Supply and Demand Assessment (SDA) – Pismo and San Luis Obispo Creeks Watershed

The Pismo and San Luis Obispo Creeks watershed covers approximately 122.5 square miles in San Luis Obispo County. The watershed includes three main streams: Upper San Luis Obispo Creek, Lower San Luis Obispo Creek, and Pismo Creek. These creeks originate in the Santa Lucia Mountains and drain westward to the Pacific Ocean near Avila Beach and Pismo Beach, respectively. Major tributaries include West and East Corral de Piedra Creeks, Cañada Verde, and Cuevitas Creek. The watershed ranges in elevation from sea level to over 2,700 feet and has a Mediterranean climate with wet winters and dry summers. Average annual precipitation is approximately 24 inches, mostly falling between November and March. The land cover is primarily shrubland, grassland, and mixed forest, with developed areas concentrated in the cities of San Luis Obispo, Pismo Beach, and surrounding communities.

Pismo Creek provides important habitat for federally threatened steelhead trout (Oncorhynchus mykiss), which rely on seasonal streamflow for upstream migration and juvenile outmigration. However, low summer baseflows, habitat fragmentation, and sedimentation impair habitat quality. The creek is listed as impaired under Section 303(d) of the Clean Water Act for multiple pollutants including pathogens, nutrients, metals, chloride, and sodium.