The United States Geological Survey ( USGS ) operates , or has operated , several stream gages along the Tuolumne River . Today , average annual river flows reach a maximum in the short stretch between Don Pedro Dam and La Grange Dam , about above the mouth , before the start of large irrigation diversions . A USGS gage recorded an average annual flow of here between 1911 and 1970 , with a maximum peak of on January 31 , 1911 , and a minimum monthly mean of in October 1912 . During the Great Flood of 1862 , the river reached an estimated peak of here , after a record of rain fell in the Tuolumne River basin between November 11 , 1861 and January 14 , 1862 , as recorded at Sonora . The gage was not in place during this time
Great Flood of 1862
Great Flood of 1862
Tuolumne River