Small-scale best management practices to protect lake water quality

Abstract

Lake Tahoe, on the border of Nevada and California in the Sierra Nevada, is the world’s 11th deepest lake and is one of the clearest high altitude lakes in the world. Since Secchi disk monitoring began in the late 1960s, average water transparency has decreased from over 30 m to about 20 m. Efforts to reduce the decline in the water clarity of Lake Tahoe have been ongoing; since the early 1970s. One unique method to reduce nonpoint source pollution of the lake is the Best Management Practice (BMP) Retrofi t program of the Tahoe Regional Planning Agency (TRPA). This bi-state agency requires all developed properties in the Lake Tahoe Basin to implement water quality BMPs. The TRPA has worked with local Conservation Districts, the USDA Natural Resources Conservation Service and University of Nevada Cooperative Extension to develop small-scale erosion control and runoff infi ltration practices. Homeowners and small business owners can install these BMPs to reduce the amount of nutrient and fi ne sediment-bearing runoff fl owing into street and highway storm drains from private properties. In turn, city and state road departments can design facilities sized only for the runoff from the public right-of-way. This saves city and state governments millions of dollars in infrastructure costs. Special techniques have been developed to capture runoff from rooftops and driveways, convey it to an infi ltration system, and let it soak into the soil. Bare soil areas must be planted and/or covered with mulch to prevent erosion. Bare areas on slopes over 50% must be treated with structures as well as vegetation. Building and landscape contractors are trained annually in proper BMP installation, and the textbook, How to Install Residential Scale Best Management Practices (BMPs) in the Lake Tahoe Basin, has been translated into Spanish. Lake monitoring since 2000 shows positive results.