Annual Report of the Chief of Engineers
on Civil Works Activities
Fiscal Year 1979
Department of the Army Corps of Engineers
Extract Report of Walla Walla District

Research and Development

A cooperative research program between the Walla Walla District and the Waterways Experiment Station is being conducted as part of a nationwide survey to investigate the effects of fluctuating water levels upon riparian shorelines and vegetation. The construction and development of an experimental pond and several shoreline plots are now completed. The experimental pond approximates the proposed worse-case conditions of peaking on McNary Reservoir through the use of pumps, automatic timers, and water-control gates.

The first year of field monitoring for all plots, experiment pond, and shoreline suggest that at least seven species of plants may survive well under peaking conditions: Russian olive, mulberry, elderberry, wild rose, willow, tufted hairgrass, and slough hedge. In general, shoreline plantings protected against sand deposition and erosion by snow fencing were found to increase algae production at the expense of some vascular plants. The higher plant life, particularly the woody species, appeared to be smothered by algae mats resulting from an inadequate flushing of the site. Other information indicates that the high alkalinity of the area binds some of the nutrients to soil particles leading to nutrient deficiencies for some plant species.