Saving the Lower San Joaquin River and Its Tributaries: The Importance of Instream Flow

In California's Central Valley, the Stanislaus, Tuolumne, and Merced Rivers begin in the southern Sierra Nevada Mountains and flow westward to join the lower San Joaquin River before flowing into the San Francisco Bay-Delta Estuary. However, as this fact sheet explains, unsustainable water diversions for agricultural irrigation and urban water supplies—recently exacerbated by increased demand due to California's historic drought—has diverted the vast majority of water from these rivers, placing them in critical condition. This has had devastating impacts on native salmon and steelhead runs and poses grave threats to the rivers' overall water quality, which extends to the health of the estuary and entire watershed. This year, California's State Water Resources Control Board (SWRCB) has an opportunity—and an obligation—to establish new water quality and flow standards in the Stanislaus, Tuolumne, and Merced Rivers to restore them and the estuary to health.