In a letter to the Environmental Protection Agency (EPA) on July 26th, NWEA asked the federal agency to consider why Oregon dischargers are being allowed to use hyporheic zones, which are supposed to be protected as thermal refuges for the protection of salmon, as pollution dumping zones. In the letter, NWEA noted the Oregon Department of Environmental Quality (DEQ) has guidance encouraging dischargers to inject polluted effluent into hyporheic zones.
What is a hyporheic zone? Under most of our rivers and streams is an area where these surface waters mix with groundwater. This area is called the hyporheic zone, an important and rich place that supports the ecological functions of surface waters and is its own habitat for living creatures as well. Water flowing in from hyporheic zones can create a thermal refuge, where cold-water fish can avoid the hot temperatures of Northwest streams and rivers. This only works, of course, if the hyporheic zone isn’t pumped full of polluted effluent.