WILDFIRE THREATENING ARROYO TOAD : FEARS ARISE CONCERNING HABITAT.

Byline: Laurence Darmiento Daily News Staff Writer

With the wildfire north of Castaic still out of control after more than four days, concerns mounted Thursday that key habitat for an endangered species was being lost among the 20,000 acres of charred chaparral.

The Southwestern arroyo toad - a species native to Southern California that was declared endangered just two years ago - makes its home among sandy stream beds in the forest's Saugus district.

While not threatening its extinction, the massive forest fire was beginning to threaten the toads' return to the area once the fire is finally knocked down, said U.S. Forest Service biologist Patti Krueger.

``This is critical habitat,'' Krueger said. ``It may decimate that portion of the toad population.''

The toad, which measures just a few inches in length and feeds on small bugs, has been found in other regions of the forest not in the fire's path, as well as in other undeveloped areas of Southern California, she said.

But the wide-scale development of the Southland - especially along the relatively flat river valleys that the toad prefers - has led to a drastic reduction of its population, Krueger said.

Despite fire's positive role in a forest ecosystem - burning old brush and germinating seeds for new plants - it would have a disproportionately negative effect on the toad, she said.

Since it is only flourishing in various isolated habitats, those habitats cannot be naturally re-populated when they are destroyed, she said.

The fire, which was believed set by a teen-age runaway north of Lake Hughes Road next to the Golden State Freeway, has started to burn mostly in a northeasterly direction. Fire officials now say it could consume as much as 70,000 acres, reaching Liebre Mountain, before it is controlled.

That region also is home to various threatened species, including the California spotted owl, the desert wood rat and the bald eagle, she said.

It is habitat as well for large mammals such as bears, mountain lions, deer and a variety of smaller animals. Krueger said the larger animals should survive well, while even insects can survive if they burrow underground.

Krueger is a member of a rehabilitation team that will examine the fire's effects, not only on plants and animals but on campgrounds and other man-made improvements.

Despite the wildfire's large size and proximity to Castaic Lake, it is not expected to affect drinking water supplies, officials said. The lake, which provides water to much of the Santa Clarita Valley, is fed by the California Aqueduct from water supplies in Northern California.

Rainfall only accounts for a small percentage of its volume. In addition, only part of its watershed has been blackened, said Robert Sagehorn, manager of the Castaic Lake Water Agency.

The lake is expected to become less clear after major rains; however, it should be possible to remove particulates through the regular treatment process, he said.

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2 Photos

Photo: (1--color) Blackened slopes from the Marple Firecan be seen along the Golden State Freeway near Castaic.

(2--color) Firefighters nap Thursday morning at the Castaic Lake recreation center, currently a base of operations for battling the blaze.

Hans Gutknecht/Daily News