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Conservation, science and collaboration on the South Fork wild rainbow fishery.

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Environmental Science and Public Policy Research Institute

Archive

Jun
28th
Sun
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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 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.
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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.
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.
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Snow is melted from the Trinity Mtn. station. 2009 was below the average of the 1971-2000 period, but total precipitation was slightly higher.
Snow is melted from the Trinity Mtn. station. 2009 was below the average of the 1971-2000 period, but total precipitation was slightly higher.
Jun
16th
Tue
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Group photo at the South Fork Boise River clean-up as part of the Trout Unlimited national stream clean-up day.
Group photo at the South Fork Boise River clean-up as part of the Trout Unlimited national stream clean-up day.
Jun
15th
Mon
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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.
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.
Jun
9th
Tue
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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.

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.

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NEVER MIND - Flows dropping like a rock. 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.

NEVER MIND - Flows dropping like a rock.

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.

Jun
6th
Sat
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HOW LONG WILL HIGH FLOWS LAST IN THE SOUTH FORK BOISE? Yesterday we displayed the above chart and noted the flow spike - discharge from Anderson Ranch Dam is at 3,500 cfs, nearly double last year’s summer flow of 1,800 cfs (old timers remember the normal summer flow at 1,600 cfs and in a future post we will report whether 1,800 cfs is the “new normal”). Today we ask how long will these high flows persist in the South Fork Boise River? Anglers will no doubt want to know when safer, slower flows will return. First, let’s examine the chart above. Take note that the flows throughout June 2008 were 600 cfs as Anderson Ranch Reservoir filled. What’s different this year?

HOW LONG WILL HIGH FLOWS LAST IN THE SOUTH FORK BOISE?

Yesterday we displayed the above chart and noted the flow spike - discharge from Anderson Ranch Dam is at 3,500 cfs, nearly double last year’s summer flow of 1,800 cfs (old timers remember the normal summer flow at 1,600 cfs and in a future post we will report whether 1,800 cfs is the “new normal”).

Today we ask how long will these high flows persist in the South Fork Boise River? Anglers will no doubt want to know when safer, slower flows will return.

First, let’s examine the chart above. Take note that the flows throughout June 2008 were 600 cfs as Anderson Ranch Reservoir filled. What’s different this year?

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One thing different than last year is Anderson Ranch Reservoir is already filled to capacity.  The chart above illustrates this year’s contents in the reservoir as compared to last year and to the long term average.  Last June the reservoir was still filling and that’s why flows were at 600 cfs through the month.
One thing different than last year is Anderson Ranch Reservoir is already filled to capacity.  The chart above illustrates this year’s contents in the reservoir as compared to last year and to the long term average.  Last June the reservoir was still filling and that’s why flows were at 600 cfs through the month.
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So we know Anderson Reservoir is full and whatever will flow into the pool from the upper South Fork Boise River and minor tributaries will have to leave the reservoir. The above chart shows this year’s flow at Featherville compared to last year’s.  For whatever reason no long-term average flow is shown, which is too bad because this year looks like an average year.  Nonetheless we know this year’s flow is higher than last year, and for the coming weeks what comes in will have to go out of the reservoir. So what’s a guess on flows for the next month?  We will use the end of May level of snow at Trinity Mountain as a proxy.

So we know Anderson Reservoir is full and whatever will flow into the pool from the upper South Fork Boise River and minor tributaries will have to leave the reservoir.

The above chart shows this year’s flow at Featherville compared to last year’s.  For whatever reason no long-term average flow is shown, which is too bad because this year looks like an average year.  Nonetheless we know this year’s flow is higher than last year, and for the coming weeks what comes in will have to go out of the reservoir.

So what’s a guess on flows for the next month?  We will use the end of May level of snow at Trinity Mountain as a proxy.