STANFORD, Calif. (AP) — Federal regulators are investigating whether Stanford University's operation of a San Mateo County dam is illegally harming threatened steelhead trout on California's central coast.

The Palo Alto Daily News (http://bit.ly/12NO71q) reports that the National Marine Fisheries Service is probing the university's operation of Searsville Dam.

The central coast population of steelhead — which live part of their lives in the ocean and part in freshwater creeks — is a threatened species under the Endangered Species Act.

Environmentalists argue the 65-foot-tall dam blocks the fish from accessing upstream habitat on San Francisquito Creek.

Stanford spokeswoman Lisa Lapin says the school is already in the midst of a two-year study meant to address concerns over the dam's effects on a number of threatened and endangered species that live in the area.