The history of the Tolay Lake Regional Park property is known to span 8,000 years.

Tolay Lake is a sacred spiritual center and a cultural landscape for the Federated Indians of Graton Rancheria, who are comprised of Coast Miwok and Southern Pomo tribal citizens. Coast Miwok people are the original descendants of the Tolay Valley. The Federated Indians of Graton Rancheria are the county's partners in stewardship of the Park’s cultural and natural resources.  

“The lake and surrounding area was highly sacred and was considered one of three areas in all of Northern California where Indian doctors from different tribes convened for sacred ceremonies and the exchange of ritual objects and songs for the purpose of healing,” according to Greg Sarris, chairman of the Federated Indians of Graton Rancheria.

Park history also tells the story of North Bay and California settlement. First farmed by settlers in the mid-1800s, the parkland has been in continuous agricultural use, even after its purchase by land agencies a decade ago. 

Tolay Lake was historically Sonoma County's largest freshwater lake. It is a naturally occurring lake that forms in wet seasons and draws down in dry seasons. Over the past 100 years, the lake bed was altered to accommodate ranching and farming. Restoration plans will return the lake to a natural system.

Tolay Lake is not a recreational lake. Paddling is not allowed when the lake is full, though occasional guided paddle trips may be offered in the future. The lakebed is not accessible to the public. 

The park is comprised of the 1,737-acre Tolay Lake Ranch property purchased by the Sonoma County Agricultural Preservation and Open Space District and transferred to Regional Parks and the 1,665-acre Tolay Creek Ranch property purchased and transferred by the Sonoma Land Trust. 

Acquisition of the lands that make up Tolay Lake Regional Park has protected the bulk of the Tolay Creek watershed, which drains to San Pablo Bay. The park also provides critical habitat linkages and wildlife corridors.