News Release
| Release Number: | 06-010 |
| Dated: | 1/20/2006 |
| Contact: | Heidi Y. Helwig, 503-808-4510 |
Portland, Ore— Although the total amount of water released will not increase significantly from current levels, four spillway gates at Fern Ridge Dam were opened today to better distribute water releases from the reservoir and to protect against erosion near the Clear Lake Road Bridge, the U.S. Army Corps of Engineers said today.
Since the heavy rains began, releases from Fern Ridge Dam have been regulated only by the outlet to the far right side of the outlet works. The outflow pattern is being changed because the area immediately downstream of the dam known as the stilling basin has been “scoured out.” The area is about 60 feet long, 15 feet deep on the upstream edge and 30 feet deep on the downstream edge, said Erik Petersen, operations manager for the Corps’ Willamette Valley Project.
“We’ve been working with Petersen and the project staff to modify the flow pattern of releases, shifting flow from the regulating outlet to the spillway gates,” said Julie Ammann of the Corps’ Reservoir Control Center. “The hope is that this will divert flow and help minimize the impacts.”
The Corps and the Lane County Emergency Management staff are looking at possible emergency repairs since the scour is about 40 feet from the Clear Lake Road bridge east abutment, Petersen said.
The Corps plans to maintain flows from Fern Ridge Dam at 4,500 cfs through next week to draft the pool down to 370 feet by Jan. 26, Ammann said. As of 1 p.m. on Jan. 20, the pool elevation was at 373.19 feet, she said.
Other reservoirs in the valley also are expected to draft to more manageable levels by the end of next week, if not earlier, Ammann said, as the Corps continues to release water downstream. When another storm arrives, projects will once again reduce releases and store as much water as possible to reduce downstream impacts, she said. The Corps will evaluate and adjust releases hourly.
The Corps works closely with the National Weather Service to run daily operational models. Based on these models, the Corps makes operational decisions about how much water to release and sends these schedules directly to the projects. On-site project operators physically make the operational changes.
The 13 dams in the Willamette Valley control runoff from 27 percent of the total Willamette Basin. Since the dams were built, they have cumulatively prevented more than $18.6 billion in flood damages.
In addition to minimizing flood damages, Corps reservoirs also are operated for hydropower, irrigation, fisheries, water supply, water quality and recreation. The Corps’ goal is to effectively balance these competing needs to serve the region and its people.