When Congress left town in early August, it left unfinished legislation that could determine the success of the Bay cleanup — the next Farm Bill.

The current bill, which sends tens of millions of dollars to Bay state farmers annually to support their conservation efforts, expires Sept. 30. It's uncertain when a replacement will be passed or how much support it will send to the Bay region.

The Senate approved a five-year bill in June and the House Agriculture Committee passed a five-year measure in July, but that bill never came to a vote on the floor.

Instead, House leaders floated the notion of a one-year extension, but that idea fizzled for lack of support. Much of the debate in the House has less to do with agriculture than it does funding levels for domestic nutrition programs, such as food stamps, which drive most of the cost of the legislation, which could tally $960 billion over 10 years.

The House ultimately passed a $383 million drought relief bill for farmers — paid for by raiding conservation program funding — and adjourned. The Senate refused to take up that legislation.

Left behind when Congress adjourned was a dim outlook for what it will do upon its return — there are only a dozen legislative days scheduled before the fall elections.

"I'm assuming we're eventually going to get there, but the path isn't very clear," said Doug Siglin, a lobbyist for the Chesapeake Bay Foundation, which has made Farm Bill conservation funding a priority since 2006.

Whether Congress passes a short-term extension, or ultimately passes a full five-year-bill, the stakes for the Bay region are huge. Agriculture is the largest single source of nutrient pollution to the Chesapeake, and the Farm Bill has historically been the largest funding source to help farmers install stream buffers, build manure storage facilities, plant cover crops and take other actions that help keep nitrogen, phosphorus and sediment from reaching waterways.

Given federal budget concerns, conservation funding will almost certainly be reduced in any bill that emerges.

The Senate version of the Farm Bill provides $58 billion for conservation programs over 10 years, while the House version would provide $57.7 billion. That represents a reduction of about $6 billion from what was provided in the 2008 Farm Bill. (Although farm bills typically only cover five years, Congress estimates costs over a 10-year period.)

The exact impact of those cuts on national conservation efforts is uncertain, as the bills seek new savings by consolidating some programs. Further, national conservation programs were often not fully funded at levels that had been approved in the 2008 legislation.

The 2008 bill was a milestone because it created a Chesapeake Bay Watershed Initiative that provided $188 million over four years to support water quality improvements on farms in the Bay region.

Such Bay-specific funding is in neither the Senate nor House versions this year. But, both versions create Regional Conservation Partnership Programs that would provide increased funding to selected high-priority regions around the country.

In a commentary, Sen. Ben Cardin, D-MD, said the language in the Senate version would "guarantee" the Chesapeake would be a priority funding region so that "our farmers will continue to have the resources they need to be active stewards of our region's most precious natural resource."

Both the Senate and the House versions guarantee that Critical Conservation Areas would receive a base of $100 million a year, plus a portion of other farm conservation program funding. The Senate bill designates 8 percent of other programs to be divided among six areas. Nationwide, that would mean more than $250 million a year for the critical areas, including the Bay watershed.

The House version would provide somewhat less funding, and divide it among eight areas.

Exactly how that would translate into Bay-specific funding is unclear, but advocates hope it would steer roughly $50 million a year to the region, which is roughly what it has received under the Chesapeake Bay Watershed Initiative. That would also help buffer the impact of overall cuts to other Farm Bill conservation programs to farmers in the Bay region.

"The focus is on maintaining enough funding so that we don't lose momentum," said Ann Swanson, executive director of the Chesapeake Bay Commission, which represents state legislatures and has been working on the bill. "There is a very strong effort in the Bay region to try to maintain farmer funding."