The Washington Suburban Sanitary Commission (WSSC) last week approved a preliminary fiscal 1981 budget that calls for a 28 percent increase in water and sewer rates, effective April 1. No final action will be taken on the budget until after a public hearing on Feb. 12.

Though by no means final, last week's action broke a 3-3 deadlock between the Montgomery and Prince George's delegations over a preliminary set of new rates to be included in the fiscal 1981 budget.

For the past month, the six Montgomery and Prince George's commissioners had disagreed along county lines on the size and timing of proposed water and sewer rate increases.

The three Montgomery County commissioners favored hiking the rates by 28 percent in April, while the Prince George's County delegation wanted to put off any rate changes until July.

But because the WSSC was legally requied to publish a budget before hearings began and the WSSC budget staff needed rate projections before such a budget could be prepared, the commission agreed to use the 28 percent level in its preliminary budget.

"I don't think the vote means that the Prince George's delegation is supporting a 28 percent rate increase to take effect in April," said Johanna Norris, head of the Prince George's WSSC delegation. "Any number of things could happen between now and the time we send the budget to the county executives. As far as we're concerned, no real decisions have been made yet."

The commission must hold a public hearing before sending a proposed budget to the two county executives by March 1. After the executives review that budget, the county councils then vote on it. While the decisions made by the two councils are not legally binding, the commissioners usually follow the advice of their legislative bodies.

"I don't see the councils approving any rate increases before the start of the new fiscal year (July 1)," said Norris.

According to Lawrence Brooks, another WSSC commissioner from Prince George's, negotiations over the size and timing of the rate increases are continuing and no settlement is likely until the financial report for the first seven months of fiscal 1980 is released and the public budget hearing is held.

In its present form, the preliminary budget calls for a $277.2 million capital and operating outlay for fiscal 1981. It forecasts that if the 28 percent rate hike does not go into effect by April 1, a 36 percent water and sewer rate increase will be required in July.

The capital improvements program in the WSSC budget, another source of conflict between the two county delegations, would require $128.4 million for fiscal 1981, nearly $96 million below last year's expenditures. Because there are several capital projects on which the two counties disagree, the budget included only carryover projects contracted during fiscal 1980.

Among the projects that have split the two counties -- and are not included in the preliminary capital improvements budget -- were a flow-diversion project and an expansion of the Piscataway Sewer Treatment Plant.

Under the flow-diversion project, Montgomery County would get additional sewer capacity at the Blue Plains Sewer Treatment Plant if Prince George's agreed to use its Western Branch Plant instead of Blue Plains.

"We don't need the extra sewer capacity right now, but we'll need it in a few years," said Jesse L. Maury, a WSSC commissioner from Montgmery County.

The public hearing on the budget is to take place in the WSSC's main office building in Hyattsville at 8 p.m. Feb. 12.