Background
In the lower Yakima River, lack of scouring spring floods, low summer flows, and abundant nutrients have created conditions for an aquatic native plant, water stargrass, to become much more abundant. Dense mats of water stargrass slow down the water causing it to warm, trap fine sediment and grow over spawning gavels inhibiting their use by fall chinook, create habitat for invasive species, and cause dramatic swings in dissolved oxygen levels, all of which create poor to lethal conditions for our native salmonids.
Planning
Mid-Columbia Fisheries is working with Benton County Conservation District to create an emergency drought-response plan to remove water stargrass from key fish areas in drought years, from below Prosser dam to the confluence with the Columbia River. In summer 2021, as a first step in developing the plan, Mid-Columbia Fisheries will map the distribution of water stargrass in the lower Yakima River.