Threats to wetlands

Sadly, wetlands are threatened by many human activities. Since colonial times, over half of the wetlands in the lower 48 states have been lost due to development, agriculture and silviculture, including 20% of Maine's wetlands. Although modern legislation has greatly slowed wetland loss, the U.S. continues to lose almost 60,000 acres per year. Moreover, the ecological health of our remaining wetlands may be in danger from habitat fragmentation, polluted runoff, water level changes and invasive species, especially in rapidly unbanizing areas.

Human activities threaten wetlands in several different ways. Stressors to wetlands can be chemical (e.g.,toxic chemicals), physical (e.g., sedimentation), or biological (e.g., non-native species).

  • Hydrologic alterations can significantly alter the soil chemistry and plant and animal communities. These alterations can be the results of: deposition of fill material, draining, dredging and channelization, diking and damming, diversion of flow and addition of impervious surfaces in the watershed, which increases water and pollutant runoff into wetlands.
  • The input of pollutants, such as sediment, fertilizer, human sewage, animal waste, road salts, pesticides and heavy metals can exceed the wetland's natural ability to absorb such pollutants and cause degradation. Pollutants can come from urban, agricultural, silvicultural and mining runoff, air pollution, leakage from landfills and dumps, and boats stirring up pollutants around marinas.
  • In addition to being impacted by hydrologic alterations and pollutants, wetland vegetation can be damaged by domestic animals grazing on them, nonnative species that compete with natives and the removal of natural vegetation.


Pictures of an algae bloom as a result of agricultural runoff

The watershed of the wetland seen above contains a substantial amount of agricultural land and is experiencing a severe algal bloom.


Picture of wetland buffer cleared for farm land

The buffer of this wetland has been cleared and coverted to agricultural fields.

Picture of soil disturbance within a wetland buffer

photo showing piles of soil within the wetland buffer

Piles of soil within the wetland buffer.


What can be done about these threats to wetlands?

Nationally, almost 75% of all wetlands are owned by private citizens, making it imperative that the public get involved in the management and protection of wetlands. Here are some things that you could do:

  • Donate your time, money and materials to local wetland and watershed protection initiatives.
  • If there are wetlands on your property, restore and protect them. Maintain wetlands and their buffer strips as open space. Avoid wetland alteration or degradation during construction projects.
  • Work with your local municipalities and state to develop laws and ordinances that protect and restore wetlands.
  • Purchase federal duck stamps from your local post office to support wetland acquisition.
  • Reduce or eliminate the amount of fertilizers, herbicides and pesticides you apply to your lawn and garden.
  • Encourage your friends and neighbors to join you in your efforts to protect wetlands in your watershed.

See the link below for more information about the threats to wetlands:

US Environmental Protection Agency's Wetland page,