The California Delta smelt controversy is an ongoing debate over the allocation of the state's limited water supply. At the heart of the conflict is a tiny, 3-inch endangered fish whose environmental protections require restricting the volume of water diverted from the Sacramento-San Joaquin River Delta. This pits the preservation of an endangered species against the agricultural industry and urban water users who rely on the water for irrigation and drinking.
The controversy centers on several distinct issues and perspectives:

Water for Fish vs. Water for People: Because the delta is a massive hub for exporting water to Southern California and the San Joaquin Valley, environmental regulations routinely mandate that water pumps be slowed or stopped to prevent the smelt from being killed. Farmers and certain politicians argue these protections restrict agricultural irrigation and cost the state millions of dollars in economic value.

High-Profile Political Scapegoating: The Delta smelt has frequently been thrust into national political rhetoric. Political figures have occasionally blamed ecological conservation efforts for systemic water shortages or even alleged that water was diverted away from firefighting efforts to protect the fish.
Ecological Necessity: Environmentalists and state officials, such as the California Department of Fish and Wildlife, assert that the Delta smelt serves as an ecological indicator for the broader health of the estuary. Maintaining a certain volume of water flow is also legally necessary to prevent saltwater from intruding into the delta, which would otherwise devastate both the ecosystem and surrounding agriculture.