Virginia has more than 7,000 miles of shoreline on the Chesapeake Bay and its tributaries, but when it comes to keeping the bay clean, the state’s members of Congress are all over the map.

In a Capitol Hill delegation in which each party’s lawmakers tend to stick together, the Chesapeake is the rare issue that has divided Virginia Republicans. The intraparty break is especially important now as the GOP-controlled House makes repeated attempts to lessen the federal government’s anti-pollution efforts.

“There is a complete split,” said Rep. Gerald E. Connolly (D), who added that the bay was a regular topic of discussion — and disagreement — at the state delegation’s monthly lunch meetings.

The House could vote Friday on a possible amendment by Rep. Bob Goodlatte (R) that would block the Environmental Protection Agency from implementing its Chesapeake cleanup plan. The EPA program, which outlines what six states and the District must do by 2025 to help clean up the bay, is supported by environmental groups but has drawn criticism from business and agricultural interests.

The House approved similar language in February during debate on a short-term spending resolution, with every Virginia Democrat voting against Goodlatte’s amendment and every Republican voting for it — except Rep. Rob Wittman (R). The language was left out when the final version of the bill became law in April.

But July 13, when the House passed a measure preventing the EPA from enforcing national water quality standards, the vote broke a bit differently. While 95 percent of House Republicans supported the legislation, three from Virginia sided with most Democrats against it — Wittman and Reps. Frank R. Wolf and Scott Rigell.

Last week, a House committee cleared a separate Wittman-authored bill, requiring a strict accounting of every dollar spent on bay restoration efforts, that has attracted a bipartisan crew of co-sponsors, including Goodlatte and several Democrats.

(In Maryland, the lines are clearer: The state’s two House Republicans have consistently voted with their party against federal cleanup efforts.)

Support for cleaning the Chesapeake seems to drift with the currents, but there is some pattern to how Virginia’s members vote.

Doug Siglin, the director of federal affairs at the Chesapeake Bay Foundation, notes that lawmakers whose districts sit on the bay or on the Potomac or Rappahannock rivers — such as Wittman, Wolf and Rigell — tend to look more favorably on cleanup efforts.

“I think those districts are very water-sensitive, and I think the representatives . . . are more sensitive to those issues than other parts of the state are,” Siglin said.

That appears true of Wittman, whose 1st District includes the Northern Neck and the banks of the Potomac and James rivers. Although he has a strongly conservative record on most issues, Wittman has been unafraid to buck his party when it comes to the Chesapeake.

“Folks agree on the ends — to clean up the bay — but they disagree on the means,” Wittman said.

He said that although he doesn’t agree with everything the EPA does, he opposes efforts to reduce the agency’s role because “in the end, everybody needs to be a partner in cleaning up the bay. . . . Virginia suffers if other states aren’t doing their jobs.”

On the other side of the debate stands Goodlatte, the vice chairman of the House Agriculture Committee, who represents a farm-laden slice of western Virginia. He thinks the EPA’s Chesapeake cleanup plan — which puts the bay on a “pollution diet” by setting limits on the “total maximum daily load” of chemicals that can flow into it — is not only bad policy, but also violates clean water law by usurping authority that belongs to the states.

The American Farm Bureau Federation and the National Association of Home Builders have filed separate suits against the EPA in federal court, making a similar case.

Goodlatte and other critics contend that the EPA’s plan could be economically ruinous for the states that have to comply.

“The fact of the matter is the impact of the decisions they’re taking from on high in Washington are having a very dramatic effect on farmers and small businesses all across the Chesapeake watershed,” Goodlatte said.

Goodlatte has not said whether he will offer another amendment blocking the EPA plan, though he could do so Friday as the House debates the bill funding the agency.

The February vote on Goodlatte’s amendment, Rep. James P. Moran Jr. (D) said, “created the most striking disparity between our respective visions of the bay.”

With Wittman on one side of the fight and Goodlatte on the other, Rigell is the man in the middle.

“I think the federal government has an interest in ensuring we have clean water,” said Rigell, whose 2nd District includes Virginia Beach and the Eastern Shore, as well as portions of Hampton and Norfolk.

He said he voted against the recent bill on water-quality standards because it “would’ve severely restricted the EPA’s ability” to regulate on what’s clearly a multi-state issue.

“Where I sometimes part ways with the EPA is the timeframe” for the cleanup, Rigell said, adding that he voted for Goodlatte’s amendment this year because the EPA’s plan is “too aggressive.”

More legislation is in the pipeline. Wittman’s bipartisan accountability bill is ready for a floor vote in the coming weeks. Connolly is pushing a measure to improve management of storm-water runoff. And Sen. Benjamin L. Cardin (D-Md.) is mulling whether to reintroduce a wide-ranging Chesapeake cleanup bill that did not make it to a vote in the last Congress.

With debate raging over the federal debt, some critics say now is the time for the EPA to scale back its plans.

“The federal government has no money,” said Wilmer Stoneman, associate director of government relations for the Virginia Farm Bureau Federation. “We’ve got to think about things we can and can’t do and see that everyone is treated fairly in the process.”

But defenders of the bay say clean water is in the financial interest of all Virginians.

“I have to emphasize this: We do a lot of talking about jobs and the economy,” Wittman said. “The bay is a jobs creator. It is an economic engine.”