Publication
NRCS Watershed Rehabilitation: Studies on PL-566 Dams in Oregon
Presentation. Oregon Water Resources Department dam safety program, Corvallis, Oregon.
- Author
- Meghan Walter
- Year
- 2017
- Topics
- Dam safety
- Source
- See the link at the end
Since 1948, local sponsors have built more than 11,800 flood control dams in 47 states with NRCS assistance under the 1944 Flood Control Act and Public Law 83-566. Those dams are reaching the end of their 50-year design lives, and the Watershed Rehabilitation program helps sponsors bring them up to current standards. This talk reports on the Oregon portfolio: Cooper Creek and Plat I for the Sutherlin Water Control District, Clear Branch for the Middle Fork Irrigation District, Wolf Creek and Pilcher Creek for the Powder Valley Water Control District, and the Bullard flood retarding structure for the Town of Lakeview.
Three findings run through the assessments. First, there are data gaps and mountains: design files are incomplete, survey and computing methods have changed, and records of extreme events are longer and larger than the originals. Second, the target keeps moving: Cooper Creek was designed in 1968 for a peak ground acceleration of 0.05g, and the 2008 USGS maps put the 10,000-year value above 0.75g; Clear Branch was designed as a significant-hazard dam and is now high hazard under three regulators. Third, surround yourself with good partners, because a single rehabilitation can involve seven regulatory agencies and specialist studies no one office can do alone.
Details
PresenterMeghan Walter, P.E., State Hydraulic Engineer, NRCS OregonFormatSlides, 2.8 MB PDFHostOregon Water Resources Department