Abstract
The removal of Milltown Dam commenced in 2006, after a century of impacts to the watershed. The last vestiges of the dam were extracted from the confluence of the Blackfoot and Clark Fork rivers in 2009. The dam that once annually blocked the migrations of 10’s of thousands of fish, limited downstream fish movements, created a reservoir that fostered illegally introduced northern pike and was a source of heavy metal inputs to the river below is gone and over 2 million cubic yards of sediments removed. The removal of the dam reversed many of its effects immediately. Connectivity was restored for all fish species and the benefits to other wildlife occurred in months. Many of the changes in the coming years will be subtle, like offering populations more resilience, and promoting the expression of life history tactics that were formerly selected against. However, we have documented drastic local changes in species composition, fish densities, and unimpeded fish passage. Monitoring these changes has occurred on a watershed scale and the activities range form in situ bioassays to population and community monitoring. Dam removal may not ameliorate all the challenges to native fish conservation; however, it may ultimately be the only way to guarantee success. The effects of dam removal are permanent and at a scale which could not be afforded by engineering solutions.
Start Date
24-4-2015 9:00 AM
End Date
24-4-2015 9:30 AM
Document Type
Presentation
Scale and Permanence: Monitoring Removal of Milltown Dam, 1998-2014
The removal of Milltown Dam commenced in 2006, after a century of impacts to the watershed. The last vestiges of the dam were extracted from the confluence of the Blackfoot and Clark Fork rivers in 2009. The dam that once annually blocked the migrations of 10’s of thousands of fish, limited downstream fish movements, created a reservoir that fostered illegally introduced northern pike and was a source of heavy metal inputs to the river below is gone and over 2 million cubic yards of sediments removed. The removal of the dam reversed many of its effects immediately. Connectivity was restored for all fish species and the benefits to other wildlife occurred in months. Many of the changes in the coming years will be subtle, like offering populations more resilience, and promoting the expression of life history tactics that were formerly selected against. However, we have documented drastic local changes in species composition, fish densities, and unimpeded fish passage. Monitoring these changes has occurred on a watershed scale and the activities range form in situ bioassays to population and community monitoring. Dam removal may not ameliorate all the challenges to native fish conservation; however, it may ultimately be the only way to guarantee success. The effects of dam removal are permanent and at a scale which could not be afforded by engineering solutions.