The following report on the Temporary Barriers Project is for your information and action, as appropriate. This report will be transmitted whenever changes occur to the operation of the barriers, and as a result of modeling and/or field monitoring of water levels in the south Delta.
STATUS AS OF: June 1 , 2007Head of
In response to fishery agency concerns over the distribution and abundance of Delta smelt, the HOR barrier was partially breached on Monday, May 21 and fully breached the next day, May 22. Minor cleanup at the site continued this week.
Agricultural Barriers (Old River near Tracy [ORT], Middle River [MR], Grant Line Canal [GLC]):
All agricultural barriers are in place but have their culvert flap gates tied open to allow two-way tidal flow. The USFWS directed the flap gates be tied open to help improve net downstream flows on Old and Middle River and facilitate the movement of delta smelt out of the south and central Delta. This action is provided for in the biological opinions which are part of the permits for the Temporary Barriers Project. DWR personnel from the Delta Field Division tied open the flap gates this week on Wednesday, May 23. Two flap gates of the six at the Middle River barrier had broken cables and were not able to be tied open. The culverts will be tied open once repairs to the cables (scheduled for June 5) are completed.
Modeling was completed this week and the results attached. Low-low water levels are projected to remain above the level of concern at the ORT and GLC monitoring stations (0.0 feet MSL) and may drop slightly lower than the level of concern at the MR station (0.3 feet MSL) for a few days. However, the projections were based upon earlier modeling assumptions which included 400 cfs diversions at Clifton Court Forebay. SWP have since reduced diversions to zero to help protect delta smelt.
Fishery agencies and DWR will be closely monitoring conditions for Delta smelt which might effect operations of the barriers during April-May. Changes in flap-gate operations on the culverts, removal of the barriers, and changes to SWP/CVP export operations are all possible actions that could be taken to protect smelt if necessary.
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Mark A. Holderman, P.E.
Chief, Temporary Barriers Project and
California Department of Water Resources
Phone: (916) 653-7429 FAX: (916) 653-6077
Cell/Pager: (916) 601-6036 E-Mail: firstname.lastname@example.org