SACRAMENTO A federal judge Thursday overturned a decision reducing the area designated as critical habitat for 15 rare vernal pool species.

Judge William Shubb ordered the U.S. Fish and Wildlife Service to reconsider its decision to delete 900,000 acres in 11 counties from its final designation of critical habitat.

That reduction included about 46,000 acres each in Butte and Tehama counties and 10,000 acres in Glenn County.

Judge Shubb gave the service 120 days to complete the review.

The action was taken as a result of a suit by six environmental groups including the Chico-based Butte Environmental Council.

Vernal pools are depressions that fill with water in the rainy season but are dry in summer.

They are home to a variety of unusual plants and animals, some of which are endangered.

The Endangered Species Act requires the Fish and Wildlife Service to delineate areas that are important to rare species' survival.

In August 2005, the service designated 858,846 acres as critical habitat for the vernal pool species, but that area was about 900,000 acres smaller than the area initially being studied.

Of that reduction, 136,000 acres were excluded from the final rule because they were part of national or state wildlife refuges or ecological preserves, department of defense or tribal lands, or lands covered by Habitat Conservation Plans or other management plans.

That accounted for most of Glenn County's reduction, as the Sacramento National Wildlife Refuge had been included in the initial proposal. Glenn was left with 155 acres of critical habitat in the final document

The other reductions were for economic reasons.