Underground mining can have both positive and adverse effects on wetlands. A wetland occurs in flat areas and have soils that are permanently saturated in water (hydric soils) and vegetation that is adapted to survive in hydric soils. When subsidence occurs in flat areas, wetlands can spontaneously form. The subsidence creates a depression allowing water to collect and remain in the depression. Over time, the soils become saturated and eventually hydric. When waterfowl (ducks, geese, etc.) visit the saturated depressions, they bring with them vegetation seeds which get deposited and, over time, will lead to the development of characteristic wetland vegetation.
The adverse effect of coal mining on wetlands is the loss of habitat/wetlands. As with streams, subsidence can significantly reduce or eliminate the water source of a wetland through land fractures. Without a water source, the hydric soils will lose moisture and the vegetation that is adapted to survive in saturated soils will perish.
As part of the permitting process, mine operators are required to delineate wetlands in each permitted area prior to mining and again five years post-mining. If a net loss in wetlands is identified during the post-mining delineation, the operators are required to develop a mitigation plan in which new wetlands of an equivalent size and quality will be created.
Data on wetlands consists of measuring acreage of small parcels of land before and after mining. The Department is still formulating a way to represent this data and more will be available in future updates.
Last updated December 23, 2020.