TUD Water Supply

The topography of Tuolumne County varies greatly from gently rolling terrain at the lower elevations, to steep hilly uplands deeply traversed by streams and tributaries that drain south to the Tuolumne River or north to the Stanislaus River. The size of Tuolumne County spans 2,274 square miles. The watershed elevation ranges from 9,000 feet elevation at the highest peak in the watershed above Pinecrest Lake to 4,200 at Lyons Reservoir. The majority of TUD customers reside in or near the community of Sonora which is at about elevation 2,000 feet. TUD also serves customers in several communities to the east up to about elevation 6,000 feet in the Sierras and west of Jamestown at an elevation of less than 1,500 feet.

Through its history, the water system, which is now operated by TUD, has changed from a utility serving mainly gold rush mining operations to one that serves the 21st century vibrant and diverse residential, tourism, institutions, commercial and industrial sectors of Tuolumne County.

The Ditch System

Approximately 95% of the water the District distributes originates from the South Fork Stanislaus River and is impounded in PG&E’s Lyons and Pinecrest Reservoirs. PG&E currently owns and operates a canal and flume system to convey water from Lyons Reservoir to the Phoenix Powerhouse. The District owns and operates a total of 71 miles of ditch, flume, pipe, and tunnel infrastructure that diverts water from the PG&E system at various locations. The District’s raw water conveyance system serves a variety of customer types and uses, including agricultural/irrigation water, ditch domestic use, commercial and industrial, wholesale, private and public water agencies, and raw water supply to other treated water agencies such as the Twain Harte Community Services District. The system also supplies water to 14 of the District’s own surface water treatment facilities. Raw water storage is augmented and regulated in Phoenix Lake and an assortment of smaller impoundments.

Raw Water Systems

Areas Served by TUD

Facilities & Infrastructure

TUD currently has an existing 1983 contract with PG&E to provide the water supply for TUD from the South Fork Stanislaus River. This water is stored in Pinecrest Lake, Lyons Reservoir, Phoenix Lake and other small reservoirs on the TUD ditch system. PG&E currently owns Lyons Reservoir and the 15.7-mile Main Tuolumne Canal that leads to its Phoenix powerhouse. From the Main Canal, TUD’s water splits into three branches – one serves Twain Harte, Soulsbyville and Tuolumne; and another feeds TUD’s network of ditches, pipelines and treatment plants that serve Crystal Falls, Big Hill and Columbia. The remainder goes into Phoenix Reservoir to serve Phoenix Lake, East Sonora, Sonora and Jamestown.

  • Water Connections – 14,105 homes and businesses
  • Delivered 1.4 billion gallons of treated drinking water in 2016
  • Operates 14 Surface Water Treatment Plants
  • 78 Treated Water Storage Tanks
  • 71 miles of ditch system, some of it originally built in the 1850s
  • Maintains 330 miles of treated water pipeline