The Carson River enters the lake at its southwestern end . The lake is very shallow there , and the shoreline can vary drastically as the lake empties and fills . The Derby Dam diverts part of the Truckee River into the Truckee Canal which enters the lake at the northeastern end , immediately adjacent to the Lahontan dam . During the 2017 California floods , the highest inflow in history filled the lake , and a weir was made to handle outflow . Oversized culverts were quickly put under US95 and lined with ripraps to let the water cross the road and protect Fallon from flooding .
2017 California floods
2017 California floods
Lake Lahontan (reservoir)