean density of 17 fish/mile (Figure 15).

Sacramento Pikeminnow

Fry. For pikeminnow fry, refer to the hardhead data described above. Because larger pikeminnow were less abundant in each reach than were hardhead, it is expected that hardhead made-up the majority of the hardhead/pikeminnow fry described above.

Juvenile. As seen for hardhead, index estimates of abundance and density for juvenile pikeminnow were higher in the Rock Creek Reach than in the Cresta Reach, where the total abundance estimate was only 20 fish (Figure 16). In contrast, abundance estimates for deep pools, shallow pools, and runs in the Rock Creek Reach were all between 300 and 400 fish (but confidence intervals were very wide indicating low confidence in point estimates). Index densities in the Rock Creek Reach showed highest densities in pools at about 250 fish/mile, with slightly lower densities in runs (187 fish/mile) and near-zero densities (6 fish/mile) in riffles (Figure 17). Like for hardhead, the juveniles were by far the most abundant non-fry size class in the Rock Creek Reach, but were a minor component of the size distribution in the Cresta Reach. The combined estimates for both reaches are virtually identical to the Rock Creek estimates due to the lack of fish from the Cresta Reach (Figure 18). The overall mean density of 118 fish/mile was approximately half the mean density of juvenile hardhead.

Small Adult. Abundance and density of small adult pikeminnow was also higher in the Rock Creek Reach than in the Cresta Reach, but all estimates were low and no reach comparisons were significantly different (Figures 16 and 17). When combined across reaches, the total index of abundance and of approximately 240 fish and index densities of 25 fish/mile were mostly distributed among pools and runs, with few fish in riffles (Figure 18). The combined density estimate for pikeminnow was approximately one- quarter of the index density for small adult hardhead, which had a similar distribution among habitat types (Figure 15).

Large Adult. Large adult pikeminnow were uncommon in both reaches with an estimated 45 observable fish in the Cresta Reach and 51 fish in the Rock Creek Reach (Figure 16). Index densities were generally similar between reaches and habitat types (at 6-21

36 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

100 Cresta Reach 100 Rock Creek Reach PM (<5") 2006 Abundance 2006 Abundance PM (<5") 80 see HH data 80 see HH data

60 60

40 40

Index AbundanceIndex 20 AbundanceIndex 20

0 0 DP SP RN RF DP SP RN RF

800 607 800 PM (5-10") PM (5-10") 600 600

400 400 376 386 335

200 200 Index AbundanceIndex AbundanceIndex

0 13 7 00 0 4 DP SP RN RF DP SP RN RF

200 200 PM (11-15") PM (11-15") 150 150

100 100 95

50 50 56 Index AbundanceIndex Index AbundanceIndex 34 33 10 0 6 0 0 6 DP SP RN RF DP SP RN RF

60 60 PM (16-20") PM (16-20") 50 50

40 40

30 30 28 26 20 20 14 14 Index AbundanceIndex 10 AbundanceIndex 10 9 5 0 0 0 0 DP SP RN RF DP SP RN RF

60 60 PM (>20") PM (>20") 50 50

40 40

30 30

20 20 18

Index AbundanceIndex 12 AbundanceIndex 10 10 10 10 66 0 0 0 0 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 16. Index estimates of fish abundance for pikeminnows according to size class, habitat type, and reach. Vertical bars are 95% confidence intervals.

37 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

1000 Cresta Reach 1000 Rock Creek Reach PM (<5") PM (<5") 2006 Density 2006 Density 800 fry lane 800 fry lane see HH data see HH data 600 600

400 400

200 (#/mi) Density Index 200 Index Density (#/mi) Density Index

0 0 DP SP RN RF DP SP RN RF

1,000 600 PM (5-10") PM (5-10") 500 800 400 600 300 282 400 234 200 187 200 Index Density (#/mi) Density Index Index Density (#/mi) Density Index 100

0 81000 0 6 DP SP RN RF DP SP RN RF

150 150 PM (11-15") PM (11-15") 125 125

100 100

75 75 66 50 50 42

Index Density (#/mi) Density Index 25 21 (#/mi) Density Index 25 14 16 9 0 4 0 0 DP SP RN RF DP SP RN RF

150 150 PM (16-20") PM (16-20") 125 125

100 100

75 75

50 50

Index Density (#/mi) Density Index 25 (#/mi) Density Index 25 19 21 9 7 6 7 0 0 0 0 DP SP RN RF DP SP RN RF

50 50 PM (>20") PM (>20") 40 40

30 30

20 20

13 10 10 Index Density (#/mi) Density Index 7 8 (#/mi) Density Index 7 4 5 0 0 0 0 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Rif f les Pools Pools Figure 17. Index estimates of fish density (#/mile) for pikeminnows according to size class, habitat type, and reach. Vertical bars are 95% confidence intervals.

38 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

1,000 Combined Reaches 1,000 Combined Reaches PM (<5") 2006 Abundance 2006 Density PM (<5") 800 800 see HH data see HH data 600 600

400 400

Index AbundanceIndex 200 200 Index Density (#/mi) Density Index

0 0 DP SP RN RF DP SP RN RF

800 400 PM (5-10") PM (5-10") 600 300

400 383 386 200 348 184

114 200 100 113 Index AbundanceIndex Index Density (#/mi) Density Index

0 4 0 4 DP SP RN RF DP SP RN RF

250 80 PM (11-15") PM (11-15") 200 60

150 129 40 42 100 32

66 20

Index AbundanceIndex 50 39 (#/mi) Density Index 11 6 0 6 0 DP SP RN RF DP SP RN RF

80 80 PM (16-20") PM (16-20") 60 60

40 40 40 33 23 20 20

Index AbundanceIndex 16 Index Density (#/mi) Density Index 12 8 0 0 0 0 DP SP RN RF DP SP RN RF

80 80 PM (>20") PM (>20") 60 60

40 40 30 20 20

Index AbundanceIndex 16 16 Index Density (#/mi) Density Index 10 8 5 0 0 0 0 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 18. Index estimates of fish abundance (left column) and fish density (right column) for pikeminnows combined across reaches, according to size class and habitat type. Vertical bars are 95% confidence intervals.

39 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______fish/mile), except for riffles where no large adult pikeminnow were observed in either reach (Figure 17). Combined estimates of abundance were 20 to 40 fish in pools and runs, with a total of 96 fish in both reaches. The combined abundance estimate was about one-half of the estimate for small adult pikeminnow, but only one-tenth of the estimate for large adult hardhead (Figure 15). Combined index densities were about 10 fish/mile (Figure 18).

Very Large Adult. Index abundance and density of very large adult pikeminnow were low in both reaches and in all habitat types, with slightly greater abundance in the Rock Creek Reach (Figures 16 and 17). Very large adult pikeminnows were not observed in riffles, as noted for large adult pikeminnows and very large hardhead. Combined reach estimates were 62 fish at seven fish/mile (Figure 18), or about two-thirds of the estimates for large adult pikeminnow and less than one-half the estimate of very large adult hardhead.

Sacramento Suckers

Fry. Sucker fry, like hardhead fry, were clearly the dominant life stage for this species in both reaches. According to expanded fry lane counts sucker fry (<5 inches) were approximately two to three-times more abundant in the Rock Creek Reach than in the Cresta Reach, however high variability made only the run and riffle habitat differences significant (Figure 19). Like hardhead and pikeminnow but unlike trout, sucker fry clearly favored pool and run habitats over riffles. In both reaches, index densities of sucker fry were highest in pools and lowest in rifles (Figure 20). Index estimates combined across reaches resulted in a total abundance estimate of over 52,000 fry with a mean density of 5,566 fish/mile (Figure 21).

Juvenile. Juvenile suckers were rarely observed in either reach with total abundance estimates of only eight fish in the Cresta Reach and 42 fish in the Rock Creek Reach (Figure 19). Unlike juvenile hardhead, index densities of sucker fry were not greater in the Rock Creek Reach than in the Cresta Reach, but were equally low (<15 fish/mile) in both reaches (Figure 20). Combined abundance and density estimates were likewise low, with a mean combined density of only four fish/mile (Figure 21).

Small Adult. The index of abundance of small adult suckers in the Cresta Reach (62 fish) was about one-fifth of the estimated abundance in the Rock Creek Reach (323 fish), resulting primarily from the statistically significant difference in shallow pool and run abundance estimates (Figure 19). In the Cresta Reach index densities were low in pool and run habitats, but were relatively high (84 fish/mile) in riffles (Figure 20). Index densities were more variable among habitat types in the Rock Creek Reach with densities of about 100 fish/mile in shallow pools and riffles. Most size classes of suckers appear to utilize a broad range of habitat types, unlike trout which are more common in fast water habitats, and pikeminnows and hardhead which appear to prefer slow water habitats. A combined index abundance of 385 suckers at 41 fish/mile were mostly distributed in shallow pools and runs, but with highest densities in riffles (Figure 21).

40 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

25,000 Cresta Reach 25,000 Rock Creek Reach SKR (<5") 2006 Abundance 2006 Abundance SKR (<5") 20,000 fry lane 20,000 fry lane

15,000 15,000 12,419 11,222 11,911 10,000 10,000

6,241 5,000 5,377 5,000 Index AbundanceIndex 3,746 AbundanceIndex 1,847 0 117 0 DP SP RN RF DP SP RN RF

300 300 SKR (5-10") SKR (5-10") 250 250

200 200

150 150

100 100 Index AbundanceIndex Index AbundanceIndex 50 50 12 11 0 2 0 33 0 0 9 DP SP RN RF DP SP RN RF

300 300 SKR (11-15") SKR (11-15") 250 250

200 200

150 150 133 100 100 104

Index AbundanceIndex 64 Index AbundanceIndex 50 50 22 25 22 11 0 4 0 DP SP RN RF DP SP RN RF

800 800 1,341 SKR (16-20") SKR (16-20") 641 600 600

400 400 353

200 200 Index AbundanceIndex Index AbundanceIndex 118 68 78 43 47 28 0 0 DP SP RN RF DP SP RN RF

300 300 SKR (>20") SKR (>20") 250 250

200 200

150 150 129 100 100 87 Index AbundanceIndex 50 AbundanceIndex 50 11 9 13 12 19 0 4 0 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Rif f les Pools Pools Figure 19. Index estimates of fish abundance for suckers according to size class, habitat type, and reach. Vertical bars are 95% confidence intervals.

41 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

20000 Cresta Reach 20000 Rock Creek Reach SKR (<5") 2006 Density 2006 Density SKR (<5") fry lane fry lane 15000 15000

10000 10000 9,308 7,855 5,769 5000 5,125 5000 3,833 3,978 Index Density (#/mi) Density Index Index Density (#/mi) Density Index 2,788 0 391 0 DP SP RN RF DP SP RN RF

250 250 SKR (5-10") SKR (5-10") 200 200

150 150

100 100

50 50 Index Density (#/mi) Density Index (#/mi) Density Index

9 9 14 0 1 0 3 0 0 5 DP SP RN RF DP SP RN RF

250 250 SKR (11-15") SKR (11-15") 200 200

150 150

100 100 100 97 84 50 50 50 Index Density (#/mi) Density Index (#/mi) Density Index 16 15 0 7 6 0 DP SP RN RF DP SP RN RF

600 600 SKR (16-20") 1,005 SKR (16-20") 500 500 480 400 400

300 300

200 200 171 118 Index Density (#/mi) Density Index 100 94 (#/mi) Density Index 100 83 64 50 26 0 0 DP SP RN RF DP SP RN RF

250 250 SKR (>20") SKR (>20") 200 200

150 150

100 100 97

50 50 Index Density (#/mi) Density Index (#/mi) Density Index 42 29 7 12 10 14 0 0 8 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 20. Index estimates of fish density (#/mile) for suckers according to size class, habitat type, and reach. Vertical bars are 95% confidence intervals.

42 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

30000 Combined Reaches 15000 Combined Reaches SKR (<5") SKR (<5") 25000 2006 Abundance 2006 Density fry lane 12000 fry lane 20000 17,463 17,288 9000 16,165 15000 7,765 6000 5,713 10000 5,060

Index AbundanceIndex 3000 5000 2,025

1,964 (#/mi) Density Index 0 0 DP SP RN RF DP SP RN RF

300 150 SKR (5-10") SKR (5-10") 250 120 200 90 150 60 100

Index AbundanceIndex 30 50 In d e x De n s ity ( # /mi) 12 12 14 12 6 0 2 0 1 4 DP SP RN RF DP SP RN RF

300 150 SKR (11-15") SKR (11-15") 250 120 200 90 92 150 137 66 126 60 100 89 37

Index AbundanceIndex 30

50 (#/mi) Density Index 33 11 0 0 DP SP RN RF DP SP RN RF

1500 700 SKR (16-20") SKR (16-20") 1250 600 500 1000 400 750 330 688 300 500 421 200 Index AbundanceIndex 250 (#/mi) Density Index 100 123 109 161 106 53 0 0 DP SP RN RF DP SP RN RF

300 150 SKR (>20") SKR (>20") 250 120 200 90 150 138 66 60 100 100

Index AbundanceIndex 30 29 50 (#/mi) Density Index 24 23 23 8 0 0 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Rif f les Pools Pools Figure 21. Index estimates of fish abundance (left column) and fish density (right column) for suckers combined across reaches, according to size class and habitat type. Vertical bars are 95% confidence intervals.

43 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Large Adult. Large adult suckers (16-20 inches) were the dominant post-fry size class in both reaches, and were substantially more abundant in the Rock Creek Reach (at 1,190 observable fish) than in the Cresta Reach (at 186 fish), however reach differences in abundance and density were only significant in runs (Figures 19 and 20). The schooling behavior of adult suckers in pool habitats resulted in highly variable counts between units and consequently wide confidence intervals around the estimates. Combined estimates (1,376 fish at 144 fish/mile) showed the lowest and highest densities in the slow water habitats (pools), with intermediate densities in fast water runs and riffles (Figure 21). Like small adult suckers, large adults were observed in all habitat types with no clear preference for fast water or slow water types.

Very Large Adult. Suckers larger than 20 inches were more frequently observed in the Rock Creek Reach than in the Cresta Reach, although only the estimates for run habitats was significantly different (Figures 19 and 20). The relationship between abundance or density and habitat type for very large adults was essentially identical to that seen with large adults, as both size classes were frequently observed together in schools. Like large adult suckers, the combined estimates for very large adults (284 fish at 30 fish/mile) showed the lowest densities in deep pools and the highest in shallow pools (Figure 21).

Smallmouth Bass

Fry. Smallmouth bass fry were observed in all habitat types in both reaches except riffles in the Cresta Reach, but index estimates of abundance and density were generally low and variable (Figures 22 and 23). In the Cresta Reach, bass fry were most common in deep pools (at 76 fish/mile) but were not observed in riffles. In contrast, bass fry were most common in riffles in the Rock Creek Reach (95 fish/mile) and least common in deep pools. When combined among reaches, bass fry were distributed within all habitat types with a total index abundance of 308 fry at a mean density of 32 fish/mile (Figure 24).

Juvenile. Smallmouth bass juveniles were observed in both reaches in relatively equal numbers and densities, where most bass were observed in pool habitats but not in riffles (Figures 22 and 23). Combining the reach data produced overall abundance estimates of 94 juvenile bass, with highest densities in pools and a mean total density of 10 fish/mile (Figure 24).

Small Adult. Small adult smallmouth bass were the most common size class after fry, and were approximately twice as abundant in the Cresta Reach as compared to the Rock Creek Reach (Figure 22). Abundance and density was highest in pools in both reaches (although no bass were observed in Rock Creek deep pools), and like all other non-fry size classes, bass were not observed in riffles in either reach. Index densities were significantly higher in deep pools and runs in the Cresta reach versus the Rock Creek Reach (Figure 23). The relative distribution of fish by habitat type was essentially identical for juvenile, small adult, and large adult bass. Although smallmouth bass are typically considered a pool-dwelling species, dive counts showed that significant

44 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

300 Cresta Reach 300 Rock Creek Reach SM B (<5") 250 2006 Abundance SM B (<5") 250 2006 Abundance

200 200

150 150 123 100 100

Index AbundanceIndex 63 50 AbundanceIndex 50 51 33 10 14 14 0 0 0 DP SP RN RF DP SP RN RF

120 120 SMB (5-10") 100 SM B (5-10") 100

80 80

60 60

40 40 36 33 Index AbundanceIndex 20 AbundanceIndex 20 15 6 4 0 0 0 00 DP SP RN RF DP SP RN RF

120 120 SM B (11-15") SM B (11-15") 100 100

80 80

60 62 60 46 40 40 25 Index AbundanceIndex 20 21 AbundanceIndex 20 5 0 0 0 0 0 DP SP RN RF DP SP RN RF

20 20 SMB (16-20") SM B (16-20") 15 15

10 10 8 7 5 55 5 Index AbundanceIndex AbundanceIndex

0 0 0 0 00 DP SP RN RF DP SP RN RF

20 20 SM B (>20") SMB (>20") 15 15

10 10

5 5 Index AbundanceIndex Index AbundanceIndex 3

0 0000 0 000 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 22. Index estimates of fish abundance for smallmouth bass according to size class, habitat type, and reach. Vertical bars are 95% confidence intervals.

45 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

300 Cresta Reach 300 Rock Creek Reach SMB (<5") SM B (<5") 250 2006 Density 250 2006 Density

200 200

150 150

100 100 95 76

Index Density (#/mi) Density Index 50 (#/mi) Density Index 50 25 25 14 10 10 0 0 0 DP SP RN RF DP SP RN RF

80 80 SM B (5-10") SMB (5-10") 60 60

40 40

25 20 22 21 20 Index Density (#/mi) Density Index (#/mi) Density Index

4 3 0 0 0 00 DP SP RN RF DP SP RN RF

80 80 SMB (11-15") SMB (11-15") 60 60

40 38 40 34 34

20 20 16 Index Density (#/mi) Density Index Index Density (#/mi) Density Index

0 0 0 0 2 0 DP SP RN RF DP SP RN RF

20 20 SM B (16-20") SM B (16-20") 15 15

10 10

7 5 5 5 5 4 Index Density (#/mi) Density Index (#/mi) Density Index

0 0 0 0 00 DP SP RN RF DP SP RN RF

20 20 SM B (>20") SM B (>20") 15 15

10 10

5 5 Index Density (#/mi) Density Index (#/mi) Density Index 2 0 0000 0 000 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools

Figure 23. Index estimates of fish density (#/mile) for smallmouth bass according to size class, habitat type, and reach. Vertical bars are 95% confidence intervals.

46 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

300 Combined Reaches 300 Combined Reaches SMB (<5") 2006 Density SM B (<5") 250 2006 Abundance 250 fry lane fry lane 200 200

150 150 137 100 100

Index AbundanceIndex 65 63 65 50 43 (#/mi) Density Index 50 45 21 19 0 0 DP SP RN RF DP SP RN RF

125 60 SMB (5-10") SMB (5-10") 50 100 40 75 30 50 48 23 40 20 13 Index AbundanceIndex 25 Index Density (#/mi) Density Index 10 6 2 0 0 0 0 DP SP RN RF DP SP RN RF

125 60 SM B (11-15") SM B (11-15") 50 100 40 75 71 34 62 30 50 20 20

Index AbundanceIndex 25 26 Index Density (#/mi) Density Index 10 8 0 0 0 0 DP SP RN RF DP SP RN RF

25 60 SM B (16-20") SM B (16-20") 50 20 40 15 12 30 10 8 20

Index AbundanceIndex 5 5 Index Dens ity (#/mi) 10 6 3 0 0 0 1 0 DP SP RN RF DP SP RN RF

25 60 SM B (>20") SM B (>20") 50 20 40 15 30 10 20

Index AbundanceIndex 5

Index Density (#/mi) Density Index 10 3 1 0 000 0 000 Deep Pools Shallow Runs Riffles Deep Pools Shallow Runs Riffles Pools Pools Figure 24. Index estimates of fish abundance (left column) and fish density (right column) for smallmouth bass combined across reaches, according to size class and habitat type. Vertical bars are 95% confidence intervals.

47 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______numbers of bass also occupy run habitats. When combined, the estimated abundance was 159 fish with a mean density of 17 fish/mile (Figure 24).

Large Adult. Large adult smallmouth bass were uncommon in both reaches with an estimated 18 bass in the Cresta Reach and only seven bass in the Rock Creek Reach (Figure 22). Index densities were less than 10 fish/mile, with zero fish observed in riffles (Figure 23). The combined index estimates were 25 fish at less than three fish/mile (Figure 24).

Very Large Adult. Only three bass over 20 inches were observed during the 2006 dive counts, all in deep pools in the Rock Creek Reach. All other counts and estimates were zero (Figures 22-24).

Comparison of 2006 Index Estimates With Prior Estimates

Four years of comparable data sets are available for comparison of annual abundance trends in the Rock Creek-Cresta reaches of the North Fork Feather River: 2002, 2004, 2005 and 2006. Index estimates of abundance for each of those years are based on identical methodologies (upstream dive counts within dive lanes). The 2002 data (TRPA 2003) was based on a feasibility study that utilized a relatively small sample size (only 2- 4 units per habitat type per reach) and non-random selection. Consequently, the 2002 estimates are likely to be relatively inaccurate (sample size effects), and confidence intervals around those estimates could not be calculated to assess precision (sampling design effects). The 2004 data (TRPA 2005b) utilized a randomized design with larger sample sizes (Table 1). Sample sizes were again increased in 2005 using optimal allocation, and those same sampling units were resampled in 2006. The 2005 and 2006 estimates by reach are statistically compared using the difference estimators described in the methods section. This more rigorous method of comparison was possible due to the sampling on repeated occasions design employed in 2006. Comparisons of combined reach estimates for all years, and reach-specific estimates from 2004 and 2005 were evaluated using the more conservative test of overlapping confidence intervals. Statistical comparisons are not made with the 2002 data due to the non-random sampling design and consequent lack of variance estimates.

Other historical data, including dive counts based on cross-sectional transects (TRPA 2001), and electrofishing based on several years of California Department of Fish and Game surveys, are also available and were qualitatively compared in a previous report (TRPA 2003). Because the transect methodology was shown to produce consistently different abundance estimates (TRPA 2003, 2005b), and because electrofishing is highly limited to shallow water habitats and is expected to represent a different proportion of the true abundance than diving, direct comparisons of those datasets with the upstream dive count data will not be made in this report. However, in the following section some general comparisons of recent annual trends will be made between the dive surveys and the concurrent electrofishing surveys (Salamunovich 2005a, 2005b, 2007).

48 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Rainbow Trout

Fry. Index abundance of trout fry were near zero in pool habitats in both reaches and in the initial three years of study, but increased significantly in Rock Creek Reach shallow pools in 2006 (Figure 25). In runs, index estimates showed minor increases from 2004 to 2005 and large increases in 2006, the Rock Creek Reach increases being statistically significant. The large decrease from 2002 to 2004 in the Rock Creek Reach is suspect due to small sample size in the 2002 study (only two units sampled). Estimates for riffles suggested a moderate increase in abundance from 2002 to 2004 in both reaches, with little change from 2004 to 2005 and statistically significant large increases from 2005- 2006. When data were combined across reaches, the same patterns emerged with little change in fry abundance in pool habitats until the 2006 increase, a possible decrease in runs from 2002 to 2004 and a large increase in 2006, and large increases in riffles from 2002 to 2004 and 2005 to 2006 (Figure 26). The combined increases in shallow pools, runs, and riffles from 2005 to 2006 were statistically significant. Most of the 2006 estimates were 3-4 times greater than the 2005 estimates.

Juvenile. Index abundance of juvenile trout appeared to increase slightly from 2002 to 2004 in most habitat types in the Cresta Reach (shallow pools were not sampled in 2002), but no clear pattern was observed from 2004 to 2005 (Figure 25). Very small decreases were observed in pools and larger decreases observed in runs and riffles in the Cresta Reach from 2005 to 2006, with the decrease in riffles statistically significant. In the Rock Creek Reach, patterns were more variable among habitat types, with runs showing a substantial increase in 2005, but riffles showing a large decrease. Small decreases were observed in all habitat types from 2005 to 2006. None of the changes between 2004 and 2006 were statistically significant. When data were combined among reaches, only very small changes were observed in pool habitats or runs, but the riffle estimates suggested an increase from 2002 to 2004, followed by a substantial but non-significant decrease from 2004 to 2006 (Figure 26). Overall, the 2006 abundance was generally about 70% to 80% of the 2005 estimates.

Small Adult. In deep pools and runs the index abundance of small adult trout increased from 2002 to 2004 in both reaches, followed by a substantial (~50%) decrease in 2005 (in deep pools), with no change or a slight increase in runs (Figure 25). From 2005 to 2006, statistically significant decreases occurred in pools along with a minor decrease in runs in the Cresta Reach. Riffle abundances in the Cresta Reach have been very low and steady throughout the study period. Similar 2005 to 2006 decreases occurred in all Rock Creek habitats with the largest proportional and statistically significant decreases occurring in runs and riffles. Combining estimates across reaches showed the same 2004-2006 decreases in pools, with minor increases in runs and riffles from 2004-2005, and substantial (statistically significant in runs) decreases from 2005 to 2006 (Figure 26). The estimated abundance in 2006 was somewhat more than one-half of the abundance in 2005.

Large Adult. Large adult trout showed increased abundance from 2002 to 2004 in pools and run habitats, but little change in riffles in both reaches (Figure 25). From 2004 to

49 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

300 Cresta Reach 300 Rock Creek Reach RBT <5 RBT <5 Abundance Abundance 250 (dive lane) 250 (dive lane)

200 200

150 150 * 100 * 100 * Index AbundanceIndex AbundanceIndex 50 50 * n/a n/a * 0 0 02 04 0506 02 04 05 06 02 04 05 06 0204 05 06 02 04 0506 02 04 05 06 02 04 05 06 0204 05 06 600 600 RBT 5-10 RBT 5-10 500 500

400 400

300 300

200 200

Index AbundanceIndex * AbundanceIndex 100 100 n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 0506 02 04 05 06 02 04 05 06 0204 05 06 700 700 RBT 11-15 RBT 11-15 600 600

500 500

400 400

300 300

200 200 * Index AbundanceIndex AbundanceIndex 100 100 * n/a * n/a * 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 300 300 RBT 16-20 RBT 16-20 250 250

200 200

150 150

100 100

Index AbundanceIndex AbundanceIndex * 50 50 * n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 60 60 RBT >20 RBT >20 50 50

40 40

30 30

20 20 Index AbundanceIndex AbundanceIndex 10 10 n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 Deep Shallow Runs Riffles Deep Shallow Runs Riffles Pools Pools Pools Pools Figure 25. Comparison of annual index estimates of abundance for rainbow trout according to reach, size class, and habitat type. Asterisks indicate statistically significant changes between adjacent years. Bars are 95% confidence intervals.

50 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

400 Combined Reaches - Abundance RBT <5 (dive lane) 300 *

200 *

100 Index AbundanceIndex * n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 700 RBT 5-10 600

500

400

300

200 Index AbundanceIndex 100 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 700 RBT 11-15 600

500

400 * 300

200 Index AbundanceIndex 100 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 350 RBT 16-20 300

250

200

150

100 * Index AbundanceIndex 50 * n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 70 RBT >20 60

50

40

30

20 Index AbundanceIndex 10 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 Deep Pools Shallow Pools Runs Riffles Figure 26. Comparison of combined index estimates of abundance for rainbow trout according to size class and habitat type. Asterisks indicate statistically significant changes between adjacent years. Bars are 95% confidence intervals.

51 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

2005, abundance decreased or remained unchanged with no significant differences in estimates. The trend continued from 2005 to 2006 with significant decreases in Cresta Reach deep pools and Rock Creek Reach runs. Many estimates from 2006 were less than 50% of the 2004 estimates. Data combined from both reaches also showed the increases from 2002 to 2004 in deep pools and runs, with relatively minor decreases in 2005 and substantial decreases in 2006 in all habitats except riffles (statistically significant in deep pools and runs) (Figure 26). Abundance in 2006 was approximately one-third of the 2005 abundance, except in riffles where the combined abundance estimates have been low and steady throughout the study period.

Very Large Adult. Trout over 20 inches in length were rarely observed during the four years of study, consequently index estimates of abundance were typically near zero in both reaches and all habitat types (Figure 25). Combining data among reaches did suggest an increase in abundance in run habitats from 2002 to 2004, followed by a decrease to near zero in 2005 and zero in 2006 (Figure 26). The abundance estimates of very large adult trout observed during the four surveys were 0 fish in 2002, 33 fish in 2004, 3 fish in 2005, and 0 in 2006.

Hardhead

Fry. Index estimates of abundance of hardhead/pikeminnow fry from expanded fry lane counts generally showed variable changes from 2002 to 2004, but consistent and mostly statistically significant increases from 2004 to 2006 (Figure 27). Abundance in riffles remained low in all years and both reaches, but showed increases in the Rock Creek Reach from 2004 to 2006. When combined across reaches, the 2004 to 2005 increase was significant in deep pools, shallow pools, and riffles, and the 2005 to 2006 increase was significant in shallow pools and runs (Figure 28). In most habitat types the 2006 abundance was more than twice the 2005 abundance.

Juvenile. Juvenile hardhead were rarely observed in the Cresta Reach in all years and habitat types (Figure 27). In the Rock Creek Reach, abundance of juveniles decreased from 2002 to 2004, but increased again to maximum abundance in 2005. Although the wide confidence intervals in deep pools in 2005 made the changes non-significant, the increase in shallow pools and runs was significant. No significant changes occurred in 2006. Like fry, juveniles were uncommon in riffles during all surveys. Data combined across reaches also showed the 2002 to 2004 decrease with the large increase the following year and little change in 2006 (Figure 28). The 2005 increases in deep pools, shallow pools, and runs were statistically significant. Overall, the 2006 abundance was about 60% of the abundance in 2005.

Small Adult. Index estimates for small adult hardhead were highly variable, with the Cresta Reach mostly showing little change from 2002 to 2004, moderate increases from 2004 to 2005, and statistically significant decreases in all habitats except riffles in 2006 (Figure 27). In the Rock Creek Reach, abundance in deep pools increased each year until 2006, decreased in shallow pools (2004 to 2005 only) before increasing in 2006, and showed little change in runs and riffles. None of the annual changes in the Rock Creek

52 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

50000 50000 Rock Creek Reach Cresta Reach 64,924 58,533 HH/PM <5 Abundance HH/PM <5 Abundance 40000 (fry lane) 40000 (fry lane) * 30000 30000

* 20000 20000 * * * Index AbundanceIndex 10000 * AbundanceIndex 10000 * n/a * * n/a 0 0 02 0405 06 02 0405 06 02 0405 06 02 0405 06 02 04 0506 02 04 05 06 02 04 05 06 0204 05 06 2000 2000 HH 5-10 3,368 HH 5-10

1500 1500

1000 1000

500 500 Index AbundanceIndex AbundanceIndex * * n/a * n/a 0 * 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 700 700 HH 11-15 HH 11-15 600 600

500 500

400 400

300 300

200 * 200 Index AbundanceIndex * AbundanceIndex 100 100 n/a * n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 500 500 HH 16-20 738 HH 16-20 400 400

300 300

200 200 *

Index AbundanceIndex 100 AbundanceIndex 100 *

n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 100 100 HH >20 173 HH >20 80 80

60 60

40 40 *

Index AbundanceIndex 20 AbundanceIndex 20 * * n/a * n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 Deep Shallow Runs Riffles Deep Shallow Runs Riffles Pools Pools Pools Pools Figure 27. Comparison of annual index estimates of abundance for hardhead according to reach, size class, and habitat type. Asterisks indicate statistically significant changes between adjacent years. Bars are 95% confidence intervals.

53 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Combined Reaches - Abundance 100000 HH/PM <5 (fry lane) 80000

60000

40000 * * Index AbundanceIndex 20000 * * n/a 0 * 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 3500

3000 HH 5-10

2500

2000

1500 * 1000 Index AbundanceIndex 500 * * n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 1000 HH 11-15 800

600

400

Index AbundanceIndex 200

n/a 0 * 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 800 HH 16-20

600

400

200 Index AbundanceIndex

n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 175

150 HH >20

125

100

75

50

Index AbundanceIndex * 25 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 Deep Pools Shallow Pools Runs Riffles Figure 28. Comparison of combined index estimates of abundance for hardhead according to size class and habitat type. Asterisks indicate statistically significant changes between adjacent years. Bars are 95% confidence intervals.

54 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Reach were statistically significant. When data were combined across reaches, the somewhat contrasting patterns of the Cresta Reach and the Rock Creek Reach produced combined estimates with little change between years (Figure 28).

Large Adult. Large adult hardhead in the Cresta Reach showed little change over the study period except for a large but non-significant decrease in shallow pools in 2005 (Figure 27). In the Rock Creek Reach, the deep pool and shallow pool estimates increased in 2005 and again in 2006. Run habitats showed a moderate decrease in 2005 and a significant increase in 2006 to about the same level. Estimates for riffles remained near zero in all years. The combined reach estimates showed minor increases in abundance in pool and run habitats but no overall change riffles (Figure 28).

Very Large Adult. Very large adult hardhead were typically more abundant in the Rock Creek Reach than in the Cresta Reach, except in riffles where they were never observed (Figure 27). In the Cresta Reach, abundance of very large adults changed little from 2002 to 2004, but increased in 2005 in deep pools and runs (the latter change was significant). In the Rock Creek Reach, abundance in deep pools and runs increased from 2002 to 2004, and continued to increase in 2005 in pools (statistically significant in shallow pools), but decreased in runs. In 2006, the increases continued in deep pools and a significant increase also occurred in runs. Likewise, the combined reach estimates showed a significant increase from 2004 to 2005 in shallow pools, with an equally substantial (but non-significant) increase in deep pools (Figure 28). Combined estimates remained essentially unchanged from 2005 to 2006.

Sacramento Pikeminnow

Fry. See the fry section under hardhead for a discussion of this size class.

Juvenile. As seen for hardhead, juvenile pikeminnow were rare in the Cresta Reach but relatively common (at least in 2005) in the Rock Creek Reach (Figure 29). In the Rock Creek Reach, abundance of juveniles appeared to decrease from 2002 to 2004, increased substantially again in 2005, and decreased to a lesser amount in 2006. The increases from 2004 to 2005 in all four habitat types and the decrease in riffles in 2006 were statistically significant, despite very wide confidence intervals in 2005. Combined reach estimates also showed the substantial increases in abundance from 2004 to 2005, with the shallow pool, run, and riffle estimates statistically significant (Figure 30). The decreases in 2006 were roughly 50% but only the change in riffles was significant.

Small Adult. Abundance of small adult pikeminnow showed variable changes from 2002 to 2004, mostly increased abundance from 2004 to 2005, and decreases in 2006 in all strata except Rock Creek Reach pool habitats (Figure 29). None of the annual changes were significant, except the decrease in Cresta Reach shallow pools in 2006, as most estimates contained wide confidence intervals that frequently included zero. The combined index estimates showed minor increases from 2004 to 2006 in pool habitats, highly variable changes in runs, and relatively little change in riffles (Figure 30).

55 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

100 100 Rock Creek Reach Cresta Reach HH/PM <5 Abundance HH/PM <5 Abundance 80 (fry lane) 80 (fry lane)

60 see HH figure 60 see HH figure

40 40

Index AbundanceIndex 20 AbundanceIndex 20

0 0 02 04 0506 02 04 05 06 02 04 05 06 0204 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 1500 1500 PM 5-10 PM 5-10 1250 1250

1000 1000

750 750

500 500 * * Index AbundanceIndex AbundanceIndex 250 250 * n/a n/a * * 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 200 200 PM 11-15 PM 11-15

150 150

100 100

50 50 Index AbundanceIndex AbundanceIndex * n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 100 100 PM 16-20 PM 16-20 80 80

60 60

40 40

Index AbundanceIndex 20 AbundanceIndex 20 ** n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 60 60 PM >20 PM >20 50 50

40 40

30 30

20 20 Index AbundanceIndex AbundanceIndex 10 10 n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 Deep Shallow Runs Riffles Deep Shallow Runs Riffles Pools Pools Pools Pools Figure 29. Comparison of annual index estimates of abundance for pikeminnows according to reach, size class, and habitat type. Asterisks indicate statistically significant changes between adjacent years. Bars are 95% confidence intervals.

56 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

1000 Combined Reaches - Abundance HH/PM <5 800 (fry lane) see HH figure 600

400

Index AbundanceIndex 200

0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 1500 PM 5-10 1250

1000

750

500 *

Index AbundanceIndex * 250 n/a * * 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 250 PM 11-15 200

150

100

Index AbundanceIndex 50

n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 125 PM 16-20 100

75

50

Index AbundanceIndex 25 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 100 PM >20 80

60

40

Index AbundanceIndex 20 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 Deep Pools Shallow Pools Runs Riffles Figure 30. Comparison of combined index estimates of abundance for pikeminnows according to size class and habitat type. Asterisks indicate statistically significant changes between adjacent years. Bars are 95% confidence intervals.

57 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Large Adult. Changes in abundance of large adult pikeminnow from 2002 to 2004 were variable, but most changes from 2004 to 2006 were decreases in abundance (Figure 29). In the Cresta Reach, substantial decreases occurred in 2005 in deep pools and shallow pools, whereas estimates in runs increased in 2005 and 2006. The increase in Cresta run habitats from zero fish in 2004 to 17 fish in 2005, as well as the decrease in shallow pools in the same year was statistically significant. In the Rock Creek Reach, decreases from 2004-2005 were minor in deep pools and runs continuing into 2006, but abundance appeared to increase in shallow pools in both years. Like the other size classes of pikeminnow (and hardhead), annual changes in abundance in riffles were generally minor and non-significant. Annual changes for the combined index estimates showed a substantial decrease through 2006 for deep pools, little change in shallow pools or riffles, and increasing abundance in runs (Figure 30).

Very Large Adult. Abundance of very large adult pikeminnow mostly decreased from 2002 to 2004 in both reaches, especially in run habitats (Figure 29). From 2004 to 2005, estimates from the Cresta Reach suggested an overall decrease in abundance, whereas abundance in the Rock Creek Reach mostly increased in 2005. The 2006 abundance closely resembles that of 2004 with the exception of an increase in Rock Creek Reach deep pool habitats. Widely overlapping confidence intervals in 2004 through 2006 made the annual changes non-significant. When combined across reaches (Figure 30), annual changes were very minor for all habitat types except for runs, which showed much higher abundance in 2002 (based on a total sample of only five run habitats).

Sacramento Suckers

Fry. Estimated abundance of sucker fry was very low and changed little from 2002 to 2004. From 2004 to 2006, however, fry lane index estimates increased in virtually every habitat type in both reaches (Figure 31). Increases were statistically significant for all habitat types in the Cresta Reach in 2005, and all except riffles in 2006. Significant increase also occurred in the Rock Creek Reach for all habitats in 2006 and for runs in 2005. The 2004 to 2006 increases were also significant for the combined reach estimates in all habitats and both years (Figure 32). The magnitude and consistency of the increases were similar to the increases seen for hardhead/pikeminnow fry in 2005 and 2006 (Figure 27).

Juvenile. Juvenile suckers were uncommon in both reaches in 2002 and in 2004. Most index estimates increased in 2005 and subsequently decreased in 2006 in the Rock Creek Reach (Figure 31). Abundance in 2006 remained below 25 fish in all reach and habitat type strata. The combined abundance estimates reflected the Rock Creek Reach data where the majority of the juvenile suckers were observed (Figure 32).

Small Adult. Most of the index estimates for small adult suckers decreased from 2002 to 2004, with the exception of Rock Creek deep pools, which also showed an increase for juveniles (Figure 31). Also like juveniles, the index abundance for small adults increased in most habitat types from 2004 to 2005, only to decrease again in 2006. The 2005 increase for Rock Creek runs and Cresta Reach riffles in 2005, as well as the 2006 Cresta

58 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

20000 20000 Rock Creek Reach Cresta Reach SKR <5 Abundance SKR <5 Abundance (fry lane) (fry lane) 15000 15000

10000 10000

5000 5000 * * * Index AbundanceIndex ** AbundanceIndex * **n/a * * n/a * * 0 0 02 04 0506 02 04 05 06 02 04 05 06 0204 05 06 02 04 0506 02 04 05 06 02 04 05 06 0204 05 06 150 150 SKR 5-10 SKR 5-10 125 125

100 100

75 75

50 50 Index AbundanceIndex AbundanceIndex 25 25 **n/a n/a * 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 800 800 SKR 11-15 700 700 SKR 11-15 600 600 500 500 400 400 300 300 200 200 Index AbundanceIndex AbundanceIndex 100 100 * * n/a * ** n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 1500 1500 SKR 16-20 2,497 SKR 16-20 1250 1250

1000 1000

750 750

500 500 * Index AbundanceIndex AbundanceIndex 250 250 * n/a * n/a * 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 200 200 SKR >20 295 175 175 SKR >20 150 150 125 125 100 100 75 75 50 50 Index AbundanceIndex AbundanceIndex * 25 25 n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 Deep Shallow Runs Riffles Deep Shallow Runs Riffles Pools Pools Pools Pools Figure 31. Comparison of annual index estimates of abundance for suckers according to reach, size class, and habitat type. Asterisks indicate statistically significant changes between adjacent years. Bars are 95% confidence intervals.

59 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

25000 Combined Reaches - Abundance SKR <5 20000 (fry lane)

15000

10000 * * * Index AbundanceIndex 5000 * n/a * * * * 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 150 SKR 5-10 125

100

75

50 Index AbundanceIndex 25 n/a * 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 800 700 SKR 11-15 600 500 400 300 200 Index AbundanceIndex * 100 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 2500 SKR 16-20 2000

1500

1000

Index AbundanceIndex 500 n/a * 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 300 SKR >20 250

200

150

100 Index AbundanceIndex 50 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 Deep Pools Shallow Pools Runs Riffles

Figure 32. Comparison of combined index estimates of abundance for suckers according to size class and habitat type. Asterisks indicate statistically significant changes between adjacent years. Bars are 95% confidence intervals.

60 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Reach decreases in pools and increase in riffles were statistically significant. The combined reach estimates also showed the variable trend for deep pools (increasing in 2004 and decreasing to similar levels through 2006), and the 2004 to 2005 increasing trend with little change in 2006 for the remaining habitat types (Figure 32). The 2005 increase for runs was again statistically significant.

Large Adult. Large adults were frequently one of the dominant size classes in both the Cresta and the Rock Creek reaches. In most cases, changes in abundance from 2002 to 2004 were positive, followed by mostly decreasing abundance from 2004 to 2005 in the Cresta Reach and mostly increasing abundance in the Rock Creek Reach (Figure 31). Because of wide confidence intervals, only the increase in Rock Creek riffles was statistically significant. In 2006, little changed in the Cresta Reach, although the increase in riffle abundance was statistically significant. In the Rock Creek Reach the abundance in deep pools and runs decreased significantly, whereas a large, but non-significant increase occurred in shallow pools. The contrasting trends in the two reaches produced combined reach estimates with very little change from 2004 to 2005, although the increase in riffles was significant, as well as concurrent increases in shallow pools and decreases in runs in 2006 (Figure 32).

Very Large Adult. Suckers greater than 20 inches in length were generally uncommon in 2002 and in 2004, but estimates increased in 2005 and 2006 in the Rock Creek Reach (Figure 31). The 2005 and 2006 estimates included wide confidence intervals and only the 2005 change in run habitats was statistically significant. Like hardhead, and to a lesser degree pikeminnow, suckers frequently occur in large schools that make dive counts highly variable between habitat units. Consequently, estimates of abundance typically contain high variances and wide confidence intervals. The combined estimates in 2005 and 2006 also contained high variability and non-significant changes, but estimates for all four habitat types suggested a consistent increase from 2004 to 2006 (Figure 32).

Smallmouth Bass

Fry. Smallmouth bass was the only species that showed consistently higher densities in the Cresta Reach than in the Rock Creek Reach. Bass fry were very uncommon in both reaches in 2002 and 2004, but increased significantly in most habitat types in 2005, only to decrease significantly (in the Cresta Reach) in 2006 (Figure 33). Data combined across reaches largely reflected the Cresta estimates, with little change from 2002 to 2004, dramatic and statistically significant increases in abundance in deep pools, shallow pools, and runs in 2005, and statistically significant declines in 2006 (Figure 34).

Juvenile. Estimated abundance of juvenile bass was very low in both reaches and all habitat types in 2002, but most estimates increased in 2004 and again in 2005 only to decrease again in 2006 (Figure 33). None of the annual changes in the Cresta Reach prior to 2006 were statistically significant; however, the 2006 decreases in the Cresta Reach were statistically significant in all habitats except riffles. Bass of all size classes, including juveniles, remained rare in riffles where index estimates were consistently near

61 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

800 800 Rock Creek Reach Cresta Reach SM B <5 Abundance SMB <5 Abundance (fry lane) (fry lane) 600 600

400 400 * * 200 200 Index AbundanceIndex * * AbundanceIndex * * n/a * * n/a ** 0 0 02 04 0506 02 04 05 06 02 04 05 06 0204 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 150 150 SMB 5-10 272 SM B 5-10 125 125

100 100

75 75 * 50 50 Index AbundanceIndex AbundanceIndex 25 * * 25 * n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 150 150 SM B 11-15 SM B 11-15 125 125

100 100

75 75

50 * 50 * Index AbundanceIndex 25 AbundanceIndex 25 n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 30 30 SM B 16-20 SMB 16-20 25 25

20 20

15 15

10 10 Index AbundanceIndex AbundanceIndex 5 5 n/a n/a * 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 20 20 SM B >20 SM B >20

15 15

10 10

5 5 Index AbundanceIndex AbundanceIndex

n/a n/a 0 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 Deep Shallow Runs Riffles Deep Shallow Runs Riffles Pools Pools Pools Pools Figure 33. Comparison of annual index estimates of abundance for smallmouth bass according to reach, size class, and habitat type. Asterisks indicate statistically significant changes between adjacent years. Bars are 95% confidence intervals.

62 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

1000 Combined Reaches - Abundance SM B <5 800 (fry lane)

600

400 * * * Index AbundanceIndex 200 * * * n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 350 SMB 5-10 300

250

200

150

100 Index AbundanceIndex 50 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 150 SM B 11-15 125

100

75

50 Index AbundanceIndex 25 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 35 SMB 16-20 30

25

20

15

10 Index AbundanceIndex 5 * n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 35 SMB >20 30

25

20

15

10 Index AbundanceIndex 5 n/a 0 02 04 05 06 02 04 05 06 02 04 05 06 02 04 05 06 Deep Pools Shallow Pools Runs Riffles Figure 34. Comparison of combined index estimates of abundance for smallmouth bass according to size class and habitat type. Asterisks indicate statistically significant changes between adjacent years. Bars are 95% confidence intervals.

63 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______zero. The combined estimates for juvenile bass also showed the consistent increases in abundance in deep pools, shallow pools, and runs until 2005, after which abundance declined in 2006 (Figure 34).

Small Adult. Small adult bass were rarely seen in the Cresta Reach during the 2002 dive counts, nor in the Rock Creek Reach during most years (Figure 33). In the Cresta Reach, however, the estimated abundance increased substantially in 2004, with additional increases in 2005 in most habitat types, and subsequent statistically significant decreases in shallow pools and runs in 2006. A dramatic, but not statistically significant increase occurred in Rock Creek Reach shallow pools in 2006. Estimated abundance combined across reaches also showed the substantial increases from 2002 to 2004, with continued increases in 2005 for shallow pools and runs, while in 2006, abundances in pools and riffles remained constant and declined in runs (Figure 34).

Large Adult. Annual trends in abundance for large adult bass were generally similar to trends for small adult bass. Very few large adult bass were observed in the Rock Creek Reach, and estimates in the Cresta Reach in 2002 were also near zero fish (Figure 33). Abundance increased from 2004 to 2005 in most reach and habitat type strata, but maximum abundance remained at less than 15 fish in Cresta deep pools. In 2006 the abundance remained relatively steady or decreased slightly in the Cresta Reach while there was a large, but statistically non-significant increase in Rock Creek Reach shallow pools. In 2006 in deep pools and runs, the abundance returned to near zero in the Rock Creek Reach. Combined reach estimates also showed the consistent increase in abundance from 2004 to 2005 (significant for runs), with variable changes in 2006 (Figure 34).

Very Large Adult. Of the three annual surveys, only two very large adult bass were observed, both of which were inhabiting pools in the Cresta Reach. Consequently, all index estimates of abundance were essentially zero (Figures 33 and 34).

Comparison of 2002-2006 Trends from Dive Counts and Electrofishing

In addition to the dive count surveys described in this report, the Rock Creek-Cresta fisheries studies included electrofishing surveys in shallow-water areas during the late fall of 2002, 2004, 2005, and 2006. Details regarding the locations, methodologies, and results of the electrofishing surveys can be found in other reports (ECORP 2003, Salamunovich 2005a, 2005b, 2007). Because of the many and vast differences in methods and interpretation of electrofishing and dive count survey data, no attempt will be made to directly compare estimates of abundance. Instead, this section will simply compare annual trends observed from the electrofishing surveys with the annual trends from the dive counts.

The annual electrofishing surveys were typically conducted in November of each year, one to two months after the dive surveys. Electrofishing surveys were mostly conducted in shallow water riffles and runs, with limited effort in pool habitats (the pool electro- fishing data will not be discussed here). Consequently, electrofishing did not effectively

64 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______sample the larger size classes of pool-dwelling species, such as hardhead, pikeminnows, and smallmouth bass. Prior to conducting the electrofishing surveys, streamflows in both reaches were dropped from the existing base flows of almost 300 cfs to less than 100 cfs for a period of 2-4 days. Two index reaches (200-400 ft long) were sampled in each reach during each year using a team of backpack electrofishers and multiple-pass methodologies. In 2005, one of the sites in the Rock Creek Reach was replaced with a more representative site shortly upstream (Salamunovich 2007). Consequently, the comparative trends in fish abundance from the two methodologies may be obscured in the Rock Creek Reach due to the change in electrofishing study sites.

Electrofishing estimates used in the following comparisons are the sums of the population estimates from the two sites in each reach, according to species. Because electrofishing was limited to run and riffle habitat, and because fish larger than 16 inches were rarely caught during those surveys, the dive count estimates used for comparison with the electrofishing data are combined estimates from run and riffle habitats only, and represent fry, juvenile, and small adult size classes only.

Rainbow Trout

Comparison of annual trends for rainbow trout showed very little similarity between the two methodologies (Figure 35). The dive count estimates showed very stable numbers between 2004 and 2006, whereas the electrofishing estimates showed a substantial decrease from 2004 to 2005, followed by a large increase in 2006.

Hardhead

As noted above for trout, the comparative trend data for hardhead was highly dissimilar between sampling techniques. The dive count estimates for both reaches showed strong and consistent increases in abundance in each year of study (Figure 35). The electrofishing trend for the Cresta Reach also showed increases from 2002-2005, but showed a decrease in 2006. In contrast, the Rock Creek estimates from the Rock Creek Reach showed a consistent, but decreasing trend in each year of study.

Sacramento Pikeminnows

Comparative estimates for pikeminnow are also at odds, and almost appear as though data were reversed among reaches! The electrofishing data showed increased abundance from 2004 to 2005 and subsequent decrease in 2006 in the Cresta Reach, whereas the dive count data showed little change (Figure 35). In the Rock Creek Reach, the electrofishing data suggested little change in abundance, whereas the dive count data showed a strong increase from 2004 to 2005 and decrease in 2006. Note that the dive count estimates for pikeminnows do not include fish <5 inches (those fry were included in the hardhead counts).

65 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Rainbow Trout Rainbow Trout 300 1200 300 1200

EF Cresta DO Cresta EF Roc k DO Rock 250 1000 250 1000 Dive Count Estimate Count Dive Dive Count Estimate Count Dive 200 800 200 800

150 600 150 600

100 400 100 400 Electrofishing Estimate Electrofishing Electrofishing Estimate

50 200 50 200

0 0 0 0 2002 2004 2005 2006 2002 2004 2005 2006

Hardhead Pikeminnow 175 30000 350 1500 EF Cresta EF Roc k EF Cresta EF Roc k

150 DO Cresta DO Rock 300 DO Cresta DO Rock 25000 1250 (DO ests do not incl fry) Dive Count Estimate Count Dive 125 Estimate Count Dive 250 20000 1000

100 200 15000 750 75 150

10000 500

Electrofishing Estimate Electrofishing 50 100 Electrofishing Estimate Electrofishing

5000 250 25 50

0 0 0 0 2002 2004 2005 2006 2002 2004 2005 2006

Suckers Bass 2000 18000 175 600 EF Cr es ta EF Roc k EF Cr es ta EF Roc k 1750 16000 DO Cresta DO Rock 150 DO Cresta DO Rock 500 14000 1500 Dive Count Estimate Count Dive 125 Estimate Count Dive 12000 400 1250 10000 100 1000 300 8000 75 750 6000 200 Electrofishing Estimate Electrofishing Estimate Electrofishing 50 500 4000 100 25 250 2000

0 0 0 0 2002 2004 2005 2006 2002 2004 2005 2006

Figure 35. Comparison of annual trend data based on direct observation (dive) surveys and electrofishing surveys according to species and reach.

66 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Sacramento Suckers

The electrofishing data and dive count data showed the good similarity in trends for suckers, where both methodologies showed minor changes in abundance from 2002 to 2004, but large increases in abundance from 2004 to 2006 (Figure 35). Both data sets suggested that the 2005 increase was stronger in the Cresta Reach than in the Rock Creek Reach, whereas the 2005-2006 increase was stronger in the Rock Creek Reach.

Smallmouth Bass

The comparative datasets were also in fair agreement for smallmouth bass, particularly in the Cresta Reach. Both datasets for the Cresta Reach showed minor increases in abundance from 2002 to 2004, followed by strong increases in 2005, and a strong decrease in 2006 (Figure 35). For the Rock Creek Reach, the dive count data suggested a similar trend with a substantial increase in 2005 and decrease in 2006, but the electrofishing data showed little change over all four years.

DISCUSSION

Annual Changes in Environmental Conditions

Comparison of annual trends in abundance can be confounded by annual changes in environmental conditions, particularly those that can significantly alter the ability of divers to observe fish (e.g., streamflow, water visibility, and water temperature). Changes in the physical habitat can also complicate trend analysis if an index site approach is used, such as the sampling on repeated occasions design employed from 2005 to 2006.

Streamflows were relatively similar at 250 to 300 cfs during the dive counts conducted between 2002 and 2006, but were somewhat lower (215 cfs) in the Rock Creek Reach in 2002 (Table 4). Annual differences in water temperatures measured during dive counts in 2004-2006, although only 3-5 degrees in magnitude, were significantly different among years (ANOVA, P<0.001), with 2004 temperatures significantly less than temperatures in either 2005 or 2006 (which themselves were not significantly different). The lower temperatures encountered in 2004 were certainly influenced by the survey date, which was approximately four weeks later in 2004 than in the following years. It is unknown to what extent the cooler water temperatures influenced index densities in 2004, but it is likely that observation probabilities were somewhat lower in 2004 than in 2005 and 2006.

Unlike water temperatures, mean water visibilities in 2004-2006 were not statistically different among years (ANOVA, P>0.4), although mean visibility during the 2002 pilot study averaged 2-3 ft less (Table 4), but this difference was not tested in the ANOVA. The lower water visibility in that year, like the lower water temperatures in 2004, would

67 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Table 4. Comparison of samping conditions according be expected to result in to year and reach. lower observation Survey Streamflow Avg Water Avg Water probabilities and lower Reach Year Dates cfs Temp oF Visibility ft index estimates of Cresta 2002 9/16 - 9/21 250 63.0 6.4 abundance, but the magnitude of that 2004 10/5 to 10/15 251 60.2 9.4 potential effect is 2005 9/9 to 9/13 290 63.3 9.3 unknown. 2006 9/6 to 9/20 290 64.4 9.2 Rock 2002 9/16 - 9/21 215 63.7 7.4 Changes in the physical 2004 10/8 to 10/19 261 59.4 9.3 habitat were not 2005 9/7 to 9/29 295 63.2 9.8 routinely measured 2006 9/10 to 9/19 300 64.0 9.5 between years, and only the 2005 and 2006 surveys retained the same sampling units. The high flow events during the winter and spring of 2005-06, with maximum flows of 41,000 cfs in late December 2005 and sustained flows of over 8,000 cfs through much of April, appeared to result in some channel changes in sampling units. Although individual habitat units remained clearly identifiable and of similar length in 2006, significant scour and fill was evident in some large pools, and may have effected the suitability of those habitat units for pool-dwelling species such as bass and hardhead.

Consistency in Dive Counts

This study relied on the use of index counts of fish by a team of divers for assessing annual trends in abundance. Calibration of dive counts to estimate total abundance, such as suggested by Hankin and Reeves (1988), is clearly infeasible in a large, deep, swift river such as the North Fork Feather River. An assessment of the reliability of dive counts is therefore useful for establishing confidence in the uncalibrated index estimates.

In 2005 and 2006, four-pass repeat counts were conducted in ten habitat units (Table 5). Coefficients of Variation (C.V.’s) of the repeat dive counts were less than 30% in most units when all size classes were combined, but were higher (20-80%) within individual size classes. The higher C.V.’s by size class were highly effected by the low counts, which produced an average difference in counts (by size class) of only 1-3 fish (i.e., a minor difference in counts can produce high C.V.’s when overall numbers are low). The relatively large number of size classifications used in this study (5) undoubtedly also contributed to the higher C.V.’s due to different diver’s estimations of individual fish lengths between counts. The mean difference in counts (max-min) of only two fish suggests that dive counts can provide reliable indexes of abundance for assessing annual changes.

Similar results were obtained from almost 150 two-pass replicate counts from the upper Sacramento River, where C.V.’s for replicate counts of total rainbow trout were typically between 10% and 20% (TRPA 2005a). In both studies, replicate counts were less reliable for very small trout (e.g., fry) and very large trout, in comparison to the more abundant juvenile and small adult size classes.

68 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Table 5. Repeat count data for rainbow trout by sampling unit and size class.

Sample Size Class Count 1 Count 2 Count 3 Count 4 Max - Min C.V. Cresta RN '05<51112140 5-104644222 11-151011167 16-2000000- Total Count:676719 Rock RN '05<51225469 5-107101213625 11-158457430 16-201211140 Total Count: 17 18 20 26 9 20 Rock SP '05<500000- 5-106664218 11-156964533 16-207757215 Total Count: 19 22 17 15 7 16 Cresta RN '06<50224482 5-103342227 11-1500000- 16-2000000- Total Count:3566328 Cresta RN '06<500111115 5-1010365749 11-153353229 16-2011001115 Total Count: 14 7 12 9 7 30 Cresta SP '06<500000- 5-100112282 11-1500101- 16-2000000- Total Count:0122277 Cresta RN '06<5000000 5-103310386 11-157323559 16-20111100 Total Count:11744751 Rock SP '06<520002- 5-1000011- 11-151222129 16-2000000- Total Count:3223123 Rock SP '06<51445449 5-104324229 11-153323118 16-203112255 Total Count: 11 11 9 14 5 18 Rock RF '06<58677212 5-104545113 11-152643446 16-2052015108 Total Count: 19 19 15 16 4 12 All Units <5----253 Combined5-10----339 11-15----239 16-20----156 Total Count:----528 Overall Means: 241

69 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Differences Between Habitat Types

Expected but unmeasured differences in diver observation probabilities prevent a rigorous comparison of fish densities between habitat types, but several general trends are apparent from the four-year dataset. For example, index densities of fry and juvenile trout were typically much higher in riffles than in pools, with intermediate densities in runs (Figure 12). Larger trout were typically most abundant in shallow pools and runs, but less common in deep pools. In contrast, hardhead and smallmouth bass were consistently observed at highest densities in pools and lowest densities (frequently near zero) in riffles (Figures 15 and 24). Pikeminnows and especially suckers appeared to frequent all habitat types, although large individuals of both species were not typically observed in riffles (Figures 18 and 21).

The above relationships are likely due to species’ preferences for various habitat characteristics, such as depth and velocity, as well as their susceptibility to predation. In most years, correlations between unit lengths and counts for rainbow trout were generally good in runs and riffles, but poor in pools (TRPA 2006). In contrast, suckers, hardhead, and bass typically showed good correlations with unit lengths in pool habitats. Habitat parameters intended to describe habitat “complexity” (mostly velocity-related variables) showed positive relationships with counts of rainbow trout, but mostly negative relationships with hardhead, pikeminnows, and bass. These latter relationships are not unexpected, because hardhead, pikeminnows, and bass are typically considered “slow- water” species that are not typically found in faster currents. In contrast, trout frequently utilize faster velocities, especially in warmer water temperatures.

Differences Between Reaches

Several notable differences between reaches were apparent based on the 2006 data and data from prior surveys. Reach-specific differences in fish densities (#/mi) were not notable for rainbow trout in any year of study. Densities of juvenile and adult hardhead, however, have been consistently higher in the Rock Creek Reach than in the Cresta Reach, although densities of hardhead/pikeminnow fry were similar between reaches in most years. Juvenile and small adult pikeminnow have likewise occurred at higher densities in the Rock Creek Reach, but larger fish showed little difference between reaches. Suckers again showed a similar pattern, with similar densities between reaches for fry, but higher densities of adults in the Rock Creek Reach.

Smallmouth bass have been a significant exception, with consistently higher densities of juvenile and adult bass in the Cresta Reach. A possible explanation for the lower densities of bass in the Rock Creek Reach is the presence of the Bucks Creek powerhouse just above Cresta Reservoir (Figure 3). When operating, the Bucks Creek powerhouse releases water much cooler than the mainstem river, and the colder water temperatures in the lower portion of the Rock Creek Reach may discourage recruitment of bass from the downstream reservoir. Spotted bass were observed in the upper Sacramento River to utilize only the lower portion of the river even though no barriers existed to restrict them

70 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______to apparently ideal habitat farther upstream (TRPA 2005a). It was speculated that cooler water temperatures effectively restricted their movement into other waters. Differences in mainstem water temperatures between the Cresta Reach and the Rock Creek Reach could, through a similar effect, be sufficient to cause the observed distribution of bass. Ongoing water temperature modeling efforts should help to assess the magnitude of temperature differences between the two reaches. Another alternative explanation is that Poe Reservoir contains a larger population of bass that are available for upstream recruitment than is present in Cresta Reservoir.

The differences in densities of juvenile hardhead and pikeminnow could arise from differences in recruitment or differences in predation. For example, index densities of hardhead and pikeminnow fry (<5 inches) were very similar between reaches, but the next larger size class (juveniles at 5-10 inches) of either species were rarely observed in the Cresta Reach. Perhaps the higher densities of smallmouth bass in the Cresta Reach result, through predation, in lower densities of juvenile cyprinids than in the Rock Creek Reach where bass are less abundant. Sucker fry were actually more abundant in the Cresta Reach in most years than in the Rock Creek Reach, but juveniles were uncommonly observed in either reach, which does not support a hypothesis of differential predation on juvenile suckers. Nevertheless, a feeding study of smallmouth bass in the two reaches could help to evaluate the potential impact of this non-native predator on native species, particularly hardhead.

Differences in recruitment of juveniles could also explain the observed patterns in juvenile densities. For example, the East Branch of the North Fork Feather River and its principal tributaries (Spanish and Indian Creeks) are relatively large, warm-water streams that extend for over 40 miles above the Rock Creek Diversion Dam. Although no recent fisheries information was found, it is assumed that the East Branch watershed contains abundant populations of hardhead, pikeminnows, and suckers. If so, recruitment of juvenile fish over Rock Creek Dam into the study area may account for elevated densities of fish in comparison to the Cresta Reach. Once again, the rarity of juvenile suckers in both reaches does not suggest differential recruitment for that species. Reconnaissance surveys in the East Branch of the North Fork would help to assess if high abundance of juvenile hardhead and pikeminnows might lead to increased recruitment of those fish into the Rock Creek Reach.

Differences Between Years

Most index estimates suggested that rainbow trout were more abundant in 2004 than in 2002, but changes from 2004 to 2006 were frequently decreasing, especially for larger trout (Figure 26). In contrast, index estimates for trout fry have generally increased over the course of this study, with the largest increase in 2006. Like trout, large annual increases in abundance have also occurred for hardhead/pikeminnow fry. Annual changes in juvenile hardhead have been more variable, and annual trends were generally decreasing for small adults, and increasing for larger adults (Figure 28). Juvenile pikeminnows showed strong increases in abundance in 2005, followed by a strong decrease in 2006 (similar to hardhead juveniles). Annual changes for larger

71 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______pikeminnows have been variable or generally minor (Figure 30). Like trout and hardhead/pikeminnow fry, densities of sucker fry increased strongly in 2006, but juvenile and small adult suckers generally showed minor decreases in density (Figure 32). Very large adult suckers, however, have shown a consistent increase in each year of study. Annual densities of smallmouth bass have been variable, but most size classes showed an increase in abundance in 2005 with a decrease in 2006 (Figure 34). Overall, the most consistent annual pattern among the fish community was a strong increase in abundance of fry (except for bass), and minimal change or a general decline for juvenile and adult fish.

The factors that may have lead to increasing abundance of fry but less change in juvenile and adult abundance are unknown. All of the principal species are spring spawners, with most trout spawning activity in April (according to data from reaches above this project area (TRPA 2002), whereas suckers and cyprinid species likely spawn over a more extended period of the spring (Taft and Murphy 1950, Villa 1985, Moyle 2002). Most spawning by rainbow trout is believed to occur in tributaries to the Rock Creek and Cresta reaches, such as Bear Ranch Creek, Grizzly Creek, Bucks Creek, and Milk Ranch Creek (Figures 2 and 3). In contrast, spawning by the other species is expected to occur in the mainstem, although reports documenting actual spawning by hardhead, pikeminnows, and suckers in the Rock Creek and Cresta reaches were not found. Recruitment of trout fry into the mainstem river may occur from mainstem-resident trout that migrated into the tributaries for spawning (although tributaries are steep with frequent barriers), or from tributary-resident fish whose progeny emigrate downstream into the mainstem (MCS 2003). The suitability of spring spawning flows could differ significantly between the large channel and highly regulated flows of the mainstem reaches versus the small, steep channels with highly variable snowmelt events in the tributaries, however the index estimates clearly show strong increases in fry abundance for all species, both mainstem spawners and tributary spawners.

Mean monthly streamflows in the project area (using the Cresta Reach as an example) were far higher than average in April and May of 2006, and slightly higher than average in May 2005 (Figure 36). High spring flows could be related to the increased recruitment of fry observed in those years. Trout and suckers both showed minor changes in fry densities in 2005, but large increases in 2006, which suggests that the very high flow regime was particularly beneficial to those species (at least in terms of the mainstem populations). In contrast, hardhead and/or pikeminnow showed large increases of fry densities in both years, perhaps suggesting that any moderate springtime flow increase is beneficial to those species. Bass fry also increased in abundance under the moderate spring flows of 2005, but unlike the native species, fry densities were much lower under the very high flows of 2006. Smallmouth bass require very slow velocity locations for successful spawning and early rearing of fry (Simonson and Swenson 1990, Allen 1996), and it is likely that the very high flows of 2006 were detrimental to recruitment for that species.

72 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Mean Monthly Streamflows in Cresta Reach

1981-2005 mean 7000 2001 2002 2003 6000 2004 2005 2006

5000

4000

3000 Mean Monthly Flow (cfs)

2000

1000

0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 36. Mean monthly streamflows in the Cresta Reach.

Possible mechanisms of increased recruitment during higher spring flows could include higher immigration of fry hatched in tributaries (for trout), greater availability of spawning habitat or greater survival to hatching in the mainstem or tributaries (all species), greater attraction or wider upstream dispersion of migrant spawners from the mainstem reservoirs (for non-trout species) or up into tributaries (for trout). For example, the extreme flows in December 2005 could have had significant effects (positive or negative) on the quantity and quality of suitable gravels for tributary trout populations. Habitat mapping data would help to assess whether upstream movement of trout from the mainstem river into tributaries is likely to be effected by flow levels. Also, comparison of annual differences in trout fry emigration with flow characteristics in tributaries could help to clarify the role of tributaries and flows on mainstem trout populations, although annual differences in trap installation times or trap operating efficiency could obscure such relationships.

If higher flows in 2005 and 2006 resulted in a greater upstream distribution of non-trout spawners in the mainstem, dive counts might be expected to show greater densities of non-game fry in upstream locations during those years. A comparison of unit-specific fry densities with river location in both reaches did not show a longitudinal relationship that would support such a hypothesis, however the dive counts are conducted 4-6 months after spawning and downstream dispersion of fry over the summer months could obscure that effect by the September dive counts.

73 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

The lack of pronounced changes in the abundance of adult trout and non-salmonid species since 2004 may indicate that any flow-related effects of the 2002 increase on fish populations had already occurred by 2004, and that the population fluctuations observed in this study are related to natural variation in recruitment, winter survival, or other factors not directly related to summer base flow levels. Studies following the Cantara Spill in the upper Sacramento River showed that trout, bass, and (possibly) pikeminnows responded much more rapidly following the spill event than did suckers (TRPA 2005a), however there is no strong evidence of species-specific rates of change in abundance in this study (note that the Cantara Spill represents and extreme example of fish population response to environmental changes).

Only additional years of fish sampling at higher flow levels will allow an assessment of whether the scheduled changes in base flows will effect “carrying capacity” for these species, or if other factors are determining the summer population levels. Such an assessment can only be considered within the context of how much natural variation can be expected among fish populations in this study area. In the upper Sacramento River, the abundance of rainbow trout over several years fluctuated by orders of magnitude of 2- 4 times even after the population appeared to have recovered (TRPA 2005a). Evaluation of numerous other long-term data sets suggested that such variability is common among trout populations, and consequently assessment of management-related changes in natural fish populations is difficult. The use of additional information, such as electrofishing data, creel census data, fry migrant trapping, age/growth studies, and survey data from other basins, can in combination help to assess the state of fish populations in the Rock Creek and Cresta reaches of the North Fork Feather River.

Comparison of Trout Densities from Other Basins

The dive count estimates from the Rock Creek and Cresta reaches were combined across habitat types and across juvenile-adult size classes to produce overall index densities for rainbow trout >5 inches within the entire study area. Because the pooling of data from different habitat types and size classes will introduce unknown biases into the index estimates (due to different but unknown diver observation probabilities), these pooled estimates should be viewed with caution. Pooled estimates were generated simply for comparison with available density estimates from dive counts in other California basins. The overall density of juvenile and adult trout in the Rock-Cresta reaches of the North Fork Feather River was approximately 200-250 fish/mile in 2005. The 2005 estimate is intermediate between the higher abundance observed in 2004 and the lower abundance in 2006, thus it might be considered representative as an “average” density over the course of this study.

The 2005 density estimate is well below the estimated density of juvenile and adult trout from the upper reaches of the North Fork Feather River, where densities based on dive counts within quadrat samples were over 800 fish/mile in the Belden Reach and over 2,500 fish/mi in the Seneca Reach (TRPA 2002). In the upper Sacramento River, which is considered a “Blue-Ribbon” trout stream by CDFG, index densities of juvenile and adult trout (>4 inches) based on identical sampling methodologies were approximately

74 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

2,000 fish/mile in 2001 (TRPA 2005a). More similar trout densities to the Rock-Cresta reaches have been observed in lower reaches of other mainstem, Sierra Nevada rivers. For example, upstream dive counts conducted in the Middle Fork and South Fork of the Yuba River (TRPA 2005c) yielded density estimates similar to this study at approximately 200-300 fish/mile (>5 inches). In the lower South Fork American River mainstem, cross-sectional transect dives conducted in 1999 also produced index estimates of 200-250 adult trout/mile, however juvenile trout were uncommon (TRPA, unpublished data). Upstream dive counts conducted in pool habitats in two lower reaches of the Middle Fork Stanislaus River in 2001 yielded index densities of trout >4 inches of about 100-200 trout/mile (pools only). In contrast, trout index densities in upper reach pools were 1,500 to 2,500 fish/mile (TRPA 2001b).

In summary, trout densities in the Rock Creek and Cresta reaches of the North Fork Feather River do not appear unlike trout densities in other large, low-elevation mainstem rivers draining the western slopes of the Sierra Nevada. But trout densities in upper reaches of the North Fork and in other “high quality” trout streams are typically five times to ten times higher than current densities in the lower reaches of the North Fork.

RECOMMENDATIONS

Continuation of the dive counts in future years after establishment of a new base flow regime is highly recommended, particularly since comparable “control” data is not available from either a nearby watershed or from years prior to the initial flow increase, and thus it is difficult to assess if the observed fish densities have responded to the initial change in flows. However, it should be cautioned that because the dive counts cannot be effectively calibrated with precise estimates of true abundance in an adequate sample of habitat units (of each habitat type), it is imperative that future dive counts be conducted in a manner to maximize the consistency in methodology in order to minimize any biases associated with changes in diver observation probabilities.

The improvement of the precision of index estimates would also greatly benefit the ability to distinguish significant changes in annual abundance, and therefore to assess flow-related effects on fish population response. The sampling design used in 2005 and 2006 was sophisticated and conducted at a high level of effort, and it is unlikely that significant further improvements can be made simply by increasing effort. Improvement of precision may be possible, however, by better characterizing the habitat characteristics that effect local fish densities, and by better assessing how specific sampling protocols influence dive counts. Such interim feasibility studies could help to improve index estimates during the next flow stage increase.

LITERATURE CITED

Allen, M.A. 1996. Equal area line-transect sampling for smallmouth bass habitat suitability criteria in the Susquehanna River, Pennsylvania. Pages B119-132 in M.

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LeClerc, C. Herve, S. Valentin, A. Boudreault, and Y. Cote, editors. Ecohydraulics 2000: Second international symposium on habitat hydraulics. Institut National de la Recherche Scientifique-Eau, Quebec, Canada.

Chao, M.T. 1982. A general purpose unequal probability sampling plan. Biometrika 69(3):653-656.

Cochran, W.G. 1977. Sampling techniques. John Wiley & Sons, New York. 428pp.

Des Raj. 1968. Sampling theory. McGraw-Hill, New York.

ECORP Consulting, Inc. 2003. Draft results of backpack electrofishing surveys for the Rock Creek-Cresta Project (FERC No. 1962), Plumas County, California. 4 March 2003 draft report prepared for Pacific Gas and Electric Company.

Hagen, J., and J.S. Baxter. 2005. Accuracy of diver counts of fluvial rainbow trout relative to horizontal underwater visibility. North American Journal of Fisheries Management 25:1367-1377.

Hankin, D.G. 1984. Multistage sampling designs in fisheries research: applications in small streams. Canadian Journal of Fisheries and Aquatic Sciences 41:1575-1591.

Hankin, D.G., and G.H. Reeves. 1988. Estimating total fish abundance and total habitat area in small streams based on visual estimation methods. Canadian Journal of Fisheries and Aquatic Sciences 45:834-844.

Hillman, T.W., J.W. Mullan, and J.S. Griffith. 1992. Accuracy of underwater counts of juvenile chinook salmon, coho salmon, and steelhead. North American Journal of Fisheries Management 12:598-603.

Li, S.K. 1988. Measuring microhabitat in swift water. Pages 183-193 in K. Bovee and J.R. Zuboy, editors. Proceedings of a workshop on the development and evaluation of habitat suitability criteria. A compilation of papers and discussions presented at Colorado State University, Fort Collins, Colorado, December 8-12, 1986. United States Fish and Wildlife Service, Biological Report 88(11). Fort Collins, CO. 408pp.

MCS. 2003. Downstream migrant trapping studies of selected tributaries of the North Fork of the Feather River, Rock Creek-Cresta Project, FERC No. 1962. Draft report by Meadowbrook Conservation Services for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Moyle, P.B. 2002. Inland fishes of California. University of California Press. Berkeley, CA. 502p.

Northcote, T.G., and D.W. Wilkie. 1963. Underwater census of stream fish populations. Transactions of the American Fisheries Society 92:146-151.

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Salamunovich, T. 2005a. Rock Creek-Cresta (FERC No. 1962) backpack electrofishing surveys of shallow-water habitats – November 2004. January 7, 2005 final report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Salamunovich, T. 2005b. Rock Creek-Cresta (FERC No. 1962) backpack electrofishing surveys of shallow-water habitats – October 2005. Draft report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Salamunovich, T. 2007. Rock Creek-Cresta (FERC No. 1962) backpack electrofishing surveys of shallow-water habitats – 2006 Draft Report prepared by Thomas R. Payne & Associates for Technical and Ecological Services, Pacific Gas and Electric Company, San Ramon, CA.

Sarndal, C-E., B. Swensson, and J. Wretman. 1992. Model assisted survey sampling. Springer-Verlag, New York. 694 pp.

Simonson, T.D., and W.A. Swenson. 1990. Critical stream velocities for young-of-year smallmouth bass in relation to habitat use. Transactions of the American Fisheries Society 119: 902-909.

Stillwater Sciences. 2005. Rock Creek-Cresta Project 2004 river pool fisheries study. Draft report to Pacific Gas and Electric Company, San Ramon, California.

Taft, A. C. and G. I. Murphy. 1950. Life history of the Sacramento squawfish (Ptychocheilus grandis). California Fish and Game 36(2):197-164.

Thomas R. Payne & Associates. 2001. Development of habitat suitability criteria for the Poe Project (FERC No. 2107), North Fork Feather River, California. Report prepared for Pacific Gas and Electric Company, San Ramon, California. 103pp.

Thomas R. Payne & Associates. 2001b. 2001 pool dive counts and comparison to current and historical shallow water CDFG electrofishing data for the Spring Gap- Stanislaus Project (FERC No.2130), Middle Fork Stanislaus River, California. Report prepared for Pacific Gas and Electric Company, San Ramon, California.

Thomas R. Payne & Associates. 2002. Habitat suitability criteria for rainbow trout and Sacramento suckers in the Upper North Fork Feather River Project (FERC No. 2105). Report prepared for Pacific Gas and Electric Company, San Ramon, California. 86pp.

Thomas R. Payne & Associates. 2003. Comparison of dive count methodologies and estimated fish abundance in the Rock-Cresta Reach of the North Fork Feather River, California. Report prepared for Pacific Gas and Electric Company, San Ramon, California. 37pp.

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Thomas R. Payne & Associates. 2005a. Recovery of fish populations in the Upper Sacramento River following the Cantara Spill. Final Report by Mark Allen and Tom Gast to the California Department of Fish & Game, Redding, California, 12/31/2006. 228pp.

Thomas R. Payne & Associates. 2005b. Use of dive counts to estimate fish population abundance in the Rock Creek - Cresta reaches of the North Fork Feather River, California. 2004 Final Report by Mark Allen and Scott Riley for Pacific Gas and Electric Company, San Ramon, California. 74pp.

Thomas R. Payne & Associates. 2005c. Middle and South Yuba rainbow trout (Oncorhynchus mykiss) distribution and abundance dive counts, August 2004. Draft Report by Tom Gast, Mark Allen, and Scott Riley for CH2MHill, Sacramento, California.

Thomas R. Payne & Associates. 2006. Use of dive counts to estimate fish population abundance in the Rock Creek - Cresta reaches of the North Fork Feather River, California. 2005 Final Report by Mark Allen and Tom Gast for Pacific Gas and Electric Company, San Ramon, California. 98pp.

Thompson, S.K. 1992. Sampling. John Wiley and Sons, New York.

Villa, N. A. 1985. Life history of the Sacramento sucker, Catostomus occidentalis, in Thomes Creek, Tehama County, California. California Fish and Game 71(2):88-106.

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Appendix A. Habitat mapping for Cresta and Rock Creek reaches. 2005-2006 sampling units are boxed. Unit Habitat Dist Unit Reach # Type Upstm Length Notes Cresta 1 RN 0 125 START AT PH TAILRACE, Robert Lamb & Nils Lunder Cresta 2 XLR 125 24 SM RIFFLE BREAK - CASCADE CHANGED TO NS , DIVE 04 Cresta 3 RN 149 75 POOL LIKE ON MARGINS, TRIB ON RT BANK Cresta 4 XLR 224 21 SM RIFFLE BREAK - CASCADE CHANGED TO NS Cresta 5 RN 245 177 TRIB AT RT BOTTOM, POOL LIKE ON MARGIN Cresta 6 XHR 423 53 SM RIFFLE BREAK Cresta 7 RN 476 214 MID-CHANNEL BOULDER AT TOP Cresta 8 DP 690 1,548 BTM @ MC BLDR, TAIL NARROW 3 LANES, CABLE CAR TO ~1300 ' SCUBA LANES 2-5 (T= Cresta 9 LR 2,238 123 TRV @ BTM, POISON OAK S&D @ BTM, SLOW ON RB, LB ~ 160', DIVE 04 Cresta 10 RN 2,361 142 BTM @ WLW CLUMP AT LBWE, SPLIT CHANNEL ABOVE, MOSTLY RIFFLE NOW Cresta 11 LR 2,503 155(175) BTM @ PINE IN LB BDRK, 1/2 UNIT HR, SC AT TOP, 125' W/O BEND Cresta 12 RN 2,659 248 BACKWATER POOL ON RB [INCL SIDE CHAN], TOP MARK RB ALDER Cresta 13 LR 2,907 109 TRANSVERSE, DIVE 04 Cresta 14 SP 3,015 433 33ft BELOW BENCHMARK ON RB (T=94',B=339',no H), DIVE 04 Cresta 15 RN 3,448 237 ANGULAR BOULDER AND STUMP RB WATERS EDGE,~40ft NS Cresta 16 XHR 3,686 73 TOP AT POOL TAIL, 1000 ft SC BEGINS Cresta 18 SP 3,758 803(973R) BTM @ 2' HI PYRAMID BLDR LB, LRG PIPE@TOP LB H,(B=576',H=227',noT), Dive 04, DP W/ Cresta 19 RN 4,561 120 MOSTLY DEAD ALDER @ TOP Cresta 20 DP 4,682 907 CAVE UNDER BEDROCK RB TOP Cresta 21 RN 5,589 73 LG BOULDER NEXT TO BEDROCK CLIFF ON LB Cresta 22 SP 5,662 231 DIVE 04 Cresta 23 RN 5,893 114 TOP @MIDDLE OF 2 GIANT BOULDERS RB Cresta 24 SP 6,007 169 LB START OF SM SAND BAR AND TIP OF FALLEN FIR, DIVE 04 Cresta 25 RN 6,176 341 FLAG JUST BELOW ISLAND Cresta 26 XHR 6,516 74 RT SIDE CHANNEL, TOP @ WILLOW ON ISLAND Cresta 27 RN 6,590 54 TOP @ LEANING TREE ON RB, RT SIDE CHANNEL Cresta 28 XHR 6,644 72 TOP @ END OF WILLOWS ON RB OF RT SIDE CHANNEL, LB SC 214' Cresta 30 DP 6,716 467 TOP T@RB ALDER NR LG BLDR,TOP B@LG LB FLAT BLDR,~70ft NS CHUTE ON RB H Cresta 31 XHR 7,183 75 TOP @ BOTTOM OF FLAGGED FIR STRANDING SITE \ (T=44',B=302',H=121') Cresta 32 SP 7,258 386 BTM @ TRV RF BREAK, TOP @HUGE MC BLDR , <> AT TOP, MARK RB ASH BTM Cresta 33 RN 7,644 104 TOP JUST BELOW LG MID CHANNEL BOULDERS \ (T=64',B=255',H=67') Cresta 34 XRN 7,747 79 30 FT OF LEFT BANK NOT DIVEABLE Cresta 35 XHR 7,826 33 SHORT RIFFLE BREAK Cresta 36 RN 7,859 216 BTM @ DANGEROUS CASCADE, TOP @ WATERFALL LB, TOP @ MC BLDR W/6" DRY Cresta 37 SP 8,075 205(225) BTM @ LB FALLS, LRG MC BLDR @ TOP, BEDROCK ON LB Cresta 38 RN 8,281 343 SC at top Cresta 39 XHR 8,625 189 314' SC ON LB, TOP EVEN WITH START OF TALUS LB MOSTLY DIVEABLE LGR Cresta 41 RN 8,813 69 TOP @ LG DEAD TREE ON LB HILLSIDE Cresta 42 DP 8,882 730 BTM @ ANGULAR BLDR RC & RB WILLOWS (T=46',B=684',no H) Cresta 43 RN 9,612 185 TOP @ RB ALDER WITH SPRING FLOWING IN Cresta 44 XHR 9,797 98 TOP TRV @ LG ROUND BOULDER LB Cresta 45 RN 9,895 268 TOP @ BTM BEAR CREEK STRAND SITE, ORNG FLAG, DIVE 04(RB320') Cresta 46 XHR 10,164 86 BTM TRV, TOP @ RB WILLOW, BLUE/ORANGE FLAGGING Cresta 47 RN 10,250 100 TOP @ LG SQUARE BOULDER RB Cresta 48 LR 10,350 97 TOP @ 20FT BELOW BENCH MARK ON RB Cresta 49 RN 10,446 166(217) BTM 20' BLW XSEC PINS, TOP @ RB ALDERS & BEAR CRK HWY SIGN, LGR UPPER 1/2 L

79 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix A. (continued) Unit Habitat Dist Unit Reach # Type Upstm Length Notes Cresta 50 RN 10,613 176 BTM UPPER END OF LRG BDRK BLDR RB, TOP @ ALDER RB Cresta 51 SP 10,789 463 BTM W <> RB, TOP@ HWY "Hi Flow" sign, (B=368',H=65',noT), DIVE 04 Cresta 52 RN 11,252 187 BTM@ HWY "Hi Flow" sign,TOP@RB ALDER w CULVRT ABV, LB~80'?, DIVE 04 Cresta 53 DP 11,440 786 TOP T@RB WLW/LB BEDRK,TOP B@PULLOUT,TOP H@RB TRAIL(T=79',B=566',H=141') Cresta 54 XHR 12,226 167 TRV BTM AT SHADY REST, LB HAS 85ft FAST CHUTE WHICH IS UNDIVEABLE Cresta 55 LR 12,392 115 BTM @ TOP WW, RB GREEN SIGN IN SHADY REST STOP AT TOP Cresta 56 RN 12,508 190 TOP @ FRONT OF LG BOULDER RB WATERS EDGE Cresta 57 LR 12,698 109 TOP @ MID-CHANNEL TRIANGULAR BOULDER Cresta 58 RN 12,806 174 TOP @ TRIANGULAR BOULDER RB Cresta 59 DP 12,980 832 BTM 100' BLW END GUARDRAIL, TOP @ tall pine LB, (T=105',B=727',no H) Cresta 60 RN 13,812 107 Cresta 61 DP 13,919 615 TOP T AT SM ALDER RB,DEAD TREE IN BEDROCK LB,T=41',B=574' Cresta 62 LR 14,534 93(56) TOP NR UP END OF TUNNEL, TRVS TOP, LR SHORT RB Cresta 63 RN 14,627 515 BTM NR TOP ARCH ROCK TUNNEL,TOP @ LG BOULDER RB w ROUND SCOUR HOLES Cresta 64 SP 15,141 265 TOP B @ HUGE BLDR RB,TOP H @ MID HUGE BLDR LB WE (B=191',H=74',no T) Cresta 65 RN 15,406 96 TRV BTM @ BLDRS, RN w/ short break btwn next run, DIVE 04(RB79') Cresta 66 RN 15,502 66 TOP @ SM WILLOW RB, DRK GREY SPOT LG BOULDER LB Cresta 67 XHR 15,568 462 BOTTOM 60 FT NOT DIVEABLE, TOP @ LG FLAT BOULDER & DEAD TREE RB Cresta 68 LR 16,031 104 TOP @ DEAD TREE ON RT HILLSIDE Cresta 69 XHR 16,135 72 Cresta 70 DP 16,208 339 TOP T@METAL BEAM LB,TOP H @ HUGE MC BLDR (T=49',B=224',H=66'), DIVE 04 Cresta 71 RN 16,547 238 TOP @ LG MID-CHANNEL BOULDER, LB SMALL COBBLE BAR Cresta 72 DP 16,785 223 TOP B@RB BDRK CLEFT,TOP@BIG LB BLDR,40ft NS (B=126',H=97',noT), DIVE 04 Cresta 73 XHR 17,008 88 UNDIVEABLE, TOP AT UPSTREAM END OF HUGE MID-CHANNEL BOULDER Cresta 74 XHR 17,096 76 ~50% OF UNIT IS UNDIVEABLE DUE TO VELOCITY AND ENTRAINED AIR,PW Cresta 75 DP 17,172 523 BTM DANGEROUS,TOP @SML PYRAMID BLDR W LB WLW (T=79',B=365',H=79') Cresta 76 XLR 17,695 97 TOP @ RUSTED TRACTOR TREAD ON LB, ~20-30% UNDIVEABLE Cresta 77 RN 17,792 180 TRVS BTM@DWNSTR END LB BDRK CLIFF RF CREST, TOP 15 FT BLW RB WLW AT WE Cresta 78 XHR 17,973 155 TOP @ LB WILLOWS GROWING OUT OF CRACK IN BEDROCK WALL Cresta 79 DP 18,128 357 BTM @ HUGE BLDR BREAK, TOP @ FLAT BLDR CHUTE T=83',B=147',H=127' Cresta 80 XHR 18,485 101 TOP EVEN WITH HIGHEST POINT ON HUGE TRIANGULAR BOULDER LB WE Cresta 81 RN 18,586 182 TOP @ UPSTREAM END OF LG MID-CHANNEL BOULDER Cresta 82 XHR 18,768 175 TOP @ HUGE FLAT BOULDER RB,~60ft NS Cresta 83 DP 18,943 222 TOP B@DEAD TREE IN BEDRK RB,TOP H@GREEN BUSH IN BEDRK RB,B=169',H=53' Cresta 84 XHR 19,165 268 Cresta 85 RN 19,433 407 TOP @ CHUTE NR LG TRIANGULAR BOULDER LB, TRVS Btm @ County line & LRG BLDR L Cresta 86 LR 19,841 152 TOP @ FLAT SM BOULDER LB WITH WILLOW,~30ft NS Cresta 87 SP 19,992 521 TOP T@PIN & ORNG MARK RB,TOP H@OLD GAGE LRG RB BLDR (T=65',B=357',H=99'), B Cresta 88 SP 20,513 68 TOP T@BEAMS@BASE LB BEDRK,TOP B@PINE SNAG LB HILL (T=68',B=122',no H) Cresta 89 RN 20,582 148 LRG FLAT-FACED ROCK ON RB TOP @ WATERS EDGE, DIVE 04 Cresta 90 LR 20,729 176 LRG BLDR ON RB WE, WILLOW DIRECTLY BEHIND, DIVE 04 (RB134') Cresta 91 RN 20,906 52 TOP @ BEGINNING OF BEDROCK SLABS ON LB WATERS EDGE Cresta 92 LR 20,958 187 TOP & BTM TRVS, TOP @ MC BLDRS Cresta 93 RN 21,146 400 BTM @ HW REFLECTOR, TOP @ LWD ON RT HILL SLOPE, DIVE 04 (LB420') Cresta 94 XHR 21,546 79 TOP @ LINE OF BOULDERS ACROSS CHANNEL Cresta 95 XRN 21,625 31 TOP @ FLAT BOULDER RB

80 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix A. (continued) Unit Habitat Dist Unit Reach # Type Upstm Length Notes Cresta 96 XHR 21,656 47 TOP @ LG BOULDER RT SIDE OF CHANNEL Cresta 97 XRN 21,703 121 TOP EVEN WITH SM BUSH ON RIGHT HILL SLOPE,~20ft NS Cresta 98 XHR 21,825 33 TOP @ LG BOULDER SITTING ON CONCRETE RB WATERS EDGE Cresta 99 XRN 21,858 52 TOP @ WHITE ANGULAR BOULDER IN CONCRETE RB Cresta 100 XHR 21,910 196 80% NOT DIVEABLE, TOP @ LRG GREEN BLDR W WHITE SPOTS ON LB BAR Cresta 101 LR 22,106 125 TOP @ ORNG PIN IN ROCK RB, SIDE CHAN ALONG DP RB & LB SC 642', DIVE 04 Cresta 103 DP 22,231 652(724) BTM NR 2 XSEC PINS LB, GRIZZLY CRK IN ~MIDDLE, DIVE 04,(T=98',B=433',H=121') Cresta 104 XHR 22,883 51 Cresta 105 RN 22,933 49 TOP EVEN WITH ENTRANCE TO GRIZZLY TUNNEL Cresta 106 LR 22,983 33 TOP @ LG BOULDER LB WATERS EDGE WITH WHITE STRIPES Cresta 107 SP 23,015 315 BTM 50' ABV TUNNEL MOUTH, TOP@ TUNNEL EXIT, (T=62',B=253',no H) Cresta 108 RN 23,330 147(160) BTM @ UP END LB CLIFF(swim around), TOP @ FIG TREE LEFT HILL SLOPE Cresta 109 XHR 23,478 104 TOP @ LG BOULDER RB WITH WHITE STRIPES Cresta 110 XLR 23,582 60 TOP @ SM WILLOW RB WATERS EDGE Cresta 111 XHR 23,642 81 Cresta 112 RN 23,723 254 Cresta 113 XHR 23,977 298 TOP WHERE BEDROCK WALL ON LB FORMS A CORNER Cresta 114 RN 24,275 193 Cresta 115 DP 24,468 395 TOP T@LB BDRK OVHANG,TOP B@ALD IN LB BDRK,(T=69',B=183',H=143'), Cresta 116 XHR 24,863 142 43.2 M CHUTE ABVE PL HEAD THAT FLOWS FROM DD PL \_DIVE 04 (RB375') Cresta 117 XDP Cresta Diversion Dam plunge pool Rock 0 Scott Riley (9/28-29/04), start just above ROCK CREEK POWERHOUSE Rock 1 RN 86 86 top @ lrg mc boulder Rock 2 HR 185 99 w/ bldrs & pockets, difficult to dive, DIVE 04 Rock 3 RN 280 95 Rock 4 XHR 397 117 top @ mc bldr Rock 5 RN 596 199 transverse @ top, split @ top Rock 6 XHR 646 50 transverse split Rock 7 RN 739 93 upper 40' all ww Rock 8 XHR 776 37 cas Rock 9 DP 1,349 573 tail =115', body = 328, head =130, beach mid pool Rock 10 XHR 1,601 252 pow, run like portions, lg bldr mc @ top Rock 11 SP 2,006 405 tail =100', run like but no distinct head Rock 12 XRN 2,111 105 pow, hip chain broke Rock 13 XHR 2,152 41 mid unit, no gps Rock 14 RN 2,244 92 Rock 15 DP 2,477 233 btm dangerous, head = 137' Rock 16 RN 2,690 213 deep almost pool like esp @ top, DIVE 04 Rock 17 XHR 2,755 65 Rock 18 SP 3,037 282 run like, DIVE 04 Rock 19 XHR 3,079 42 Rock 20 RN 3,170 91 Rock 21 XHR 3,262 92 Rock 22 DP 3,792 530 (tail=54',body=378',head=98'),wp off rd nr lg bldr/willow, DIVE 04 (LB579') Rock 23 XHR 4,266 474 pow Rock 24 RN 4,398 132 orange flag lb at top

81 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix A. (continued) Unit Habitat Dist Unit Reach # Type Upstm Length Notes Rock 25 DP 4,743 345 transverse at top river bends left Rock 26 XHR 4,778 35 Rock 27 RN 4,994 216 Rock 28 XLR 5,210 216 rif/run/pow below buck's pwrhouse Rock 29 XRN 5,282 72 BUCKS POWERHOUSE Rock 30 SP 5,718 436 BTM @ mc bldr, 10' abv PH, head @ riff break = 112', TOP @ old brdg abutments Rock 31 XHR 5,800 82 top @ break Rock 32 RN 5,915 115 w/ some pockets & bldrs, top @ last emerg mc bldr almost pl tail, Bucks PH BRDG Rock 33 SP 6,646 731 long & rn like, @1265 trib enters rb, head =157', top @ lg mc bldr Rock 34 RN 6,785 139 BTM nr confl Bucks Crk, top @ upper end mc bld, Storrie HW sign in mid unit Rock 35 SP 6,975 190 width ~90', top @ cas/falls Rock 36 XRN 7,202 227 deep slot @ top, falls @ btm dangerous Rock 37 HR 7,303 101 vry difficult, top @ lg mc bldr, transverse Rock 38 RN 7,568 265 top @ lg bldr near lb w/ some lbs and bkwtr rb, storrie lb Rock 39 SP 7,715 147 top btwn lg bdrk/bldr on lr/rb, storrie on lb Rock 40 RN 7,884 169 BTM nr Storrie flagpole, sml split on rb, DANGEROUS BOTTOM Rock 41 SP 8,073 189 bdrk rb top@ mc bldr, DIVE 04 (171') Rock 42 XRN 8,125 52 all ww, 5' falls at top Rock 43 XRN 8,188 63 too dangerous at btm Rock 44 XHR 8,280 92 flag at top Rock 45 RN 8,463 183 DANGEROUS DROP @ BTM OPP Lorens home, TOP @ RB emerg blds w <> on RB oak Rock 46 LR 8,525 62 BTM @ emerg bldrs, top TRV @ lg mc bldr w/ willows in front of it Rock 47 XDP 9,056 531 body =312', head = 108', fill& construction equip on rb Rock 48 RN 9,319 263 top @ tele pole on rb, lg bldr lb Rock 49 LR 9,379 60 top @ lg emerg bldr LB, DIVE 04 Rock 50 RN 9,494 115 shallow, top @ constriction formed by lb extending frm lb Rock 51 LR 9,643 149 BTM 10' abv lrg LC bdrk bldr, TOP @ break & RB caution light, lower 1/2 runDIVE 04 Rock 52 RN 9,749 106 top @ rf break Rock 53 XHR 9,804 55 Rock 54 RN 9,959 155 flag at top Rock 55 LR 10,021 62 lots of ww, top at mc bldr, DIVE 04 (RB69') Rock 56 SP 10,191 170(206) BTM @ low end of LB bdrk wall, huge bld mid unit,top lft is rif, top@mc bld Rock 57 XHR 10,311 120 rf/pw, too dangerous, too much ww, top@ mc willow on bldr Rock 58 RN 10,443 132 rn/pw steep bdrk rb, lots of bldrs& deep pkts, top ds caution sign Rock 59 HR 10,512 69(82) BTM @ top LB wall, bldrs & pckts, dangerous on left, top@ flat mc bldr, difficult Rock 60 RN 10,626 114 top @ bldr constrictions Rock 61 RN 10,765 139 lg blds w/ pckts and narrow fast areas, DIVE 04 (RB159') Rock 62 DP 10,997 232 bdrk wall lb, top body @ mc bld, top tail @ line mc Rock 63 XHR 11,063 66 cas Rock 64 RN 11,169 106 pow, lg bldrs at top Rock 65 XHR 11,310 141 pow/cas top@mc bldr & narrow chute Rock 66 RN 11,740 430 lg blds (pow), sm rif break in mid, DIVE 04, top @ end Rockcrest Brdg turnout, mark RB tree Rock 67 XHR 11,772 32 Rock 68 RN 11,823 51 bldr break at top Rock 69 XHR 11,871 48 cas/pow Rock 70 LR 11,940 69 pow, top @ elaborately scoured bdrk mc

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Appendix A. (continued) Unit Habitat Dist Unit Reach # Type Upstm Length Notes Rock 71 XHR 12,092 152 pow top just below bridge Rock 72 SP 12,277 185 BTM @ BRIDGE; w/ lg house size bldrs Rock 73 XHR 12,380 103 pow top @ 5' falls Rock 74 XRN 12,430 50 btm too dangerous Rock 75 HR 12,557 127 BTM @ TRV break, pow, TOP w flag and <> RB bldr, RB chute NS Rock 76 RN 12,630 73 pow Rock 77 XHR 12,661 31 huge bldrs and narrow chute at top Rock 78 SP 12,970 309 pow, portions run-like, many lg bldrs, upper 30' ww, dif to sample Rock 79 XHR 13,076 106 lg chunk of metal in water on rb Rock 80 RN 13,398 322 pow, sm break nr mid, upper 15' all ww, top at 2' drop Rock 81 XHR 13,804 406 Rock 82 XSP 13,892 88 rt side mostly lg PW/RF, top at 3' pourover, corner pool, changed to NS, DIVE 04 Rock 83 DP 14,252 360 vry lg bldrs, rt side pkts w/ dangerous pourover into undercut Rock 84 XHR 14,445 193 pow/rif sm waterfall frm culvert lb, riprap frm rd on rb Rock 85 DP 14,604 159 bdrk wall lb, difficult to determine depth, DIVE 04 (RB140') Rock 86 XHR 14,768 164 run like portions in midddle Rock 87 XRN 14,839 71 pow/too dangerous Rock 88 XHR 14,963 124 narrow and fast Rock 89 XRN 15,018 55 Rock 90 XHR 15,077 59 3-4' drop at top Rock 91 XRN 15,138 61 too dangerous Rock 92 LR 15,260 122 pw, rt side very pockety, top @ 2' drop Rock 93 XHR 15,855 595 rt side ok to dive, very pockety but leftside steep and dangerous Rock 94 DP 16,146 291(251) btm dangerous drop, top @ huge mc bld just below Tobin bridge, DIVE 04 (RB268') Rock 95 XHR 16,288 142 TOBIN BRIDGE Rock 96 XDP 16,538 250 Mark Allen start in pool under tobin bridge, measured w/ rangefinder,constr equip Rock 97 XHR 16,723 185 rb shorter (inside bend) Rock 98 SP 16,977 254 upper 50' is head Rock 99 XHR 16,998 21 short break Rock 100 SP 17,073 75 short/wide w/plunge @ ww at top rb Rock 101 XHR 17,108 35 Rock 102 RN 17,562 454 BTM @ lrg oak by btm turnout, pow w slow deep pockets, top @ 5' plunge, btm wide Rock 103 XHR 17,578 16 20' wide bld at top mc Rock 104 RN 17,888 310 deep slow pow, top at ww chute Rock 105 XHR 17,905 17 ww cas Rock 106 RN 18,012 107 pw-very wide with huge bldrs & splits Rock 107 XHR 18,025 13 entering low grad area Rock 108 RN 18,148 123 pw,shallow, short rif at top Rock 109 SP 18,298 150 BTM @ top of huge MC bldr, run-like w/o pow, top@ lb slanted bldr Rock 110 RN 18,523 225 short rif break in mid, sheet metal in middle lb Rock 111 XHR 18,591 68 Rock 112 LR 18,676 85 Rock 113 XSP 19,155 479 super wide in body, ~7-8 divers, head 80' from sm mc bld Rock 114 LR 19,346 191 sm side channel on rb, upper 1/2 fast Rock 115 RN 19,689 343 severe trans rif at top, upper 50' sp like Rock 116 XHR 19,962 273 trv very wide , shallow, ~sc on rb, upper 1/2 doable but vry wide

83 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix A. (continued) Unit Habitat Dist Unit Reach # Type Upstm Length Notes Rock 117 DP 20,858 896 tail ~100' very wide, head upper 80' from rb sandbar, Rock 118 LR 21,058 200 lb deeper/faster, top @ lb pourover bld Rock 119 RN 21,518 460 upper 1/3 narrow and fast Rock 120 SP 21,818 300 LB run like, DIVE 04 Rock 121 LR 21,928 110 top at rb snag Rock 122 RN 22,128 200 BTM betw 2 RB snags, lower 1/2 w/ eddy rb, TOP <> at LB aldeer Rock 123 HR 22,278 150 fast portion HAZARDOUS (no lines), upper 1/2 slower Rock 124 RN 22,493 215 BTM @ RC bdrk bldr w alder, top @ last bldr w/ rif in btm pool, TOP <> in RB tree Rock 125 SP 22,873 380 lower ~100 tail, body wide and shallow-glide Rock 126 RN 23,398 525 BTM @ lower end Indain Jim playgrnd, glide, top 15' dwnstrm 2' dmtr live oak rb Rock 127 LR 23,542 144 BTM nr top Indian Jim school, top at mc bldr lb sc Rock 128 RN 23,708 166 lb sc (~15%) Rock 129 LR 23,953 245 sc leaves ~40'abv btm, top run-like to mc bldr bar Rock 130 SP 24,096 143 BTM nr aband campgrnd w bldrs at top RF, TOP <> at LB tree Rock 131 RN 24,305 209 DIVE 02 (part) Rock 132 XLR 24,378 73 trv lr, trib lb Rock 133 RN 24,621 243 shallow, rif like, DIVE 02 Rock 134 XLR 24,658 37 short rif break Rock 135 DP 24,888 230 bedrock cliff rb, upper 60' head, DIVE 02 Rock 136 XHR 25,046 158 upper 1/2 trv, Rock 137 DP 25,945 899 tail lower ~100' in bw behind TRV rf, upper 80' head, DIVE 02/04 (LB985') Rock 138 XHR 25,958 13 split Rock 139 DP 26,488 530 BTM in SC @ RB headpin, up 80' head abv bedrk pt Rock 140 RN 26,653 165 sc lc/rc:60/40, rc run or pow, rf break in middle Rock 141 XHR 26,813 160 ww drop, split at top Rock 142 DP 27,553 740 tail ~100' widest at btm, head upper 100' Rock 143 LR 27,738 185 w/ pow/rn, chambers ck at top & in SP tail Rock 144 SP 28,360 622(523) BTM @ crk mouth, tail lower ~80', upper 1/2 narrow with current Rock 145 LR 28,426 66 fast but shallow Rock 146 DP 29,566 1,140 Btm @ dezd snag RB, tail lower 150', very wide in mid, upper 200' glide Rock 147 XRN 29,603 37 short run/glide to separate 2 pools Rock 148 SP 30,018 415 tail lower 100', head upper 100', run like Rock 149 XHR 30,228 210 fast and deep with ww Rock 150 RN 30,366 138 middle very fast may x out Rock 151 XHR 30,744 378 upper 1/2 lr but split Rock 152 XRN 31,398 654 portions rf like, split at top, too complex on upper 1/2 Rock 153 RN 31,769 371 BTM @ split w RB bdrk slab, lb split, but less complex Rock 154 LR 31,938 169 some rn portions, TOP <> RB tree Rock 155 RN 32,515 577 wide,shallow, slow @ ROGERS FLAT BRIDGE @ 245', DIVE 04, TOP <> RB tree Rock 156 LR 32,596 81 Rock 157 RN 32,978 382 aband bridge@16140, incl 2 short rif breaks, DIVE 04 (RB372') Rock 158 SP 33,411 433 shallow w/ vel, RN like, tail=lower 100', head at mc bld, DIVE 04 (RB399') Rock 159 XHR 33,547 136 Rock 160 LR 33,764 217 BTM @ upper Helo pad, w/ pow & rn, areas of flooded willows on lb,TOP <> RB bldr Rock 161 RN 33,912 148 BTM 50' blw top EF site, TOP @ RB log, <> at bldr, similar to below but less ww, pw Rock 162 XHR 33,958 46 wide with many emergent objects

84 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix A. (continued) Unit Habitat Dist Unit Reach # Type Upstm Length Notes Rock 163 RN 34,056 98 pw, just below start of pool, sc on lb, red flagging Rock 164 DP 34,513 457(519) HWY turnout sign near btm, last 100' = tail, TOP <> at RB bldr Rock 165 RN 34,551 38 short gld between pools Rock 166 SP 35,088 537 shady in am, no tail, head=upper 200' rn Rock 167 LR 35,160 72 short break between units Rock 168 RN 35,714 554 shallow/fast gld lower 1/2, upper 1/2 slower w/ eddy on lb Rock 169 LR 35,950 236 trv rf break @ btm, much is shallow rn, lots of orang flags, DIVE 04, spwn gravel LB Rock 170 RN 36,122 172 very similar to lr below, less rf/ww Rock 171 XHR 36,130 8 short rf break Rock 172 RN 36,426 296 BTM 40' blw LB tele pole & concrete RR, pow, rf break in mid, fast chutes below top Rock 173 SP 36,627 201 probably visib from surface Rock 174 XHR 36,843 216 upper 1/2 ok but drops at btm Rock 175 RN 37,208 365 slow and moderate depth, top@ last mc bld Rock 176 SP 37,591 383 similar to rn below, but deeper and slower, upper 1/2 = head Rock 177 XHR 37,861 270 lb sc, rb turns rt, top at lrg log on rb Rock 178 LR 38,057 196 fast but ok, top at rb tele pole Rock 179 DP 38,817 760 tail is btm 80' of rn, red flags and rebar near btm, top @ mid of TRV RF, DIVE 04 Rock 180 XLR 38,838 21 ~90 deg trv rf Rock 181 SP 39,481 643 severe trv @ btm w tel cable box, lower 150' lb tail, ovh lines, TOP <> LB bldr Rock 182 XHR 39,660 179 split Rock 183 XDP 41,188 1,528 huge dp, bdrk pt along hw, tail is lower ~100' rn, turnout abv pl Rock 184 XHR 41,266 78 incl deep rn above huge mc bld Rock 185 DP 41,821 555(635) BTM @ top SC, tail = lower 150', head is upper ~150', TOP 20' abv tree on road Rock 186 XHR 42,118 297 Rock 187 DP 42,412 294 USGS GAGE at btm, no tail, upper ~100' head Rock 188 XHR 42,450 38 ww break Rock 189 RN 42,527 77 DIVE 04 Rock 190 LR 42,585 58 fast but ok Rock 191 RN 42,733 148 Rock 192 LR 42,870 137 steep hr at btm Rock 193 SP 43,022 152 DIVE 02? Rock 194 HR 43,157 135 btm cas, DIVE 02/04 Rock 195 RN 43,768 611 BTM ~120' below rock warning sign, upper deep, DIVE 02, TOP @ LB concrete w steel Rock 196 XHR 43,922 154 sc w/ deep bw pool in lc, hr on rc (90%Q), Rock 197 RN 44,098 176(157) BTM @ top of LB BWP, thick brush lb, TOP <> @ RB bldr Rock 198 XHR 44,129 31 short break Rock 199 RN 44,258 129 top at metal rail in mc Rock 200 XDP 44,891 633 short tail abv rn? Very wide and deep along rb bdrk wall Rock 201 XHR appears to cont up to dd plunge pool Rock ROCK CREEK DIVERSION DAM

85 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix B. Photographs of habitat units surveyed in 2005 and 2006 (photos may only be available on CD).

86 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. Index estimates of for 2004-2006 dive counts according to reach, size class, habitat type, and species. Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 CrestaFry (<5)Deepn466466466 466 (dive Pool Abundance 0 0 3 0 517 3,078 0 5,640 12,358 see HH fry data 10 189 26 lane) Variance 0 0 5 0 57,613 207,573 0 8,052,534 8,624,396 20 2,774 121 + 95% C.I. 0 0 5 0 617 1,171 0 7,295 7,549 14 135 28 Density #/mi 0 0 2 0 318 1,891 0 3,464 7,591 6 116 16 Variance 0 0 2 0 21,737 78,315 0 3,038,139 3,253,896 8 1,047 46 + 95% C.I. 0 0 3 0 379 719 0 4,481 4,637 9 83 17 Shallown566566566 566 Pool Abundance 0 0 2 0 221 932 224 3,275 4,834 see HH fry data 2665 Variance 0 0 0 0 3,965 17,239 50,509 461,056 301,143 4 165 0 + 95% C.I. 0 0 1 0 162 338 624 1,745 1,411 5 33 2 Density #/mi 0 0 3 0 302 1,275 306 4,481 6,614 3 90 7 Variance 0 0 1 0 7,423 32,272 94,556 863,122 563,756 7 309 1 + 95% C.I. 0 0 2 0 221 462 854 2,388 1,930 7 45 2 Run n 5 12 12 5 12 12 5 12 12 5 12 12 Abundance 31 39 84 6 631 1,893 385 5,196 6,076 see HH fry data 12 238 12 Variance 201 93 1,382 46 32,375 248,311 128,167 1,582,565 6,343,296 30 3,697 50 + 95% C.I. 39 21 82 19 396 1,097 994 2,769 5,543 15 134 16 Density #/mi 23 29 62 4 467 1,401 285 3,845 4,496 9 176 9 Variance 110 51 757 25 17,724 135,942 70,167 866,403 3,472,747 16 2,024 27 + 95% C.I. 29 16 61 14 293 812 735 2,049 4,102 11 99 12 Rifflen566566566 566 Abundance 54 52 169 0 277 206 0 481 68 see HH fry data 0290 Variance 574 130 464 0 5,470 9,973 0 23,956 381 0 154 0 + 95% C.I. 67 29 55 0 190 257 0 398 50 0 32 0 Density #/mi 176 174 565 0 926 689 0 1,608 227 0 97 0 Variance 6,067 1,454 5,188 0 61,163 111,514 0 267,866 4,260 0 1,722 0 + 95% C.I. 216 98 185 0 636 858 0 1,330 168 0 107 0 CrestaFry (<5)Deepn466466466 466 (fry Pool Abundance 0 0 7 5 1,151 6,241 149 19,538 33,198 see HH fry data 15 537 123 lane) Variance 0 0 31 10 172,470 3,705,133 7,571 43,467,694 97,136,700 45 10,630 3,157 + 95% C.I. 0 0 14 10 1,068 4,948 277 16,948 25,335 21 265 144 Density #/mi 0 0 4 3 707 3,833 92 12,001 20,392 9 330 76 Variance 0 0 12 4 65,071 1,397,909 2,856 16,399,916 36,648,683 17 4,011 1,191 + 95% C.I. 0 0 9 6 656 3,039 170 10,410 15,562 13 163 89 Shallown566566566 566 Pool Abundance 0 0 0 0 515 3,746 1,019 7,685 25,983 see HH fry data 2 160 10 Variance 0 0 0 0 16,752 1,044,239 237,957 1,234,437 36,717,699 3 1,956 21 + 95% C.I. 0 0 0 0 333 2,627 1,354 2,856 15,576 5 114 12 Density #/mi 0 0 0 0 705 5,125 1,394 10,515 35,551 3 219 14 Variance 0 0 0 0 31,361 1,954,871 445,468 2,310,932 68,737,502 6 3,662 39 + 95% C.I. 0 0 0 0 455 3,594 1,853 3,908 21,312 7 156 16 Run n 5 12 12 5 12 12 5 12 12 5 12 12 Abundance 0 28 48 6 1,628 5,377 1,272 6,713 19,327 see HH fry data 12 335 14 Variance 0 201 504 35 364,646 1,266,800 1,275,952 2,745,856 25,378,047 93 6,611 78 + 95% C.I. 0 31 49 16 1,329 2,477 3,136 3,647 11,088 27 179 19 Density #/mi 0 21 36 4 1,205 3,978 941 4,967 14,300 9 248 10 Variance 0 110 276 19 199,632 693,532 698,542 1,503,266 13,893,650 51 3,619 43 + 95% C.I. 0 23 37 12 983 1,833 2,321 2,699 8,204 20 132 14

87 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. (continued) Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 Rifflen566566566 566 Abundance 13 20 26 3 216 117 19 535 237 see HH fry data 0300 Variance 85 15 96 5 3,917 986 192 23,988 6,706 0 114 0 + 95% C.I. 26 10 25 6 161 81 38 398 211 0 27 0 Density #/mi 42 67 87 10 722 391 62 1,789 793 0 100 0 Variance 898 168 1,073 53 43,798 11,025 2,030 268,224 74,984 0 1,275 0 + 95% C.I. 83 33 84 20 538 270 125 1,331 704 0 92 0 CrestaJuvenileDeepn 466 4 6 6 4 6 6466466 (5-10) Pool Abundance 46 44 39 0 4 2 77 39 33 205 0 13 51 68 36 Variance 368 163 213 0 1 1,125 250 150 15,920 0 32 261 87 87 + 95% C.I. 61 33 38 0 0 3 107 41 31 402 0 14 51 24 24 Density #/mi 28 27 24 0 2 1 47 24 20 126 0 8 31 42 22 Variance 139 61 80 0 0 0 424 94 57 6,006 0 12 98 33 33 + 95% C.I. 37 20 23 0 0 2 66 25 19 247 0 9 32 15 15 Shallown566566566566566 Pool Abundance 17 15 5 0 4 0 2 35 19 3 3 7 22 36 15 Variance1191910 2 0 1 6730146464697 + 95% C.I. 3011303 0 32114106522217 Density #/mi 23 21 7 0 5 0 3 48 26 4 4 10 30 49 21 Variance 223 36 2 0 3 0 2 125 56 26 11 7 120 129 12 + 95% C.I. 4215405 0 42919148730299 Run n 5 12 12 5 12 12 5 12 12 5 12 12 5 12 12 Abundance 267 221 172 6 0 3 6 4 8 0 12 0 12 39 6 Variance 5,472 2,495 665 35 0 9 35 1 31 0 54 0 297 83 5 + 95% C.I. 205 110 57 16 0 6 16 2 12 0 16 0 48 20 5 Density #/mi 197 164 127 4 0 3 4 3 6 0 9 0 9 29 4 Variance 2,996 1,366 364 19 0 5 19 1 17 0 30 0 163 45 3 + 95% C.I. 152814212051229012035154 CrestaJuvenileRifflen 566 5 6 6 5 6 6566566 (5-10) Abundance 107 130 73 0 0 3 0 0 0 0 0 0 0 0 0 Variance 818 222 260 0 0 2 0 0 0 0 0 0 0 0 0 + 95% C.I. 79 38 41 0 0 4 0 0 0 0 0 0 0 0 0 Density #/mi 348 435 244 0 0 9 0 0 0 0 0 0 0 0 0 Variance 8,647 2,482 2,907 0 0 21 0 0 0 0 0 0 0 0 0 + 95% C.I. 258 128 139 0 0 12 0 0 0 0 0 0 0 0 0 CrestaSmallDeepn 466 4 6 6 4 6 6466466 Adult Pool Abundance 134 70 36 21 98 11 236 212 109 26 37 34 62 58 62 (11-15) Variance 1,506 95 114 41 1,223 22 5,838 463 431 56 134 207 563 27 345 + 95% C.I. 124 25 27 20 90 12 243 55 53 24 30 37 76 13 48 Density #/mi 82 43 22 13 60 7 145 130 67 16 23 21 38 36 38 Variance 568 36 43 15 461 8 2,203 175 163 21 51 78 212 10 130 + 95% C.I. 76 15 17 13 55 7 149 34 33 15 18 23 46 8 29 Shallown566566566566566 Pool Abundance 14 37 6 21 57 4 65 155 74 7 24 10 36 59 25 Variance 65 9 4 347 122 1 202 484 86 10 64 1 266 70 14 + 95% C.I. 22 8 5 52 28 3 39 57 24 9 21 3 45 22 10 Density #/mi 19 51 9 29 78 6 89 212 101 10 33 14 49 81 34 Variance 122 17 7 650 228 2 378 906 161 19 120 2 498 131 26 + 95% C.I. 31 11 7 71 39 4 54 77 33 12 28 4 62 29 13

88 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. (continued) Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 Run n 5 12 12 5 12 12 5 12 12 5 12 12 5 12 12 Abundance 192 174 124 19 68 22 25 63 31 12 25 6 31 47 21 Variance 3,197 1,707 831 237 1,619 151 559 218 71 140 46 11 1,266 66 28 + 95% C.I. 157916343892766331933157991812 Density #/mi 142 129 92 14 50 16 18 47 23 9 18 4 23 35 16 Variance 1,750 935 455 130 886 83 306 119 39 77 25 6 693 36 15 + 95% C.I. 11667473266204924142411573139 Rifflen 566 5 6 6 5 6 6566566 Abundance 13 15 18 0 12 25 0 2 0 3 2 0 0 4 0 Variance3129430 17500 1 0610030 + 95% C.I. 1514170 11180 3 0730040 Density #/mi 41 50 60 0 40 84 0 7 0 10 7 0 0 13 0 Variance 329 324 481 0 190 559 0 11 0 63 11 0 0 34 0 + 95% C.I. 50 46 56 0 35 61 0 9 0 22 9 0 0 15 0 CrestaLargeDeepn 466 4 6 6 4 6 6466466 Adult Pool Abundance 46 31 4 123 31 43 134 109 94 51 16 14 5 12 8 (16-20) Variance 193 14 5 2,293 87 141 516 226 488 156 37 21 10 41 9 + 95% C.I. 44 10 5 152 24 31 72 39 57 40 16 12 10 16 8 Density #/mi 28 19 3 76 19 26 82 67 58 31 10 9 3 7 5 Variance 73 5 2 865 33 53 195 85 184 59 14 8 4 15 3 + 95% C.I. 27 6 3 94 15 19 44 24 35 24 10 7 6 10 5 Shallown566566566566566 Pool Abundance 2 11 11 205 61 47 178 74 75 19 1 5 2 4 5 Variance 3 12 8 7,425 54 185 1,821 134 58 35 0 3 4 1 1 + 95% C.I. 5 9 7 239 19 35 118 30 20 16 1 4 5 2 3 Density #/mi 3 15 15 280 83 64 244 101 103 26 1 7 3 5 7 Variance 6 22 15 13,900 101 346 3,409 251 109 66 1 5 7 1 2 + 95% C.I. 7 12 10 327 26 48 162 41 27 22 2 6 7 3 4 Run n 5 12 12 5 12 12 5 12 12 5 12 12 5 12 12 Abundance 87 51 16 105 90 68 43 54 55 0 17 26 0 6 5 Variance 3,469 404 20 2,370 1,374 175 358 232 277 0 35 175 0 9 3 + 95% C.I. 164 44 10 135 82 29 53 34 37 0 13 29 0 6 4 Density #/mi 64 38 12 78 67 50 32 40 41 0 13 19 0 4 4 Variance 1,899 221 11 1,297 752 96 196 127 152 0 19 96 0 5 2 + 95% C.I. 121337100602239252701022053 Rifflen 566 5 6 6 5 6 6566566 Abundance 0 2 0 16 10 28 0 2 0 0 1 0 0 0 0 Variance010503 320 1 0000000 + 95% C.I. 030205 140 3 0020000 Density #/mi0705233940 7 0030000 Variance0110529383540 110050000 + 95% C.I. 0906416480 9 0060000 CrestaVeryDeepn 466 4 6 6 4 6 6466466 Large Pool Abundance 0 0 0 10 3 11 0 32 18 10 11 12 5 0 0 Adult Variance 0 0 0 48 5 10 0 163 11 7 13 34 12 0 0 (>20) + 95% C.I. 0002268033899151100 Density #/mi000 6 2 7 0 2011677300 Variance000182 4 0 6143513500 + 95% C.I. 000144 5 0 205569700

89 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. (continued) Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 Shallown566566566566566 Pool Abundance 0 0 0 5 2 9 5 4 13 7 2 6 0 1 0 Variance00026 6 4 4 62904000 + 95% C.I. 000140 6 6 5 61525020 Density #/mi000 7 3 127 5 181038010 Variance000490 117 7 115418010 + 95% C.I. 000190 9 8 7 92027020 Cresta Very Run n 5 12 12 5 12 12 5 12 12 5 12 12 5 12 12 Large Abundance 6 0 0 19 15 13 0 6 2 6 0 6 0 0 0 Adult Variance 35 0 0 418 47 51 0 3 3 35 0 13 0 0 0 (>20) + 95% C.I. 16 0 0 57 15 16 0 4 4 16 0 8 0 0 0 Density #/mi4001411100 4 2404000 Variance190022926280 2 21907000 + 95% C.I. 12 0 0 42 11 12 0 3 3 12 0 6 0 0 0 Rifflen 566 5 6 6 5 6 6566566 Abundance 0 0 0 0 0 4 0 0 0 0 2 0 0 0 0 Variance000004000020000 + 95% C.I. 000005000040000 Density #/mi000 0 0 140 0 0070000 Variance000 0 0 480 0 00220000 + 95% C.I. 000 0 0 180 0 00120000 RockFry (<5)Deepn566566566 566 (dive Pool Abundance 0 7 23 0 17 4,194 3,276 10,127 13,438 see HH fry data 8462 lane) Variance 0 16 131 0 226 2,889,557 1,381,749 18,149,399 11,877,962 27 165 0 + 95% C.I. 0 10 29 0 39 4,370 3,264 10,951 8,859 14 33 1 Density #/mi 0 5 16 0 12 2,936 2,293 7,089 9,406 6 32 2 Variance 0 8 64 0 111 1,415,829 677,031 8,892,869 5,819,981 13 81 0 + 95% C.I. 0 7 21 0 27 3,059 2,285 7,666 6,201 10 23 1 Shallown588588588 588 Pool Abundance 12 5 45 6 59 3,049 1,968 12,500 8,087 see HH fry data 6237 Variance 41 22 207 15 575 838,310 398,569 6,639,113 4,319,181 25 68 24 + 95% C.I. 18 11 34 11 57 2,165 1,753 6,093 4,914 14 19 12 Density #/mi 9 4 34 4 44 2,285 1,457 9,368 6,061 4 17 5 Variance 22 12 116 8 323 470,880 218,387 3,729,202 2,426,092 14 38 13 + 95% C.I. 13 8 25 8 42 1,623 1,297 4,566 3,683 10 15 9 Run n 6 16 16 6 16 16 6 16 16 6 16 16 Abundance 0 23 151 0 139 5,837 4,323 3,808 7,714 see HH fry data 02526 Variance 0 33 1,452 0 6,049 618,807 15,603,074 287,755 2,072,739 0 69 300 + 95% C.I. 0 12 81 0 166 1,677 10,154 1,143 3,069 0 18 37 Density #/mi 0 11 73 0 67 2,827 2,094 1,844 3,736 0 12 13 Variance 0 8 341 0 1,419 145,148 3,659,870 67,496 486,183 0 16 70 + 95% C.I. 0 6 39 0 80 812 4,918 554 1,486 0 9 18 Riffle n 6 10 10 6 10 10 6 10 10 6 10 10 Abundance 96 79 160 5 554 1,108 9 1,154 2,094 see HH fry data 0236 Variance 2,243 424 453 15 245,667 126,871 44 324,219 508,329 0 161 26 + 95% C.I. 122 47 48 10 1,121 806 17 1,288 1,613 0 29 12 Density #/mi 145 119 242 8 836 1,672 14 1,742 3,161 0 35 9 Variance 5,110 966 1,032 34 559,725 289,062 100 738,698 1,158,172 0 367 59 + 95% C.I. 184 70 73 15 1,692 1,216 26 1,944 2,434 0 43 17

90 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. (continued) Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 RockFry (<5)Deepn566566566 566 (fry Pool Abundance 0 2 25 3 139 11,222 6,678 16,393 43,878 see HH fry data 37314 lane) Variance 0 6 176 5 12,312 5,761,073 6,091,903 18,179,112 67,029,793 5 1,020 207 + 95% C.I. 0 6 34 6 285 6,170 6,853 10,960 21,046 6 82 37 Density #/mi 0 1 17 2 97 7,855 4,675 11,475 30,714 2 51 10 Variance 0 3 86 2 6,033 2,822,819 2,984,919 8,907,427 32,843,354 2 500 101 + 95% C.I. 0 4 24 4 200 4,319 4,797 7,672 14,732 4 57 26 Shallown588588588 588 Pool Abundance 6 7 44 30 132 12,419 4,129 13,832 27,034 see HH fry data 03633 Variance 20 21 546 151 1,353 13,275,553 1,365,947 6,015,066 27,175,082 0 195 152 + 95% C.I. 12 11 55 34 87 8,616 3,245 5,799 12,327 0 33 29 Density #/mi 4 5 33 22 99 9,308 3,056 10,367 20,261 0 27 25 Variance 11 12 307 83 760 7,456,903 748,440 3,378,674 15,264,294 0 110 85 + 95% C.I. 9 8 41 25 65 6,457 2,402 4,346 9,238 0 25 22 Runn 616166 16166 1616 61616 Abundance 0 9 61 36 399 11,911 8,309 9,009 19,321 see HH fry data 02851 Variance 0 42 295 370 20,550 2,302,582 44,197,053 1,198,387 7,286,602 0 73 832 + 95% C.I. 0 14 37 49 306 3,234 17,089 2,333 5,754 0 18 61 Density #/mi 0 4 30 17 193 5,769 4,024 4,363 9,357 0 14 25 Variance 0 10 69 87 4,820 540,096 10,366,897 281,095 1,709,151 0 17 195 + 95% C.I. 0 7 18 24 148 1,566 8,277 1,130 2,787 0 9 30 Riffle n 6 10 10 6 10 10 6 10 10 6 10 10 Abundance 18 28 124 5 285 1,847 284 2,318 4,389 see HH fry data 04563 Variance 142 211 1,471 11 39,925 191,886 16,734 995,742 2,258,099 0 1,267 2,571 + 95% C.I. 31 33 87 8 452 991 333 2,257 3,399 0 81 115 Density #/mi 27 42 187 8 430 2,788 429 3,499 6,625 0 68 95 Variance 324 481 3,352 25 90,965 437,191 38,127 2,268,689 5,144,832 0 2,887 5,858 + 95% C.I. 46 50 131 13 682 1,496 502 3,407 5,131 0 122 173 RockJuvenileDeepn 566 5 6 6 5 6 6566566 (5-10) Pool Abundance 55 24 24 47 20 0 213 1,905 1,109 3 737 335 22 15 4 Variance 434 130 30 989 76 0 16,452 324,126 98,649 4 51,928 25,302 285 104 14 + 95% C.I. 58 29 14 87 22 0 356 1,463 807 6 586 409 47 26 10 Density #/mi 38 17 17 33 14 0 149 1,333 776 2 516 234 15 10 3 Variance 213 64 15 485 37 0 8,061 158,816 48,336 2 25,444 12,398 140 51 7 + 95% C.I. 40 21 10 61 16 0 249 1,024 565 4 410 286 33 18 7 Rock Juvenile Shallow n 5 8 8 5 8 8 5 8 8 5 8 8 5 8 8 (5-10) Pool Abundance 139 162 122 0 13 12 0 755 442 6 624 376 0 29 33 Variance 764 2,323 1,103 0 50 38 0 100,863 124,596 15 50,246 25,838 0 138 432 + 95% C.I. 77 114 79 0 17 15 0 751 835 11 530 380 0 28 49 Density #/mi 103 121 91 0 10 9 0 566 331 4 468 282 0 22 25 Variance 419 1,305 620 0 28 21 0 56,655 69,986 8 28,223 14,513 0 78 243 + 95% C.I. 57 85 59 0 13 11 0 563 626 8 397 285 0 21 37 Runn 616166 16166 16166161661616 Abundance 163 256 243 0 16 11 60 488 425 36 782 386 0 106 0 Variance 1,433 853 1,596 0 43 47 3,381 4,226 3,767 2,609 50,112 17,815 0 6,039 0 + 95% C.I. 97 62 85 0 14 15 149 139 131 131 477 284 0 166 0 Density #/mi 79 124 118 0 8 5 29 236 206 17 379 187 0 51 0 Variance 336 200 374 0 10 11 793 991 884 612 11,754 4,179 0 1,417 0 + 95% C.I. 47 30 41 0 7 7 72 67 63 64 231 138 0 80 0

91 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. (continued) Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 Riffle n 6 10 10 6 10 10 6 10 10 6 10 10 6 10 10 Abundance 298 125 122 0 23 9 0 23 1 0 144 4 0 0 0 Variance 8,994 347 134 0 115 22 0 209 1 0 2,742 3 0 0 0 + 95% C.I. 244 42 26 0 24 11 0 33 2 0 118 4 0 0 0 Density #/mi 450 189 184 0 35 14 0 35 2 0 217 6 0 0 0 Variance 20,492 791 305 0 262 50 0 476 2 0 6,247 7 0 0 0 + 95% C.I. 368 64 40 0 37 16 0 49 3 0 179 6 0 0 0 RockSmallDeepn 566 5 6 6 5 6 6566566 Adult Pool Abundance 152 61 40 387 201 22 268 393 331 75 72 95 8 7 0 (11-15) Variance 9,317 963 91 13,878 30,694 82 17,131 12,425 1,380 1,092 1,320 1,539 40 7 0 + 95% C.I. 268 80 25 327 450 23 363 287 95 92 93 101 18 7 0 Density #/mi 106 43 28 271 141 15 188 275 232 52 50 66 6 5 0 Variance 4,565 472 45 6,800 15,039 40 8,394 6,088 676 535 647 754 20 3 0 + 95% C.I. 18856172293151625420167646571125 0 Shallown588588588588588 Pool Abundance 453 190 146 30 105 133 308 148 221 48 27 56 6 11 46 Variance 5,022 2,403 1,671 91 1,345 1,449 11,120 941 5,045 505 152 416 12 33 591 + 95% C.I. 197 116 97 26 87 90 293 73 168 62 29 48 10 14 57 Density #/mi 335 142 109 22 79 100 228 111 166 36 20 42 4 8 34 Variance 2,752 1,350 939 50 755 814 6,093 529 2,834 277 85 234 7 19 332 + 95% C.I. 146 87 72 20 65 67 217 54 126 46 22 36 7 10 43 Runn 616166 16166 16166161661616 Abundance 211 289 126 0 155 104 121 127 131 18 79 33 0 15 5 Variance 5,664 1,622 201 0 1,108 435 4,182 648 456 290 1,554 130 0 171 19 + 95% C.I. 193 86 30 0 71 44 166 54 46 44 84 24 0 28 9 Density #/mi 102 140 61 0 75 50 59 62 63 9 38 16 0 7 2 Variance 1,329 380 47 0 260 102 981 152 107 68 365 30 0 40 4 + 95% C.I. 944215034228126222141120134 Riffle n 6 10 10 6 10 10 6 10 10 6 10 10 6 10 10 Abundance 46 81 22 18 76 64 0 7 3 5 26 6 0 0 0 Variance 500 253 98 184 750 278 0 9 4 16 93 26 0 0 0 + 95% C.I. 57 36 22 35 62 38 0 7 4 10 22 12 0 0 0 Density #/mi 69 122 33 27 115 97 0 11 5 8 39 9 0 0 0 Variance 1,139 576 223 419 1,709 633 0 21 9 36 212 59 0 0 0 + 95% C.I. 87 54 34 53 94 57 0 10 7 16 33 17 0 0 0 RockLargeDeepn 566 5 6 6 5 6 6566566 Adult Pool Abundance 39 31 11 94 236 118 110 254 314 25 22 9 0 3 0 (16-20) Variance 416 118 21 3,375 8,753 3,624 1,561 8,093 4,696 89 184 26 0 5 0 + 95% C.I. 57 28 12 161 240 155 110 231 176 26 35 13 0 6 0 Density #/mi 27 22 8 66 165 83 77 178 220 17 15 6 0 2 0 Variance 204 58 10 1,654 4,289 1,776 765 3,965 2,301 44 90 13 0 2 0 + 95% C.I. 40 20 8 113 168 108 77 162 123 18 24 9 0 4 0 Shallown588588588588588 Pool Abundance 169 108 42 24 244 641 24 202 210 12 25 28 0 0 7 Variance 466 1,005 506 127 13,014 87,686 141 2,962 1,328 62 116 90 0 0 22 + 95% C.I. 60 75 53 31 270 700 33 129 86 22 25 22 0 0 11 Density #/mi 125 81 31 18 183 480 18 151 157 9 19 21 0 0 5 Variance 255 565 284 70 7,310 49,253 77 1,664 746 34 65 51 0 0 12 + 95% C.I. 44 56 40 23 202 525 24 96 65 16 19 17 0 0 8

92 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. (continued) Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 Runn 616166 16166 16166161661616 Abundance 84 92 36 718 678 353 205 121 172 24 21 14 0 2 0 Variance 1,331 322 98 479,070 17,781 1,947 43,038 319 631 211 70 10 0 0 0 + 95% C.I. 94 38 21 1,779 284 94 533 38 54 37 18 7 0 1 0 Density #/mi 41 45 17 348 328 171 99 59 83 12 10 7 0 1 0 Variance 312 76 23 112,371 4,171 457 10,095 75 148 49 16 2 0 0 0 + 95% C.I. 45 19 10 862 138 46 258 18 26 18 9 3 0 0 0 Riffle n 6 10 10 6 10 10 6 10 10 6 10 10 6 10 10 Abundance 14 12 15 9 83 78 0 2 8 0 2 0 0 0 0 Variance 66 22 103 14 491 500 0 3 27 0 1 0 0 0 0 + 95% C.I. 21 11 23 10 50 51 0 4 12 0 2 0 0 0 0 Density #/mi 21 18 23 14 125 118 0 3 12 0 3 0 0 0 0 Variance 150 50 235 32 1,119 1,139 0 7 62 0 2 0 0 0 0 + 95% C.I. 32 16 35 15 76 76 0 6 18 0 3 0 0 0 0 RockVeryDeepn 566 5 6 6 5 6 6566566 Large Pool Abundance 3 0 0 0 16 12 14 30 50 11 11 18 0 0 3 Adult Variance 4 0 0 0 75 55 65 150 180 24 24 52 0 0 5 (>20) + 95% C.I. 60002219223134141319006 Density #/mi 2 0 0 0 11 8 10 21 35 8 8 13 0 0 2 Variance20003727327388121225002 + 95% C.I. 4000161316222410913004 Shallown588588588588588 Pool Abundance 0 0 0 6 60 129 6 61 54 6 16 10 0 0 0 Variance 0 0 0 25 460 4,950 15 243 233 12 43 30 0 0 0 + 95% C.I. 0 0 0 14 51 166 11 37 36 10 16 13 0 0 0 Density #/mi 0 0 0 4 45 97 4 46 40 4 12 7 0 0 0 Variance000142582,780813613172417000 + 95% C.I. 00010381258 282771210000 Runn 616166 16166 16166161661616 Abundance 24 2 0 0 60 87 48 8 21 6 12 10 0 0 0 Variance18100 06272172,3833 737204000 + 95% C.I. 35 1 0 0 53 31 125 4 6 16 9 4 0 0 0 Density #/mi1210 0 2942234 10365000 Variance4200 0147515591 2951000 + 95% C.I. 1700 0 2615612 3852000 Riffle n 6 10 10 6 10 10 6 10 10 6 10 10 6 10 10 Abundance 0 0 0 0 4 19 0 0 0 0 0 0 0 0 0 Variance000 0 5 730 0 0000000 + 95% C.I. 000 0 5 190 0 0000000 Density #/mi000 0 6 290 0 0000000 Variance000 0 111660 0 0000000 + 95% C.I. 000 0 8 290 0 0000000 Both Fry (<5) Deep n 9 12 12 9 12 12 9 12 12 9 12 12 (dive Pool Abundance 0 7 26 0 534 7,272 3,276 15,767 25,796 see HH fry data 18 235 28 lane) Variance 0 16 136 0 57,839 3,097,130 1,381,749 26,201,933 20,502,358 47 2,939 121 + 95% C.I. 0 9 26 0 536 3,921 2,780 11,405 10,089 16 121 25 Density #/mi 0 2 8 0 175 2,379 1,072 5,158 8,439 6 77 9 Variance 0 2 15 0 6,191 331,493 147,892 2,804,451 2,194,413 5 315 13 + 95% C.I. 0 3 8 0 175 1,283 909 3,731 3,301 5 40 8

93 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. (continued) Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 Shallow n 10 14 14 10 14 14 10 14 14 10 14 14 Pool Abundance 12 5 47 6 280 3,981 2,192 15,775 12,921 see HH fry data 88912 Variance 41 22 207 15 4,540 855,549 449,078 7,100,169 4,620,324 29 233 24 + 95% C.I. 15 10 31 9 147 2,015 1,545 5,806 4,683 12 33 11 Density #/mi 6 2 23 3 134 1,912 1,053 7,578 6,207 4 43 6 Variance 9 5 48 3 1,048 197,406 103,618 1,638,261 1,066,073 7 54 6 + 95% C.I. 7 5 15 4 71 968 742 2,789 2,250 6 16 5 Run n 11 28 28 11 28 28 11 28 28 11 28 28 Abundance 31 62 235 6 770 7,730 4,708 9,004 13,790 see HH fry data 12 263 38 Variance 201 126 2,834 46 38,424 867,118 15,731,241 1,870,320 8,416,035 30 3,766 350 + 95% C.I. 32 23 109 15 403 1,914 8,972 2,811 5,963 12 126 38 Density #/mi 9 18 69 2 225 2,263 1,378 2,636 4,037 4 77 11 Variance 17 11 243 4 3,292 74,297 1,347,889 160,253 721,105 3 323 30 + 95% C.I. 9 7 32 4 118 560 2,626 823 1,746 4 37 11 Rifflen111616111616111616 111616 Abundance 150 131 329 5 831 1,314 9 1,635 2,162 see HH fry data 0526 Variance 2,817 554 917 15 251,137 136,844 44 348,175 508,710 0 315 26 + 95% C.I. 120 50 65 9 1,075 793 15 1,266 1,530 0 38 11 Density #/mi 155 135 339 5 857 1,355 9 1,685 2,229 0 54 6 Variance 2,993 589 974 16 266,870 145,417 47 369,987 540,579 0 335 28 + 95% C.I. 124 52 67 9 1,108 818 15 1,305 1,577 0 39 11 Both Fry (<5) Deep n 9 12 12 9 12 12 9 12 12 9 12 12 (fry Pool Abundance 0 2 32 8 1,290 17,463 6,827 35,931 77,076 see HH fry data 18 610 137 lane) Variance 0 6 207 15 184,782 9,466,206 6,099,474 61,646,806 164166493 50 11,650 3,364 + 95% C.I. 0 5 32 9 958 6,855 5,840 17,494 28,549 17 240 129 Density #/mi 0 1 10 3 422 5,713 2,234 11,755 25,216 6 200 45 Variance 0 1 22 2 19,778 1,013,189 652,840 6,598,196 17,571,107 5 1,247 360 + 95% C.I. 0 2 10 3 313 2,243 1,911 5,723 9,340 5 79 42 Shallow n 10 14 14 10 14 14 10 14 14 10 14 14 Pool Abundance 6 7 44 30 647 16,165 5,148 21,517 53,017 see HH fry data 219643 Variance 20 21 546 151 18,105 14,319,792 1,603,904 7,249,503 63,892,781 3 2,151 173 + 95% C.I. 10 10 51 28 293 8,245 2,920 5,866 17,416 4 101 29 Density #/mi 3 3 21 14 311 7,765 2,473 10,336 25,467 1 94 21 Variance 5 5 126 35 4,177 3,304,084 370,078 1,672,718 14,742,332 1 496 40 + 95% C.I. 5 5 24 14 141 3,960 1,403 2,818 8,366 2 49 14 Run n 11 28 28 11 28 28 11 28 28 11 28 28 Abundance 0 37 109 42 2,027 17,288 9,581 15,722 38,648 see HH fry data 12 363 65 Variance 0 243 799 405 385,196 3,569,382 45,473,005 3,944,243 32,664,649 93 6,684 910 + 95% C.I. 0 32 58 46 1,276 3,883 15,255 4,082 11,748 22 168 62 Density #/mi 0 11 32 12 593 5,060 2,805 4,602 11,313 4 106 19 Variance 0 21 68 35 33,004 305,833 3,896,231 337,952 2,798,782 8 573 78 + 95% C.I. 0 9 17 13 373 1,137 4,465 1,195 3,439 6 49 18 BothFry (<5)Rifflen111616111616111616 111616 (fry Abundance 31 48 150 8 501 1,964 303 2,853 4,626 see HH fry data 07563 lane) Variance 227 226 1,567 16 43,842 192,872 16,926 1,019,730 2,264,805 0 1,381 2,571 + 95% C.I. 34 32 85 9 449 942 294 2,166 3,228 0 80 109 Density #/mi 32 49 155 8 516 2,025 312 2,941 4,769 0 77 65 Variance 241 240 1,665 17 46,589 204,955 17,986 1,083,612 2,406,686 0 1,468 2,732 + 95% C.I. 35 33 88 9 463 971 303 2,233 3,327 0 82 112

94 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. (continued) Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 Both Juvenile Deep n 9 12 12 9 12 12 9 12 12 9 12 12 9 12 12 (5-10) Pool Abundance 101 68 63 47 24 2 290 1,944 1,142 208 737 348 73 83 40 Variance 802 293 243 989 76 1 17,577 324,376 98,799 15,924 51,928 25,334 546 191 101 + 95% C.I. 67 38 35 74 19 3 313 1,269 700 298 508 355 55 31 22 Density #/mi 33 22 21 15 8 1 95 636 374 68 241 114 24 27 13 Variance 86 31 26 106 8 0 1,881 34,719 10,575 1,704 5,558 2,712 58 20 11 + 95% C.I. 22 12 11 24 6 1 103 415 229 98 166 116 18 10 7 Shallow n 10 14 14 10 14 14 10 14 14 10 14 14 10 14 14 Pool Abundance 156 177 127 0 17 12 2 790 461 9 627 383 22 65 48 Variance 883 2,342 1,104 0 52 38 1 100,930 124,626 29 50,252 25,842 64 207 439 + 95% C.I. 69 105 72 0 16 13 2 692 769 12 488 350 18 31 46 Density #/mi 75 85 61 0 8 6 1 379 221 4 301 184 11 31 23 Variance 204 540 255 0 12 9 0 23,288 28,756 7 11,595 5,963 15 48 101 + 95% C.I. 33 51 35 0 8 6 1 332 369 6 235 168 9 15 22 Run n 11 28 28 11 28 28 11 28 28 11 28 28 11 28 28 Abundance 430 477 415 6 16 14 66 492 433 36 794 386 12 145 6 Variance 6,905 3,348 2,261 35 43 56 3,416 4,227 3,798 2,609 50,166 17,815 297 6,122 5 + 95% C.I. 188 119 98 13 13 15 132 134 127 116 460 274 39 161 5 Density #/mi 126 140 121 2 5 4 19 144 127 11 232 113 4 42 2 Variance 592 287 194 3 4 5 293 362 325 224 4,298 1,526 25 525 0 + 95% C.I. 55 35 29 4 4 4 39 39 37 34 135 80 11 47 1 Rifflen 111616111616111616111616111616 Abundance 405 255 195 0 23 12 0 23 1 0 144 4 0 0 0 Variance 9,812 569 394 0 115 24 0 209 1 0 2,742 3 0 0 0 + 95% C.I. 224 51 43 0 23 10 0 31 2 0 112 4 0 0 0 Density #/mi 418 263 201 0 24 12 0 24 1 0 148 4 0 0 0 Variance 10,427 605 419 0 122 25 0 222 1 0 2,914 3 0 0 0 + 95% C.I. 231 53 44 0 24 11 0 32 2 0 116 4 0 0 0 Both Small Deep n 9 12 12 9 12 12 9 12 12 9 12 12 9 12 12 Adult Pool Abundance 286 131 76 408 299 33 504 605 440 101 109 129 70 65 62 (11-15) Variance 10,823 1,058 205 13,919 31,917 104 22,969 12,888 1,811 1,148 1,454 1,746 603 34 345 + 95% C.I. 24672322793982335825395808593581341 Density #/mi 93 43 25 133 98 11 165 198 144 33 36 42 23 21 20 Variance 1,158 113 22 1,490 3,416 11 2,458 1,379 194 123 156 187 65 4 37 + 95% C.I. 80 24 10 91 130 7 117 83 31 26 28 30 19 4 14 Shallow n 10 14 14 10 14 14 10 14 14 10 14 14 10 14 14 Pool Abundance 467 227 152 51 162 137 373 303 295 55 51 66 42 70 71 Variance 5,087 2,412 1,675 438 1,467 1,450 11,322 1,425 5,131 515 216 417 278 103 605 + 95% C.I. 164 107 89 48 83 83 245 82 156 52 32 44 38 22 54 Density #/mi 224 109 73 24 78 66 179 146 142 26 24 32 20 34 34 Variance 1,174 557 386 101 338 335 2,612 329 1,184 119 50 96 64 24 140 + 95% C.I. 79 51 43 23 40 40 118 40 75 25 15 21 18 11 26 Run n 11 28 28 11 28 28 11 28 28 11 28 28 11 28 28 Abundance 403 463 250 19 223 126 146 190 162 30 104 39 31 62 26 Variance 8,861 3,329 1,032 237 2,727 586 4,741 866 527 430 1,600 141 1,266 237 47 + 95% C.I. 213 119 66 35 107 50 156 60 47 47 82 24 80 32 14 Density #/mi 118 136 73 6 65 37 43 56 47 9 30 11 9 18 8 Variance 759 285 88 20 234 50 406 74 45 37 137 12 108 20 4 + 95% C.I. 62 35 19 10 31 15 46 18 14 14 24 7 24 9 4

95 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. (continued) Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 Rifflen 111616111616111616111616111616 Abundance 59 96 40 18 88 89 0 9 3 8 28 6 0 4 0 Variance 531 282 141 184 767 328 0 10 4 22 94 26 0 3 0 + 95% C.I. 52 36 25 31 59 39 0 7 4 11 21 11 0 4 0 Density #/mi 60 99 41 19 91 92 0 9 3 8 29 6 0 4 0 Variance 564 300 150 196 815 349 0 11 4 23 100 28 0 3 0 + 95% C.I. 54 37 26 32 61 40 0 7 4 11 21 11 0 4 0 Both Large Deep n 9 12 12 9 12 12 9 12 12 9 12 12 9 12 12 Adult Pool Abundance 85 62 15 217 267 161 244 363 408 76 38 23 5 15 8 (16-20) Variance 609 132 26 5,668 8,840 3,765 2,077 8,319 5,184 245 221 47 10 46 9 + 95% C.I. 58 26 11 178 209 137 108 203 160 37 33 15 7 15 7 Density #/mi 28 20 5 71 87 53 80 119 133 25 12 8 2 5 3 Variance 65 14 3 607 946 403 222 890 555 26 24 5 1 5 1 + 95% C.I. 19 8 4 58 69 45 35 66 52 12 11 5 2 5 2 Shallow n 10 14 14 10 14 14 10 14 14 10 14 14 10 14 14 Pool Abundance 171 119 53 229 305 688 202 276 285 31 26 33 2 4 12 Variance 469 1,017 514 7,552 13,068 87,871 1,962 3,096 1,386 97 116 93 4 1 23 + 95% C.I. 50 69 49 200 249 646 102 121 81 23 23 21 4 2 11 Density #/mi 82 57 25 110 147 330 97 133 137 15 12 16 1 2 6 Variance 108 235 119 1,743 3,015 20,275 453 714 320 22 27 21 1 0 5 + 95% C.I. 24 33 24 96 120 310 49 58 39 11 11 10 2 1 5 BothLargeRunn 112828112828112828112828112828 Adult Abundance 171 143 52 823 768 421 248 175 227 24 38 40 0 8 5 (16-20) Variance 4,800 726 118 481,440 19,155 2,122 43,396 551 908 211 105 185 0 9 3 + 95% C.I. 157 55 22 1,570 284 95 471 48 62 33 21 28 0 6 4 Density #/mi 50 42 15 241 225 123 73 51 66 7 11 12 0 2 1 Variance 411 62 10 41,251 1,641 182 3,718 47 78 18 9 16 0 1 0 + 95% C.I. 46 16 7 459 83 28 138 14 18 10 6 8 0 2 1 Rifflen 111616111616111616111616111616 Abundance 14 14 15 25 93 106 0 4 8 0 3 0 0 0 0 Variance 66 23 103 64 494 532 0 4 27 0 1 0 0 0 0 + 95% C.I. 18 10 22 18 48 49 0 4 11 0 3 0 0 0 0 Density #/mi 14 14 15 26 96 109 0 4 8 0 3 0 0 0 0 Variance 70 24 109 68 525 565 0 4 29 0 2 0 0 0 0 + 95% C.I. 19 11 22 19 49 51 0 4 11 0 3 0 0 0 0 Both Very Deep n 9 12 12 9 12 12 9 12 12 9 12 12 9 12 12 Large Pool Abundance 3 0 0 10 19 23 14 62 68 21 22 30 5 0 3 Adult Variance 4 0 0 48 80 65 65 313 191 31 37 86 12 0 5 (>20) + 95% C.I. 500162018193931131421805 Density #/mi10036 8 520227710201 Variance000 5 9 7 7 3420349101 + 95% C.I. 200 5 7 6 6 1310447302 Shallow n 10 14 14 10 14 14 10 14 14 10 14 14 10 14 14 Pool Abundance 0 0 0 11 62 138 11 65 67 13 18 16 0 1 0 Variance 0 0 0 51 460 4,956 19 247 239 41 43 34 0 0 0 + 95% C.I. 0 0 0 16 47 153 10 34 34 15 14 13 0 1 0 Density #/mi 0 0 0 5 30 66 5 31 32 6 9 8 0 0 0 Variance000121061,1444 57559108000 + 95% C.I. 000 8 22745 1616776010

96 Rock Creek-Cresta Dive Count 2006 Report TRPA, 7 February 2007 ______

Appendix D. (continued) Size Habitat RAINBOW TROUT SUCKERS HARDHEAD PIKEMINNOWS SMALLMOUTH BASS Reach Class Type Statistic 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 2004 2005 2006 Run n 11 28 28 11 28 28 11 28 28 11 28 28 11 28 28 Abundance 30 2 0 19 75 100 48 14 23 12 12 16 0 0 0 Variance216004186742682,3836 10722017000 + 95% C.I. 33 1 0 46 53 34 110 5 7 19 9 9 0 0 0 Density #/mi910 6 2229144 7445000 Variance 19 0 0 36 58 23 204 1 1 6 2 1 0 0 0 + 95% C.I. 1000141610321 2633000 Rifflen 111616111616111616111616111616 Abundance 0 0 0 0 4 23 0 0 0 0 2 0 0 0 0 Variance000 0 5 770 0 0020000 + 95% C.I. 000 0 5 190 0 0030000 Density #/mi000 0 4 240 0 0020000 Variance000 0 5 820 0 0020000 + 95% C.I. 000 0 5 190 0 0030000

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