Anderson Reservoir is draining at the same rate as last year.
Flows should step down at about the same time as last year in the coming weeks. Look for 600 cfs soon.
The Boise River reservoir system overall is carrying more water than at this time last year.
Flows from Anderson Ranch Reservoir are now at the “normal” summer discharge. Anderson Reservoir will now slowly begin to empty, and the drawdown will increase through the summer.
Flows at the Featherville gage fell below last year’s flows for the 2nd half of June. So much for the earlier post and predictions.
Snow is melted from the Trinity Mtn. station. 2009 was below the average of the 1971-2000 period, but total precipitation was slightly higher.
Group photo at the South Fork Boise River clean-up as part of the Trout Unlimited national stream clean-up day.
Flows at Featherville on the upper South Fork Boise have settled to about 2,300 cfs and are slightly lower than at this time last year. However, with Anderson Ranch Reservoir at 99 percent full you can expect water managers to pass all inflows and keep the lower SFB at higher flows for quite some time.
Saturday’s post contains one error showing snowpack at Trinity Mtn. Snotel site and June flows: total snow depth was used instead of Snow Water Equivalency. The above chart shows flows dropping like a rock. We will post an updated chart of remaining snow as compared to last year.
The amount of snow remaining on Trinity Mountain can be a useful indicator of how much water is expected to flow into the upper South Fork Boise River and thence American Falls Reservoir.
As the above chart indicates, there is less snow remaining on the mountain than last year. Anderson Ranch is full but it appears that future flows into the reservoir through the month of June will continue to drop.
