Established in 1984, the Transmission Agency of Northern California (TANC or Agency) is a California Joint Powers Agency.

Its membership currently consists of the California cities of Alameda, Biggs, Gridley, Healdsburg, Lodi, Lompoc, Palo Alto, Redding, Roseville, Santa Clara, and Ukiah; the Sacramento Municipal Utility District (SMUD); the Modesto Irrigation District (MID); and the Turlock Irrigation District (TID). The Plumas-Sierra Rural Electric Cooperative is an associate member of TANC.

TANC currently owns approximately 87 percent of the California-Oregon Transmission Project (COTP) and has transmission rights contracted from the Pacific Gas and Electric Company.  The Agency is a member of WestConnect, wesTTrans and the Western Electricity Coordinating Council and is registered at North American Electric Reliability Corporation as a Transmission Owner, Transmission Planner and a Transmission Service Provider.