The Martha’s Vineyard Commission last Thursday unanimously approved a family plan to protect Flat Point Farm in West Tisbury as a working farm for the future.

The plan was submitted by the Fischer family which has owned the 91-acre farm nestled between two coves of the Tisbury Great Pond for several generations.

The plan, which is preliminary, calls for dividing 67 acres of the farm into two large conservation parcels and splitting the remaining land into five four-acre lots — sized so guest houses would not be allowed — along with three one-acre youth lots that will be awarded to family members in the future.

The property is currently protected under chapter Chapter 61A of the Massachusetts General Laws, which offers a property tax reduction for land that is farmed. The plan was approved by the town planning board earlier this year and was referred to the Martha’s Vineyard Commission for a review as a development of regional impact (DRI).

Because it is a form B preliminary plan, the decision is not recorded on linen; the idea of the preliminary plan review was to obtain feedback from the commission.

Earlier this month the land use planning committee unanimously recommended that the full commission approve the plans.

Discussion last Thursday was brief and included a report from Linda Sibley, chairman of the land use planning committee. Commission member Douglas Sederholm raised concerns that the Fischer family still has not addressed the issue of nitrogen loading into Tisbury Pond.

According to the calculations of the commission water resource planner Bill Wilcox, the farm contributes roughly two and a half times as much nitrogen to the Tisbury Great Pond as would otherwise be allowed under the commission’s 2007 water quality policy.

The policy seeks to regulate development in light of the amount of nitrogen going into the pond, but it is aimed mainly at residential and commercial subdivisions, since the major source of nitrogen is septic systems.

Because of the considerable complexities involved, the policy does not address agricultural operations

Mr. Sederholm said he had read the minutes of the land use planning committee meeting, which he did not attend, and was still worried that the Flat Point Farm plan did not meet the water quality policy standards. But since it is a preliminary plan, he noted that the commission will get another chance to review the issue in the future.

“I am a little unclear of the significance of approving a [Form B] plan. It sounds like it’s meaningless, essentially. They can’t go out and record this, and they can’t go out and actually do what is in the plan . . . but as long as it is absolutely deadlocked certain they have to come back [for approval] of their final plan, then I am comfortable with this,” he said, adding:

“I am not comfortable with the open-ended nature of these ongoing water quality issues.”