Monterey Peninsula Water Management District

Quarterly Water Supply Strategy Report: April-June 2001

March 19, 2001

1.         Management Objectives

The District desires to maximize the long-term production potential, protect the environmental quality of the Seaside and Carmel Valley basins, and meet the regulations in the Section 4(d) Rule adopted by the National Marine Fisheries Service (NMFS), which prohibits, "removing water or otherwise altering streamflow when it significantly impairs spawning, migration, feeding, or other essential behavioral patterns"[of steelhead].  To accomplish these goals, a water supply strategy and budget for production within the Cal-Am water distribution system is reviewed quarterly to determine the optimal strategy for operations, given the current hydrologic and system conditions. 

2.         Quarterly Water Supply Strategy: April - June 2001

On March 6, 2001, staff from the District, Cal-Am, the CDFG, and the NMFS met to discuss the proposed water supply strategy for the April-June 2001 period. This group will meet again on May 7, 2001 to negotiate the 2001 Memorandum of Agreement (2001 MOA) that will govern releases and diversions from Los Padres and San Clemente Reservoirs during the May-December 2001 period.  The MOA discussions will be based on additional inflow data that will be available at that time, which will allow a more accurate analysis of projected inflows.  Accordingly, the diversion and release rates that are specified in the MOA will supersede the rates described in the April-June 2001 water supply budget.

Based on the runoff that had occurred since the beginning of the water year, it was agreed that the projections for the upcoming quarter should assume near normal values.  For its analysis, District staff calculated that the October-February unimpaired runoff at San Clemente Dam was 17,214 acre-feet (AF), which is only 60% of the expected runoff in a normal year.  Subsequently, the early March storms produced substantial runoff, totaling approximately 10,000 AF during the first seven days of March.  Based on this runoff and the assumption that March inflow will total 25,000 AF, staff calculated that total runoff for the October-March period will be 42,200 AF, or about 4% above the expected median flow.  Based on an assumption that runoff during the remainder of the water year would be at a similar level, staff calculated monthly inflows of 8,300, 3,100, and 1,500 AF for the months of April, May, and June 2001, respectively.  

Table 1 shows a monthly breakdown of the recommended diversion and release schedule under the assumed near normal inflow conditions. Table 1 shows expected inflows, outflows, and storage volumes at Los Padres and San Clemente Reservoirs for the March - June 2001 period.  For this analysis, it was assumed that Cal-Am production would total 15,285 AF during WY 2001, including 4,000 AF from the Seaside Basin and 11,285 AF from the Carmel River Basin.  Monthly production was calculated by multiplying total annual production times the average fraction of annual production for each month (based on production data from 1988 to 1997).  These fractions range from 0.0585 (5.85%) in February to 0.1079 (10.79%) in August.

For this analysis, it was assumed that Cal-Am would maintain a diversion rate from San Clemente Reservoir to the Carmel Valley Filter Plant of 12 cubic feet per second (cfs) during April, 5 cfs during May, and 3 cfs during June.  During April and May 2001, the proposed budget allows Cal-Am to operate Scarlett No. 8, and Laureles Wells Nos. 5 and 6, in lieu of diverting water from San Clemente Dam.   The operation of Cal-Am Wells in the upper Carmel Valley or direct diversion of 12 cfs is based on the assumption that inflows equal or exceed 140 cfs in April, 50 cfs in May, and 25 cfs in June. The diversions will be decreased, or increased, if rainfall and runoff are substantially different from the conditions assumed for the period.  As discussed above, the allowable diversion rate will be analyzed as part of the MOA negotiations in May 2001, when additional information regarding the recessional rate of the Carmel River is available.

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