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Salt & Nutrient Management Plan Pajaro Valley Water Management Agency. Stakeholder Workshop #2 March 28, 2013. Agenda. SNMP Overview Existing Groundwater Conditions Loading Analysis Approach Nutrient l oading r isk analysis/findings Salt loading r isk analysis/findings - PowerPoint PPT Presentation
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Salt & Nutrient Management Plan Pajaro Valley Water Management Agency
Stakeholder Workshop #2March 28, 2013
1
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 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
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
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
5
[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%)
8
[Cl] Range (mg/L) acres (%)0-100 55,500 (82%)
>100– 250 8870 (13%)>250– 500 2600 (4%)
>500 644 (1%)
MEAN [Cl]
9
MAX [Cl]
[Cl] Range (mg/L) acres (%)0-100 52,900 (78%)
>100– 250 10,400 (15%)>250– 500 3170 (5%)
>500 1200 (2%)
10
[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]
11
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%)
12
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%
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
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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
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
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
21
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
23
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
25
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%
27
Surface water infiltration N Risk Analysis
28
• 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
29
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
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
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
N loading ACROSS sources
32
Sources in PVGB• Seawater Intrusion• Irrigation practices• Surface water recharge
Salt loading risk analysis
33
• Seawater Intrusion
34
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
35
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
37
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
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 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.
41
Increase sewer
Groundwater Quality
NO3 dist [mg/L]
Septic LeakageLegacy 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.
43
Stakeholder Feedback
OBJECTIVE DEVELOPMENT APPROACH
CONCERNS OR DESIRES
POTENTIAL AREAS OF OBJECTIVE DEVELOPMENT BY TEAM