This afternoon, the Public Authorities Control Board signed off on a loan from the state’s clean water fund to help finance the new Tappan Zee Bridge. The board approved half of the $511 million loan that Governor Andrew Cuomo is seeking, but the administration called it “the first installment” of the loan, creating the expectation of more clean water money to finance the extra-wide highway bridge. The approval, likely to be further challenged by advocates, could set a dangerous precedent for other governors looking to raid clean water funds for highway construction.

The board’s three voting members — Assembly Speaker Sheldon Silver, State Senator John DeFrancisco, and Governor Andrew Cuomo’s budget director, Robert Megna — each could have vetoed the loan. Silver and DeFrancisco said today they voted for the smaller loan to limit the negative impact on the state’s clean water revolving fund.

“This will do nothing to impair the ability to make loans,” DeFrancisco said of the $255 million loan, which will fund, among other things, environmentally-harmful dredging, according to Bloomberg. “These things have to be done. Why not out of an environmental fund?”

Environmental advocates disagreed. “It is simply not true to say that the $255 million loan is ‘environmental’ funding, when the vast majority of that sum is for bridge construction and related work,” said New York League of Conservation Voters President Marcia Bystryn. “Clean-water loans are meant for clean-water projects — not for a bridge — and today’s vote could set a dangerous precedent that will inspire states around the country to start diverting clean-water dollars.”

“A raid is a raid, and a quarter billion dollars in public money should not be bandied about behind closed doors without proper public scrutiny,” said Environmental Advocates of New York Executive Director Peter Iwanowicz. “Using clean water funds to build a bridge is not creative leadership, it is behaving like a kid in a candy store.”

The state played down its use of a federally subsidized clean water loan on a highway project by insisting it would pay off the debt. “This loan will be repaid and then recycled to benefit other clean-water projects across the state,” said Environmental Facilities Corporation president and CEO Matthew J. Driscoll. The EFC’s board of Cuomo appointees approved the loan last month. Driscoll added that he hopes the bridge project can secure the other half of the loan in 2016.

“The Thruway Authority is committed to an unprecedented level of environmental stewardship,” said Thruway Authority executive director Thomas J. Madison, “and also to keeping tolls on the new spans as low as possible.”

The financing plan for the Tappan Zee remains a mystery to the public, and many opposed to the loan hoped the control board would use its power to wrest some more information from the Cuomo administration about how the state is going to pay for the bridge. That didn’t happen today. “We are no closer to knowing the Governor’s math for this loan or this bridge than we were a month ago,” Iwanowicz said.