After a month of testing, state officials have confirmed that the Amsterdam-Churchill sewage lagoons are leaking. What remains unclear is why.

The lagoon system has a “massive leak,” a Montana Department of Environmental Quality spokesman said Thursday. But until more testing is done, authorities won’t be clear as to the cause.

The facility, built in 1975, is permitted to discharge 78,000 gallons per day. But draw-down tests conducted in January indicate the lagoons are generating a daily flow of 86,7000 gallons, about 8,700 gallons over the allowable limit, said Mike Abrahamson, environmental engineer with DEQ’s Technical and Financial Assistance Bureau.

“Their sampling confirmed our estimates ... the flows are exceeding what the system is designed for,” he said.

How the Amsterdam-Churchill Sewer District can correct the problem will depend on the results of further testing to determine the extent and cause of the leakage, he said.

“At this point, we’re basically under the assumption the system is leaking. It’s up to them what next step they want to pursue,” he said.

The district has several options to correct the problem, but the most important step is to conduct an engineering study to pinpoint the scope of the leakage, Abrahamson said. Grants may be able for improvements.

“The ball is basically in their court,” he said of the district. “If they say they are going to do nothing, then the issue will probably be turned over to the DEQ enforcement division. At this point, we believe they are leaking excessively into the ground water.”

The enforcement division is the agency’s hammer and can institute fines, but generally works with public facilities to bring them back into compliance, DEQ officials have said.

The problem first came to light after a routine inspection in 2005, according to state records. Based on population numbers along with estimated allowable seepage for the three lagoon cells and accounting for evaporation, DEQ came up with a potential leakage estimate of 82,700 gallons per day, or 30.1 million gallons per year.

At that rate, DEQ was unable to account for more than 20 million gallons per year of influent flows.

The actual tests showed 4,000 daily gallons above the initial leakage estimate, Abrahamson said. But until a deeper probe is conducted, it is difficult to pinpoint the problem.

“At this point, we believe they are leaking excessively into the groundwater,” he said. “Basically, we only know that there is about 87,000 gallons going into the system of what’s obviously wastewater, but then it’s assumed there’s also a lot of groundwater infiltration at this point.”

District Chairman Hank Dyksterhouse could not be reached for comment Thursday.

But Gallatin City-County Health Department Environmental Health specialist Tim Roark said the department will monitor the situation and will not recommend any future hook-ups to the facility.