Salt & Nutrient Management Plan Pajaro Valley

1. Salt & Nutrient Management Plan Pajaro Valley Stakeholder Meeting #2 March 28, 2013

2. 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

3. SNMP Development Process

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

5. Existing Groundwater Conditions • Approach • 295 PVWMA Production/Monitoring Wells w/ data • 14 City of Watsonville Production Wells • Summarize samples by site/constituent for 2002-2011 • Interpolate decadal average and max concentrations using IDW for 5 closest wells (3 wells for max) • Results are interpolated concentration contours

12. Groundwater Condition Summary PVGB Area: 67,500 acres

13. 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

14. Nitrate Loading Risk Analysis

15. 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

20. Agricultural N Risk Analysis

21. Agricultural N Risk Analysis

22. Septic N Risk Analysis • Septic GIS data Monterey and SC Co • Monterey Co data generated using CAD plans by 2N. • 4500 of septic systems in PVWMA • Risk is presence and soil type

23. Septic N Risk Analysis

24. 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

26. Stream Infiltration N Risk Analysis

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

28. 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

29. N loading across sources Agriculture: 2100 t N/yr • Tulare/Salinas • ≈ 40% high fertilizer demand crops • ≈ 145 lbsN/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

30. 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

31. 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 • 0-0.5 miles inland: Moderate Risk • >0.5 miles inland: Low Risk

32. Salt Loading Risk Analysis • Seawater Intrusion

33. Salt Loading Risk Analysis

34. Salt Loading Risk Analysis • Irrigation Salt Loading Risk • Annual water use • Irrigation water TDS content • WHC

35. Salt Loading Risk Analysis • Summary of Findings

36. 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

37. SNMP Objective Development

38. Final Questions/Comments