Salt & Nutrient Management Plan Pajaro Valley Water Management Agency

Stakeholder Workshop #2March 28, 2013

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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

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SNMP Development Process

Primary Tasks Schedule

Task 1. Stakeholder Outreach Stakeholder Meetings at critical milestones

Task 2. Conceptual Model Draft included

Task 3. Salt and Nutrient Loading Analysis Draft included

Task 4. Assimilative Capacity Estimate Draft Fall 2013

Task 5. Develop or update objectives Draft Fall 2013

Task 6. Develop or update priority program/projects Draft Fall 2013

Task 7. SNMP Monitoring Plan Draft Spring 2014

Task 8. Conduct anti degradation analysis Draft Spring 2014

Task 9. Complete SNMP Summer 2014

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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

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

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[TDS] Range (mg/L) acres (%)0-450 35,300 (52%)

>450– 1000 27,900 (41%)>1000– 1800 3,550 (5%)

>1800 637 (1%)

MEAN [TDS]

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MAX [TDS]

[TDS] Range (mg/L) acres (%)0-450 29,300 (43%)

>450– 1000 30,500 (45%)>1000– 1800 6,950 (10%)

>1800 900 (1%)

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[Cl] Range (mg/L) acres (%)0-100 55,500 (82%)

>100– 250 8870 (13%)>250– 500 2600 (4%)

>500 644 (1%)

MEAN [Cl]

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MAX [Cl]

[Cl] Range (mg/L) acres (%)0-100 52,900 (78%)

>100– 250 10,400 (15%)>250– 500 3170 (5%)

>500 1200 (2%)

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[NO3] Range (mg/L) acres (%)0-10 25,500 (38%)

>10– 45 28,400 (42%)>45– 100 10,500 (16%)

>100 3,260 (5%)

MEAN [NO3]

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MAX [NO3]

[NO3] Range (mg/L) acres (%)0-10 24,600 (36%)

>10– 45 23,100 (34%)>45– 100 12,600 (19%)

>100 7,410 (11%)

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Groundwater Condition Summary

PVGB Area mapped: 67,500 acres

Constituent ThresholdFraction acreage above threshold

AVERAGE (%)

Fraction acreage above threshold MAX (%)

TDS 1000 mg/L 6% 11%Chloride 100 mg/L 18% 22%

Nitrate-NO3 45 mg/L 21% 30%

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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.

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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

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Soil [NH4+, NO3

-]

Atmosphere [N2(g)]

Groundwater [NO3-]

Relevant components of the NITROGEN CYCLE

Plants [N organic]

mineralizationuptake

Air Pollution [N2O]

Septic/sewer systems[NH4

+, NO3-]

deposition

applications leaks

Animal waste[NH4

+, NO3-]

fixation

leaching

Fertilizer[NH4

+, NO3-]

deni

trifi

catio

n

mineralization

Controllable sources

Key reservoirs

KEY

process

Upgradient sources

Downgradient migration

Irrigation water[NH4

+, NO3-]

Stormwater[NH4

+, NO3-]

runoff

Nitrogen – NO3 Risk Analysis

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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

Relative Soil Water Holding Capacity

Land Use Category Acres %Artichokes, Vegetable Row 9,138 13

Horticulture Nurseries 1,343 2Strawberries 7,994 11Caneberries 5,003 7

Deciduous (Orchards) 2,179 3Other, Unknown Ag, Vines/Grapes 1,142 2

Non-agriculture land uses 43,158 62Total 69957 100

Irrigation category % of Ag landHigh 55%

Moderate 31%

Low 15

Agricultural land 32,362

Non-agricultural land 38,068

Fertilizer category Measured% of ag land

Expected% of ag land

VERY HIGH na

High 39%

Moderate 48

Low 12

Agricultural land 26,799 acres

Non-agricultural land 43,158 acres

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Agricultural N Risk Matrix

Water Holding Capacity (AF) Water

(AF/acre/year) Fertilizer

(lbs. N/acre/year) Very High (1.5 - 2.3)

High (1.25 - 1.5)

Mod (0.75 - 1.25)

Low (< 0.75)

High (2.4 - 3.0+)

High (150 – 250+) MOD RISK HIGH RISK HIGH RISK HIGH RISK

Mod (1.8 - 2.3)

High (150 – 250+) MOD RISK MOD RISK HIGH RISK HIGH RISK

Mod (1.8 - 2.3)

Mod (76 - 149) LOW RISK MOD RISK MOD RISK HIGH RISK

Low (0.5 - 1.7)

Mod (76 - 149) LOW RISK LOW RISK MOD RISK MOD RISK

Low (0.5 - 1.7)

Low (35 - 75) LOW RISK LOW RISK LOW RISK LOW RISK

Ag nitrate loading risk Acres % of Ag Land

HIGH 14,312 53MODERATE 10,224 38

LOW 2,263 8Total Ag land 26,799 100

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Septic N Risk AnalysisFactors are presence and soil typeSeptic GIS data Monterey and SC CoMonterey Co data generated using CAD plans by 2N. 4500 of septic systems in PVWMA

Septic nitrate loading riskNumber of

septic systemsSC/Mo %

HIGH 1889 1023 / 866 42

MODERATE 2152 1955 / 197 48

LOW 431 311 / 120 10

Total 4472 100

Septic N Risk Analysis

Septic risk SCC /MoC %

HIGH 1023 / 866 42

MODERATE 1955 / 197 48LOW 311 / 120 10Total 4472 100

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Sewer N Risk AnalysisFactors area presence and soil typeSewer GIS data Monterey and SC CoMonterey Co data generated using CAD plans by 2N. 146 miles of sewer lines in PVWMA

Sewer riskTotal

Length (miles)

%

HIGH 19.4 13%

MODERATE 72.7 50%

LOW 53.7 37%Total 145.8 100%

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Surface water infiltration N Risk Analysis

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• Agricultural Irrigation o Potential opportunity to manage fertilizer appso Similar outcome as fertilizer risk

• Riparian land use risko Buffer approach

• Urban storm water runoffo Localizedo Low recharge in Sloughs

• Atmospheric o Uncontrollable

• Animal Wasteo Minimal presence

Subordinate Sources N loading

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N loading ACROSS sources

• Viers et al 2012 aka Harter ReportN loading to gw mass balance in

Salinas/Tulare GWB• Applicable N loading/unit source/yr– Fertilizer applications (Ag)– Sewer – Septic– WWTP

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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

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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

N loading ACROSS sources

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Sources in PVGB• Seawater Intrusion• Irrigation practices• Surface water recharge

Salt loading risk analysis

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• Seawater Intrusion

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Plant Growth

SALT leaching

Evapotranspiration

Soil SALT adsorption

SALT leaching

Evapotranspiration

Soil SALT adsorption

Plant Growth

Aquifer SALT

Aquifer SALT

Irrigation volumes

SALT CYCLING ON IRRIGATED LAND

HIGH

HIGH

Low

Low

HIGH

HIGH

HIGH

HIGH L

Salt content of irrigation waterHIGH Low

Low

Low

Low

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Factors• Annual water use• Irrigation water TDS content• Soil water holding capacity

Irrigation salt loading risk

Water Holding Capacity (AF)

Water USE Irrigation Water TDS Very High High Mod Low

(AF/acre/year) (mg/L) (>1.5) (1.25 - 1.5) (0.75 - 1.25) (< 0.75)

All categories High MOD RISK HIGH RISK HIGH RISK HIGH RISK (>1000) High Mod MOD RISK MOD RISK HIGH RISK HIGH RISK (2.4 - 3.0+) (450-1000) Mod Mod LOW RISK MOD RISK MOD RISK HIGH RISK (1.8 - 2.3) (450-1000) Low Mod LOW RISK LOW RISK MOD RISK MOD RISK (0.5 - 1.7) (450-1000)

All categories Low LOW RISK LOW RISK LOW RISK LOW RISK (<450)

Salt Loading Risk Analysis

• Summary of Findings

Irrigation salt risk Acres %

HIGH 8,978 28

MODERATE 13,721 43LOW 9,246 29

Total Ag land 31,945 100

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Assimilative Capacity Discussion

• Required Task of SNMP• Intent of task is to identify areas of concern and areas

where standards are met• No specific GW standards for PVGB

• Clarification from Regional Board requested

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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

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Pajaro River Watershed IRWM WQ Goal and ObjectivesWater 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.

SNMP Objective Development

Actions

Join a gym Physical Health

Weight (lbs)

Diet, ExerciseGenetics

Jog (mi/wk)

Increase sewer

Groundwater Quality

NO3 distr [mg/L]

Septic LeakageLegacy pollution

Septic density (# area)

Alternative Objectives

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.

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Increase sewer

Groundwater Quality

NO3 dist [mg/L]

Septic LeakageLegacy pollution

Septic density (#/area)

Protect groundwater resources from contamination including salts and nutrients.

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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.

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Stakeholder Feedback

OBJECTIVE DEVELOPMENT APPROACH

CONCERNS OR DESIRES

POTENTIAL AREAS OF OBJECTIVE DEVELOPMENT BY TEAM