Introduction
Summer flow augmentation is implemented annually from Dworshak Reservoir (Clearwater River) to increase water velocities and decrease water temperatures in the four Lower Snake reservoirs when juvenile fall Chinook salmon are rearing and migrating seaward. The period of summer flow augmentation also corresponds with adult fall Chinook salmon and steelhead movement into the Snake River.  Previous research has shown that while summer flow augmentation decreases water temperatures, little is presently known regarding three-dimensional velocity and temperature variations downstream of the Snake/Clearwater River confluence. The goals of this multi-year study are to both gather information on the Lower Snake reservoir environment and to relate this data specifically to migrating juvenile salmonids. This information will be of use to various river managers (e.g. fisheries, hydropower, etc.,) to help isolate and study locations of concern throughout the lower Snake River system. This information also helps meet two of the Action Items discussed in the 2000 FCRPS Biological Opinion: RPA 143 (monitor and model Snake River water temperatures under various alternative release strategies), and RPA 141 (correlating juvenile salmonid migrant response to water temperature).

During previous years of this multi-year project, PNNL collected bathymetric, meteorologic, hydrodynamic, and water quality data in the area upstream of Lower Granite Dam (LGR). These data were entered into a database and analyzed using various mathematical tools to better understand the complex three-dimensional hydrodynamics downstream of the Clearwater/Snake River confluence. This dataset has also been used to develop boundary condition input files and calibration datasets for a three-dimensional computational fluid dynamics (CFD) model of Lower Granite Reservoir (Cook et al., 2003, and Cook and Richmond, 2004). In addition to data collected directly by PNNL in LGR, the US Army Corps of Engineers (USACE) also collected data in the four Lower Snake reservoirs. These data were provided to PNNL and were used during Project Year 1 to construct boundary condition input files for two-dimensional CFD models of the reservoirs impounded by Ice Harbor, Lower Monumental, and Little Goose dams.
During the Project Year covered by this Statement of Work, the project will focus on numerical modeling of the reservoirs.  The 3-D CFD model will be combined with the Fish Individual Numerical Simulator (FINS) model (Scheibe and Richmond, 2002) to better understand fish movements in thermally stratified portions of the reservoir. At the confluence of the Snake and Clearwater Rivers, density driven flows are generated due to the large thermal difference between the two rivers, and the complex three-dimensional currents that develop may influence migrant fish behavior (Cook and Richmond, 2004). By coupling the FINS model with the 3-D CFD model, we hope to provide additional insights into the river's environment and its influence on migrating salmonids. PNNL staff will also coordinate with the RPA143 Modeling Group to focus efforts regarding thermal modeling of the entire Lower Snake River.

Technical Approach
This statement of work covers the third year of a multi-year project. The first Project Year focused heavily on in-situ mapping of thermal and hydrodynamic conditions in LGR. Although this dataset is adequate in quality and quantity for calibrating the 3-D CFD model, it spans a single migration season (2002). Additional field data were collected to validate the model during the 2003 migration season. Field data were also collected during the summer of 2004 to support RPA 143 modeling activities (not the 3-D CFD model), although only six sites were monitored.

In addition to data collection, PNNL applied 3-D hydrodynamic and water quality models to LGR. Halfway through Project Year 1, the RPA 143 Modeling Group identified the preferred model to simulate the Lower Snake River. In agreement with the RPA 143 model selection, this project modeled the three reservoirs downstream of LGR using the recommended 2-D laterally-averaged model CE-QUAL-W2. However, because of the large thermal gradients laterally across the river near the Snake and Clearwater River confluence, PNNL continued modeling LGR using a 3-D CFD model. This added simulated dimension (i.e. the lateral dimension) in the LGR model is required to simulate exposure histories and other parameters that may be important to migrating salmonids.

PNNL continued to calibrate and refine the 3-D CFD model of Lower Granite Reservoir during Project Year 2. One of the primary improvements was the use of Flow-3D, a non-hydrostatic Reynolds-averaged Navier-Stokes model, for the confluence region. By utilizing this CFD model, simulation results near and downstream of the confluence zone were improved.

Validation of the 3-D LGR model and 2-D models of the reservoirs downstream of LGR were curtailed during Project Year 2 to perform fieldwork during the summer of 2004. This fieldwork was considered critical to the RPA143 Modeling Group and was time-sensitive, whereas modeling could be postponed until Project Year 3 without loss. Modeling tasks deleted from Project Year 2 were included in Year 3 (FY2005).

References
Cook, CB and MC Richmond (2004). Monitoring and Simulating 3-D Density Currents at the Confluence of the Snake and Clearwater Rivers, in Critical Transitions in Water and Environmental Resources Management, edited by G. Sehike, D. Hayes and D. Stevens, American Society of Civil Engineering Press, 2004.

Cook CB, MC Richmond, CL Rakowski, SP Titzler, AM Coleman, and MD Bleich (2003). "Numerically Simulating the Hydrodynamic and Water Quality Environment for Migrating Salmon in the Lower Snake River", PNNL-14297, Pacific Northwest National Laboratory, Richland, WA.

Richmond MC, JA Serkowski, CB Cook, TJ Carlson, and JP Duncan 2004. "Characterizing the Fish-Passage Environment at The Dalles Dam Spillway", World Water and Environmental Resources Congress 2004, American Society of Civil Engineers, June.

Scheibe TD, and MC Richmond.  2002.  "Fish Individual-based Numerical Simulator (FINS): A particle-based model of juvenile salmonid movement and dissolved gas exposure history in the Columbia River Basin."  Ecological Modelling 147(3):233-252.

Project Management
The Project Manager (PM) and Point of Contact (POC) for all technical matters is Dr. Christopher B. Cook, Senior Research Engineer, Hydrology Group, Pacific Northwest National Laboratory, PO Box 999, MSIN K9-33, Richland, Washington, 99352. Telephone: 509-375-6878, Fax: 509-372-6089, Email: chris.cook@pnl.gov
The lead POC for BPA is Mr. John Piccininni, Fish & Wildlife Project Manager, Policy and Planning Group - KEWR, Bonneville Power Admin., P.O. Box 3621, Portland, OR 97208. Telephone: 503-230-7641, FAX: 505-230-4564, Email: jppiccininni@bpa.gov

Collaborative Arrangements and Coordination
In addition, we will also be coordinating with the following agencies/projects:
a) BPA project 1991-029-00
b) BPA project 1993-029-00
c) NMFS forum water quality team/RPA 143 sub-group