The cornfields may still be parched, but the political drought that has dried up new water projects on Capitol Hill since the late 1970s appears to be ending.

The House Appropriations Committee today is to consider an $118.9 million supplemental spending bill for 32 navigation, flood control, water supply, hydroelectric and erosion abatement projects in 26 states for fiscal 1984.

The proposal amounts to a tiny down payment on roughly $13 billion in water projects that another House committee wants to authorize for the next decade. A Senate committee is considering a smaller version of the same measure.

At least two of the projects, one of which was on former president Jimmy Carter's 1977 "hit list" that helped block financing of new projects over the past few years, already have drawn fire from environmental groups. "They've resurrected two of the worst water projects we've ever seen . . . the bottom of the barrel . . . real dogs," said Brent Blackwelder, Washington representative of the Environmental Policy Center.

One of the projects is the Narrows Dam on the South Platte River in northeastern Colorado, on the Carter list, which environmentalists say would destroy wildlife habitats in violation of international treaties. The other is the Animas-LaPlata reclamation project in southwestern Colorado, which environmentalists contend would pump water from below a pile of uranium mill tailings and use three times as much electricity as it would provide.

But the demand for new projects has grown steadily since the number of new starts, once 30 to 40 a year, declined to a trickle after Carter took aim at what he called wasteful, environmentally damaging dams and related projects. And the congressional purse strings have loosened generally in Congress since the heavy cost-cutting of the first two years of the Reagan administration.

President Reagan, who has never turned off the spigot for water projects despite spending cutbacks in other areas, proposed $33.2 million for 16 new projects in fiscal 1984. This is less than one-third of the amount that has been proposed by the House Appropriations subcommittee on public works.

The subcommittee-drafted bill is on top of a regular energy and water appropriations bill, appoved by Congress and signed by Reagan, that funded ongoing water projects but left new projects for a supplemental appropriations bill.

The water projects supplemental measure will be considered in conjunction with an omnibus stopgap "continuing resolution" to fund the government agencies for which regular appropriations bills are not passed by the start of the new fiscal year on Oct. 1. As drafted by committee leaders, the continuing resolution would last until Nov. 15 and include about half the 13 regular appropriations bills for next year. However, by limiting the stopgap financing to 45 days, the panel hopes to keep up pressure for passage of regular appropriations bills and discourage troublesome "riders" that could complicate the passage of the continuing resolution.

Failure to pass the bill by the end of the fiscal year on Sept. 30 would lead to at least technical shutdowns of agencies for which regular appropriations bills have not passed.

In an unusual development, the Appropriations Committee also is to consider a miscellaneous supplemental appropriations bill for fiscal 1984, including roughly $400 million in veterans' compensation, a stipend for the widow of the Rep. Larry McDonald (D-Ga.), who was a passenger on the Korean airliner shot down by the Soviets, and a request from the administration for nuclear weapons funding.

Such supplementals usually come well after the start of the fiscal year, but this one is required because Congress was unusually speedy in passing at least a few of its fiscal 1984 money bills this year, committee aides said.