New accurate maps of Chesapeake Bay wetlands will help in studies of areas critical to the health of bodies of water like the Bay, U.S. researchers say.

Two U.S. Department of Agriculture scientists used satellite data to created new maps 30 percent more accurate than existing ones, a USDA release said Friday.

Because many wetlands are forested, it can be hard to see the wetlands on aerial photography. Trees block the view and maps drawn from aerial photographs are subjective, causing more loss of accuracy, the release said.

With the satellite data, Agricultural Research Service soil scientist Greg McCarty and USDA Forest Service ecologist Megan Lang were able to create accurate maps showing flow paths into the Bay -- and determine whether water flows without filtration directly into the Bay, or whether it flows first through forested wetlands that might filter out possible pollutants.

Because forested wetlands had been thought to be isolated from each other and the Bay, researchers say, the Clean Water Act did not offer them the same regulatory protections as other wetlands.

Accurate maps such as the new satellite versions are vital to Chesapeake Bay cleanup efforts and state and national wetland conservation debates, the USDA said.