A river flows along a channel, while a lake is a body of standing water is the correct choice. Rivers carry flowing water through channels; lakes hold water in basins, often with inlets or outlets.

Rivers connect mountain snowpack, valleys, ecosystems, farms, and communities. Seasonal runoff helps replenish waterways, while reservoirs and diversion structures change how water is available. River management therefore involves tradeoffs among agriculture, energy, habitat, and recreation.