The Massachusetts WPA identifies eight public interests that wetlands serve.
- PROTECTION OF PUBLIC & PRIVATE DRINKING WATER SUPPLIES – Wetlands contribute to both the quality and quantity of public and private drinking water supplies by contributing to the ground water supply, protecting against storm damage, and prevention of pollution.
- POLLUTION PREVENTION – Wetland plants and soils slow down the flow of water, allowing suspended sediments to settle out. The plants and soils of Vegetated Wetlands remove or detain sediments, nutrients (such as nitrogen and phosphorous) and toxic substances (such as heavy metal compounds) that occur in run-off and flood waters. Some nutrients and toxic substances are detained for years in plant root systems or in the soils. Vegetated Wetlands are areas where ground water discharges to the surface and where, under some circumstances, surface water discharges to the ground water.
- GROUNDWATER SUPPLY – Not only does groundwater contribute to drinking water supplies, as mentioned above, it is also very important in maintaining water levels in many rivers, streams, lakes and ponds. Finally, groundwater provides a vital source of water to plants between rainstorms.
- FLOOD CONTROL – The profusion of vegetation in Vegetated Wetlands acts to slow down and reduce the passage of floodwaters during periods of peak flows by providing temporary floodwater storage and by facilitating water removal through evaporation and transpiration. During dry periods the water retained in Vegetated Wetlands is essential to the maintenance of base flow levels in rivers and streams, which in turn is important to the protection of water quality and water supplies.
- STORM DAMAGE PREVENTION – During a storm, wetland vegetation stabilizes the soil and prevents erosion from wind, ice, and fast-moving water. Friction from the plants found in wetlands also slows down the velocity of potentially damaging storm waters.
- PROTECTION OF FISHERIES – In addition to preventing contamination, wetlands provide a valuable food source and habitat to many fish species.
- WILDLIFE HABITAT – Wetlands provide habitat for various animals. Birds, mammals, reptiles, and amphibians use wetlands for food, shelter, breeding and nesting. Wetlands are also valuable migratory areas.
- PROTECTION OF LAND CONTAINING SHELLFISH – In coastal areas, wetlands provide habitat and protection against pollution for shellfish such as mussels, clams, and oysters. Though Georgetown does not have coastal wetlands, the Parker River flows through the town and out to the shellfish beds in Newbury. It is therefore important to prevent contamination from entering the river in Georgetown and polluting shellfishing areas downstream.