Rain that falls directly into the lake adds to the depth as does water that flows into the lake from streams in the lake s watershed. While all of the water that falls directly into the lake increases the lake depth, only some of the water that falls on the ground in the watershed will flow into the lake. The ground will absorb the first 2 millimeters of any rainfall in a day. The city uses 12 million liters of water from Crystal Lake every day. Water evaporates from all of the lakes lowering the lake levels an average of 1.0 millimeter per day.
Channels connect the lakes.
If the depth of a lake exceeds its overflow depth, then water will flow into the next lake or into a river. Water can flow through the channels at the rate of 20 million liters per day. Water stops flowing in the channel when the depth of the lake drops below its overflow depth. The table below defines properties of the lakes.