ITEM:

CONSENT CALENDAR

 

 

 

10.

RECEIVE SEMI-ANNUAL GROUNDWATER QUALITY MONITORING REPORT

 

 

 

Meeting Date:

August 16, 2004

Budgeted:

Yes

 

 

 

From:

David A. Berger,

Program/

2.6 Hydrologic Monitoring

 

General Manager

Line Item No.:

2-6-1

 

 

 

 

Prepared By:

 

Tom Lindberg

Cost Estimate:

N/A

 

General Counsel Approval:

N/A

 

Committee Recommendation:

N/A

 

CEQA Compliance:

N/A

 

 

SUMMARY:Water quality results from the Spring 2004 sampling of the Monterey Peninsula Water Management Districtís (District) well network in the Carmel Valley aquifer are presented in Exhibit 10-A and briefly summarized below.Results from Spring 2003 are also provided for comparison.

 

RECOMMENDATION:Because there have not been significant changes, and because all constituents of concern are well below State Drinking Water Standards, no action is necessary at this time.Staff recommends approval of this item with adoption of the Consent Calendar.

 

BACKGROUND:From the 1981 inception of the Districtís ground water quality monitoring program through 1994, the District worked cooperatively with the Monterey County Water Resources Agency (MCWRA), which provided data collection and analysis services to the District.However, in 1995 the District assumed all field data collection responsibilities and now works directly with the Monterey County Consolidated Chemistry Lab to conduct the water quality analyses, as a cost saving measure.

 

As part of the Districtís Strategic Plan development, the District conducted an assessment of the ground water quality monitoring program in 1996.As a result, it was determined that some modifications could be made to the sampling schedules in both the Carmel Valley and Seaside Basins without compromising the effectiveness of the program.Accordingly, collection of samples from the Carmel Valley monitor wells has been reduced from semi-annual to annual.The sampling schedule for Carmel Valley is staggered, with upper valley wells (i.e., upgradient of the Narrows), sampled in Spring and lower Carmel Valley wells in Fall, coinciding with the historically higher nitrate concentrations in these respective areas.Collection of samples from the Seaside Basin monitor wells was also reduced to once per year in Fall, coinciding with the historically low water levels in the basin at this time of the year.This sampling reduction resulted in an approximate annual savings of $4,000 in laboratory costs for the program.

 

DISCUSSION/ANALYSIS:Carmel Valley Aquifer Monitor Wells - Results from the Spring 2004 and Spring 2003 samplings are provided in Exhibit 10-A.Three shallow monitor wells in the upper Carmel Valley are sampled each Spring, as per the sampling modification described above.The locations of these sampling points are shown on the map in Exhibit 10-B.Review of these water quality results indicates no significant change in overall water quality in Spring 2004 compared to samples collected in Spring 2003. Although the Practical Quantification Limit (PQL) for two constituents, Iron and Manganese, was reduced to 0.001 milligrams per liter (mg/l), none was detected in any of the samples from Spring 2004.Potassium concentrations were unexplainably higher in two of the wells (16S/2E-33Q1 and 17S/2E-10B1), but there is no California Title 22 Drinking Water Standard for Potassium. Historically, Potassium levels were higher in 2002 and 2001, so there is no cause for concern.All constituents for which Drinking Water Standards exist are within acceptable limits.

 

It should be noted that relatively high nitrate concentrations (up to 22 milligrams per liter [mg/L]) were measured earlier in two upper Carmel Valley monitor wells in Spring 1998, although the observed nitrate concentrations were well below the drinking water standard of 45 mg/L.The Carmel Valley Master Plan established an ďaction levelĒ of 25 mg/l of nitrate due to concern about the limitations of septic systems in this unsewered portion of Carmel Valley. The relatively high readings were attributed to the flushing effect of severe storm events in the Winter of 1998.Results of more recent samplings from all three shallow wells indicate that nitrate concentrations have returned to more normal levels.

 

LIST OF EXHIBITS:

10-A††† Ground Water Quality Monitoring Results for Spring 2004 and Spring 2003

10-B††† Map of Monitor Well Locations in Upper Carmel Valley

 

 

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