Author Archives: aim

Folsom Storage Continues to Drop

Posted on Monday, March 30th, 2015

Folsom Lake Storage is dropping slowly as inflow continues to diminish.  Note that the 24-hour pulse flow (for temperature management) resulted in the release of approximately 600 AF.folsom storage and inflow and LAR flow 3-30-15

Latest Temperature Data

Posted on Sunday, March 29th, 2015

Our field folks gathered temperature data at Rossmoor on Saturday 3-28-15.  You can see that conditions continued to be warm on Saturday 3-28, but not as warm as Friday 3-27.  We don’t have the Sunday Rossmoor temps yet, but the William Pond temperatures indicate that we had some cooling on Sunday 3-29.  I con’t explain why Hazel temps jumped on Sunday.River Temps 3-29-15

Reclamation Acts to Address Temperature

Posted on Sunday, March 29th, 2015

Reclamation operators solicited opinions from State and Federal biologists and Water Forum stakeholders during a special session of the American River Group (ARG) on Friday March 27.  Meeting participants advocated for a range of possible actions: from keeping flows at 500 cfs to increasing flows to 800 cfs for a number of days.

One of the key items of discussion was the observed river temperatures at Rossmoor Bar and foretasted warm days over the weekend.  This graphic (complements of the Water Forum) was presented to illustrate the relatively high river temperatures and the warm weather forecast:

DRAFT_WF_Temperature traces_v3_short3

After discussion and data sharing, Reclamation chose to initiate a power bypass (lower river outlets) to send colder water downstream AND send an 800 cfs pulse of of water for 24 hours.  NMFS staff concurred with the plan.  The intent of the pulse is to reduce the travel time through Lake Natoma and get the colder water down to the gravel as quickly as possible.  This is especially important given the predicted warm weather over the weekend.

The Sac Bee had an article about the issue today [Click Here].

You can see the lower release temperatures in this graph:Shutter Pull and Power Bypass 3-29-15

This graph shows the start of the pulse flow:Start of Pulse Flow 3-29-15


Temperature and Steelhead Incubation

Posted on Thursday, March 26th, 2015

Several people let me know that I had a typo in the temperature thresholds given in a previous post.  Here is a correct – and more comprehensive – list of temperatures and their effects on incubating Steelhead:

Temperature and Steelhead Incubation

Folsom Storage and LAR Flow Projections

Posted on Thursday, March 26th, 2015

Following are two graphs that illustrate projected Folsom Lake storage and LAR Flow.


  • Folsom storage peaked 575.4 TAF on March 16.
  • Reservoir inflow had been declining rapidly since around Feb 9.
  • With the LAR flow cuts (100 cfs drop each day on 3-24 thru 3-26) the the reservoir  outflow comes pretty close to matching the inflow.
  • However, Reclamation projects that inflow will continue to wane and storage will drop through the end of March.
  • Storage will peak again at under 600 TAF by the end of May.
  • Storage may drop as low as 150 TAF by the end of November.

Folsom storage and LAR Flow - zoom in Folsom storage and LAR Flow


Notes:  These graphs are based on the information distributed by Reclamation on 3/19/15 (see post below from that date).  We have “discounted” the Folsom stroage by 35 TAF to correct for the actual LAR flows during the first part of March (Reclamation scenario was based on March flow at 500 cfs all month; actual flow was 800 cfs through the 21rst).

Water Temperature: Above Healthy

Posted on Thursday, March 26th, 2015

Here are the latest water temperature data.  Note that we were above the healthy zone (above 57 deg F) and into the lethal zone (above 59 deg F) for several hours yesterday at Rossmoor Bar and at William Pond.  Temperatures upstream are expected to be cooler.

Note also: the gravel and water gauges at Rossmoor are measuring warmer than the cdec gauge at William Pond.  We assume this is because the Rossmoor gauges are more affected by direct sunlight. Water and Gravel temps 3-26-15


Additional Notes:

  • Hazel: AHZ cdec gauge.
  • William Pond: AWP cdec guage.
  • Rossmoor Water: Water Forum temporary gauge – average of three sites; each gauge is installed in white, slotted PVC pipe at gravel surface.
  • Rossmoor Gravel: Water Forum temporary gauge – average of three sites; each gauge is installed in white, slotted PVC pipe at about 12 inches deep in the gravel.

Temperatures at Rossmoor (Update 3/25/15)

Posted on Wednesday, March 25th, 2015

Our field team pulled temperature readings at the Rossmoor Bar:

Rossmore 3-25-15-v2


Please keep in mind

  1. that water and gravel temperatures are expected to be cooler as you move upstream
  2. The incubating Steelhead start feeling unhealthy above 57 deg F and can’t survive long aboe 59 deg F