PB PHOTO | The manor house at Sylvester Manor.

Supervisor Jim Dougherty has urged the Town Board to join him in Riverhead when the Suffolk County Legislature conducts a hearing next month on a Setauket legislator’s proposal to impose a 90-ban on land preservation purchases.

In a memo to Town Board members and the Community Land Preservation Board, the supervisor said two pending Sylvester Manor development rights purchases — worth more than $7 million, of which the county is paying 70 percent and the town 30 percent — are considered “safe” from a moratorium “but that’s a relative term — let’s close those deals.”

He said the proposal by Legislator Kara Hahn isn’t likely to pass but “it is a portent of a serious mood change possibly emerging in Hauppauge.”

Legislators, in fact, second guessed one of the Sylvester Manor acquisitions last month before voting 15-1 to support it, with the legislator’s presiding officer suggesting that further deals should be subject to a public referendum. The legislators went on to vote down an acquisition in Riverhead.

Supporters noted the public had voted eight times over the last 20 years to support open space funding programs.

A public hearing on the Hahn moratorium proposal is set for Tuesday, March 13 in the Rose Caracappa Legislative Auditorium of the Riverhead County Center at 2:30 p.m.

The supervisor said he had been asked to attend and speak against the proposal and also would “mobilize” members of the East End Supervisors and Mayors Association, of which he is chairman.

He asked the 2-Percent board to send a representative. “Letters are good but bodies in the room have more effect,” he wrote.