Although Mr. Leopold believes the state should pay the county an estimated $104,000 on the principle of fairness, Mr. O'Malley believes the bill goes against current procedures and could set a damaging precedent.

The bill was spurred in October when MDE negotiated a $1 million fine from Constellation Energy Group and BBSS for the fly ash contamination at wells in Gambrills, but did not pay Anne Arundel back for $104,000 worth of tests from a county Health Department investigation.

"(W)hile the intent of the bill's supporters to ultimately shift the costs that local governments incur for testing and monitoring of well water to parties who violate our state's environmental laws may have merit, the bill is deficient in that it does not directly confront that issue," the governor said in a veto message.

The legislation passed unanimously in the House and by a 45-1 margin in the Senate. The General Assembly could override the veto at its next regular or special session with a three-fifths majority.

Overall, there was little opposition to the bill other than from MDE. Local senators and delegates argued it was simply a fairness issue and all levels of government should work in partnership.

Ultimately, however, Mr. O'Malley sided with MDE, concerned about setting a precedent; where the money would come from, and paying local governments for upholding their responsibilities.

Current law does not allow MDE to factor in testing costs when assessing fines or reimbursement, Mr. O'Malley said in his message. Therefore, the money would likely come from MDE's "already tightly constrained General Fund budget."

The best strategy, the governor says, is to have a policy discussion about whether MDE should consider reimbursement when assessing fines in every jurisdiction, not just Anne Arundel County.

"(The legislation) does not accomplish that public policy goal - instead, it diverts resources of the department to reimburse a single local government a specific amount for a past event, and an uncapped, indeterminate amount for future events, for functions the County has agreed to perform," Mr. O'Malley's veto message says.

County Executive John R. Leopold blasted the decision today as an "anti-environment veto" that will damage the relationship between the state and local governments.

"The governor's veto sends the chilly message 'We're going to discount the efforts of local governments to protect the health and welfare of its citizens,'" Mr. Leopold said. "I'm disappointed in the governor's lack of fairness."

The county was proactive and took the lead on the investigation, the county executive said, and MDE's points were a "feckless, defensive argument." In fact, MDE knew as early as 1999 that fly ash dumped at the site could threaten nearby groundwater with cancer-causing chemicals, according to documents obtained by The Capital last year.

"Clearly, it was exactly the right precedent," Mr. Leopold said.

Del. James King, R-Gambrills, whose district includes the contaminated groundwater, said that the county intervened in a state's failures. If the state is concerned about losing money in payments to counties, it should fine violators more.

This would protect the county taxpayer from footing the bill for work that should be done by the state without draining the state's budget, he said.

"Increase the fine to the violator and increase the payment to the county. It comes at no expense to the taxpayer," he said.

The irony of the situation, he said, is that the people whose groundwater and wells were contaminated with carcinogens are paying for someone to protect them.

"Now the taxpayer is going to have to pay for what Constellation has done and that's completely unfair," he said.

House Speaker Michael E. Busch, D-Annapolis, said he had not yet looked at the governor's veto. But "maybe there are other ways to resolve the issue," without changing public policy, he said.

But the county has the option of trying to get reimbursed by the companies responsible for the contamination, rather than by the taxpayers, said Joe Bryce, a senior policy and legislative advisor for Mr. O'Malley.

"For whatever reason, they chose not to do that," Mr. Bryce said. "From the department's perspective, they felt there is something that can be done in these circumstances."

When the county first learned of the fine, it didn't try to collect money from Constellation because that option was not mentioned then. But upon learning of the veto, Mr. Leopold said he instructed the county Office of Law to approach Constellation and try and collect a reimbursement.

The veto comes at a time when concerns about fly ash are surfacing across the country.

On Wednesday, PPL Corp., an Allentown, Pa., power company, was fined $1.5 million for a 2005 fly ash spill into the Delaware River.

On Tuesday, the Oregon Department of Ecology fined a rock supply company $3,000 for spilling around 10,000 pounds of fly ash in a creek.

In October, MDE fined Constellation $1 million for contaminating groundwater in Gambrills. If the governor hadn't vetoed the bill, Anne Arundel County would have been reimbursed with funds collected from this fine.