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 20 , 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 begin next week and is expected to be complete by Friday, June 27. The ORT barrier catwalks were installed this week with the help of divers, enabling the culvert flap gates to be tied open to the catwalks. The ORT weir notch was then re-closed this week on Wednesday. Flap gates on the MR, ORT, and GLC barriers remain tied open, however, we intend to untie all but a few flap gates at the ORT barrier next week to help improve water levels. The culverts at the ORT barrier remaining tied open will be to possibly help improve circulation and therefore water quality on Old River.
A look at CDEC data for this week shows water levels were higher this week at the three sites monitored above the barriers, due partially to the higher strength tides and the full closing of the ORT barrier on Wednesday. Next week levels are expected to drop due to the weaker tides late in the week. However, we intend to close the GLC barrier and untie most of the flap gates next week which should offset these reductions. We included actual water levels through early 6/23/08. Actual water levels at the MR barrier 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) but dropping below the level of concern at the MR station (0.3 feet MSL) as well as the GLC monitoring station (0.0 feet MSL). Conditions on Grant Line Canal won’t improve significantly until the GLC barrier is fully closed which is expected later this week (Thursday, 6/26). Water levels are expected to be lower this week during the quarter moon phase when tidal strength is weaker. We have notified the fishery agencies of our intent to close the GLC barrier and untie the flap gates on the barrier culverts this week. We have requested DWR field division staff to untie the flap gates on all the barriers later this week, preferably by Thursday. Three culverts on the ORT barrier will continue to have their flap gates tied open to improve circulation on Old River and perhaps improved water quality slightly on Old River.
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.
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Mark A. Holderman, P.E.
Chief, Temporary Barriers Project and
California Department of Water Resources
Phone: (916) 653-7429 FAX: (916) 653-6077
Cell/Pager: (916) 601-6036 E-Mail: email@example.com