Vernal pools at Costa Mesa park need protection, agency finds

The environmentally sensitive vernal pools at an Orange County regional park are being threatened by everything from pedestrians to pesticides and need to be better protected, the U.S. Fish and Wildlife Service has found.

After an 11-month review of the seasonal pools at Fairview Park in Costa Mesa, the wildlife service said the city should take action, including fencing off the area to protect the pools, which are home to the endangered San Diego fairy shrimp.

The report comes after the federal agency began looking into a dispute over unpermitted work to a pair of walking trails and the negative effect that work might have on the vernal pools, a wetland-like habitat.

City officials and their environmental consultants plan to meet with the agency to “clarify the recommended measures, refine the scope of work and develop a work plan to help preserve vernal pools,” the city said in a statement.

The federal agency’s suggested mitigation measures include various watershed restoration efforts and posting more educational materials about the park’s biology.

The wildlife service is also recommending large amounts of new fencing within a 95-acre area of the park, which would restrict access to areas now open to the public.

The fencing would create a larger buffer between public-access areas and the seasonal ponds, which grow as they are filled by rainfall. The largest of the pools is roughly three acres.

The report concludes that the seasonal pools have suffered over the years. Pedestrians, dogs, bicycles, cars, pesticides, herbicides, installed landscaping and improvements to a nearby high school football stadium are listed as potential culprits.

Fencing for the stadium, which abuts Fairview Park, has hurt the ability for water — which the fairy shrimp need — to collect in one of the vernal pools, the report states.

Another of the vernal pools had been used as part of a temporary parking area, the report notes.

That pool and another near an Estancia High School fence have been roped off by the city since September to discourage public access.

The federal report does not address the unpermitted work to the hiking trails, the issue that initially caught the agency’s attention.

Since the Daily Pilot first reported the improvements made to the trails, no one has taken responsibility for the job. The city has spent at least $19,000 removing the decomposed granite that was used to improve the pathways.

bradley.zint@latimes.com