A truce was declared Wednesday night in the on-and-off sewer war between Montgomery and Prince George's counties as the two county council reached several tenative agreements on the controversial issues of waste disposal and sewage capacity.

Both counties want a large share of the available sewage treatment capacity - and the development it would allow.And Prince George's officials were annoyed by Montgomery's plan to build a sludge-composting plant at a site near the Prince Georg's border.

At Wednesday night's session, both councils agreed a face-to-face meeting in July to discuss the allocation of sewage capacity.

Montgomery officials were informed last month that they have used up their treatment capacity at the Blue Plains plant in Washington, and thus face the possibility of renewed mortorium on development. Prince George's has treatment capacity left for about 100,0000 new homes - based on an average of 400 per gallons per day for a single-family dwelling. During the next 15 years county planners anticipate that Prince George's will need about 75,000 new homes.

For that reason, Montgomery has asked that Prince George's turn over part of its excess capacity. Thus far, however, Prince George's officials have balked.

The councils also tentatively agreed on a compromise site for the sludge composing plant, which would further treat the semisolid residue of the sewage treatment process. Although Montgomery Council President Neal Potter said that Montgomery will continue with plans for a plant in Calverton, in the populous eastern corner of the county, he said his council would gladly accept to plans for a plant in southern Prince George's.

"The advantages of Western Branch [the prince George's location] are obvious," Potter said. "The area is less populous and there would be less hardship on citizens from both counties.

The Calverton location has been under fire from citizens in both counties who live near the proposed site. After Wednesday's meeting, however, some Prince George's officials said that the location of the sludge plant could again become an issue at the July and the composing plant could be something that could be a tradeoff," Prince George's Council administrator Samuel Wynkoop said yesterday.