Ponds Proliferate, but Wetland Losses Continue

The good news in the recently-released report by the U.S. Fish and Wildlife Service-Status and Trends of Wetlands in the Conterminous United States: 1998 to 2004-is the continued decline in the rate of wetland loss. The bad news is that while the rate of wetland loss has declined, tidal salt marshes and shrub swamps continue to be lost at significant levels. Unfortunately, the report's seemingly-good conclusion that the nation has achieved "no net loss of wetlands" is misleading. The "no net loss of wetlands" is largely due to the proliferation of ponds, lakes and other "deepwater habitats," as the report points out. These ponds include ornamental lakes for residential developments, stormwater detention ponds, wastewater treatment lagoons, aquaculture ponds and golf course water hazards.

This study found that between 1998 and 2004, there was a net gain of 191,750 acres of wetlands and other waters, 32,000 acres of net gain annually. This is the first time ever that the study reported a net gain in water resources acreage and this is an important achievement. However, the significant increase in new pond acreage (700,000 acres, an 11% increase) accounts for this net gain by a magnitude of more than three fold. A closer evaluation of the report reveals a net loss of more than half a million acres of naturally occurring wetlands. For example, estuarine emergent wetlands (salt marshes) were reduced by 5,540 acres (0.9%, the same loss rate as reported between 1985-1997), freshwater emergent wetlands declined by 142,570 acres (0.5%), and freshwater shrub wetlands declined by 900,800 acres (4.9%) during the 6-year study time frame.

The study summarizes gains and losses through the country. On a regional basis losses may continue to exceed gains. According to the study the region of the country that experienced the greatest losses were the Atlantic and Gulf coastal plains. Wetland losses were also significant in the prairie pothole region, the Great Lake states, and in rapidly developing urban areas.

The NWI has also conducted wetland trends studies in specific geographic regions areas. A regional study of Southeastern Virginia between 1994-2000 showed a net loss of nearly 2,100 acres of wetlands, a 1.3 percent decline in just six years. In southern Michigan a report underway between Ducks Unlimited and U.S. Fish and Wildlife Service documented a net loss of 30,311 acres between 1978 and 1998. A study of wetland change in Oregon's Willamette Valley between 1982 and 1994 showed a net wetland loss of 6,549 acres, a 2.5% loss over that time period.

This report is the latest in a series of reports to Congress on the status and trends of the nation's wetland resources. The Emergency Wetlands Resources Act of 1986 requires the U.S. Fish and Wildlife Service to produce national status and trends reports for Congress at 10-year intervals. President Bush, in his Earth Day 2004 address, directed the U.S. Fish and Wildlife Service to complete the current study ahead of schedule as part of an announced policy objective to increase the quantity and quality of the nation's wetlands.

Why does this wetland/pond distinction matter? Natural wetlands have the capacity to provide multiple wetland functions and related benefits to society. Depending on the type of wetland and its location in the landscape, these services include water quality improvement, waterfowl and shorebird habitat, floodwater reduction, shoreline stabilization, fish habitat and other functions. In contrast, special purpose ponds and ornamental lakes that have little if any vegetation may provide limited wetland functions and services-most commonly stormwater retention-but cannot replace the many functions and valued social and economic services performed by natural wetlands.

A tragic example is the loss of thousands of acres of estuarine marsh along the Louisiana coast, a loss that contributed to the devastation of coastal areas by hurricanes Katrina and Rita. It was widely reported in the news that pre-hurricane wetland losses resulted in greater hurricane damage because these wetlands were no longer present to act as a buffer against the storm surge as it swept inland. Gulf Coast wetlands have been lost at a rate of up to 40 square miles a year for several decades. For these reasons, wetland scientists and managers remain concerned about the continued loss of diverse and productive wetland habitats nationwide.

The ecological tradeoffs between wetland losses and pond gains are touched on but not addressed comprehensively in the recently released report because the study methods are not designed to evaluate changes in wetland quality, just quantity by type. Monitoring changes in the quality and condition of the nation's wetlands and other waters is a much more difficult and expensive endeavor. Many factors can cause losses in wetland condition and thus their ability to function properly. Examples of these factors include the encroachment of development, discharges of stormwater, the conversion of plant diversity into a managed monoculture, and the introduction of invasive species. As illustrated by the national study and in the regional examples, the phrase "no net loss" necessarily needs to consider the actual losses of existing natural wetlands and the changes in wetland type as well as the condition of wetlands to more fully characterize the status and trends of our nation's wetlands.

The declining trend in wetland loss is encouraging, but we still have much work to do before we can conclude that we are meeting the policy goals of "No Net Loss" and even further before we can claim to meet net gain targets of the quantity-and especially the quality-of the nation's wetlands.

The full report: U.S. Fish and Wildlife Service-Status and Trends of Wetlands in the Conterminous United States: 1998 to 2004 can be found at: http://wetlandsfws.er.usgs.gov/ Previous U.S. Fish and Wildlife Service Status and Trends Reports: http://wetlandsfws.er.usgs.gov/status_trends/index.html

Regional Status and Trends Analyses

Southeastern Virginia

The NWI has also conducted wetland trends studies in specific geographic regions areas. A regional study of Southeastern Virginia between 1994-2000 showed a net loss of nearly 2,100 acres of wetlands, a 1.3 percent decline in just six years. Vegetated wetlands declined by 2,545 acres while nonvegetated waters (mainly ponds) increased by about 450 acres. Changes in wetland types is another factor to consider when evaluating net gains and losses. In Southeastern Virginia, forested wetlands experienced a net loss of 3,306 acres, while palustrine emergent wetlands saw a net gain of 930 acres, which is attributed to timber harvest practices. When forested wetlands are cutover, a cycle of changing plant communities begins. Estuarine wetlands in Virginia declined by 101 acres during this same period with eighty-three percent of the losses attributed to conversion to open water (85 acres). Over 2,400 wetland acres (mostly forested wetlands) in this region of Virginia were converted to upland mostly due to residential development (1,580 acres or 65.2% of overall loss). While Virginia has shown a no net loss through its regulatory program since 2000, the statistics point out the significance of how losses, gains and trends are presented.

Southern Michigan

In Michigan, Ducks Unlimited (DU) is cooperating with the U.S. Fish and Wildlife Service to update NWI's and to evaluate changes in wetland habitat over a 20 year period (roughly 1978 to 1998). This evaluation has been completed in the southern half of Michigan's Lower Peninsula - the region of the state most historically altered by both farming and urban development. While the DU study reports an increase of 12,655 acres of wetlands during this 20 year period, it also documents the loss of 42,876 acres (1.7% of the wetlands present in that region in 1978), for a net loss of 30,211 acres. Significantly, about 75% of the wetlands lost were either forested or emergent systems. A decline in emergent wetland habitat is of particular concern to DU due to impacts on waterfowl populations. Loss of forested wetland is of concern to wetland managers in Michigan given the difficulty of replacing this type of habitat. As reflected in the national study, many "new" wetlands are artificial ponds; the average size of "new" wetlands is less than an acre.

Examples of ponds:

Northern Indiana

Central Arkansas

Western Indiana

Indiana

Maryland - Montgomery County

Kansas