In an abrupt about-face from an announcement made just two months ago, the state Division of Marine Fisheries said this week that Sengekontacket Pond will be closed to shellfishing after all this summer.

The DMF announced that it had not conducted enough water quality tests to warrant a reopening of the pond, which has been closed to shellfishing for the last three summers following elevated bacteria levels three years ago, believed to be caused by waterfowl.

The closure begins June 1 and runs until Oct. 1.

The announcement caught town leaders in Edgartown and Oak Bluffs by surprise — especially the town shellfish constables.

“I was not a happy man,” Edgartown shellfish constable Paul Bagnall told his selectmen at their meeting on Monday afternoon. “Unfortunately, the state did not do what they said they were going to do.”

“Bad news!” wrote Oak Bluffs shellfish constable David Grunden in an e-mail that he sent around in his town on Tuesday.

In late March, DMF shellfish biologist J. Michael Hickey told Mr. Bagnall and Mr. Grunden that the towns would be allowed to reopen Sengekontacket for the summer season, on condition that the pond would face a five-day closure following a rainfall of more than three-quarters of an inch in a 24-hour period. The state would then conduct water testing to determine if the pond was suitable for reopening.

But Mr. Hickey said yesterday that the announcement was unofficial, and as summer drew near the state decided that it would not be safe to open with pond without further testing.

“Back in March, we were looking at the data and it looked like we could open [Sengekontacket] for the summer. What we didn’t realize was that we didn’t have enough data that reflected drier weather and lower amounts of rainfall,” Mr. Hickey told the Gazette. “Normally, our telling the town that we’re going to do an opening and then not doing it is one of these things that just almost never happens,” he admitted. But he added that the main concern is for the health of people eating the shellfish. “We just, from a public health point of view, felt that we needed to do more work,” Mr. Hickey said.

He said water testing must be conducted during periods of both wet and dry weather. But testing during dry periods somehow fell short in the past year. “We’re juggling over 300 shellfish areas throughout the state where we’re doing some amount of work, in a number of different rainfall areas,” Mr. Hickey said. “As we got going here, writing up the final reports that we have to do in order to justify an opening, we started seeing some gaps in the data that we just need to take care of.”

Sengekontacket has been tested regularly for bacterial contamination since the summer of 2007, when the two towns were forced to close and reopen the pond several times after tests determined high levels of fecal coliform bacteria in the water. The pond was closed permanently toward the end of the 2007 summer season, and has not reopened for a summer since. It has been open between Oct. 1 and May 31.

“The bacteria that we’re concerned about . . . are fecal coliform bacteria. They tend to multiply in warmer weather. That’s the indicator organism that the shellfish program uses nationally. It’s a national standard. That’s what we have to abide by,” Mr. Hickey said. “What we’re seeing [in Sengekontacket] in the summertime is that bacteria levels are kind of erratic.”

He said the contamination could be caused by a number of factors, and increased bacteria levels are often prompted by heavy rainfall, making it necessary to test during both wet and dry spells. “Sometimes you’ll have situations where, during dry weather, it’s not a problem, but during wet weather, the fecal bacteria are washed in from the land, off of plants. It can be bird droppings, it can be wild animals, it can be pets. There are a number of sources. It could even be seepage from septic systems and those sorts of things,” said Mr. Hickey. “In the case of Sengie, I really think it’s probably more birds than anything.”

For the past three years, the Edgartown and Oak Bluffs shellfish departments have worked in earnest to address the problem, with the aim of lifting the routine seasonal closure. The towns have conducted their own water testing, independent of the state and funded by the two towns and the Friends of Sengekontacket. Tests from last year turned up cleaner than the previous two summers, raising hopes that the pond might reopen this summer. And until this week, it look as if that would happen.

Selectmen in both towns are unhappy with the news.

“I have an announcement to make that makes me want to shoot myself,” said Oak Bluffs selectman Duncan Ross before announcing the closure at the selectmen’s meeting Tuesday night. “The issue is something about how [the state] didn’t get enough information on three-eighths of an inch, or six-eighths of an inch, or something bizarre as that,” he said.

In Edgartown on Monday, Mr. Bagnall told selectmen that it is possible one missing water sample prompted the closure. “When pushed, I think [the state] will say they wanted 14 clean sample rounds last summer. We got 13, and I think it’s not quite good enough,” he said.

Mr. Bagnall said the towns would have completed the testing themselves if they’d had the option, but the state wouldn’t allow it.

The selectmen said since it was up to the state to make sure enough test rounds were completed, it should be up to them to fix it. “The state should bend over backward to come down here and fast-track something for us,” said Arthur Smadbeck. “They dropped the ball.”

But Mr. Hickey said yesterday that’s not going to happen, and that the pond will likely remain closed for the next two summers, and possibly longer. “It won’t open this summer,” he said. “Potentially next summer, if we get sufficient data of the kind we need, and the different weather events we need. Then that’s possible. But it could take two years. I don’t know how else to say that. We’re hoping we can do it in one summer. It may take two. I’d rather under-promise.”

Mr. Grunden said he fears the worst. “I’m not very optimistic,” he said this week. He said a dredging project that is on the horizon for Oak Bluffs could help, by improving the water quality through better circulation.

But Mr. Smadbeck pointed out that Edgartown completed an expensive dredging project on its side of the pond two years ago, apparently to no avail.

“I am frustrated because we spent hundreds and hundreds of thousands of dollars on dredging. If there is testing that needs to be done, if there is something we need to be doing, we need to know that,” he said.

Meanwhile, Mr. Hickey said he expects the DMF to waste no time in launching a new round of testing. “This is something that’s going to be up and running,” he said. He described an action plan that includes a testing schedule for the coming year, with additional sample stations around the pond and a review of water conditions in the spring of 2011. But the weather remains a variable.

“In order to get the kind of conditions we want, it could take a couple of summers. We need to see it during dry weather and we need to see it during wet periods. If we have a really wet summer, we might not see the dry weather conditions that we’re looking for. If we have a totally dry summer, then we might not then have the intermediate rainfalls,” Mr. Hickey said.

“We don’t feel particularly good about this, but I just don’t think it’s safe to open the pond this summer until we have more data, and we know for sure what’s driving the water quality issues.”