Post-control Site Restoration

The direct physical and chemical effects of post-control site restoration included as part of the proposed activities are essentially the reverse of the pre-control activities. Bare earth is protected by seeding, planting woody shrubs and trees, and mulching. This immediately dissipates erosive energy associated with precipitation and increases soil infiltration. It also accelerates vegetative succession necessary to restore the delivery of large wood to the riparian area and stream (in the case of control efforts in streams or downstream of control areas), root strength necessary for slope and bank stability, leaf and other particulate organic matter input, sediment filtering and nutrient absorption from runoff, and shade. Microclimate will become cooler and moister, and wind speed will decrease.


In addition to revegetation, site restoration may include restoring or repairs to streambanks. Streambank restoration activities require bioengineered solutions that include vegetation and large wood as the major structural elements to increase bank strength and resistance to erosion stabilization (Mitsch 1996, WDFW, WDOT, WDOE, and USACE 2003). The intent of these activities is to restore riparian function and allow habitat to develop, and allow the banks to respond more favorably to hydraulic disturbance than conventional hard alternatives.

Invasive and Non-native Plant Control—The proposed use of chemicals to control dreissenids is designed to minimize the risk of adverse effects on aquatic habitat and the associated native fish and wildlife species. Chemical (including fuel) transport, storage, and emergency spill plans will be implemented to reduce the risk of an accidental spill of fuel or chemicals. A catastrophic spill would have the potential for significant adverse effects to water quality. The risk of an accidental spill is considered to be minor if best management practices are strictly followed.


An environmental fate and transport analysis is provided for three of the most commonly used chemicals and biocides to control dreissenids – potash, copper sulfate, and Pseudomonas fluorescens—to evaluate the risk of effects to water quality from this program. The types of dreissenid control actions proposed offer the best and most effective solutions to eradicate dreissenids. Each type of treatment is likely to affect fish and aquatic organisms through a combination of pathways, including disturbance, chemical toxicity, dissolved oxygen and nutrients, water temperature, sediment, forage, and vegetation.


Herbicide applications

Surface water contamination with herbicides occurs when herbicides and biopesticides are applied intentionally or accidentally into ditches, irrigation channels or other bodies of water, or when soil-applied herbicides are carried away in runoff to surface waters. Direct application into water sources is generally used for control of aquatic species. Under the proposed action, herbicides and biocides would be applied directly to the surface of the water. Any juvenile fish in the margins of streams and water bodies are more likely to be exposed to herbicides as a result of overspray, inundation of treatment sites, percolation, surface runoff, or a combination of these factors.


Groundwater contamination is another important pathway. Most herbicide groundwater contamination is caused by “point sources,” such as spills or leaks at storage and handling facilities, improperly discarded containers, and rinses of equipment in loading and handling areas, often into adjacent drainage ditches. Point sources are discrete, identifiable locations that discharge relatively high local concentrations. Proposed conservation measures minimize these concerns by ensuing proper calibration, mixing, and cleaning of equipment. Non-point source groundwater contamination of herbicides is relatively uncommon, but can occur when a mobile herbicide is applied in areas with a shallow water table. Proposed conservation measures minimize this danger by restricting the formulas used, and the time, place and manner of their application to minimize offsite movement. In addition, a thorough analysis of the hydrological and geochemical setting of any project site is integral.


Downstream transport is another important pathway. ADD INFO HERE