A proposal to further limit the quantity of pollutants dumped into the Potomac River by the Blue Plains regional sewage treatment plant could result in a moratorium on development in both Montgomery County and the District of Columbia, county and city officials said yesterday.

City officials say they are more optimistic than the county about the effect of the proposal made by the federal Environmental Protection Agency. But both they and the county representatives have begun intense political maneauvering in an effort to prevent the loss of sewage treatment capacity without which new construction is impossible.

Montgomery, which extricated itself from an eight-year-long sewer moratorium last year, faces a new halt to development because it is nearly exhausted its treatment capacity at Blue Plains.

The city is approaching a similar crisis, which threatens the completion of $1.3 billion worth of development under way or being planned.

The proposal to cut down on the pollutants emitted by Blue Plains is contained in a draft of a permit renewal, which the EPA requires every five years.

It would tighten the existing permit's requirements in two key areas, according to William Colony, the district EPA official. It would limit the quantity of pollutants discharged into the river and require prevention of most raw sewage overflows into the river, which occurs after storms.

The latter requirement has made the greatest impact on Blue Plains users because, under strictest interpretations, it could force a reduction in the quantity of sewage now treated at the plant, Colony said.

"One reading is that you couldn't add any more hookups to Blue Plains, period," Colony said, adding, "I don't necessarily sucscribe to that view."

The EPA is seeking comments on the proposal from Blue Plains users and environmnetalists in advance of a public hearing May 21. The new permit could take effect as early as July 1, although some of its river clean-up standards would not be enforced until Jan. 1, 1981, Colony said.

Participants in the maneauvering-described by one observer as "50 percent politics and 50 percent engineering"-are all the plant's principal users, including Prince George's and Fairfax counties.

But the greatest effects of the new pollution limits would be felt in Montgomery County and the city. Both Prince George's and Fairfax have other sewage treatment plants and would not be seriously affected.

Administrators of the jurisdictions using Blue Plains have scheduled a meeting for today to begin trying to negotiate a compromise.

"I am optimistic we will work it out," said Herbert Tucker, director of D.C.'s Department of Environmental Services.

The urgency of Montgomery's position was emphasized yesterday by County Executive Charles W. Gilchrist's sharply worded comments in a letter to Prince George's officials. Gilchrist outlined what he said Montgomery needs immediately to prevent another construction halt.

He told the Montgomery County Council it is "unconsicionable" that Prince George's has refused to allow Montgomery to use excess sewage treatment capacity in Prince George's sewage plants paid for jointly by Montgomery and Prince George's ratepayers to the bicounty Washington Suburban Sanitary Commission.

"The resultant cost is of millions of dollars in capital expenditure for the ratepayer, and severe economic hardship for the builders and citizen of both counties," Gilchrist wrote. Repeatedly we have sought agreement from Prince George's County officials on this basic premise."

Chief among Gilchrist's demands was access to the 36 million gallons a day of uncommitted WSSC-financed sewage treatment capacity. That is enough for 90,000 new homes.

In another move, made yesterday at Gilchrist's request, the County Council upheld its preliminary position and voted to defer until next year support for about $50 million in projects needed to complete a 25-mile water supply pipeline that crosses Montgomery into Prince George's.

The $107 million project, designed largely to benefit Prince George's after the mid-1980s, has been under construction periodically since 1966. Six of the seven council members agreed with Gilchrist that there is no evidence it is needed now.

In another development in the feuding between the two counties, Prince George's County Council Chairman Williams B. Amonett chided what he called Montgomery's "apparent negative attitude" and asked the WSSC for a feasibility study of constructing a bicounty sewage sludge composting on Western Branch in Prince George's.

He said Montgomery's plans to proceed with its own plant next to the Prince George's boundary would result in two plants at three times the cost of one facility.

Earlier this year, Prince George's officials flatly refused to build a bicounty composting plant within their county's borders.