MARGARETVILLE - Developers of a proposed golf resort near the Belleayre Mountain Ski Center have conceded they used a flawed model to calculate potential stormwater runoff from the property.

Representatives of the Belleayre Resort at Catskill Park made the concession last week at a state Department of Environmental Conservation "issues conference" that was to determine whether the developers' draft environmental impact statement adequately addresses potential harmful effects of the project and the document need to be reexamined at an adjudicatory hearing.

Opponents of the project have long held that the stormwater model, which is used to determine how much more phosphorous would be introduced into area reservoirs serving New York City if the project goes forward, were flawed.

"This was significant," said Ian Michaels, a spokesman for the city Department of Environmental Protection. "It shows that a major part of the stormwater runoff component of the DEIS is incorrect and we've been saying that for a while now. This is the first time that we have an admission that those models are incorrect."

The city agency spent more than a half-million dollars studying the impact statement and has expressed serious reservations about the resort's potential effect on the Ashokan Reservoir which supplies much of the city's drinking water. The agency brought three witnesses to the issues conference, including the designer of the modeling program, who testified that the developers' study was fundamentally flawed due to a failure to calibrate and verify results using site specific data.

Dan Ruzow, an attorney for resort developers Crossroads Ventures LLC, said the stormwater runoff model was used on the advice of the Department of Environmental Protection, which attacked the results at the issues conference. Michaels confirmed that the agency had suggested the developers use the modeling program back in 1999, but pointed out that it was not required, and, in any case, was not used correctly.

According to Ruzow, the modeling program was designed to predict runoff in the heavily developed East-of-Hudson watershed and was inappropriate for use in the Catskill region. Ruzow said the stormwater study would be redone, and he downplayed the importance of the issue.

"This is no different from what we've been doing all along," said Ruzow. "When a question is raised, we say, 'OK, we'll take a look at it. We don't want to ignore things which may be important."

The impact statement projected the resort would add 25-50 kilograms per year of phosphorous to the Ashokan Reservoir. According to Ruzow, the reservoir's state-mandated maximum daily load for phosphorous is 60,000 kilograms, and the reservoir can currently accommodate roughly 35,000 kilograms of added phosphorous before reaching that limit.