Incorrect beta cadster. St vrain suffers from lack of information due to gauges in poor locations and gauges that were turned off.
Kevin's ssv estimate is a relative correlation from higher elevation gauges but is a low estimate of what's in ssv and a rough correlation. It's the best online info for ssv boaters who don't have a visual stick reading.
Ssv used to be estimated by subtracting nsv below button rock from st vrain at Lyons, but they turned off that nsv gauge. There is no good way to estimate flows on nsv below button rock when it is filling due to no gauge. Gotta talk to the water guys and see what they are releasing. Once button rock fills what comes in must go out, and there are two gauges on nsv above button rock.
Proving grounds is below button rock, so no gauge.
Not sure what south brach is, but I think it's a small low elevation trib, not to be confused with south saint vrain.