Stakeholder Meeting #2 March 28, 2013

Agenda SNMP Overview Existing Groundwater Conditions Loading Analysis Approach Nutrient loading risk analysis/findings Salt loading risk analysis/findings Assimilative Capacity Discussion SNMP Objective Development Discussion

SNMP Development Process Primary TasksSchedule Task 1. Stakeholder Outreach 4 Stakeholder Meetings at critical milestones Task 2. Conceptual ModelDraft included Task 3. Salt and Nutrient Loading AnalysisDraft included Task 4. Assimilative Capacity EstimateDraft Fall 2013 Task 5. Develop or update objectivesDraft Fall 2013 Task 6. Develop or update priority program/projects Draft Fall 2013 Task 7. SNMP Monitoring PlanDraft Fall 2013 Task 8. Conduct anti degradation analysisDraft Fall 2013 Task 9. Complete SNMP Draft Spring 2014 Final Summer 2014

Stakeholder Feedback Process Draft sections iteratively vetted with stakeholders Go to PVWMA website for report and Stakeholder comment form Must be submitted in writing, compiled on comment site Recommended alternatives required Comments due by 04/12/2013 Responses tracked and available to all

Existing Groundwater Conditions Approach 295 PVWMA Production/Monitoring Wells w/ data 14 City of Watsonville Production Wells Summarize samples by site/constituent for Interpolate decadal average and max concentrations using IDW for 5 closest wells (3 wells for max) Results are interpolated concentration contours

TDS Concentration Range acres / % of total mg/L35,300 / 52% >450 mg/L – 1000 mg/L27,900 / 41% >1000 mg/L – 1800 mg/L3,550 / 5% >1800 mg/L637 / 1%

TDS Concentration Range acres / % of total mg/L29,300 / 43% >450 mg/L – 1000 mg/L30,500 / 45% >1000 mg/L – 1800 mg/L6950 / 10% >1800 mg/L900 / 1%

Chloride Concentration Range acres / % of total mg/L55,500 / 82% >100 mg/L – 250 mg/L8870 / 13% >250 mg/L – 500 mg/L2600 / 4% >500 mg/L644 / 1%

Chloride Concentration Range acres/% of total mg/L52,900 / 78% >100 mg/L – 250 mg/L10,400 / 15% >250 mg/L – 500 mg/L3170 / 5% >500 mg/L1200 / 2%

Nitrate Concentration Range acres / % of total 0-10 mg/L25,500 / 38% >10 mg/L – 45 mg/L28,400 / 42% >45 mg/L – 100 mg/L10,500 / 16% >100 mg/L3260 / 5%

Nitrate Concentration Range acres/% of total 0-10 mg/L24,600 / 36% >10 mg/L – 45 mg/L23,100 / 34% >45 mg/L – 100 mg/L12,600 / 19% >100 mg/L7410 / 11%

Groundwater Condition Summary PVGB Area: 67,500 acres Constituent Concentration Threshold Fraction above threshold AVERAGE (%) Fraction above threshold MAX (%) TDS1000 mg/L 611 Chloride100 mg/L1822 Nitrate-NO345 mg/L2130

Loading Analysis Approach Relative risk for each primary source Utilize available data and applicable literature Minimize focus on accurate and precise values Maximize focus on primary factors driving loading Focus confidence on relative risk designations to prioritize locations/practices where improvements would be most beneficial

Nitrate Loading Risk Analysis

Agricultural N Risk Analysis Ag land use PVWMA 2009, 2011 and 2012 categorize crop types Fertilizer use as N lbs/acre/yr by crop type Data/info used Irrigation use as ac ft/acre/yr by crop type Data info used Soil holding capacity NRCS soil survey; relative classification

Land Use CategoryAcres% of total Artichokes, Nursery, Vegetable Row17,77825 Strawberries5,8988 Raspberries and Blackberries3,9776 Deciduous (Apple Orchards)2,9144 Other, Unknown Agriculture, Vine/Grapes1,7943 Fallow or other non-agricultural land uses38,06854 Total70,429100

Annual fertilizer application category Measured (%) Expected (%) Very High 0%40% High 73%33% Moderate 21% Low 6% Total agricultural land use (Acres) 32,362 Total non-agricultural land use (acres) 38,068

Annual irrigation intensity category% High 55 Moderate 31 Low 15 Total agricultural land use 32,362 Total non-agricultural land use 38,068

Agricultural N Risk Analysis

Agricultural nitrate loading riskAcres% of total HIGH15,89949 MODERATE14,15044 LOW2,2967 Total agricultural land use 32,344100

Septic N Risk Analysis Septic GIS data Monterey and SC Co Monterey Co data generated using CAD plans by 2N of septic systems in PVWMA Risk is presence and soil type

Septic nitrate loading risk Number of septic systems SC/Mo% HIGH / MODERATE / LOW / Total Septic N Risk Analysis Septic nitrate loading risk Number of septic systems SC / Mo County % of total HIGH / MODERATE / LOW / Total

Sewer N Risk Analysis Sewer GIS data Monterey and SC Co Monterey Co data generated using CAD plans by 2N. 146 miles of sewer lines in PVWMA Risk is presence and soil type

Sewer nitrate loading risk Total Length (miles) % of total HIGH % MODERATE % LOW % Total %

Stream Infiltration N Risk Analysis

Nutrient Loading Risk Analysis Other Sources Riparian Zone Land Use Risk Buffer approach Urban Stormwater Runoff

N loading across sources Viers et al 2012 N loading to gw mass balance Estimate N loading/unit source/yr Use for order of magnitude comparisons for PVGB

N loading across sources Agriculture: 2100 t N/yr Tulare/Salinas ≈ 40% high fertilizer demand crops ≈ 145 lbs N/acre/yr applied PVGB ≈ 85% high fertilizer demand crops ≈ 200 lbs N/acre/yr applied AVE : 134 lbs N/acre/yr leached to groundwater Use 130 lbs N/acre/yr * 32,000 acres of ag

N loading across sources SEWER (67 t N/ yr) Fraction of N per person lost (1-25%) 25% of 55,000 people waste SEPTIC (66 t N/yr) Fraction of N per person lost (85%) 16,100 people on septic WWTP (11 t N/yr) 6.6 million GPD treated Mass Balance: 96% annual nitrate loaded  Ag practices

Salt Loading Risk Analysis Seawater Intrusion: Developed using GW well Cl concentrations 20% of groundwater volumes >100 mg/L Chloride Risk Boundaries Within existing seawater intrusion boundary (2011): High Risk miles inland: Moderate Risk >0.5 miles inland: Low Risk

Salt Loading Risk Analysis Seawater Intrusion

Salt Loading Risk Analysis

Irrigation Salt Loading Risk Annual water use Irrigation water TDS content WHC

Salt Loading Risk Analysis Summary of Findings Irrigation salt loading riskAcres % of total Ag-Land HIGH8,97828 MODERATE13,72143 LOW9,24629 Total agricultural land use31, Non-agricultural land use34,004

Assimilative Capacity Discussion Potential intent is to identify if places where conditions are perhaps below standards. No specific GW standards for PVGB Current areas of known issues Clarify from Regional Board requested

SNMP Objective Development

Final Questions/Comments