September 2008 was the wettest on record in
Swamps, bogs, saltmarshes, heaths, peat lands, fens, and vernal pools; these are all wetlands. Wetlands have long been thought of as having little value, primarily just a source of biting insects with little use for development. But wetlands provide much greater benefits in the service of flood control. In inland areas wetlands receive runoff and direct rainfall and retain that water temporarily to be released slowly over time. The EPA estimates that 1 acre of wetlands can store 1 million gallons of water. Wetlands along rivers provide pathways for increased water levels and slow down flow rates, reducing erosion and absorbing flood waters. Along the coast, marshes absorb and disperse the energy of incoming storm surges. This service is provided at no cost and requires no maintenance. Pretty good deal.
Unfortunately, we are losing our wetlands to a number of
influences. Slowly but surely the
increasing demand for houses and roads is taking its toll on the
landscape. By 1980
In addition to loss from direct human use, wetland loss will be driven by climate change. As sea level rises, coastal wetlands will become flooded and eventually submerged permanently. Conservative predictions place sea level rise in the next century between 7 and 23 inches. With these systems gone coastal communities will be more susceptible to flood events like the ones on Mothers Day in 2006 and Patriots Day in 2007.
The effects of these changes are being felt in areas downstream when large rain events swell our rivers and they over top their banks. Without enough upstream storage, the rain flows off the landscape and quickly spreads out into the floodplains along rivers and streams, and quite often into someone’s backyard.
The costs associated with flooding aren’t small. The Town of
The value of Maine’s 5 million acres of wetlands has been calculated (by the Clean Water Network) at around $31 billion for the services they provide which, aside from flood mitigation, include fish and bird habitat, water treatment, ground water recharge, and scenic and recreational opportunities.
A number of legislative acts provide protections for wetlands, most notably the Federal Clean Water Act of 1972 championed by our own Senator Edmund Muskie. At the state level the Maine Natural Resource Protection Act regulates moving of earth in and around wetlands and Maine Shoreland Zoning laws regulate land use within the area surrounding wetlands. The effectiveness of these laws however is often limited by lack of enforcement due to shortages of funding and manpower.
Sometimes wetland loss is permitted. Work on roads and bridges often involves the filling of portions of wetlands. The law requires these losses to be compensated for by the creation of new wetlands or wetland restoration. The replacements usually take the form of engineered drainage swales and retention ponds. Unfortunately these are often not an adequate substitute for the original system. An Army Corps of Engineers study found that only 17% percent of wetland mitigation sites functioned as adequate replacements. The substitute wetlands may be in a completely different location and the ecology may be dramatically different.
So what is to be done?
Numerous organizations are hard at work to address these issues. Municipalities are constantly updating there
zoning ordinances and incorporating new techniques for stormwater
management. People are becoming more
aware of the risks of living in areas prone to flooding as we have seen on a large
scale in the Midwestern and
This view has recently been supported by the National Marine
Fisheries Service which recently called for a moratorium on development in the
flood plains around
The solution to the problem of wetland loss is relatively straight forward, but requires the willpower of all of us to succeed. Landowners can help by voluntarily limiting activities around wetlands. If your land borders a wetland, think about not mowing right to the waters edge. Instead, consider leaving a wide buffer of trees and vegetation that will help reduce the impacts of flooding and runoff. Rain barrels and rain gardens can be used to capture rainwater from your roof and parking area. You can even allow a part of your yard to grow into a natural meadow full of wildflowers which will attract songbirds and wildlife. If each of us can help restore the natural landscape the result will be savings to our communities and benefits to public health and the environment.