there's gauges (none of which seem to have left their dormant "seasonal" status as of yet). Check the middle saint vrain near peaceful valley, which contributes about 85% of the flow:
There's also the south saint vrain near ward:
However, given that the left hand diversion essentially dewaters the south saint vrain just below the peak to peak (http://www.dwr.state.co.us/SurfaceWa...&MTYPE=DISCHRG
), the flow that you see in the ssv @ ward almost never makes it into the SSV run. The rest of the flow in the creek aside from the MSV comes from random little feeder creeks. In general, I'd say that if the MSV reads 150cfs or more, its game on for SSV. A lot of times in the past, the run has felt like approx. 175 when the MSV gauge is in the 120 to 140 range. That's my 2 cents.