Actual SFAR Water Year 2017-2018: Below Normal

Below Normal: 2.351 MAF of Full Natural Flow measured at Folsom Lake for the American River Oct 2017 through Sept 2018

2017-2018 Water Year – Final Determination – South Fork of the American River

With the end of September also comes the end of the 2017-2018 California water year. Measurements for the Full Natural Flow for the American River at Folsom, as measured by the Department of Water Resources, puts the South Fork of the American River as having had a Below Normal water year.

Actual versus Forecasted

The final Forecast in May estimated 2.367 MAF and a Below Normal water year. With the final measurement placing it as a Below Normal water year with 2.351 MAF, the May forecast was off by less than 1%. Well done.

Guaranteed Minimum Flows

The Final Water year measurement of a Below Normal water year will be used for flows from November 1st until two days after the next forecast is released in early February. The next Forecast will be the February forecast, and it’s typically issued around the 8th of the month. The new February forecast will take effect 3 days after it’s issued.

October through early February

1. Saturday & Sunday: 1,500 cfs 9am-12pm

2. Monday & Friday: 1,300 cfs 9am-12pm

3. No guaranteed raftable flows Monday through Friday

4. Minimum Flow: 250 cfs

November through early February

1. Saturday & Sunday: 1,300 cfs 9am-12pm

2. No guaranteed raftable flows Monday through Friday

3. Minimum Flow: 200 cfs

The first 2018-2019 Water Year forecast should be released around February 8th, with it taking effect 3 days after issuance.

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Extra Details for Geeks

Related Links and References

1. SFAR River Flow Agreement

2. Quick B120 Report – Just the numbers

3. Detailed DWR Bulletin 120 Report – Note: this report is typically released a week or two after the quick report comes out.

4. Short Executive Summary

5. American River at Folsom – Full Natural Flow (FNF) record of what actually happened.

6. Snow Water Content – graph

7. Most Recent Snow Water Content Data – table – Limited to American River Basin

8. NOAA Sierra Nevada snow analysis

9. California Snow Water Equivalents – map

About the Forecasts

1. Forecasts are issued February through May around the 2nd Tuesday or the 8th of each month. They take effect 3 days after being released.

2. The final forecast is issued in May, and is used to determine the flow schedule through October.

3. The final (actual) water year report is released in October and is used to determine flows for November until 3 days after the February forecast is released.

4. While some bias might slip in, as much as possible the above information is purely based on the forecasts and not based on gut intuition or predictions.

This page is maintained as an archive of previous forecasts. More Current and Previous forecasts are archived here for reference.

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