Incision Impacts on Salmon in the Columbia River Basin - Watershed Program - Environmental Conservation

Extensive incision throughout the Columbia Basin has disconnected many streams from their floodplains, converting productive riparian habitat into arid, sagebrush-dominated uplands.

Installation of monitoring wells allows us to measure long-term change in water levels in floodplain aquifers as incised streams begin to recover and aggrade. From left to right, NOAA Fisheries personnel Louis Tullos, Jason Hall & Michael Pollock.

Extensive incision throughout the Columbia Basin has disconnected many streams from their floodplains, converting productive riparian habitat into arid, sagebrush-dominated uplands.

Project Title

The effect of incision on stream ecosystems in the semi-arid regions of the Columbia River Basin

Description

Channel incision is a widespread phenomenon in the western United States. It has resulted in considerable loss of off-channel and wetland habitats for stream-dwelling fishes. However, causes of this incision are not well understood, and may include climate fluctuations, increased runoff due to grazing or cultivation or removal of beaver dams. How much stream habitat has been lost to various causes cannot be estimated therefore preventing estimates of how much habitat can be recovered through various restoration techniques.

This project examines patterns of habitat loss in several river basins, describes potential causes of incision and estimates how much habitat is likely to be recovered through a variety of restoration techniques. The project first focuses on the spatial pattern of channel incision on the landscape in order to identify some of the morphological controls that govern locations of channel incision. This project:

Maps the extent of channel incision problems in several river basins.
Seeks to understand the causes of incision through morphological assessments of incised channels and investigation of historical records.
Estimates recovery rates for different management scenarios.

This project will also investigate the magnitude of habitat losses using historical records and field studies.
The likely outcome of different restoration techniques within watersheds will be evaluated based on the types
of actions that might be taken, erosion rates and water storage capacity.

Investigators

Dr. Michael M. Pollock, Dr. Tim Beechie and Dr. Phil Roni

Collaborators

Dr. Chris Jordan (Conservation Biology Division)

Support

NOAA Fisheries

Project Status

Data collection and analyses ongoing. Preliminary data has been collected and is being analyzed.