Annual Report of the Chief of Engineers
on Civil Works Activities
Fiscal Year 1980
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. An experimental pond, which approximates the proposed worst-case conditions of peaking on McNary Reservoir through the use of pumps, automatic timers, and water control gates, and two shoreline plots in the reservoir itself are the test sites used for the plantings.
The first year of field monitoring (FY 1979) suggested that at least seven species of plants may survive well under peaking conditions: Russian olive, mulberry, elderberry, wild rose, willow, turted 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.
The second year of field monitoring (FY 1980) suggests that four herbaceous and woody species may be capable of surviving 18-hour periods of flooding. In addition, 15 species may be capable of surviving 10 hours of flooding, 20 species capable of surviving 6 hours of flooding, and 22 species capable of surviving at water's edge.
A second research program being conducted by agreement with the Waterways Experiment Station involves the administration of McNary Lock and Dam, Lake Wallula, as a Recreation Research and Demonstration Unit. This agreement includes two research work units which are design, carrying capacity, and user behavior and methodology to determine concessionaire opportunity.