Foster Creek drains the north side of the Waterville Plateau. The creek has three forks that join together a few miles south of Bridgeport before discharging to the Columbia River just below Chief Joseph Dam and just east of Bridgeport. State Highway 17 follows the East Fork up to the glacier scoured upper northern part of the plateau. As the creek descends down for the glacial scoured upper plateau it descends through an area of glacial lake sediments deposited in the valley from the ice dammed Columbia River Martin (2001). The fine silts are subject to rapid erosion and over a stretch of the valley has formed a badland area (mini-badland-southeast-of-bridgeport).
When the creek reaches the glacial lake sediments, the creek is subject to forming deeply incised arroyos. Blanton (2004) discusses the complexity of arroyo development and riparian management along the West Fork of Foster Creek.
One of the issues of arroyo development is the deeply incised stream lowers the water table along the creek except in the bottom of the arroyo. That reduces the width of the riparian zone and the beneficial habitat (note that the arroyo banks have beneficial habitats as well such as burrows for cliff swallows). The lower water table and narrowed stream channel also impacts down stream sections of the creek. More intense peak flows during storm events or snow melts can be one result or the reverse: a loss of storage in the areas of the lowered water table may mean lower flows in the dry periods.
An approach to back up the water is to copy something that has been missing in the watershed. Jay guided me to a project on Foster Creek that is being used throughout the west -- a beaver dam analog.