California Ag Irrigation Association
Central Valley Groundwater Nitrate Contamination and Implications for the Irrigation Industry Parry KlassenExecutive Director
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Regional Water Boards’ Authorities
Clean Water Act (Federal)◦ National Pollutant Discharge Elimination System Permits(NPDES)
◦ 303(d) list of impaired waters◦ Total Maximum Daily Loads (TMDLs) for impairing pollutants
Porter‐Cologne Water Quality Control Act (State)◦ Waste Discharge Requirements (WDRs) (new program)◦ Conditional waivers of WDRs (old program)◦ Basin Plans for all regions in State◦ CV Salts working to change salt/nitrate language
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Water Quality Regulatory FrameworkCalifornia Irrigated Agriculture
Regional Water Board◦ Irrigated Lands Regulatory Program (ILRP)◦ Waste Discharge Requirements (WDR)
◦ Encompasses Surface Water and Ground Water Quality◦ Not water supply
◦ Enrollment required for owners/operators of commercial irrigated cropland in:◦ Coalition, or◦ Individual General Order, or◦ Individual WDR
Central Valley CoalitionsSacramento Valley Water Quality Coalition
◦ Bruce Houdesheldt
California Rice Commission
◦ Tim Johnson
San Joaquin County & Delta Water Quality Coalition
◦ Michael Wackman
Westside San Joaquin River Watershed Coalition
◦ Joseph C. McGahan
East San Joaquin Water Quality Coalition◦ Parry Klassen
Westlands Water Quality Coalition
◦ Charlotte Gallock
Southern San Joaquin Valley Water Quality Coalition
◦ 7 new coalitions
Coalition OverviewIn operation since 2003
3,506 Landowner / operators
697,848 irrigated acres
◦ Madera, Merced, Stanislaus, Tuolumne, Mariposa counties
Average size of member operation◦ 199 acres
Member dues: $50 per membership, $3.75/acre
$3.1 million annual budget◦ Surface/groundwater monitoring◦ Outreach
Addressing Nitrate in Drinking Water
Correcting current and legacy nitrate contamination will take years (i.e., decades)
Irrigated lands and dairy order are key strategies
User protection needs to occur much sooner
Central Valley Regional Water Quality Control Board
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Salinas Valley
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Known Nitrate Sources (Regional)
Figure 1. Estimated groundwater nitrate loading from major sources within the Tulare Lake Basin and Salinas Valley, in Gg nitrogen per year (1 Gg = 1,100 t). http://groundwaternitrate.ucdavis.edu/files/139110.pdf ; Viers, J.H., et al (2012). Nitrogen Sources and Loading to Groundwater
Member Responsibilities
Complete Farm Evaluation (everyone)
Complete Nitrogen Management Plan • In high vulnerability groundwater area; submit to ESJ annually◦ Certified by 3rd party or grower trained
• Low vulnerability keep on site; no certification required
Sediment and Erosion Control Plan• In areas identified as high vulnerability for erosion and sediment discharge
Participate in annual outreach events
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Central Valley Irrigated Lands Regulatory Program
What Is Now Required
Responding to “petition” against ESJWQC Waste Discharge Requirements; adopted Dec 2012; petitioned immediately
Orders Regional Water Board to modify WDR extensively
State Board order includes mandates to
◦ Monitor all domestic wells on member parcels
◦ Requires all member information goes to Regional Water Board
◦ Farm Evaluations
◦ Nitrogen Management Plans
◦ Creates “Irrigation and Nitrogen Management Plan”
◦ Report “Total Water Applied”
◦ Report Et (evapotranspiration)
Could apply to all California Irrigated Lands Programs
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State Water Resources Control Board
How Does This All Fit Together?Farm Evaluation FE
Nitrogen Management Plan NMP
Nitrogen Management Plan Summary Report NMPSR
Nitrogen Management Plan Summary Report Analysis NMPSRA
Groundwater Quality Management Plan GQMP
Management Practices Evaluation Program MPEP
Groundwater Assessment Report GAR
Groundwater Trend Monitoring Program GTMP
Grower Reporting Coalition Reporting Outreach / Education
MPEPField StudiesModeling
No Nitrogen Leaching
Practices are OK
Leaching NitrogenRevise BMPs
Re-Study
Groundwater Assessment Report (GAR)Identify High Vulnerability Areas
Groundwater Quality
Management Plan
Groundwater Trend Monitoring Program
Coalition Region
Percent of Acreages for Irrigation Management Practices
Overview of Data Collected2015 Crop Year Reporting
Members in High Vulnerability areas (60+ acres) required to report N fertilizer applications
Status as of 8/15/16Required 1,192Received 1,114Percent Returned 94%
Township Aggregation of NMP Summary Reports
Red dotted line represents A/Y = 1. Based on 68 lbs of N per 1000 lbs almond nut meats (per UC/ABC studies)
Red dots = potential outliers
Recommended fertilizer rate for mature trees
Almonds ‐ Box and Whisker Plot by Crop (all ages)
Specific Crop MgmtUnits
Sum of Acres
Almonds Year1 11 433.7Almonds Year2 23 1,489.6Almonds Year3 77 7,069.5Almonds Year4 26 2,015.5Almonds Year>4 1355 116,268.4Almonds Year NR 104 10,122.6All Almonds 1596 137,399.3
Red dotted line represents A/Y = 1. Based on 68 lbs of N per 1000 lbs almond nut meats (per UC/ABC studies)
Almonds ‐ Box and Whisker Plot by Specific Crop Age
Member Outreach on NMP Summary Report
Packet of information to be mailed/emailed to members Fall 2016
Contents:
Reporting Component ◦ Summary of reported data (A/Y) and when possible, A/R◦ Comparison to other growers with same crop
Education Component◦ Information on nitrogen crop consumption curves (where available)◦ Applications and yield ‐ UCCE recommendations
Efficient Nitrogen Management: Applying the 4 R’s PrincipleApply the Right Rate
Apply at the Right Time
Apply in the Right Place
Use the Right Source
Almond Nitrogen Crop Consumption CurvesTiming of Nitrogen Application to Match Crop Need/Use
Nitrogen in Irrigation Water“PUMP AND FERTILIZE”
Nitrate‐N (NO3‐N) in well water is “useful” source of nitrogen for crop production.
Determine the concentration of nitrogen in your irrigation water source (well, etc).
Example: ◦ well water = 35 ppm nitrate‐N (NO3‐N). ◦ apply 30 ac/inches water per acre per season◦ 35 ppm nitrate‐N x 0.225 = 7.875 lbs N/acre inch x 30 inches = 236.25 lbs N per acre.
Management Practices Evaluation Program Study ObjectivesIdentify whether site‐specific and/or commodity‐specific management practices are protective of groundwater quality within high vulnerability groundwater areas
Determine if newly implemented management practices are improving or may result in improving groundwater quality
Develop an estimate of the effect of Member’s discharge of constituents of concern on groundwater quality in high vulnerability areas. A mass balance and conceptual model of the transport, storage, and degradation/chemical transformation mechanisms for the constituents of concern or equivalent method approved by the Executive Officer
Utilize the results of evaluated management practices to determine whether practices implemented at represented Member farms (i.e., those not specifically evaluated, but having similar site conditions), are sufficiently protective of groundwater quality or if management practices need to be improved.
Examples of Potential Measurements in MPEP Field Studies
Groundwater
N Applied as:◦ Commercial fertilizer◦ Cover crops/manure/compost◦ Irrigation water
N Harvested with crop◦ N stored (where applicable)
N in Vadose Zone◦ Soil cores
N in Leachate◦ Suction Lysimeters
Also measure water applied through irrigation and rainfall on site
Where Can Irrigation Industry Help?Assist in adoption of precision irrigation systems1. Sell best equipment2. Service after the sale / Technical Service Providers
Bring existing systems to highest efficiency possible◦ Distribution uniformity critical for:
◦ Efficient water use ◦ Proper application of nitrogen fertilizers
Assist Coalitions in Education and Outreach1. We need “teachers” with practical knowledge2. Create industry “speakers bureau”
Where Can Irrigation Industry Help?State Board Proposing that growers report:◦ Total Applied Water◦ Crop ET (evapotranspiration)
Are those the best metrics to show growers are protecting water quality?
Is there better information we can collect to improve◦ Distribution Uniformity
How can we minimize over irrigation / excessive nitrate leaching to groundwater?
Example of a good DU Example of a poor DU
The problem with a poor DU ◦ If enough water is applied to ensure every plant is given adequate water, we overwater other plants.
Drip requires constant maintenance
Uniform fertigation applications
High distribution uniformity
Backflow prevention
Prerequisites:
Inject here
Travel time: how long does the fertilizer need to distribute evenly?
Furthest point from injection location
Travel time depends mostly on:• Injection location• Flow rate of tape• Length of beds
Irrigation System Uniformity (2009 ‐2012)
Irrigation Method
number of fields Average Mininum Maximum
drip 27 78 23 96sprinkler 10 66 50 86
Distribution Uniformity
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ % DUlq ‐‐‐‐‐‐‐‐‐‐‐‐‐‐
1. Start injection after drip system is fully pressurized and leaks are fixed
2. Inject upstream of a filter to prevent clogging of drip emitters3. Injecting slowly as possible provides a more uniform
distribution4. After injection, irrigate a sufficient time with clean water to
flush out all of the injected fertilizer from the drip system5. Avoid over‐irrigating in subsequent irrigations to prevent
leaching losses of nitrate
Uniform Fertigation Applications Words of WisdomMichael Cahn, UCCE
Know Your Soil‐ Placement of Sensors
Water movement on various soil textures
◦ In sandy soils, water readily moves downward due to the force of gravity.
◦ In clayey soils, water slowly moves out in all direction by capillary action.
Questions?