As a result, water levels on the southern and western sides of each lake are rising relative to the rest of the lake. 8 Human Activities Human activities also affect lake levels. Water diversions into and out of the Great Lakes Basin and within the Basin, consumption of water, the construction of dams and canals, and dredging affect water levels and flows. The impacts of human activities on lake levels is discussed in later chapters. Wetlands Wetlands have an essential role to play in controlling water levels in the Great Lakes ecosystem.
Wetlands are reservoirs that moderate the sometimes extreme water level changes in the lakes.
In periods of high precipitation, wetlands store large quantities of water, gradually releasing it later. In periods of normal or low precipitation, wetlands are discharge areas, which maintain the water levels of water bodies in the Great Lakes Basin. Wetlands are also important areas for groundwater recharge. They trap water and allow it time to seep deep into the ground to replenish aquifers. Because wetlands are thickly vegetated, they act as a buffer zone for shorelines against the waves coming off the lakes.