Removal of sediment from residential stormwater to improve water quality in Lake Tahoe

In Lake Tahoe sediment influx from stormwater runoff directly contributes to impaired clarity. Although urban development is minimal within the region, its impact on sediment loads is significant. In residential settings, containment of stormwater in infiltration systems that allow percolation into the soil is thought to be more effective than collection and treatment of surface water runoff. As a result, residential parcels in the Lake Tahoe basin are required to have on-site infiltration systems. While effective for mitigating sediment flux into the lake, these systems are costly to install and require maintenance to maintain full function and prevent premature failure due to clogging. Mandatory sediment trapping devices, which remove larger sediment particles and debris prior to conveying stormwater to the infiltration system, have become required. However, there is limited information regarding sediment trapping devices that are designed for this purpose. Here, an on-site stormwater treatment device, consisting of a 200-micron mesh nylon insert, was tested to evaluate how it could be used to improve performance of residential stormwater infiltration systems. The device removed 88.6% of suspended solids, reducing the median concentration of suspended solids to 72 mg/L. The device appears suitable for the application, and will enhance the economics and sustainability of residential stormwater management in the Lake Tahoe region.