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Salt & Nutrient Management Plan Pajaro Valley Water Management Agency

Salt & Nutrient Management Plan Pajaro Valley Water Management Agency. Stakeholder Workshop #2 March 28, 2013. Agenda. 9 am – 1pm . SNMP Overview (10 min) Existing Groundwater Conditions (30 min) Loading Analysis Approach Nutrient l oading r isk analysis/findings (1 hr )

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Salt & Nutrient Management Plan Pajaro Valley Water Management Agency

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

  2. Agenda 9 am – 1pm • SNMP Overview (10 min) • Existing Groundwater Conditions (30 min) • Loading Analysis Approach • Nutrient loading risk analysis/findings (1 hr) • Salt loading risk analysis/findings (30 min) • Assimilative Capacity Discussion (15 min) • SNMP Objective Development Discussion (30 min) • Stakeholder Next Steps (10 min)

  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 http://www.pvwma.dst.ca.us/board-and-committees/salt-nutrient.php • 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 • Analyze existing groundwater data • 295 PVWMA Production & Dedicated Monitoring Wells • 14 City of Watsonville Production Wells • Calculate statistics by site and constituent for the 10-year period: 2002-2011 • Map statistical results and then interpolate the decadal average and maximum concentrations using Inverse Distance Weighted method • To protect the confidentiality of the well owner, results are maps that show interpolated concentration contours, but do not display individual well data

  6. Inverse Distance Weighted Method • Predicts values at unmeasured locations based on measured values surrounding the prediction location. • Local influence from measured data diminishes with distance. • Method is being used to develop SNMPs elsewhere in the state.

  7. Metered & UnmeteredWells

  8. Groundwater Average TDS

  9. Groundwater Maximum TDS

  10. Groundwater Average Cl

  11. Groundwater Maximum Cl

  12. Groundwater Average NO3

  13. Groundwater Maximum NO3

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

  15. SNMP Pollutant Loading Analysis RISK ANALYSIS APPROACH • Relative risk for each primary source • Identify primary factors driving potential 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.

  16. 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

  17. 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

  18. Agricultural Fertilizer NO3 Loading Risk Analysis Factors evaluated • Soil water holding capacity • Land use patterns • Annual irrigation volumes • Amount of N applied as fertilizer Data sources used • NRCS Soil survey • PVWMA Ag crop land use data (2012 and 2011) • PVWMA and MCWRA water usage data and grower surveys • NASS survey data and published literature values

  19. Agricultural Fertilizer NO3 Loading Risk Analysis Soil water holding capacity • NRCS data used for 1-100 cm soil depth • 4 categories based on amount of water held by soil, soil texture data and slope • Categories are specific to the diversity of soil conditions within the Pajaro Valley Categories • Low – capacity to hold up to 0.75 AF per acre • Moderate – capacity to hold 0.75 – 1.25 AF per acre • High – capacity to hold 1.25 – 1.5 AF per acre • Very High – capacity to hold 1.5 – 2.3 AF per acre

  20. Relative Soil Water Holding Capacity

  21. Agricultural Fertilizer NO3 Loading Risk Analysis Land use patterns • PVWMA Ag land use data averaged for 2011 – 2012 • 6 categories based on crop groups specific to agricultural land use within the Pajaro Valley Categories • Vegetable row crops including artichokes, broccoli, cabbage, cauliflower, celery, lettuce, spinach and other leafy greens • Horticulture nurseries including bulb production facilities, cut flower operations, landscape plants and transplant operations • Strawberries • Caneberries • Deciduous trees – orchards • Other agriculture production including vines, grapes and miscellaneous crops

  22. PVGB Ag Land Use

  23. Agricultural Fertilizer NO3 Loading Risk Analysis Irrigation intensity • PVWMA usage data, MCWRA usage data, and published literature data sources • 3 categories based on range of values by crop group • Categories are specific to the irrigation requirements based on both crop and cool climate within the Pajaro Valley • Individual agriculture operations may have usage patterns different than values used for each crop group Categories • Low – usage of 0.5 – 1.7 AF per acre, such as grapes and orchards • Moderate – usage of 1.8 – 2.3 AF per acre, such as strawberries, caneberries and other acreage on drip irrigation • High – usage of 2.4 – 3.0 + AF per acre, such as double cropped vegetable row crops and other acreage utilizing sprinkler irrigation

  24. Irrigation Intensity

  25. Agricultural Fertilizer NO3 Loading Risk Analysis Agriculture crop fertilizer use • NASS surveys, PVWMA surveys, and published literature data sources • 4 categories based on a range of values by crop group • Categories are specific to the diversity of crops and the soil fertility conditions within the Pajaro Valley • Individual agriculture operations may have usage patterns different than values used for each crop group Categories • Low – usage of 35 – 75 lbs. N per acre, such as grapes, certain horticultural operations and miscellaneous crops • Moderate – usage of 76 – 149 lbs. N per acre, such as orchards, caneberries • High – usage of 150 – 250 lbs. N per acre, such as strawberries , vegetable row crops and certain horticultural operations • Very High – usage of over 250 lbs. N per acre, as may occur under certain conditions of crop production

  26. Fertilizer Intensity

  27. Agricultural Fertilizer NO3 Loading Risk Analysis Soil Water Holding Capacity Fertilizer Intensity Irrigation Intensity Based on crop type Agricultural N Risk Matrix

  28. Agricultural Fertilizer NO3 Loading Risk Analysis Agricultural N Risk Matrix

  29. Agriculture N Risk

  30. Septic N Risk Analysis • Factors : 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 • Density exceeds 400 units/sq mi in some locations

  31. Septic N Risk Analysis Septic N Risk

  32. Sewer N Risk Analysis • Factors : 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

  33. Sewer N Risk

  34. Surface water infiltration N Risk Analysis Factors : stream bed conductivity and mean Q3 [NO3]

  35. Streamflow Infiltration

  36. Surface water infiltration N Risk Analysis Streamflow N Risk

  37. 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

  38. N loading ACROSS sources

  39. N loading ACROSS sources Agriculture: 1742 t N/yr Mass of N leaching to gw per year per acre * acres of Ag in PVGB 130 lbs N/acre/yrx 26,799 acres of ag • 134 lbs N/acre/yr (Viers et al 2012; study area average) • 123 lbs N/acre/yr (Viers et al 2012; Mo Co area average)

  40. 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 (80 t N/yr) • 6.6 million GPD treated, 50% infiltrated @ 16 mg/L NO3 Stream flow recharge (746 t N/yr) • USGS annual recharge (AF/yr) * NO3 SW conc. 18,300 AF/yr * 30 mg/L

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

  42. Seawater Intrusion Seawater Intrusion Risk

  43. 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

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

  45. Irrigation Salt Risk

  46. Surface water infiltration SALT Risk Analysis Factors : stream bed conductivity and mean Q3 [TDS]

  47. Streamflow Salt Risk

  48. 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

  49. 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

  50. 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.

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