Wet: Raftable flows 7 days a week through Labor Day.

The South Fork of the American River water year forecast as of March 8, 2019: Wet

The March Water Supply Forecast Report for 2019 was released Friday March 8th at 2:52 PM, with the Water-Year forecasted for Wet. Specifically it’s forecasting the Full Natural Flow (FNF) of the American River below Folsom at 3.710 million acre-feet (MAF), with Wet being considered ≥ 3.5 MAF.

Central California Snow Water Equivalents

This shouldn’t come as any surprise (though I am a little surprised it jumped over Above Normal all the way into Wet) with the vast amount of rain and snow that has fallen on the Sierra Nevada’s over February. This forecast represents an increase of 65% over the 2.245 MAF that had been forecasted the start of February (prior to multiple atmospheric rivers setting up residence over California).

As of March 1st, Central California’s snow water content is now at 137% of the April 1st average, and 156% of normal. And 1.126 MAF of Full Natural Flow has been recorded at Folsom Lake through February. For comparison, these numbers on February 1st had been only 63%, 100%, and 0.425 MAF respectively.

The current forecast has an 80% probability range of 2.980-4.670 MAF, which leaves a good chance of dropping to Above Normal (2.6-3.5 MAF), but fairly reasonable that it won’t drop to Below Normal. Keep in mind though that our brains are terrible at truly understanding what 80% probability means. It’s better to consider that if this exact forecast played out over 10 different years, one of those years would fall below that range, and one of those years would increase to above that range, and the other eight would fall within the range.

campers rafting on the south fork of the american river

Guaranteed Minimum Flows

The March forecast will be used to determine minimum guaranteed flows from March 11th through Mid-April [The new forecast takes effect 3 days after it is issued. Each forecast is typically issued around the 8th].


  • Monday-Friday: 1,500 cfs 9am-12pm
  • Saturday & Sunday: 1,750 cfs 7am-1pm
  • Minimum Flow: 250 cfs

Forecasted based on Current Data

If the forecast of Wet holds, future guaranteed flows will be as follows. [If it drops to Above Normal, the amounts will decrease, but we won’t loose any days].


  • Monday-Friday: 1,500 cfs 9am-12pm
  • Saturday & Sunday: 1,750 cfs 7am-1pm
  • Minimum Flow: April: 350 cfs | May: 500 cfs

Summer Flows – Sat May 25th through Mon September 2nd

  • Monday-Friday: 1,500 cfs 8am-12pm
  • Saturday & Sunday: 1,750 cfs 7am-1pm
  • Minimum Flow: June: 500 cfs | July 350 cfs | Aug: 300 cfs

September 3-30

  • Thursday and Friday: 1,300 cfs 9am-12pm
  • Saturday & Sunday: 1,500 cfs 9am-12pm
  • No guaranteed raftable flows Monday through Wednesday
  • Minimum Flow: 250 cfs

October 2019

  • Monday and Friday: 1,300 cfs 9am-12pm
  • Saturday & Sunday: 1,500 cfs 9am-12pm
  • No guaranteed raftable flows Tuesday through Thursday
  • Minimum Flow: 250 cfs

 November 2019 through early February 2020

  • Saturday & Sunday: 1,500 cfs 9am-12pm
  • No guaranteed raftable flows Monday through Friday
  • Minimum Flow: 250 cfs

The next forecast should be released around April 8th, with it taking effect 3 days after issuance.

Snow water content graph for Central California as of March 5, 2019

Extra Details for Geeks

Related Links and References

About the Forecasts

  • Forecasts are issued February through May around the 2nd Tuesday or the 8th of each month. They take effect 3 days after being released.
  • The final forecast is issued in May, and is used to determine the flow schedule through October.
  • 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.
  • 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.

As new forecast are released, this page will be kept as an archive of previous forecasts. For the most current forecast, or to view previous forecasts, please view our archive of water year forecasts here.