U.S. Fish & Wildlife Service

Sacramento Fish & Wildlife Office

Main Delta Update Page

Delta Flow Update 6-17-2008

The Service has determined that the following recommendation will be protective of delta smelt. The projects will maintain the 7-day average combined OMR flow more positive than -2,000 cfs with combined exports not increasing more than 1,000 cfs on any given day unless

average salvage over any two consecutive days reaches or exceeds 40 delta smelt per thousand acre feet (TAF) exported (ds/TAF) or
average salvage over a three day period reach or exceed 30 ds/TAF

If one of the two triggers are met, then export facilities immediately start operating to an OMR flow no more negative than -1,500 cfs. Maintain the Agricultural Barriers flap gates open.

These actions are needed to protect delta smelt for the following reasons:

Delta water temperatures are about 22 degrees C (three station average of Mossdale, Rio Vista and Antioch) which is above the range of peak delta smelt spawning, which is 12-18 degrees C. The peak of spawning has likely passed, although a recent Spring Kodiak trawls caught a few pre-spawned delta smelt, meaning further spawning is possible. Temperatures in the delta remain below the lethal temperature of 25 degrees C.

Delta smelt caught at the salvage facilities have continued over the past week:

Date	Smelt Caught at SWP*	Smelt Caught at CVP*
6/10/08	57	10
6/11/08	0	0
6/12/08	42	0
6/13/08	14	16
6/14/08	22	24
6/15/08	26	16
6/16/08	12	16
Total for week	173	82

*All smelt numbers are expanded salvage

A total of 1936 delta smelt have been salvaged this year.

Delta smelt were found in the most recent 20 mm survey (Survey 6, May 27 to May 30) in the central Delta. Delta smelt were found in the Cache Slough and at the confluence, although smelt were also caught in the central Delta on the San Joaquin River and in Frank's Tract. Smelt continue to be within the influence of the pumps in the central and south Delta.

This action is needed to help reduce delta smelt entrainment in the south Delta and to reduce risks as water temperatures are increasing in the south Delta.