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:  July 20 , 2007

Head of Old River Barrier (HORB):

The Spring HOR barrier has been completely removed.  The HOR barrier will be re-installed in the fall upon request by DFG.

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

All agricultural barriers are in place but only the GLC and MR barriers have been operating normally most of this week.  The flap gates on the ORT barrier culverts have been tied open to help improve circulation and water quality on Old River.  However, today we had the flap gates untied and the gates are now operating normally at the ORT barrier.  This was in response to South Delta Water Agency (SDWA) alerting us that some water level problems were occurring in Tom Paine Slough.  After consulting with DWR’s O&M staff and SDWA, we decided to untie the flap gates to help improve water levels at least during the rest of the neap tide that is currently occurring.  We may resume tying open the flap gates, on all or some of the nine culverts at the ORT barrier, if conditions improve during the next spring tide beginning early next week.  



Modeling was done earlier this week but it did not include the change to untie the ORT barrier culverts flap gates.  The modeling shows water levels remaining above the level of concern at the ORT, and GLC monitoring stations (0.0 feet MSL) and the level of concern at the MR station (0.3 feet MSL).  However, with the culverts operating normally at the ORT barrier, actual water levels should be about ½ foot higher at the ORT station and somewhat less improved at the other sites.



Modeling Outputs:

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


I’ll be out of the office on vacation the next two weeks.  Simon Kwan will be transmitting these updates for me during that time. 

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: