In the final four weeks of the General Assembly, deals and double-crosses are multiplying, nowhere faster than in the House Environmental Matters Committee. There, several leading vote-traders on the committee said the 24 members have crafted several marriages of convenience designed to ensure passage of controversial bills to ease strip-mining regulations, ban phosphate detergents and possibly lift by 1987 the moratorium on taking rockfish from Maryland waters.

Two of the measures -- bills to allow coal mining on steep mountain slopes and ban phosphates -- have been the object of intense and expensive lobbying campaigns by industry on the one hand, and environmentalists and the Hughes administration on the other. Both bills were scheduled for a vote in committee today.

But Chairman Larry Young (D-Baltimore) abruptly canceled the scheduled votes to give the opposing sides on those issues additional jockeying time.

"There are so many factions and fractions that need more time on those bills," Young said.

Even in this political town where deal-making over a trio of essentially unrelated bills is nothing new, the jockeying on Young's committee struck several observers as the most arcane in this legislative session, which has 26 days to run.

One arrangement would trade votes in support of steep-slope mining for votes approving the phosphate ban. Another would marry the phosphate ban to a legislative review of the rockfish moratorium.

Lobbyists for the Maryland Coal Association, which favors the steep-slope bill, and soap manufacturers who oppose the phosphate ban, grumbled openly about the vote-trading. Such complaints fell on deaf ears.

"Paula Hollinger and I are working one deal," declared Del. Lawrence A. LaMotte, referring to his fellow Baltimore County Democrat. LaMotte said he and Hollinger were gathering votes to pass the phosphate ban in return for votes to approve a bill sponsored by Eastern Shore delegates that would give the General Assembly authority to review the rockfish moratorium in 1987, two years before its scheduled end.

"The only way to get phosphates is to cut the rockfish moratorium at the 1987 session," said LaMotte.

The phosphate ban fairly sailed out of the Senate today on a 39-to-5 vote, but several House committee members, including Young himself, gave it little chance of final passage.

Young, reflecting some of the deals that may already have been cut in his committee, confidently predicted passage of the steep-slope bill and the legislative review of the rockfish moratorium.

That dismayed officials in the state Natural Resources Department, many of whom spent hours today pacing the hall outside Young's committee room.

If Young's committee approves the strip-mining bill but kills the phosphate ban "then that's a double whammy on two of the most environmentally important issues of this session," said John Griffin, the department's deputy secretary.

Griffin's boss, Secretary Torrey C. Brown, was slightly more matter-of-fact. "This just happens to be the time of year when all the 'snakes' come out," he said.