Effect of motorized watercraft on summer nearshore turbidity at Lake Tahoe, California–Nevada

The Lake Tahoe clarity trend is dominated by a consistent long-term decline attributed to the influx of nutrients and fine inorganic particles. The South Lake Tahoe nearshore clarity can be affected by factors such as wind waves, streamflow, boating, and urban stormwater, and the turbidity in the nearshore is greater during the summer than during the winter. In this study we measured the summer nearshore turbidity from 2 piers in South Lake Tahoe and found the summer nearshore transparency to be influenced by wind, boating, and lake currents, but not streamflow or urban stormwater. During summer 2012 the average daily increase in turbidity of Lake Tahoe's southern nearshore was 1.19 NTU following high intensity boating and 0.10 NTU following low intensity boating. Wave action and turbulence from boating in Lake Tahoe's shallow nearshore are likely to suspend sediment and release nutrients; however, there are no restrictions for boat operation in Lake Tahoe's shallow nearshore.