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 13 , 2007

Head of Old River Barrier (HORB):

Work on the HOR barrier work began April 11 with preparing the gravel pad for the culvert structure.  Barrier closure is scheduled for April 22 to correspond to the beginning of the Vernalis Adaptive Management Plan (VAMP) experiment.  However closure may be delayed slightly due to the need to remove part of a sand bar that accumulated over the winter that is in the way of construction of the gravel pad.  Work will continue on the barrier after the 22th to complete the barrier, final grading, cleanup, etc.  Culverts will be open/closed based upon modeling which will show if we can close some or all of the culverts and still protect downstream water levels.

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

Barrier installations began April 2, 2007. At the ORT barrier site, crews are working on placing the culvert in the channel.  At the MR barrier site, construction was completed April 10.  Work on the GLC barrier boat ramp began this week.  The GLC barrier will only have the boat ramp only installed, leaving the middle portion open, however modeling will be done prior to April 21 to determine if full closure of the GLC barrier is necessary by April 21 to protect water levels.


Modeling will begin during the barrier construction with the forecast of water levels looking at the week before and after April 22.  This will give us an indication of whether water levels will be adequate with the HOR barrier culverts opened or closed, and whether the GLC barrier needs to be closed on or after April 21.


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, delaying filling of the GLC center section, 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: