Letter: Linked are salmon and aquifers
Monday, November 12, 2012
Thousands have watched the fish jumping at Lucia and Moulton falls on the lovely East Fork of the Lewis River. We take family and friends and consider it part of our quality of life. Whether the fish are chinook, coho, chum or steelhead, we find it beautiful and restorative. These magnificent creatures are endangered.
Other than direct runoff, our water in Clark County comes from the sand and gravel aquifer and from the huge Troutdale aquifers, which underlie the whole Portland metro area, including Clark County. How are these connected to salmon runs?
Dennis Dykes, geohydrologist, says that rivers and aquifers interact. In the wet season, the streams feed the aquifers. In the dry seasons, aquifers feed the rivers. Aquifers help maintain the river water levels, flow rates and cool water temperatures necessary for salmon.
Therefore, we at Friends of Clark County are concerned by evidence that a local gravel mine may have breached the Troutdale aquifer near the East Fork. Data reported by InStream Conservation show an ongoing five-year decrease in the ground water base near the mine. Summer water temperatures are periodically more than high enough to kill salmon.