Horse Creek Dam Removal

Location: Horse Creek, Tributary to Sisquoc River, Central California
Clients and Partners: Los Padres National Forest, Stoecker Ecological, American Rivers, California Department of Fish and Wildlife, Community Environmental Council.

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Horse Creek is a tributary to the Wild and Scenic designated Sisquoc River in northern Santa Barbara County. Horse Creek lies entirely within the Los Padres National Forest, with most of the watershed lying within the San Rafael Wilderness. This stream is believed to have historically served as spawning and rearing habitat for Southern Steelhead, an anadromous form of rainbow trout listed as endangered under the Federal Endangered Species Act.

On October 20, 2006, a defunct dam located on lower Horse Creek was demolished using explosives. The 4.5-foot tall and 60-foot wide dam was built in 1968 and likely served as a debris and sediment catchment basin. Shortly after construction it completely filled-in with sediment. Over time, the downstream channel incised below the dam, creating a drop over the dam face that exceeded 8 feet.

Michael Love & Associates (MLA) performed a pre-removal geomorphic site survey and assessment with the assistance of Stoecker Ecological. The 2005 report, Stream Channel Assessment for Horse Creek Dam Removal Project characterized existing channel geomorphology and predicted channel response associated with removal of the dam. The assessment included estimation of equilibrium channel geometry with release of the stored sediment, consideration of the sediment transport capabilities of the receiving channel, and evaluation of the sediment release in the context of the overall watershed sediment yield.

Following demolition of the dam in 2006, MLA and Stoecker Ecological conducted post-project physical monitoring in 2008 and 2011 to document channel response after high flow events and a expansive wildfire within the watershed. The purpose of the monitoring was to quantify the stream response, which can be used to help inform future small dam removal projects within the arid Southern California hydrologic region. The monitoring report, Horse Creek 2011 Post Dam Removal Monitoring Survey,summarized the geomorphic survey of the stream channel upstream and downstream of the removed dam, describes the findings, and lists considering for future dam removals within landscapes of similar wildfire, hydrologic, and sediment regimes.

Demolition Video