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

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Presentation on theme: "Salt & Nutrient Management Plan Pajaro Valley Water Management Agency Stakeholder Workshop #2 March 28, 2013 1."— Presentation transcript:

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

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 2

3 SNMP Development Process Primary TasksSchedule Task 1. Stakeholder Outreach 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/projectsDraft Fall 2013 Task 7. SNMP Monitoring PlanDraft Spring 2014 Task 8. Conduct anti degradation analysisDraft Spring 2014 Task 9. Complete SNMPSummer

4 Stakeholder Feedback Process Plan developed in iterative sections Drafts vetted with stakeholders Go to PVWMA website for report and Stakeholder comment form – Comments must be submitted in writing, compiled on comment site Comments due by 04/12/2013 Responses tracked and available to all 4

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 Interpolate decadal average and max concentrations using IDW for 5 closest wells Results are interpolated concentration contours 5

6 [TDS] Range (mg/L)acres (%) ,300 (52%) >450– ,900 (41%) >1000– 18003,550 (5%) > (1%) MEAN [TDS]

7 7 MAX [TDS] [TDS] Range (mg/L)acres (%) ,300 (43%) >450– ,500 (45%) >1000– 18006,950 (10%) > (1%)

8 8 [Cl] Range (mg/L)acres (%) ,500 (82%) >100– (13%) >250– (4%) > (1%) MEAN [Cl]

9 9 MAX [Cl] [Cl] Range (mg/L)acres (%) ,900 (78%) >100– 25010,400 (15%) >250– (5%) > (2%)

10 10 [NO 3 ] Range (mg/L)acres (%) ,500 (38%) >10– 4528,400 (42%) >45– 10010,500 (16%) >1003,260 (5%) MEAN [NO 3 ]

11 11 MAX [NO 3 ] [NO 3 ] Range (mg/L)acres (%) ,600 (36%) >10– 4523,100 (34%) >45– 10012,600 (19%) >1007,410 (11%)

12 Groundwater Condition Summary PVGB Area mapped: 67,500 acres 12 ConstituentThreshold Fraction acreage above threshold AVERAGE (%) Fraction acreage above threshold MAX (%) TDS1000 mg/L 6%11% Chloride100 mg/L18%22% Nitrate-NO 3 45 mg/L21%30%

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. 13

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 14

15 15 Soil [NH 4 +, NO 3 - ] Atmosphere [N 2(g) ] Groundwater [NO 3 - ] Relevant components of the NITROGEN CYCLE Plants [N organic] mineralization uptake Air Pollution [N 2 O] Septic/sewer systems [NH 4 +, NO 3 - ] deposition applications leaks Animal waste [NH 4 +, NO 3 - ] fixation leaching Fertilizer [NH 4 +, NO 3 - ] denitrification mineralization Controllable sources Key reservoirs KEY process Upgradient sources Downgradient migration Irrigation water [NH 4 +, NO 3 - ] Stormwater [NH 4 +, NO 3 - ] runoff Nitrogen – NO 3 Risk Analysis

16 Agricultural Fertilizer NO 3 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 16

17 Relative Soil Water Holding Capacity

18 Land Use CategoryAcres% Artichokes, Vegetable Row9,13813 Horticulture Nurseries1,3432 Strawberries7,99411 Caneberries5,0037 Deciduous (Orchards)2,1793 Other, Unknown Ag, Vines/Grapes1,1422 Non-agriculture land uses43,15862 Total

19 Irrigation category % of Ag land High55% Moderate31% Low15 Agricultural land 32,362 Non-agricultural land 38,068

20 Fertilizer category Measured % of ag land Expected % of ag land VERY HIGHna High 39% Moderate48 Low12 Agricultural land 26,799 acres Non-agricultural land 43,158 acres

21 Agricultural N Risk Matrix 21

22 Ag nitrate loading risk Acres% of Ag Land HIGH14,31253 MODERATE10,22438 LOW2,2638 Total Ag land26,799100

23 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 of septic systems in PVWMA

24 Septic nitrate loading risk Number of septic systems SC/Mo% HIGH / MODERATE / LOW / Total Septic N Risk Analysis Septic riskSCC /MoC% HIGH1023 / MODERATE1955 / LOW311 / Total

25 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

26 Sewer risk Total Length (miles) % HIGH % MODERATE % LOW % Total %

27 Surface water infiltration N Risk Analysis 27

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

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 29

30 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 30 N loading ACROSS sources

31 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 31 N loading ACROSS sources

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

33 Seawater Intrusion 33

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

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

36 Salt Loading Risk Analysis Summary of Findings Irrigation salt risk Acres% HIGH8,97828 MODERATE13,72143 LOW9,24629 Total Ag land31,945100

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 37

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 38

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: 1.Meet or exceed all applicable groundwater, surface water, wastewater, and recycled water quality regulatory standards. 2.Identify and address the drinking water quality of disadvantaged communities in the Pajaro River Watershed. 3.Protect groundwater resources from contamination including salts and nutrients. 4.Address impacts from surface water runoff through implementation of Best Management Practices or other surface water management strategies. 5.Meet or exceed delivered water quality targets established by recycled water users. 39

40 SNMP Objective Development 40 ActionsJoin a gym Physical Health Weight (lbs) Diet, Exercise Genetics Jog (mi/wk) Increase sewer Groundwater Quality NO 3 distr [mg/L] Septic Leakage Legacy pollution Septic density (# area)

41 Alternative Objectives Protect groundwater resources from contamination including salts and nutrients. Reduce the distribution of maximum groundwater NO 3 concentrations to < 15% of total PVGB area by Reduce septic density to 40/sq mi in Freedom and Corralitos by Increase sewer Groundwater Quality NO 3 dist [mg/L] Septic Leakage Legacy pollution Septic density (#/area) Protect groundwater resources from contamination including salts and nutrients.

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. 42



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