English: The USGS put together time-lapse video of the breach of the Marmot Dam, on the Sandy River in Oregon. Hydrology experts from the USGS Oregon Water Science Center and the USGS Cascades Volcano Observatory are studying this removal, the largest planned removal in the Pacific Northwest thus far.

Real-time USGS streamgages and other high-tech instruments are monitoring erosion, sediment transport, water quality, temperature changes, and turbidity of the water. This work is done in partnership with Portland General Electric (PGE), the owner of the dam, and other State and Federal agencies and university colleagues.

Removal of the Marmot Dam began in July 2007, and the final breach that unshackled the river occurred on October 19, 2007. As part of its decommissioning of the 100-year-old Bull Run Hydroelectric Project, PGE also plans to remove a smaller dam on the Little Sandy River in 2008.