Giant pumps hum inside a warehouse-like building, pushing water from the Sacramento-San Joaquin River Delta into the California Aqueduct, where it travels more than 400 miles south to the taps of over half the state’s population.

But lately the powerful motors at the Harvey O. Banks Pumping Plant have been running at reduced capacity, despite a second year of drought-busting snow and rain.

The reason: So many threatened fish have died at the plant’s intake reservoir and pumps that it has triggered federal protections and forced the state to pump less water.