News Release
| Release Number: | 00-015 |
| Dated: | 2/15/2000 |
| Contact: | Matt Rabe, 503-808-4510 |
Portland, Ore. – The U.S. Army Corps of Engineers this week is testing the spillway flow deflectors at John Day Dam to verify they are working as expected.
The testing began Feb. 11 and will continue through Monday, Feb. 21. At the same time, to help with the John Day Dam tests, the river level behind The Dalles Dam, which is 24 miles downstream of John Day, will be lowered to between 155 feet to 156 feet. The level behind The Dalles Dam normally is held between 157 feet and 160 feet this time of year.
The deflectors were installed at the base of the dam’s spillway during 1997 and 1998. The deflectors divert water spilling over the spillway and keep it from plunging deep into the river, where it can cause high levels of nitrogen to become trapped in the water. This can cause a condition in migrating salmon similar to the bends in humans.
Researchers from the Corps’ Waterways Experiment Station in Vickburg, Miss., will use eight different spill patterns to collect their data, involving one to 18 of the spillway bays. Water releases over the spillway will range from no spill to 180,000 cubic feet per second. In addition, water is also being released through the powerhouse.
The tests were requested by the National Marine Fisheries Service.
As a result of the changing release patterns, vessels downstream of John Day Dam may experience challenges in maneuverability near the navigation lock.
Spill at John Day Dam has been found to cause supersaturation beyond the federal and state water quality standard of 110 percent. The Corps is studying ways to modify spillways to reduce total dissolved gas supersaturation.