In a move that could make building easier in a limited number of wetlands, the Environmental Protection Agency and Corps of Engineers have directed their field staffers not to assert jurisdiction over certain "isolated" wetlands without checking with headquarters first.

EPA officials say the guidance, issued Jan. 10, aims to interpret a two-year-old U.S. Supreme Court ruling that found the Corps overstepped its authority by claiming jurisdiction over a type of isolated wetland. In that case, Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers, the court said the Corps couldn't claim regulatory authority over wetlands located in a single state that weren't connected to another water body and weren't navigable.

EPA officials portrayed its new guidance as narrowly drawn. Ben Grumbles, EPA's deputy assistant administrator for water, estimated that up to 20% of the nation's 100 million acres of wetlands were isolated. But he said that definitions of "isolated" vary. The amount of non-navigable, intrastate wetlands would be an unspecified share of that 20%.

Grumbles said, "We are reaffirming the jurisdiction of the federal government over the vast majority of wetlands throughout the country."

Several days before the EPA announced its action, National Association of Home Builders President Gary Garczynski said that his group's position is that "the federal government cannot require a permit when a landowner wants to fill an isolated wetland that is located only within one state and has no connection to navigation."

Garczynski said, "If federal agencies want to regulate isolated wetlands, they should instruct Congress to amend the Clean Water Act."

In the SWANCC case, the Corps asserted jurisdiction over a 533-acre abandoned sand and gravel pit in northern Illinois because ponds had developed on the tract and had become a migratory bird habitat. The Cook County, Ill., agency had sought to dispose nonhazardous solid waste on the site.

Besides the guidance, EPA and the Corps issued an advanced notice of proposed rulemaking, seeking comments and data on the scope of their wetlands authority, following the high court's "SWANCC" decision.

Grumbles also said President Bush's fiscal 2004 budget proposal would seek $20 million for EPA's wetlands grants program, up $5 million from the current level.