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:  April 27 , 2007

Head of Old River Barrier (HORB):

The HOR barrier is closed with three culverts closed and three open.  For now, we’re keeping three open to allow some downstream flow into Old River to help with circulation. 

Agricultural Barriers (Old River near Tracy [ORT], Middle River [MR], Grant Line Canal [GLC]):

Barrier installations began April 2, 2007. The ORT and MR barriers are closed and culverts operating tidally.  On April 25th we received approval from the USFWS approval to close the GLC barrier to protect water levels for irrigation diversions.  Work to close the center portion of the barrier and complete the boat ramp began this week and should be done early next week.


Modeling was completed this week and the results attached.  We looked at forecasts with the HOR barrier culverts all closed, but the levels with three culverts open (current situation) typically doesn’t change significantly at the modeled locations.  Also, the modeling was done with flap gates operating tidally at the ORT and MR barriers.  The model estimated closing the GLC barrier on May 1, however actual closure may be a day or two later. 

Modeling Outputs:

Middle River at Howard Road Bridge
Doughty Cut above GLC Barrier
Old River near Tracy Road Bridge


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.  


These weekly updates are also available for your information on our website

If you know of anyone else that should be receiving this update, please let me know by email, and I'll add them to the mailing list.  Thanks!


Mark A. Holderman, P.E.
Chief, Temporary Barriers Project and Lower San Joaquin
Bay-Delta Office

California Department of Water Resources
1416 9th St., P.O. Box 942836
Sacramento, CA 94236-0001

Phone: (916) 653-7429  FAX: (916) 653-6077
Cell/Pager: (916) 601-6036 E-Mail: