The state Department of Environment and Natural Resources recently denied Chatham's request to send treated wastewater into the Cape Fear River Basin because it had already granted other local governments' requests.

DENR recently gave Pittsboro permission to discharge 4 million gallons a day into the Haw River, which feeds into Jordan Lake. Parts of western Wake County, including Cary, will be able to discharge as much as 38 million gallons a day into the Cape Fear River below Moncure.

That galls Chatham Commissioner Patrick Barnes.

"What rankles me the most is Jordan Lake is in Chatham County, but it's Cary's drinking water supply," and now Cary will be discharging sewage into Chatham County, he said.

Barnes said DENR blindsided him and several other county officials with the news at a meeting earlier this month.

"I went there with high expectations," he said. "We were told we're last to the trough and that nothing was left. Western Wake got it all."

Barnes has long wanted to get a sewer system in the county. Pittsboro and Siler City have sewer systems, but the rest of the county uses septic tanks and spray fields.

The discharge allocation that Chatham sought where the Rocky River meets the Deep River would have enabled the county to build its own sewer plant.

Mike Templeton of DENR's Division of Water Quality said the state has to calculate carefully how much treated sewage gets dumped in rivers in order not to pollute them.

DENR divided the sewage allocations among existing dischargers: Pittsboro and the Western Wake Partnership, which is made up of Cary, Apex, Morrisville and Holly Springs, Templeton said.

Chatham could purchase discharge allocations from the other towns if those towns don't need all of their allocation, Templeton said. The county also could look at piping its sewage into a watershed outside of Chatham. But Templeton concedes that would be expensive.

"At least there are some possibilities," he said.

Barnes said he is not sure how much longer the county can rely on septic tanks and spray fields, where treated sewage is spread on open land. Some have said the effluent on spray fields could get washed into Jordan Lake and pollute it. The lake provides much of the Triangle's drinking water.

"We have to look at reality," Barnes said. "If we keep creating [septic tanks and spray fields], we will ruin our groundwater. And those with wells will have a problem with us."

Barnes added that commissioners might have to consider a development moratorium. In the past few years, the county has approved nearly 7,000 new homes.

"We're definitely playing catch-up," he said. "And it's not going to be a fun time doing it."

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