MERCED, Calif.--A federal wildlife agency is warning of more potential endangered species problems for the proposed site of the University of California at Merced.

In comments on an environmental report for the planned 10th UC campus, the U.S. Fish and Wildlife Service says that a seasonal wetland harboring the endangered Conservancy fairy shrimp lies just one-half mile east of the main campus site — close enough to be harmed by related human activity.

The Conservancy fairy shrimp is a tiny, delicate crustacean that propels itself through the water with 11 pairs of swimming legs. Its eggs can survive for years in the soil beneath dry pools, ready to hatch when winter rains refill the pools.

But its survival is in peril. Only 17 populations of the Conservancy fairy shrimp are known to exist. And regulators say they are worried that building UC Merced will attract large numbers of people and other traffic to the nearby pool, upsetting water chemistry and flows.

"The addition of more than 47,000 people living and working on the campus and community will bring hikers, joggers, equestrians, mountain bikers, dog walkers, off-road vehicle users and other recreationalists into crucial habitats ... adjacent to the campus," service officials said in their comments.

The fairy shrimp population is in a "rare and unusual pool" that is easily visible from the campus, the service said. A shallow, clay-lined depression called a vernal pool, it fills with water from winter rains, then slowly dries out in spring and summer, bringing life to scarce, dormant plants and animals.

Already, the presence of vernal pools and related environmental concerns have forced one change in the campus site. Initially slated for a spot about one mile northeast of Lake Yosemite, where numerous vernal pools can be found, the site was moved last winter to a 910-acre parcel centering on the Merced Hills Golf Course, immediately south of the lake.

The service is the principal agency enforcing the Endangered Species Act. It could derail the new site if it seemed likely to issue an official opinion that campus development would jeopardize the species' survival. But a service official said it's too early to say whether that will happen.

"We haven't gone through that analysis yet," said Vicki Campbell, conservation planning division chief in the service's Sacramento field office. "But we did want to make Merced County and the University of California aware that we are very concerned about that pool and how close it is to their campus."

UC officials predict they will be able to deal with that concern and move ahead with their project, which is scheduled to begin construction early next year and receive its first 1,000 students in fall 2004.

"We recognize that this [vernal pool] is an important concern, and we will create a plan that protects this habitat," said UC spokesman James Grant.

The service was not the only powerful federal agency to make critical comments about the UC Merced plans.

The Environmental Protection Agency, which will be involved in the review process for whatever wetlands the UC project modifies or eliminates, said that UC planners should give more serious consideration to building a smaller campus with taller buildings. In the environmental report, UC officials rejected that option for reasons that included the "visual quality" of the campus, EPA officials noted.

Other commenters proposed a different location for a 2,133-acre off-campus community that UC planners envision for a site just south of the campus boundary at Bellevue Road and Lake Road. UC officials have formed a joint venture with the Virginia Smith Trust, which owns the golf course and other lands near Lake Yosemite, for the first phase of the off-campus community development.

Many of the commenters, including several farm groups, said they would prefer that the off-campus community be located wholly or partly west of Lake Road, in an area that already lies within Merced's urban growth boundaries. The current plan places the community entirely east of Lake Road.

Environmentalists and others also made procedural objections, finding fault especially with the fact that UC and Merced County produced separate environmental reports for the UC campus and the off-campus community. Having two reports, they alleged, makes it difficult to gauge the full effects of the UC project.

But dozens of other commenters praised the project and said it was high time to move ahead.

"UC Merced gives hope to a region plagued by double-digit unemployment [and] low educational attainment and [is] home to some of the hardest-working individuals on planet Earth," wrote Brett Baker, president of the Merced chapter of the Building Industry Association of Central California.