San Joaquin, S. Fork - Mono Hot Springs to Middle Fork, to Mammoth Pool

San Joaquin, S. Fork, California, US


Mono Hot Springs to Middle Fork, to Mammoth Pool

Usual Difficulty V+ (for normal flows)
Length 31 Miles
Avg. Gradient 136 fpm
Max Gradient 320 fpm

River Description

This section was finally boated in late August of 2008, by Darin Mcquoid, Kevin Smith, Ben Stookesbury and Matt Thomas. They took 4 days to travel about 40 miles. They actually put in on Mono Creek below Mono diversion, because SCE was releasing 500 cfs from Edison reservoir down Mono Creek to the SF San Joaquin and then to Mammoth Pool. SCE had to transfer water for downstream farmers despite having several critical powerhouses down for maintanence.

Darin has a trip report with photos at JeffersonStateCreeking.

Ben has a trip report with video at: August 30th, 2008: South Fork San Joaquin

To our knowledge, up until 2008 there had been no descents of the SF San Joaquin past the Mt. Tom heliport and perhaps no descents since the early trips reported in Holbeck & Stanley. Lack of flow information and lack of dependable flows are big reasons for this. The scenery is fantastic and much of the boating is excellent. The boating that lies past Mt Tom to the middle fork confluence is steep and committing. Many difficult and challanging portages must also be overcome. 500 cfs is an optimum flow according to the first descent team.

After one reaches the Middle Fork confluence, additional issues arise as one must deal with the combination of flows and the remaining serious rapids and portages down to Mammoth Pool. During a spring or early summer run, flows in the middle fork will be high. Even side creeks in the SF will add more flow over the course of the run. The 2008 team reported that the 650 cfs flow (approximate) was an excellent level for the middle fork between the south fork confluence and Mammoth Pool.

There are a few situations in which boatable flows may be found in the SF San Joaquin.

Spring sills from Florence can provide moderate flows but usually provide flows that are high to much too high for boating. Even when moderate flows are released from Florence, the natural flows in the middle fork will be very high during any spring releases. These flows are good if boaters are willing to take out at Mt. Tom Heliport or at the Rattlesnake Crossing trail. Both options involve very long hikes.

Releases into Mono Creek from Edison reservoir sometimes occur in the summer. The timing and amount of these releases may provide the best potential for boating all the way down to the middle fork and on to Mammoth Pool.

Mono Hot Springs; 6560' elevation, topozone map, google map.

Middlie Fork confluence, 3700' elevation.

Mammoth Pool, is around 3400' elevation.

Average gradient from Mono Hot Springs to the middle fork is 136 feet per mile, but the first half is low gradient and the second half is high gradient. There are several sections of 300 + feet per mile.

Other information sources:

JeffersonStateCreeking 2008 trip report with photos

StreamTeam Status: Not Verified
Last Updated: 2008-11-30 09:51:51


Rapid Summary

Mile Rapid Name Class Features (Legend)
4.0Mono Creek confluence
6.6Rattlesnake Crossing trailAccess
21.0Middle Fork confluence

Rapid Descriptions

Mono Creek confluence

During certain release events, Mono Creek may provide almost the entire boatable flow into this reach.  When that is the case, boaters will have to either hike in to the SF on one of several trails or hike a trail that follows Mono Creek, or descend Mono Creek itself.

Rattlesnake Crossing trail

A trail bridge crosses the river, offering potential access to or from the river. 

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