A small reptile, 4 to 7 inches long, white with a patchwork of brick-like black markings and feet so webbed it can "swim" through loose sand, is becoming this valley's equivalent of the snail darter.

The snail darter was the tiny member of the perch family whose threatened extinction stymied completion of Tennessee's $98 million Tellico Dam for a dozen years. Congressional action last September finally exempted the dam from the Endangered Species Act and allowed its use.

The Coachella Valley's reptile inhabits a sun-scorched, windblasted stretch of desert east of Palm Springs.

This sandy area once was thought to be so inhospitable that no one would ever want to live there.

But the unexpected demand for desert housing and shopping areas has pushed development into the lizard's habitat.

The result is a controversy involving environmentalists, desert developers, politicians, the U.S. Fish and Wildlife Service and the Office of Endangered Species.

The object of this brouhaha, Uma inornata, or the fringe-toed lizard, exists in three stretches of California desert: the Coachella Valley, the Imperial Sand Dunes near Brawley and in the Mojave.

Zoologists disagree whether the three desert habitats support separate species or separate subspecies of the same lizard, because, as time passes, the lizard's coloration adapts to the hue of the dunes it inhabits.

But they agree that the white fringe-toed lizard exists nowhere except in the Coachella Valley.

They also agree that any change affecting the blowing sand where the lizard lives threatens its future. One biologist has predicted that if the present rate of development continues in the valley, the lizard will disappear in 50 years.

That prospect was sufficient to prompt the state Fish and Game Commission to declare the fringe-toed lizard an endangered species on June 27.

Environmentalists will seek a similar listing with the federal government, designation of part of the valley as the lizard's "critical habital" and extablishment of a preserve to ensure the lizard's continued existence.

But local business leaders, developers and landowners, eyeing the recent population migration toward Southern California's deserts, argue such action will strangle growth in the Coachella Valley, causing a loss of up to $25 million in revenue each year.

The area's congressman, Rep. Jerry Lewis (R-Calif.), fears a federal endangered species designation would affect future federal funding for the valley and interrupt flood-control work under way by the U.S. Army Corps of Engineers.

"If you are not worried about the general economic impact on the valley, one certainly has to be concerned about the availability of adequate flood control for those people, who are my constituents," Lewis remarked. "There could be another species endangered -- homo sapiens."

A federal listing of the lizard as endangered could influence future grants for Federal Housing Administration and Veterans Administration housing loans, water and sewar services and future flood control projects, developers say.