The Laguna de Santa Rosa is the Russian River’s largest tributary and the second largest freshwater wetland in Northern California. As a valuable environmental resource, the Laguna serves as a natural detention basin that lowers the River’s downstream flood levels by more than 10 feet. Over the last 200 years, land clearance, farming, urbanization and channelization in the 250-square-mile watershed have accelerated erosion and sedimentation. The result has been a reduction in the Laguna’s flood storage capacity and loss of wetland area. In order to preserve this important resource, it was critical to identify the source of the sediment and the rate of sediment deposition in the Laguna. Working with the US Army Corps of Engineers, PWA devised a solution to reduce sediment transport and prevent further deterioration of the Laguna’s flood protection capacity and wetland ecology.