Design of Optimum Selective Withdrawal Operation for Temperature Management at Round Butte Dam, Lake Billy Chinook, Oregon Presentation to WEFTEC 2000 by Curtis DeGasperi - Foster Wheeler Tarang Khangaonkar – Foster Wheeler Steven Breithaupt – Foster Wheeler Kevin Marshall – Portland General Electric (PGE) October 18, 2000

Study Area – Deschutes Basin

Study Area – Lake Billy Chinook Deschutes River Basin Lake Billy Chinook Columbia River Portland, Oregon

Study Area

Study Area – Problem Definition Cool river runoff Warm river runoff

Problem Definition Pelton Round Butte Project – Existing Condition –Inflow from three different tributaries –Release of colder bottom 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

Problem Definition

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

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

Development of BETTER Water Quality Model

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 ( ) and (January-July 1999)

BETTER Model Segmentation

BETTER Model Geometry Deschutes branch geometry

BETTER Model 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

Water Quality Inputs Temperature 1995

Temperature Calibration Forebay Temperature Profiles

Temperature Verification – Forebay Temperature Profiles

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

Surface/Bottom Water Blending Blend 13: regression to Rereg temperature Percentage of Surface Water Withdrawn

Blend13 vs. Existing Condition - LBC 1995 temperature Existing Blend 13 Crooked Branch Metolius Branch Deschutes Branch Existing

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