Salt & Nutrient Management Plan Pajaro Valley Water Management Agency

1. Salt & Nutrient Management Plan Pajaro Valley Water Management Agency Stakeholder Workshop #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 • Plan developed in iterative sections • Drafts vetted with stakeholders • Go to PVWMA website for report and Stakeholder comment form • <LINK> • <LINK> • Comments must be submitted in writing, compiled on comment site • Comments due by 04/12/2013 • Responses tracked and available to all

5. Existing PVGB 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 • Results are interpolated concentration contours

6. MEAN [TDS]

7. MAX [TDS]

8. MEAN [Cl]

9. MAX [Cl]

10. MEAN [NO3]

11. MAX [NO3]

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

13. SNMP Pollutant Loading Analysis RISK ANALYSIS APPROACH • Relative risk for each primary source • Identify primary factors driving loading • Identify available data to inform factor contribution • Categorize relative contribution of sources based on factors in risk matrices • Generate spatially explicit distribution of relative risk within PVGB area.

14. SNMP Pollutant Loading Analysis ADVANTAGES • Relative risk for each primary source • Sensitive to same inputs as complex models, but less debate on accuracy. • Transparent and easy to communicate • Focus confidence on relative risk designations • Informs priority locations/practices where improvements would be most beneficial

15. Nitrogen – NO3 Risk Analysis Relevant components of the NITROGEN CYCLE Atmosphere [N2(g)] Air Pollution [N2O] fixation deposition Stormwater [NH4+, NO3-] denitrification Plants [N organic] runoff Animal waste [NH4+, NO3-] Irrigation water [NH4+, NO3-] mineralization mineralization uptake Septic/sewer systems [NH4+, NO3-] Fertilizer [NH4+, NO3-] Soil [NH4+, NO3-] applications leaks KEY leaching Controllable sources Groundwater [NO3-] Key reservoirs Downgradient migration Upgradient sources process

16. Agricultural Fertilizer NO3 Loading Risk Analysis Factors • Soil holding capacity • Amount of N applied as fertilizer • Annual irrigation volumes Data data used • NRCS soil survey • PVWMA Ag crop land use data (2012 and 2011) • B Platt grower surveys • Literature values

17. Relative Soil Water Holding Capacity

21. Agricultural N Risk Matrix

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

24. Septic N Risk Analysis

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

27. Surface water infiltration N Risk Analysis

28. Subordinate Sources N loading • Agricultural Irrigation • Potential opportunity to manage fertilizer apps • Similar outcome as fertilizer risk • Riparian land use risk • Buffer approach • Urban storm water runoff • Localized • Low recharge in Sloughs • Atmospheric • Uncontrollable • Animal Waste • Minimal presence

29. N loading ACROSS sources • Viers et al 2012 aka Harter Report N loading to gw mass balance in Salinas/Tulare GWB • Applicable N loading/unit source/yr • Fertilizer applications (Ag) • Sewer • Septic • WWTP

30. 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

31. 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 HARTER: Mass Balance: 96% annual nitrate loaded to grounwater is from agricultural practices

32. Salt loading risk analysis Sources in PVGB • Seawater Intrusion • Irrigation practices • Surface water recharge

33. Seawater Intrusion

34. SALT CYCLING ON IRRIGATED LAND Salt content of irrigation water HIGH Low Evapotranspiration HIGH Evapotranspiration Low Irrigation volumes Plant Growth HIGH Plant Growth HIGH Low L Soil SALT adsorption HIGH Soil SALT adsorption Low SALT leaching Low SALT leaching HIGH Aquifer SALT Low Aquifer SALT HIGH

35. Irrigation salt loading risk Factors • Annual water use • Irrigation water TDS content • Soil water holding capacity

36. Salt Loading Risk Analysis • Summary of Findings

37. Assimilative Capacity Discussion • Required Task of SNMP • Intent of task is to identifyareas of concern and areas where standards are met • No specific GW standards for PVGB • Clarification from Regional Board requested

38. SNMP Objective Development Useful strategy implementation objectives are: • Future vision statements and time frame • Measurable • Used to communicate and track progress toward future vision • Used to guide strategy/project development and prioritization • Used to guide monitoring needs, purpose and use of data

39. Pajaro River Watershed IRWM WQ Goal and Objectives Water Quality Goal: Protect and improve water quality for beneficial uses consistent with regional community interests and the RWQCB basin plan objectives through planning and implementation in cooperation with local and state agencies and regional stakeholders. Water Quality Objectives: • Meet or exceed all applicable groundwater, surface water, wastewater, and recycled water quality regulatory standards. • Identify and address the drinking water quality of disadvantaged communities in the Pajaro River Watershed. • Protect groundwater resources from contamination including salts and nutrients. • Address impacts from surface water runoff through implementation of Best Management Practices or other surface water management strategies. • Meet or exceed delivered water quality targets established by recycled water users.

40. SNMP Objective Development Actions Increase sewer Diet, Exercise Genetics Septic Leakage Legacy pollution Physical Health Groundwater Quality Join a gym Septic density (# area) Jog (mi/wk) NO3distr [mg/L] Weight (lbs)

41. Alternative Objectives Protect groundwater resources from contamination including salts and nutrients. Protect groundwater resources from contamination including salts and nutrients. Reduce the distribution of maximum groundwater NO3 concentrations to < 15% of total PVGB area by 2034. Reduce septic density to 40/sq mi in Freedom and Corralitos by 2034. Increase sewer Septic Leakage Legacy pollution Groundwater Quality Septic density (#/area) NO3dist [mg/L]

42. Challenges with measurable objectives • Difficulty and reluctance to prioritize if results in missed opportunities • Political or regulatory implications if targets are not achieved. • Broader community vision as PVWMA does not authority to require priority strategies to be implemented.

43. Stakeholder Feedback OBJECTIVE DEVELOPMENT APPROACH CONCERNS OR DESIRES POTENTIAL AREAS OF OBJECTIVE DEVELOPMENT BY TEAM