The Chesapeake Bay drainage lost wetlands during the 1980s at a rate that was almost unchanged from recent decades, according to preliminary data prepared for the Bay Program. During the seven-year study period, the watershed lost nearly 2 percent of its remaining nontidal and about 0.5 percent of its remaining tidal wetlands, the figures show.

Roughly 22,000 acres of vegetated wetlands were lost between 1982 and 1989, according to the data, a number that indicates little change from the more than 2,800 acres a year that were lost during an earlier 1956-1979 study, though there were differences in the types of wetlands lost.

The findings will be included in a wetlands “status and trends” report being completed for the Bay Program by the U.S. Fish and Wildlife Service. The findings were based on a statistical analysis of aerial photos acquired during the 1980s for various portions of the Bay’s 64,000 square-mile watershed.

The data covers a time when most states had no nontidal wetland programs and when the federal regulatory programs were evolving. The figures did offer some evidence that regulatory programs could slow the rate of loss.

Still, any continued losses are important because the region has already lost a large amount of its original wetlands. Text accompanying the data cautioned that “…the significance of the vegetated wetland losses is not simply reflected by the acreage lost alone, since prior to the study period, many wetlands had already been destroyed, making the remaining wetlands more important and future losses more serious.”

Since colonial times, more than half of the watershed’s wetlands may have been lost, according to some estimates. Lost with those wetlands were their ability to absorb nutrients, provide habitat, filter water, and provide other important ecological functions.

The report estimated that about 1.7 million acres of wetlands remain in the Bay watershed, of which about 12 percent are tidal wetlands — those in areas near the Bay which are impacted by the Chesapeake’s tides — and 88 percent are nontidal wetlands located further inland. This was more than an earlier estimate of 1.2 million acres. The new number does not reflect an actual increase, officials said, but rather improvements in the photo survey.

Continued wetland losses during the 1980s did not surprise most officials interviewed, though. During the study period, neither Maryland nor Virginia had a program to regulate impacts on nontidal wetlands. Nontidal wetland regulations were new in the 1980s, and carried out almost entirely by the Army Corps of Engineers, which spent the early part of the decade developing its regulatory program and the last part of the decade — amid much controversy — trying to identify wetlands and apply those regulations on the land.

“When these laws were first passed, everyone didn’t quite understand what it all meant,” said Tom Filip, of the Corps’ Baltimore District. “Even in ’85 to ’89, we were still trying to figure out what was a wetland.”

Many broad categories of wetlands were exempted from regulation for much of the decade. “The ability of the Corps to regulate forestry and agricultural practices was substantially limited during that time,” said Mike Slattery, permit section chief in the nontidal wetlands and waterways division of the Maryland Department of Natural Resources. “I don’t consider the losses that surprising given the caveats in there — given the fact that the corps had limited ability to deal with those widespread activities, and given the fact that they didn’t put a lot of focus on nontidal wetland impacts until 1986.”

Other loopholes in the federal program also contributed to the loss. For example, all isolated wetlands are exempt from federal regulation unless there is an interstate commerce connection, such as migratory waterfowl nesting. Also, a national “general permit” expedites approval of activities that impact less than 1 acre of wetlands. In some cases, the general permit can apply to areas as great as 10 acres.

The USF&WS also uses a scientific wetland identification technique for its inventories which is generally considered to be broader than the identification criteria used by regulators during most of the 1980s, officials said. As a result, many of the areas lost during the study period were never considered wetlands by regulators.

The figures only cover portions of the states that rest within the Chesapeake Bay watershed. Exact figures for the states, and the kinds of wetlands lost, are still being refined. But the preliminary figures indicates that Virginia — the state with the most wetlands — also lost the most during the 1980s, with an estimated 15,000 to 20,000 acres disappearing over the seven-year period. Maryland lost nearly 5,000 acres, while Pennsylvania gained about 4,500 acres of wetlands in the watershed, partly as the result of ponds filling with sediments and being colonized by marsh vegetation. The balance of the changes took place in the Delaware, New York and West Virginia portions of the drainage.

The largest sources of losses — in order of magnitude — were flooding for reservoirs and lakes, agriculture, pond construction, and urban and suburban development.

Many officials believe that the loss rate has slowed in recent years as federal and state protection efforts have been strengthened. “I think we’ve made some dramatic changes in improving our regulatory program since 1989,” said Frank Dawson, head of Maryland DNR’s tidal wetland division and chairman of the Bay Program’s Wetlands Workgroup.

The data offer some evidence that regulatory programs dramatically reduce losses. Both Maryland and Virginia established tidal wetland programs during the 1970s. As a result, the new figures found that tidal wetlands in the 1980s were lost at a rate of about 100 acres a year — down from about 550 acres annually in the earlier study. Much of the tidal wetland loss was attributed to rising water levels which drowned coastal wetlands and to losses of wetlands in areas not covered by regulations.

Similarly, new state nontidal wetland protection programs could mean that future inventories will show fewer losses.

Maryland’s nontidal wetland law took effect in 1991 and regulates many of the wetlands exempted by the federal program. Since that time, Slattery said, the state has achieved a no-net-loss of wetlands “on paper” as people have been required to build replacement wetlands for those destroyed. Not all those wetlands have yet been built, he said. “Obviously, we don’t have all that mitigation in the ground, up and running and functioning as wetland ecosystems after only two years,” he said. “We simply could not have built them that fast.”

Pennsylvania is the only Bay Program state that had a nontidal wetland regulatory program during the survey period. Its wetland program began in 1980, and underwent major revisions in 1991. Pennsylvania generally requires replacement whenever wetlands are destroyed, usually regardless of the size affected. About half the state’s wetlands are located in the Chesapeake watershed, said Ken Reisinger, chief of the Department of Environmental Resources’ Wetlands Division. Reisinger said the numbers in the report provide evidence that a wetlands regulatory program can successfully “halt wetland losses.”

For a regulatory standpoint, Virginia’s nontidal wetlands remain the most vulnerable. The state wetland program reviews corps permits to determine whether a particular project will have an impact on water quality. If so, the state can recommend that the permit be denied. Officials say the state routinely requires mitigation for projects that require permits to offset losses. Because the program only reviews corps permits, though, it often cannot stop the loss of wetlands exempted by loopholes in the federal program. But the Chesapeake Bay Preservation Act provides some authority for nontidal wetlands protection in coastal counties covered by the act.

The final status and trends report is expected to be completed this spring. Besides providing overall wetland trends, and trends for the portions of individual states that fall within the Bay drainage, the document will present trends for particular kinds of wetlands, and for particular geographic regions. Officials hope to use the information to determine where increased wetland protection efforts should be targeted.