Weirs are barriers built in a stream to pool water for irrigation, recreation, and sometimes to generate power. They are found in many of our local streams, even though most are no longer in use, and often cause problems for juvenile fish. During times of low streamflow, these structures tend to be too tall for young fish to jump, and during high streamflow, the narrow opening in the weir causes the water to flow too quickly for young fish to navigate.
History of One Weir
Many years ago, crews at Camp Adams installed a weir on Nate Creek in the Milk Creek Watershed, to create a swimming hole for the retreat. Unfortunately, within a year the sediment buildup caused the swimming hole to become useless. This year, the current owners of Camp Adams felt it was time to return the stream to its original state, so they contacted the Clackamas Soil and Water Conservation District for assistance. Jenne Reische, riparian specialist, visited site visit and explained that once a stream is backed-up, gravel and debris that normally travels through the stream system becomes trapped. This causes the sediment build-up behind the weir and starves the lower part of the stream of needed woody debris and spawning gravel. Removing a weir and allowing a stream to flow naturally not only improves fish habitat downstream, but also opens up good habitat upstream.
Fixing the Problem
After many months of planning and permitting, the fall in-stream work window arrived and crews from Oregon Department of Fish and Wildlife brought in heavy equipment to remove the concrete and wood structure in Nate Creek. Prior to the weir removal, biologists routed the stream through a pipe to keep the deconstruction process from sending sediment and debris from the deconstruction downstream. As the water left the construction area, biologists quickly captured any stranded fish and released them downstream.
Removing the weir made Nate Creek a free-flowing stream. Additional improvements include two log jams and boulder clusters to provide places for insects to reside and young fish to rest. Crews planted native trees, shrubs, and small plants on the streamside to provide bank protection, shade, and habitat for the native birds and wildlife.
Success in the Stream
The Clackamas Soil and Water Conservation District and Camp Adams staff happily report that there is one less weir in the Milk Creek Watershed! “The Camp Adams community is excited and honored to be a part of local community efforts to restore and preserve the health and vitality of the Milk Creek watershed,” explained Natalie and Bob Becker, camp managers. “It is central to the mission of Camp Adams to use the natural resources of the property in ways that raise awareness of the dire need for conversations about our environment.”
“This is not a do-it-yourself type of project,” adds Reische, project manager for the District. “There are permits, in-stream timelines, and many considerations for protecting the water quality in the stream. We recommend interested landowners contact the Conservation District to help them navigate this process.”
For more information on weir removal on your property, contact Clackamas Soil and Water Conservation District at 503-210-6000.