The Transportation Department's budget for fiscal 1984 reflects more strongly than in the past the "user-pays" philosophy that the Reagan administration espoused when it took office, as well as new "user-fee" taxes that Congress has passed to finance aviation improvements and reconstruct highways, bridges and mass transit systems.

It also reflects a continuation of the administration's opposition to federal operating assistance for local mass transit systems. That assistance, which local transit systems can use to pay salaries or buy fuel, amounts to about $1 billion in the current fiscal year. It has been trimmed in President Reagan's proposed budget to $275 million for fiscal 1984, a cut transit advocates regard as a bit dramatic.

"We always expect a little Mickey Mouse when we deal with the Office of Management and Budget," a transit lobbyist noted, "but this year we got Disneyland."

Last week a group of environmental and transit organizations wrote to Transportation Secretary Elizabeth Hanford Dole and charged that the proposal "flagrantly disregards" an agreement in the Surface Transportation Assistance Act of 1982, passed by the lame-duck Congress in December. That act is the one that raised gasoline and trucking taxes amid promises that $1.1 billion of the new revenue would go for transit capital projects, such as new buses and rail cars.

The legislation included an authorization of $875 million in federal transit operating aid for fiscal 1984. Thus the administration's proposal of $275 million is not only a significant drop from current levels, but also a big dip from what transit systems thought they had already won on Capitol Hill.

Because of the cut in proposed operating assistance, total transit outlays would decrease from $3.9 billion this year to $3.8 billion in 1984, even though the new gas tax money will be part of the program.

Proposed highway outlays would jump from $8.8 billion this year to $12 billion in fiscal 1984, reflecting the gasoline tax increase.

When the administration took office in fiscal 1981, according to the DOT budget briefing book, 45 percent of the DOT's budget authority was financed through user fees. The administration's proposed fiscal 1984 budget shows 69 percent of budget authority financed from user fees, which would reduce substantially the DOT's share of the government's general funds.