The transformation from irrigation ditch to engineered reservoir was driven by partnership. In July 1910, the Oakdale Irrigation District and the South San Joaquin Irrigation District jointly paid $650,000 to co-own the water rights Charles Tulloch had assembled along the Stanislaus River. It was a significant investment for two agricultural districts, but the Stanislaus was a reliable snowmelt river, and controlling its flow meant controlling the fate of thousands of acres of cropland downstream. The two districts eventually received their first federal license from the Federal Energy Regulatory Commission to begin the Tulloch Project, with a permit effective from January 1, 1955. When that permit expired in 2004, a new license issued in February 2006 extended operations through January 1, 2046.

Lake Tulloch is the lowest link in a chain of three reservoirs along the Middle Fork of the Stanislaus River known as the Tri-Dam Project. Upstream, Donnells Dam and Beardsley Dam form the Upper Works, catching snowmelt high in the Sierra Nevada of Tuolumne County. Lake Tulloch, the Lower Works, sits at roughly 504 feet elevation where the foothills flatten toward the Central Valley. The entire system -- dams, tunnels, penstocks, and powerhouses -- was fully operational by 1957, just two years after the partnership was formally agreed upon. In the 1980s, small hydroelectric plants were added to each dam, converting the irrigation infrastructure into a dual-purpose system that generates electricity alongside its original mission of watering fields. The Turlock Irrigation District now controls these power plants, while the Tri-Dam Project's administrative offices operate from Strawberry, California, high in the Sierra.

Lake Tulloch holds a distinction unusual for California: private homes line its shores. In a state where most reservoir shorelines are publicly owned and development is prohibited, Tulloch's banks are dotted with houses whose backyards slope directly to the water. This anomaly reflects the lake's origins as a cooperative irrigation project rather than a state or federal water supply, which placed its shoreline under different development rules than reservoirs managed by agencies like the Bureau of Reclamation. The result is a community that feels more like a lakeside neighborhood than a typical reservoir recreation area, with docks, boathouses, and lawns reaching to the waterline. At 1,260 acres, the lake is large enough for serious boating but intimate enough that neighbors recognize each other on the water.

The Stanislaus River feeds Lake Tulloch with water released from the dams above, and that water stays cold even through the dry heat of a Central Valley summer. The temperature makes Tulloch productive fishing water. Rainbow trout and brown trout thrive in the cooler depths, while largemouth and smallmouth bass hold in the warmer shallows and coves. Catfish, crappie, and bluegill round out the catch. The South Lake Tulloch RV Campground and Marina offers 130 waterfront sites ranging from lakefront cabins to tent sites with fire pits, along with a restaurant, general store, gas dock, and boat rentals. Boating, swimming, and camping draw visitors from the valley floor, many of whom are escaping the triple-digit temperatures that bake the lowlands from June through September. Up here in the foothills, the elevation provides a few degrees of relief and the water provides the rest.