Curtis DeGasperi - Foster Wheeler Tarang Khangaonkar – Foster Wheeler A Water Quality Model of Lake Billy Chinook: Application to Issues Associated with Anadromous Fish Passage and Bull Trout Presentation to WALPA by Curtis DeGasperi - Foster Wheeler Tarang Khangaonkar – Foster Wheeler Kevin Marshall - PGE April 13, 2000 My presentation covers a portion of an ongoing hydrodynamic and water quality modeling effort conducted for Portland General Electric (PGE) as part of their adaptive management plan to restore anadromous fish passage above Round Butte Dam on the Deschutes River in eastern Oregon. PGE is also in the process of renewing their FERC license and obtaining a 401 Water Quality Certification from the state of Oregon. PGE’s primary goal is the restoration of anadromous fish passage. Fish passage attempts were made when the dam was first constructed in the mid 1960s…however, these attempts were unsuccessful and fish passage efforts were discontinued. A secondary goal is to attempt modifications in existing project operations to meet water quality goals within the lake and downstream.

Lake Billy Chinook (LBC) - Study Area - Columbia River Portland, Oregon Deschutes River Basin This figure shows the study area, the Deschutes River basin in eastern Oregon drains north to the Columbia River. The Willamette basin and Portland are just to west. The Pelton Round Butte Project and Lake Billy Chinook is located about mid-point in the basin at an elevation of 1950 feet (600 m) Lake Billy Chinook

Lake Billy Chinook (LBC) - Study Area - Cool river runoff This figure shows the study area, the inflow tributaries, the Round Butte Dam and Lake Billy Chinook formed by the dam. The crooked and Deschutes river temperatures are always 5 deg.C warmer than Metolius River. In the summer, the lake is warmer than Metolius but is cooler than Crooked and Dechutes, and there is a strong pycnocline at approximately 10-20 meter depth. The Metolius River enters the Lake and dives under the pycnocline. The Dechutes and Crooked Rivers ride on top of the hypolimnion towards the confluence. The discharge however occurs from the bottom. Therefore the warm Crooked River waters and the juveniles continue to travel upstream into Metolius instead of trying to find the outlet. Warm river runoff

Problem Definition Pelton Round Butte Project – Existing Condition Inflow from three different tributaries Release of colder water at Round Butte Seasonal stratification in Lake Billy Chinook (LBC) Complex flow patterns in the reservoir Result Ineffective fish passage at Round Butte Dam Modification of downstream temperature regime Pelton Round Butte project is located on the Dechutes River. It consists of three dams the Round Butte, the Pelton, and the Rereg Dam. Round Butte Dam is located at the confluence of three tributaries that are distinct in their flow and temperature characteristics. The discharge at Round Butte occurs in a peaking mode and occurs at the bottom. Release of cold water and surface heating in the summer results in a pronounced stratification. The net result is a complex circulation pattern which results in ineffective passage of fish.

Objective and Modeling Approach Primary Objective: Re-establish downstream fish passage at Round Butte Dam Provide required downstream attraction flow Make effective modification of reservoir flow patterns Secondary Objective – Address project-related in-lake and downstream water quality issues Modeling Approach - Develop the ability to simulate hydrodynamic behavior and water quality response of Lake Billy Chinook The overall objective of this project is to design structural and operational changes at the Round Butte dam that would allow for effective fish collection. Ideally, the structural and operational changes would effectively alterr the flow patterns in the reservoir, provide required attraction flow The specific objective of this modeling study was to develop the ability to simulate the hydro thermal response of Lake Billy Chinook. The models would allow testing of proposed alternatives to evaluate if the Lake is going to respond in a favorable manner and in a significant manner to make the expenditure worthwhile.

Development of BETTER Water Quality Model Background Water quality limited [303(d)] listing for Lake Billy Chinook for chlorophyll a and pH Lake productivity establishes available food sources and also affects dissolved oxygen (DO) and pH levels Objective Develop a predictive water quality (eutrophication) model of Lake Billy Chinook The need for a water quality model of Lake Billy Chinook was felt because o f two reasons. One was that Lake Billy Chinook has been listed on the Sate of Oregon’s water quality limited list. In order to continue operations PGE needs a Section 401 water quality certificate. To obtain this certificate, PGE needed to demonstrate to ODEQ that it had the ability to achieve compliance in the future through modification of their operations. This could be accomplished with the help of a Water quality model. Secondly, the proposed operational changes would impact DO and phytoplankton levels. These have implications with respect to fisheries issues.

Development of BETTER Water Quality Model

Development of BETTER Water Quality Model Recommend preliminary calibration to existing 1995 data Calibrate model to match observed in-lake temperature, TSS, DO, pH, alkalinity, algal biomass, and nutrients Apply the calibrated model to proposed Blend 13 operational modification

Field Data Station Locations (1994-1997) and (January-July 1999) In 1999 PGE maintained continuous temperature monitoring stations near the tributary inflow locations and the forebay. They also maintained monthly temperature profiling locations, one in each arm and the forebay. In addition PGE collected bi-weekly profiles at 4 more locations. This was suplemented by the ENSR synoptic monitoring stations at 4 locations. Together this provided a comprehensive coverage of the entire study area. PGE collected wind data at three stations (forebay, Metolius, and Dechutes) ENSR conducted continuous current profile monitoring from April through July at four locations. ENSR also monitored temperature profiles at the same locations.

BETTER Model Segmentation

BETTER Model Geometry Deschutes branch geometry

BETTER Model Inputs Hydrology – Tributary flow and temperature, and powerhouse withdrawal Climatology – Air and dew point temperature, wind speed, solar radiation Water Quality – DO, pH, alkalinity, nutrients, organic matter, algae

Tributary Inflows and Rainfall 1995

Meteorological Inputs - 1995

Water Quality Inputs Temperature 1995

Water Quality Inputs Nutrients and Algal Biomass 1995

In-Lake Water Quality Algal Biomass and Succession 1995

BETTER Model Calibration Data Temperature Dissolved Oxygen (DO) pH Algal Biomass Turbidity Transparency Alkalinity Nutrients

Temperature Calibration Forebay Temperature Profiles - 1995

DO Calibration July 1995

pH Calibration July 1995

Algae and Nutrients Calibration Ammonium-N Nitrate-N Ortho-P Chlorophyll a

Temperature Verification – Forebay Temperature Profiles - 1999

Model Alternative Studies Detail Specifications of Alternatives 1-4

Development of Selective Withdrawal Alternative Design Criteria - Compliance with temperature standards Release of cold surface waters in winter and spring Deeper colder water stored for release in summer Release of surface water with deeper colder water as needed Hydrodynamic model results indicated that surface withdrawal provides currents beneficial to fish collection

Temperature Correlation RBD and Rereg

Surface/Bottom Water Blending Blend 2: regression to Rereg temperature Percentage of Surface Water Withdrawn

Surface/Bottom Water Blending Blend 4: regression to Rereg temperature Percentage of Surface Water Withdrawn

Percentage of Surface Water Withdrawn Surface/Bottom Water Blending Blend 13: regression to Rereg temperature Percentage of Surface Water Withdrawn

Blend13 vs. Existing Condition - LBC 1995 temperature Deschutes Branch Existing Metolius Branch Crooked Branch

Blend 13 vs. Existing Condition LBC Dissolved Oxygen Existing Condition – Forebay Time Series Blend 13 – Forebay Time Series

Blend 13 vs. Existing Condition LBC pH Existing Condition – Forebay Time Series Blend 13 – Forebay Time Series

Summary and Conclusions Temperature calibration/verification complete Preliminary water quality calibration complete Model Application to Blend 13 Selective Withdrawal run Increase in in-lake and discharged DO Improves in-lake and downstream temperatures Small increase in pH Proposed model improvements Sampling to define tributary BOD and detritus loads