Evaluation of the Effect of Water Management on
Fall Chinook Spawning and Rearing Habitat,
and on Stranding of Juvenile Fall Chinook in
the Hanford Reach of the Columbia River

The Problem

Hanford Reach of the Columbia River.

Hydroelectric operations at Priest Rapids Dam on the Columbia River can cause water elevations downstream in the Hanford Reach to fluctuate dramatically. This can alter habitat, cause stranding of juvenile fish, and influence spawning habitat for fall chinook salmon. The unimpounded Hanford Reach supports one of the healthiest populations of fall chinook salmon in the Columbia River basin. Currently, tools for evaluating water management strategies and hydroelectric operations exist for only one third of the Hanford Reach. Fishery managers need tools and information for managing the aquatic resources for the entire Hanford Reach.

Objectives

This study will obtain detailed bathymetric, water velocity, and habitat information for the remainder of the Reach to evaluate the effects of management scenarios and operations for the entire Hanford Reach.

Methodology

A lidar survey will be conducted to collect detailed bathymetry for 34 miles of the Hanford Reach. Lidar

Lidar survey system.

is a detection system like sonar, but uses a laser to determine distance. In this application, lidar produces highly accurate, georeferenced elevation data. This data will be manipulated in a GIS and combined with other datasets so it can be used to conduct two-dimensional velocity modeling. This effort will allow us to model different flows through the Hanford Reach that will then allow us to examine hydroelectric operations on juvenile fall chinook salmon rearing habitat and adult spawning habitat. This will involve using previously established rearing and spawning habitat models in a GIS-based analysis to estimate the area of habitat impacted by different operational scenarios.

Highlights and Key Findings

Bathymetric surveys will be conducted in the spring of 2003. Past work in the Hanford Reach on this project found that juvenile fall chinook salmon habitat decreased as flows increased and that more rearing habitat is available in low-flow years. In addition, decreases in flows due to power generation at Priest Rapids Dam and the head of the Hanford Reach causes stranding of juvenile fall chinook salmon. Our modeling efforts produced estimates of stranding and entrapment area produced over a range of flow decreases.

Where Are We Headed In 2003

The primary focus this year will be bathymetric data manipulation and analysis once the lidar survey is completed.

Project Contact

Kenneth Tiffan
U.S. Geological Survey
Western Fisheries Research Center
Columbia River Research Laboratory
5501-A Cook-Underwood Rd.
Cook, WA 98605-9717

Email: ken_tiffan@usgs.gov
Phone: 509-538-2299
Fax: 509-538-2843

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