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:  May 23 , 2008


Head of Old River Barrier (HORB):

The spring HOR barrier work will not be installed this year due to a court decision by US District Court Judge Wanger that prohibited the installation of the spring barrier to increase protections for delta smelt.  This is an interim decision that effects the 2008 season only.  The fall HORB is not effected.

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

Work began May 12 at the DMC barrier.  The work is proceeding more quickly than originally planned, so now the barrier is expected to be closed by May 30.  The Middle River barrier construction began on May 20 and was completed May 21.  Crews began construction of the Grant Line Canal north abutment (boat ramp) on May 19.  Partial closure (completion of the boat ramp) is expected by June 4.  Full closure of the GLC barrier will be determined afterwards depending on water levels and delta smelt issues.  All flap gates on the barriers will be tied open until after the Vernalis Adaptive Management Plan experiment is concluded in accordance with the Wanger decision.  After VAMP, the flap gates may be untied (operating normally) if necessary to protect south Delta water levels but only with fishery agencies approval. 



Modeling was done this week with the results attached.  Actual Low-low water levels are improving as the barrier installation continues.  Middle River saw a large improvement in water levels once the MR barrier was closed.  However, projecting water levels during the barrier installation period as the work progresses is not easily done by the model.  Modeling shows Low-low water levels projected to drop below the level of concern at the ORT and GLC monitoring stations (0.0 feet MSL) as well as the level of concern at the MR station (0.3 feet MSL), however the model seems to be over-estimating the lows and under-estimating the highs compared with actual conditions.  Staff is investigating this and will determine if corrections need to be made to the model input.  

Click here to see modeling outputs


Fishery agencies and DWR will be closely monitoring conditions for Delta smelt which might effect operations of the barriers during May/June.  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: