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DRAFT

3-3618

CONSERVATION FISH FLOW RECOMMENDATIONS FOR SELECTED OKANAGAN LAKE TRIBUTARIES

TROUT CREEK INSTREAM FLOW ASSESSMENT

Introduction This report discusses the instream flows for fish and fish habitat in Trout Creek, and reviews issues related to water use and storage within the watershed. The estimates of instream flows were completed using standard-setting techniques used in British Columbia that combine fish use and periodicity with hydrological and hydraulic data. Instream flows for Trout Creek, primarily for areas downstream of the District of Summerland water intake, were developed using estimates of naturalized mean monthly flows. Unfortunately, there was insufficient site-specific hydraulic, hydrologic and habitat data to better estimate instream flow needs for Trout Creek.

Besides the lower creek, instream flows are critical throughout the watershed to support resident fish and the instream ecosystems that support fish: primary (algal growth) and secondary productivity (benthic invertebrates). The analysis of the instream flows with available flows identifies opportunities for monitoring and data collection that would provide critical information to better manage water in the system for the benefit of all users. This is a key result of the work completed to date.

Overview of Instream Flow Standards

The responses of biological and physical systems to stream flow are at the core of the current standards used to outline instream flow needs for BC streams. They are based on the principle that the abundance or biomass of fish and supporting ecosystem components is positively correlated to the amount and quality of aquatic habitat. While current standards used in BC are new and evolving, the principles they embrace are scientifically defensible and supported by data.

BC has enormous physical and biological diversity, and on a site-specific basis there is variability in the fish distribution, timing and use, and geomorphology and hydrology of individual stream and river systems. The standards employed are not set-in-stone; they provide guidance and direction. They clearly identify periods of issue and non issue with respect to water use - through consumptive use, storage and diversion - and the biological and physical needs of riverine systems.

As outlined earlier, instream flow needs represent both fish and ecosystem requirements, therefore are applied in systems that support fish, as well as non fish-bearing streams that have only fish habitat - flow, food (benthos) and nutrients.

While not attempting to quantify risk, the divergence of available stream flow from flows identified through these techniques could infer limiting habitat conditions and decreased potential fish production. It may also assist in determining where and when both biological and physical monitoring may be appropriate to better assess these potential issues, and the mitigation likely required to prevent impacts if stream flows are to be altered.

Applied Instream Flow Standards

Based on the level of hydrological information available, we have applied two currently available standard-setting methods referenced in the British Columbia Instream Flow Standards for Fish (2002).

The first method is Ptolemy's Method which uses seasonal instream flows as a percent of the mean annual discharge (MAD) based on fish species and lifestage requirements. A derivative of the Tennant Method - one of the most widely used instream flow methods­this standard has been modified with instream flow studies and assessments conducted throughout BC involving the migration, spawning and rearing requirements of salmonids.

Table 1 outlines Ptolemy's Method standard-setting flows with respect to the biological and physical needs for stream systems adapted from Hatfield, Lewis and Ohlson (2002). Figures 1 and 2 represent some of the data used to support the standards identified in Table I, specifically with respect to spawning and rearing flows.

The second method used to generate instream flows for Trout Creek was another modification of the Tennant Method called the Tessman Method. This method is particularly useful where mean monthly flows have been estimated, and instream flows are set as either a percent of mean annual discharge (MAD) or mean monthly flows (MMF). Table 2 outlines the Tessman Method as it is applied to determining instream flows for Trout Creek.

Both these techniques are standard-setting, and do not utilize reach or stream specific habitat attributes, hydraulic geometry, watershed hydrology or other factors that completely describe the flow-habitat relationship Trout Creek. We have also examined the MWLAP habitat assessment data to comment on potential thresholds and impacts to habitat, but only where the data is strong enough to support those corroborations.

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Hydrology The generalized hydrology for Okanagan Lake tributary systems, including Trout Creek, was completed by Rood (200 I). Watershed and hydrological data specific to Trout Creek is summarized in Tables I, 2 and 7 in that document, and in Appendices A and B.

Annual Flows Estimates of total annual flow or mean annual runoff (MAR) supported by stream flow gauging and monitoring are not currently available for the Trout Creek watershed. Current gauging and measurements are limited to seasonal measurements at water storage facilities and continuous measurements at the intake weir, all conducted by the District of Summerland. Intermittent readings and gauges are located in various locations in the watershed, but systematic gauging has not been implemented that would provide allow for determination of total runoff.

Measurements of total annual runoff or flows have been generated by Letvak (1984, 1989) Obedkoff (1998) and Rood (2001) for Trout Watershed. Over 75% of the total flow in all Okanagan Lake tributary systems occurs from April to August in response to melt and runoff from snow pack (Rood, 1989; Obedkoff, 1998). The total annual flow reviewed and accepted by Rood (2001) was 110 mm resulting in a mean annual discharge (MAD) of2.65 m3/s .

Snow data has been collected in the watershed at three stations - two in upper Trout Creek and one in the Isintok Lake. Active snow pillow data from Brenda Mines (2F 18P) indicates that snow pack begins decreasing April 1 st and melt is completed by the middle of May in a normal year. It is not known if existing snow pillow data has been compared to annual estimates to total runoff for periods of record where there is overlap between gauged readings and consumption data.

Instream flow calculation and water management decision making processes have begun to incorporate adjustment instream flows based on total annual runoff. It provides a rational adjustment of instream flows to reflect the year-to-year hydrological variability to which fish have adapted to through time. A recent study completed for a water supply reservoir on Vancouver Island used total annual runoff to assist in determining resulting in stream flows (nhc, 2002).

Naturalized Mean Monthly Flows

Determining naturalized flow, or the flow that would occur without any reservoirs, diversions or water consumption, is a prerequisite for evaluating instream flows using the techniques outlined. We refer to these adjusted flows as naturalized flows to differentiate them from natural flows in an unregulated system. Trout Creek mean monthly flows were estimated by adding mean daily flow observations, adjusted to estimates of the total annual flow and adjusted to normalized values. The MWLAP data was used to generate estimates of monthly flow that was compared to estimates of mean monthly flow from Rood (2001) in Figure 3 and Table 3. The naturalized mean monthly flows were also

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plotted against flows from Rood (2001) to illustrate the effects of normalizing to non­regulated basins (Figure 4). Normalization of flows resulted in increased flows, noticeably in April when flow would be routed to fill storage and in August and September when demand for irrigation is high (Table 4).

Trout Creek Instream Flows

Historicallnstream Flows Historic instream flows have been referenced in several documents (Sheppard and Ptolemy, 1999; Wysocki, 2000). Pinsett (1974) recommended minimal optimum flows of 0.58 m3/s from April to September, 0.29 m3/s from October to March, and an absolute minimum flow of 0.29 m 3/s. Wightman and Taylor (1978) suggested minimum spawning flows of 0.42 m3/s, incubation and rearing flows of 0.28 m 3/s and absolute minimum flows of 0.14 m3/s.

Many references enclosed in the Canada - British Columbia Okanagan Basin Agreement (OBA, 1973) in both Tech. Supplement I and IX. In summary, the OBA suggests a total of 7,800 acre-feet (9.62 Mm3 or 2,037 Mgal) of instream flows for Trout Creek for the purposes of trout and kokanee production.

The other reference to instream flows is contained in the District of Summerland Water System master plan (Associated Engineering, 1997). These flows are listed as being referenced to MWLAP but no references area enclosed in the report and no records of these flows are available (S. Matthews, 2002, pers. comm.).

Application of Instream Flows The proposed instream flows for Trout Creek begin with application of the conservation flows proposed by Rood (2001), and are presented in Table 5 along with OBA and CDS flows. Naturalized mean monthly flow exceeds required instream flows for fish in all but three months.

Next, direct application of Ptolemy's and Tessman Model criteria were applied to the naturalized flows for Trout Creek. The results are presented in Table 6 and in Figure 5. Ptolemy's model was applied strictly according to fish use periodicity as describe in Figure 6 with data extracted from Rood (2001) and OBA (1974).

Direct application of the Ptolemy model results in specified flows for kokanee spawning in excess of naturalized mean flows in September and October. Although there is insufficient habitat data to refute or confirm the findings, it does highlight a potential concern for habitat (spawning area) or flows (migration) to be a limiting factor for kokanee.

Both Tessman and the conservation flow model (Rood, 2001) provide similar results with nearly identical mean annual flows. In either case, naturalized flows satisfy either flow standard in most months or have very small differences. Naturalized inflows appear

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to provide more than adequate geomorphic and off-channel connectivity, and the relatively small amount of storage relative to the total annual flow confirms that typically these flow standards will be achieved in most years.

Typical hydraulic geometry highlights reveals that width, depth and velocity are relatively insensitive to changes in flow between 50 to 200 percent MAD (Figure 7). However, this assumes a channel morphology that is unaltered or in regime. Lower Trout Creek has been channelized and has bedrock control in it's lower reaches, therefore it may behave differently than illustrated in this generalized illustration.

Review of the habitat analyses performed for Trout Creek reveal that for the entire canyon reach, widths and depths are maintained at flows greater than approximately 0.4 m 3/s. These channel characteristics are relatively insensitive to increases in flow from this figure and relatively sensitive to reductions in flow below this number.

The behaviour and response of wetted width, riffle area and depth of flow suggest that flows in the range near or greater than approximately 0.4 m3/s maintain these habitat measures. These flows are approximately equal to those specified by Ptolemy Model, Tessman and the nhc conservation flows (Rood, 2001), and would support notional base flow retention or minimum flows of approximately 0.4 m3/s.

Collection of additional transect data in reaches these utilized by fish and in areas with different channel morphology would provide better information. As discussed in the Trout Creek Habitat Summary, additional sampling would improve correlation between parameters.

Summary We suggest the instream flows for lower Trout Creek be notionally based on the MWLAP data collected and analyzed, and the analysis of mean monthly flows using two applicable standard-setting techniques. These flows are basically provided by use of an average of the three flows without incorporating flows required for kokanee spawning by application of Ptolemy's Model. These instream flows are provided in Figure 7 and Table 8, and should be adjusted to reflect flows at the point-of-diversion.

The review of historical instream flows quoted for Trout Creek reveal that all are fairly similar, and set flows for rearing and spawning conditions. The review of limited habitat data for the lower portions of trout creek and literature support the notion that naturalized instream flows during the non-freshet period were likely optimum with respect to the utilization and production of fish.

A review of limited habitat data for the lower creek suggests that minimum flows less than 0.4 m3/s present increased risk to overall aquatic habitat, which includes ecosystem components that support fish and fish habitat. This analysis does not include the effects of temperature due to low flows and extreme climatic conditions.

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During this review, most physical data was collected and reviewed, and a number of reports were reviewed. A priority should be placed on the re-establishment of a long term gauging station for flows in lower Trout Creek. This station should be done concurrently with efforts by CDS to collect gauging data on their storage structures within the watershed - most importantly the intake weir and Thirsk Dam.

The habitat data collected by MWLAP on the lower reaches of Trout Creek is weak, and does not provide strong correlations to macro habitat types or basic hydraulic parameters that are commonly used as measures of fish habitat. We suggest that a fish habitat assessment be developed specifically to address flow related impacts in Trout Creek, as well as identify potential mitigations to address limiting biological factors that might occur with reduced flows.

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Figure 1

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Scatterplot of Salmonid Rearing Flows in Be Streams (Ptolemy, 2000)

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Naturalized Mean Annual Discharge (m3/s)

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Figure 2

Scatterplot of Salmond Migration and Spawning Flows for Be Streams (Ptolemy, 2000)

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Naturalized Mean Annual Discharge (m3/s)

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Figure 3 Calculate Mean Monthly Flows for Trout Creek

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Figure 5 Naturalized versus Instream Flows

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13 Tessman Model

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Figure 6 Fish Periodicity Chart for Trout Creek (Rood, 2001)

Rainbow Start End Peak Wt Bin Adult Migration AprOl May 15 Apr 30 1 3

Spawn May_15 Jun 21 Jun 07 1 31 Incubate May 15 Jul 15 1 11

Fry Rearing Jul15 Od21 1 1 I

Parr Rearing Jan 01 Dec 31 1 1

Kokanee Adult Migration Sep 01 Oct 07 Sep 21 1 3

Spawn Sep 15 Od31 Od01 1 3J Incubate Sep 15 Mar 21 1 11

Fry Rearing Mar 15 May21 .' 1 1 Parr Rearing

JAN FEB MAR

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 'C

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Figure 7 Typical Stream Hydraulic Geometry

Generalized Response of Hydraulic Geometery to Flow (Tennant Stream Data)

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Figure 8 Proposed Trout Creek Instream Flows

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13 · -­Naturalized Flows

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Table 1 Ptolemy's Method for Instream Flows

Percent Mean Annual Biological or Physcial Duration

Requirement Discharge

> 55% monthsAdult Rearing 20% monthsJuvenile Rearing

I20% monthsOver-wintering 20% monthsIncubation

50% - 100% daysSteelhead Passage 1.56 MAD 0.63 days - weeks Spawning/Migration

50% weeksSmolt Emmigration 10% daysShort-term Maintenance

>400% days - weeks Channel Geomorphology weeks100%Off-channel Connectivity

-

Table 2 Tessman's Method for Instream Flows

Condition MMF < 40% MAD

MMF ;:: 40% MAD and 40% MMF < 40% MAD

'------40% M M F ;:: 40% MAD

Flow J MMF

40% MAD

40% MMF I

Table 3 WSC, MWLAP and Rood (2001) Flow Data

Month WSC Data

Estimated MMF (MWALP Data) 1999 2000 2001 Avg

Rood MMF

January February March April May June July August September October November December

0.29 0.31 0.44 0.89 9.74 8.75 1.90 0.40 0.35 0.67 0.48 0.34

- - - -- - - -- - - -- - - -- - - -- - - -

1.63 0.86 0.99 1.46 1.85 0.26 0.26 0.84 0.13 0.47 0.17 0.32

- - - -- - - -- - - -

0.37 0.40 0.57 1.15

12.59 11.31 2.45 0.51 0.45 0.87 0.62 0.43

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Table 4 Estimates of Mean Monthly Flow

Month Rood 2001 nhc 2002 Flow Dift. I

m 3/s m 3/s % January 0.37 0.44 18% February 0.40 0.44 9% March 0.57 0.76 33% April 1.15 3.59 212% May 12.59 12.46 -1% June 11.31 8.05 -29% July 2.45 2.46 0% August 0.51 0.92 79% September 0.45 0.75 65% October 0.87 0.67 -23% November 0.62 0.65 5% December 0.43 0.48 I10%

Average 2.64 2.64 -

Table 5 Referenced Instream Fish Flows

OSA Rood 2001CDS reccomended flows conservation flows minimum flows Month

Ac-ft % MAD m3/s m3/s m3/s

January 0.28600 0.28 20% 0.53 February 600 0.30 0.28 20% 0.53 March 600 0.28 0.28 20% 0.53 April 600 0.29 100%0.28 2.65 May 600 0.28 0.28 200% 5.30 June 600 0.29 0.075 100% 2.65 July 600 0.28 0.075 40% 1.06 August 600 0.28 0.075 30% 0.80 September 0.24500 25% 0.660.42 October 900 0.41 0.42 20% 0.53 November 600 0.29 0.28 20% 0.53 December 600 20%0.28 0.28 0.53 _Average _ 0.29 0.25 1.36

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•

Table 6 Instream Mean Monthly Flows for Trout Creek

Month MMF Ptolemy's Method

Tessman's Flows factor = 40%

m3/s LF % MAD m3/s % MAD m3/s January 0.44 OWII 20% 0.53 17% 0.44 February 0.44 OWII 20% 0.53 17% 0.44 March 0.76 OWII 20% 0.53 29% 0.76 April 3.59 S/M - 2.87 54% 1.44 May 12.46 S/M - 2.87 189% 4.98 June 8.05 S/M - 2.87 122% 3.22 July 2.46 AR 55% 1.45 40% 1.06 August 0.92 FR 20% 0.53 35% 0.92 September 0.75 S/M - 2.87 28% 0.75 October 0.67 S/M - 2.87 25% 0.67 November 0.66 IIFR 20% 0.53 25% 0.66 December 0.48 IIFR 20% 0.53 18% 0.48

'---- AveraQe 2.64 1.58 0.50 1.32

Table 7 Proposed Trout Creek Instream Flows

Month Instream Flow

m3/s

January 0.50 February 0.50 March 0.60 April 2.32 May 4.38 June 2.91 July 1.19 August 0.75 September 0.71 October 0.60 November 0.57 December 0.51

Average 1.30

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