How can changes to drainage areas damage wetlands?

Changes to drainage areas can severely damage wetlands by disrupting the delicate hydrological processes—such as the timing, duration, and quantity of water—that are essential for maintaining these ecosystems.1

Human-driven drainage, which involves digging ditches, installing tile lines, or using pumps to remove water, is often performed to reclaim land for agriculture or development. These activities cause damage in several ways:23

• Loss of Habitat and Biodiversity: By removing the water that defines a wetland, drainage destroys the specialized habitat required by plants and animals adapted to low-oxygen or anoxic conditions. This often leads to a decline in biodiversity, as the area can no longer support the species that rely on it for food and refuge.41
• Soil Subsidence: In wetlands containing organic soils like peat and muck, drainage improves aeration, which increases the rate of oxidation. This causes the organic material to decompose and disappear, leading to a significant sinking or subsidence of the land surface.3
• Disruption of Ecosystem Services: Wetlands act as the "kidneys of the landscape," filtering water, recharging aquifers, and storing carbon. Drainage impairs these vital functions, reducing the ecosystem's ability to cleanse water and mitigate flooding.4