Hetch Hetchy reservoir spills during the spring of many years. Most spill flows will probably be too high for boating in this section, so your best bet will be at the very beginning and the very end of spill. There is a USGS gauge available for this section. Ben Stookesbury reported after a 2008 trip that he would have prefered more than 200 cfs, but not a lot more.
|TUOLUMNE R AB EARLY INTAKE NR MATHER CA|
|usgs-11276600||200 - 600 cfs||V||00h47m||347 cfs (running)|
|9y318d11h31m||Tuolumne [CA]||O'Shaughnessy Dam, Hetch Hetchy||n/a||Thomas O'Keefe|