Wednesday, May 28, 2008 - 11:00 AM
419

Benthic community response to flow restoration downstream of a diversion dam on the bridge river, british columbia

Chris J. Perrin1, Shauna A. Bennett1, and Paul Higgins2. (1) Limnotek Research and Development Inc, 4035 West 14 Avenue, Vancouver, BC V6R 2X3, Canada, (2) BC Hydro, 6911 Southpoint Drive, Burnaby, BC V3N 4X8, Canada

Beginning in 2000 continuous flow averaging 3 m3/s was released from the Terzaghi Dam that impounds the Bridge River in British Columbia, Canada. The water release wetted a downstream river reach that was dry for 37 years following dam construction and it supplemented flows further downstream. Periphyton and benthic invertebrate community attributes in each of three hydrologically different river reaches downstream of the dam were compared and contrasted between a block of 4 years before implementation of minimum flow and a block of 6 years following implementation of minimum flow. Rapid development of a diverse benthic community was found in the previously dry reach that was closest to the dam. Smaller change in abundance and composition of benthic invertebrates was found further downstream where wetted areas changed little between the two blocks of years. For the range of flows tested, change in wetted area was most important while flow augmentation was less important in restoring benthic communities.


Web Page: flow restoration, benthic invertebrates, dam

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