ITEM: CONSENT CALENDAR 4. CONSIDER EXPENDITURE OF FUNDS TO OBTAIN A CURRENT ESTIMATE OF THE STORAGE CAPACITY OF LOS PADRES RESERVOIR AND AUTHORIZE THE GENERAL MANAGER TO ENTER INTO CONSULTANT AGREEMENTS FOR OBTAINING DATA Meeting Date: October 20, 2008 Budgeted:  Partial From: Darby Fuerst, Program/ General Manager Line Item No.:  Project 2-2-3 Prepared By: Larry Hampson Cost Estimate:  $35,000 General Counsel Approval: N/A Committee Recommendation: The Administrative Committee considered this item on October 14, 2008 and recommended approval. California American Water has agreed to reimburse the District for 50% of the total cost. CEQA Compliance: N/A SUMMARY: Staff proposes to obtain and analyze data concerning the present storage capacity of Los Padres Reservoir, which is located on the Carmel River approximately 25 miles upstream of the Pacific Ocean (see Los Padres Reservoir vicinity map, Exhibit 4-A). This proposed project will provide an estimate of current storage capacity in Los Padres Reservoir and a baseline to quantify increased sedimentation expected from the Basin Complex Fire. The original capacity of the reservoir has been reduced from 3,030 acre-feet (AF) in 1948 to an estimated 1,200 AF at present. After the Basin Complex Fire burned the watershed above the reservoir in July 2008, the U.S. Forest Service Burned Area Response Team (BAER) estimated that up to 372 AF of sediment could wash into the reservoir in the winter of 2008-09 and up to 600 AF of sediment could wash into the reservoir in the next five to ten years. Data from reservoir soundings and the topography of exposed sediments adjacent to the reservoir would be used to update the present elevation-capacity table. The reservoir sounding would be conducted by California State University at Monterey Bay, and the adjacent topographic data would be obtained by the Moss landing Marine Laboratories. The scopes of work and estimated costs are attached as Exhibits 4-B and 4-C. Work would be completed as soon as possible and prior to winter rains. The total cost of the analysis is estimated to be up to$35,000.

RECOMMENDATION:  District staff recommends that the Board authorize the General Manager to enter into agreements with the Foundation of California State University at Monterey Bay to conduct the work described in Exhibit 4-B at an estimated cost of $16,500, and with Moss Landing Marine Laboratories to conduct the work described in Exhibit 4-C at an estimated cost of$16,000.  Staff also recommends that the Board authorize the General Manager to expend up to an additional $2,500 for unanticipated conditions and services associated with obtaining these data. The total not-to-exceed cost under both agreements is$35,000.

BACKGROUND:      The most recent survey of Los Padres Reservoir capacity was in 1998, when California American Water (CAW) estimated that the reservoir held 1,569 AF of water at the spillway elevation of 1,040 feet above mean sea level (referenced to the 1929 National Geodetic Vertical Datum, or NGVD).  In their recent application to the Public Utilities Commission for a rate increase, CAW estimates that the reservoir capacity has decreased to 1,200 AF due to sedimentation.  Thus, with an initial reservoir capacity estimated at 3,030 AF in 1948, the long-term average annual loss of storage capacity is estimated to be approximately 30 AF/year.  As a result of the Basin Complex Fire in July 2008, the US Forest Service estimated that up to 372 AF of sediment could wash into the reservoir in the winter of 2008-09 and up to 600 AF could wash in during the next five to 10 years.  This represents more than an order of magnitude greater than the long-term sedimentation rate and, should this event occur, would severely limit the capability of CAW to release water from storage during the dry season to maintain aquatic habitat in the Carmel River downstream of Los Padres Dam.  An accurate determination of the rate of sedimentation at this reservoir is necessary in order to effectively implement a long-term policy for managing the reservoir and river downstream of Los Padres Dam.

Loss of storage capacity is associated with intense rainfall events on the steep slopes in the upper Carmel River watershed that cause high sedimentation rates.  Particularly high rates of sedimentation are common during wet years due to landslides.  However, the highest annual rate of sedimentation recorded at Los Padres Reservoir was 600 acre-feet during the winter of 1977-78 after the Marble Cone Fire of August 1977.  The Marble Cone Fire burned 178,000 acres and was the largest fire in California history at that time.  The 2008 Basin Complex Fire and Indians Fire together burned 240,000 acres.  The 2003 Cedar Fire in San Diego County burned 280,000 acres, making it the largest fire in California history.

Reservoir sounding and topographic data from exposed sediments would be used to update the present elevation-capacity table that is based on a 1998 sounding by CAW.  The cost of the analysis is estimated to be up to $35,000. No funds for this work were included in the Fiscal Year 2008-09 budget because the fire occurred after the budget was adopted. Staff proposes to fund the work with a combination of funds from other budgeted items, contingency fund and a contribution of 50% of the project cost from CAW. A reservoir sounding would be conducted by CSUMB using boat-mounted LiDar (Light Detection and Ranging) equipment that is tied into a base station using GPS (Global Positioning System). Terrestrial data along the exposed sediments would be gathered by Moss Landing Marine Laboratories, which is associated with California State University at San Jose, using land-based LiDar equipment with GPS survey control. All data are expected to be accurate to within 0.5 feet of the true location. It is expected that the reservoir will remain accessible for a sounding and to gather land-based data for the remainder of fall 2008. However, significant rainfall during this period could impair access to portions of the reservoir and affect the schedule for completing data acquisition. IMPACT ON STAFF/RESOURCES: The total not-to-exceed amount for this project would be$35,000.  In addition, the District would provide contract oversight and perform portions of the analysis associated with developing a new elevation-area-capacity table for the reservoir.  Funds for this work were not included in the Fiscal Year 2008-09 Budget, as the Basin Complex Fire occurred after the budget was adopted.  However, staff proposes using the $15,000 budgeted under Project 2-2-3 (Monitor lower Carmel River sediment transport changes) and$2,500 in Mitigation Program contingency funds.  CAW has agreed to reimburse MPWMD for 50% of the total cost or up to \$17,500.  Larry Hampson, the District’s Water Resources Engineer, will supervise the work.

EXHIBITS

4-A      Los Padres Reservoir Vicinity Map

4-B      Foundation of CSUMB Proposal:  Los Padres Reservoir Bathymetry – Fall 2008

Moss Landing Marine Laboratories Proposal for High Resolution, Topographic Survey of the Los Padres Reservoir

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