Slot-machine revenues declined sharply at Foxwoods and Mohegan Sun last month, closing the books on the casinos’ dwindling payments to the state in the 2012-13 fiscal year.

The casinos combined to contribute $296.4 million to the state’s General Fund in the 12 months that ended June 30, a 13.9 percent decline over the $344.3 million they paid the previous fiscal year.

The decline was much more than anticipated when the state adopted its 2012-13 budget.

While the state comptroller’s office most recently estimated the casinos’ 2012-13 payments at $297.7 million, the state’s 2012-13 budget was based on an estimate of $336.2 million, according to Gian-Carl Casa, the Office of Policy and Management’s undersecretary for legislative affairs.

“So, compared to the forecast made in May of 2012, the shortfall was $39.8 million (nearly 12 percent,)” Casa said in an email.

At this point, he said, the state is anticipating $285.3 million in casino payments in the 2013-14 fiscal year.

“We should have a better idea in a few months,” he said.

Foxwoods’ 2012-13 payments totaled $138.5 million, while Mohegan Sun’s came to $157.9 million.

In the six years since the casinos’ combined payments to the state peaked at $430.5 million in the 2006-07 fiscal year, they’ve fallen more than 31 percent.

State Comptroller Kevin Lembo acknowledged the “generally downward trend” in a statement released through a spokeswoman.

“Gaming revenues tend to be volatile and competition is growing, which is why Connecticut must maintain its focus on developing a diverse economic development strategy, particularly in Eastern Connecticut, so that we don’t become heavily reliant on any one revenue or employment source,” Lembo said.

Foxwoods reported Monday that it “won,” or kept, $43.4 million wagered at its machines last month, a 12.3 percent decline from June 2012. Mohegan Sun’s $50.5 million win for the month was down 7.9 percent.

Foxwoods sent $10.9 million of its June slots win to the state, while Mohegan Sun contributed $13.3 million.

The casinos posted their last year-over-year increases in December 2011.

In May, Mohegan Sun’s decline was less than 1 percent, while Foxwoods was down 4.4 percent.

“Unfortunately, June was a soft month nationwide, in Atlantic City and in jurisdictions across the United States,” Ray Pineault, executive vice president and chief operating officer of Mohegan Sun, said in a phone interview. “Here, we were up against some really good weather, particularly on weekends. I think people had a lot of pent-up demand to be outside.”

Mohegan Sun does “a good portion of our business” on weekends, Pineault said.

Resorts World Casino at Aqueduct racetrack in the New York City borough of Queens, the Northeast’s leader in slots revenue, posted a June win of $66.1 million, up 22.4 percent over the same month the previous year.

In a statement, Scott Butera, Foxwoods’ president and chief executive officer, said Foxwoods had a good month overall.

“June produced solid financial results despite the decrease in slot revenue, as other business lines performed well,” he said. “In addition, the closing of our restructuring earlier this month puts us in solid financial condition and allows us to continue to make significant investments in our entertainment facilities.”

The restructuring enabled the Mashantucket Pequot Tribe, which owns Foxwoods, to reduce its long-term debt from more than $2.2 billion to around $1.7 billion.

b.hallenbeck@theday.com

June 2013 slot machine revenues

FoxwoodsTotal win (in millions): $43.4Yearly change: -12.3%State contribution (in millions): $10.9* Hold: 8.57%Operating units: 5,839

Mohegan SunTotal win (in millions): $50.5Yearly change: -7.9%State contribution (in millions): $13.3* Hold: 7.89%Operating units: 5,530*Hold is the average percent of total wagers kept by the casino.