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 13 , 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 with closure being completed on Wednesday, June 4.  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) was completed on Monday, June 2.  Full closure of the GLC barrier will be determined afterwards depending on water levels and delta smelt issues.  Flap gates on the MR and GLC barriers remain tied open.  However, this week we were informed that the ORT barrier flap gates have not been fully open since the barrier was closed June 4.  The installation contractor was unable to install the culvert catwalks that allow the flap gates to be raised and tied in the open position.  This was due to higher than expected water levels and tides last week that covered the mounting sockets located on the culvert frames.  The contractor will have to use divers to guide the placement of the catwalks, but because of the complexity in coordinating diving operations to ensure safety, the work won’t be done until Tuesday, June 17th.  In the meantime, the barrier was notched on Wednesday, June 11th to allow two-way flow similar to what would be provided by the culverts being tided open.  The flap gates may be untied (operating normally) if necessary to protect south Delta water levels but only with fishery agencies approval.  Currently fishery requirements dictate that the gates will remain tied open until at least June 17.

 

Modeling:

We included actual water levels through mid-day 6/16/08.  Actual water levels at all barriers are better than modeled forecasts.  The modeling shows water levels remaining generally above the level of concern at the ORT station (0.0 feet MSL) and the level of concern at the MR station (0.3 feet MSL), however levels are slightly below the level of concern at the GLC monitoring station (0.0 feet MSL).  Conditions on Grant Line Canal won’t improve significantly until the GLC barrier is fully closed.  Water levels are expected to be lower next week during the quarter moon phase when tidal strength is weaker.  Also, irrigation demands are expected to increase due to the warmer weather and the maturity of crops.  Exports will likely increase eventually after June 20, the date the Wanger court decision ceases to apply.  We will be notifying the fishery agencies of our intent to close the GLC barrier and untie the flap gates on the barrier culverts beginning after June 20.  The barrier contractor will begin work at the GLC barrier early next week with closure of the barrier within five to seven days.  Untying the flap gates will occur early next week as well.

Click here to see modeling outputs


Notes:

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:

http://baydeltaoffice.water.ca.gov/sdb/tbp/index_tbp.cfm

 


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: markho@water.ca.gov