http://www.extension.org/72802 The Yakima Valley is a large agricultural area where there are multiple potential sources of nitrate in groundwater. Potential sources are intermingled, i.e., homes with septic systems are on the same properties as the dairies or adjacent to farms and/or dairies. In 2012, Region 10 of the US Environmental Protection Agency undertook a study to source track and identify nitrogen sources in the Yakima River Basin as part of an enforcement effort focusing on dairies. EPA position was that the targeted dairies did not properly apply nutrients to land application fields at agronomic rates, resulting in groundwater contamination. The study area is underlain by 3 aquifers, a shallow perched aquifer likely related to irrigation return flows, an alluvial aquifer and an underlying basalt aquifer. The three aquifers are hydrologically connected either through natural pathways or through wells completed into more than one aquifer. Because none of the potential sources are isolated, source tracking requires an in-depth knowledge of aquifer properties such as aquifer thickness, groundwater flow direction, hydraulic conductivity, and vertical leakance in addition to understanding localized effects of ditches, drains and production wells on groundwater flow. EPA focused on groundwater chemistry, assuming that indicators such as pesticides and other trace organic compounds would tie the groundwater nitrate to a specific source. EPA’s study failed to yield clear indicators pointing to specific sources and did not collect hydrologic data for its 2012 report to gain a detailed understanding of aquifer properties. This presentation will address how to accurately characterize the hydrogeology below dairy production areas and land application fields, and how to proactively manage nutrients to protect dairies from unsubstantiated enforcement actions.

1. Technical Evaluation of Reports by U.S.
Environmental Protection Agency on
Nitrate in Water Wells in the Yakima
River Basin, Yakima County, Washington
2015 Waste To Worth Conference
Seattle, Washington
Jay Lazarus and Elke Naumburg, PhD
Glorieta Geoscience, Inc.
PO Box 5727
Santa Fe, NM 87502
(505) 983-5446
www.glorietageo.com

2. Purpose and Scope
• Technical evaluation of 3 reports prepared by Region 10 EPA
Staff
• Evaluation funded by the Washington State Dairy Federation
and Dairy Producers of New Mexico
• Relation between Nitrate in Water Wells and Potential Sources
in the Lower Yakima Valley, Washington, EPA-910-R-12-003,
September, 2012 (Report)
• Quality Assurance Project Plan, Yakima Basin Nitrate Study
Phase 2 – Initial Nitrate/Coliform Screening of Domestic Wells
February 2010 Sampling Event, Yakima County, Washington,
U.S. EPA Region 10, January 27, 2010 (QAPP2)
• Quality Assurance Project Plan For Yakima Basin Nitrate Study
Phase 3 – Comprehensive Analytical Source Tracer Sampling
April 2010 Sampling Event, Yakima County, Washington, U.S.
EPA Region 10, April 27, 2010 (QAPP3)

3. Purpose and Scope
This presentation will address how to
accurately characterize the hydrogeology
below dairy production areas and land
application fields, and how to proactively
manage nutrients

4. Groundwater & Nitrate

5. Challenge: Complex Setting
Common challenge: multiple sources of
nitrate are intermingled:
• Dairies
• Farm fields with chemical/organic
fertilizers
• Orchards with chemical/organic fertilizers
• Homes with septic systems
New Mexico
Washington

6. Challenge: Complex Setting
• Hypothetical example:
• What is the source of or pathway
for nitrate in the monitoring
location?
o Neighbor’s improperly installed/maintained
septic system?
o Improperly completed wells providing
conduits to ground water?
o Farmland upgradient from dairy?
o Farmland where farmer over-applies
commercial fertilizer?
o Farmland where farmer uses manure
obtained from dairy?
o Orchards?
• How would you determine this?

7. Challenge: Monitoring Wells
• Additional challenges in Yakima:
o Few to no monitoring wells present
o Existing wells (irrigation & domestic) are completed at a range of depths
o Completion information (depth, screen depth) for many existing wells is unavailable
Location of monitoring wells in Yakima Valley, Source: Dept. of Ecology

8. Source Tracking
• In Yakima, EPA focused on groundwater chemistry, assuming
that indicators such as pesticides and other trace organic
compounds would tie the groundwater nitrate to a specific
source.
• However, organics behave very differently from the highly
mobile nitrate…
• Aquifer characteristics and sampling well completion
information were not fully assessed but directly affect the
movement of nitrate in groundwater and
• Thus, the choice of study design prevented conclusive
results.

9. Regional Hydrogeology
Because none of the potential sources are isolated,
source tracking requires an in-depth knowledge of
aquifer properties such as
• Groundwater flow direction
• Aquifer thickness
• Hydraulic conductivity
• Vertical leakance
In addition, need to understand localized effects of
• Ditches/drains and
• Production wells on groundwater flow

10. Regional Hydrogeology
• The Yakima Valley is underlain by 3 aquifers:
o a shallow perched aquifer likely related to irrigation return flows,
o an alluvial aquifer
o an underlying basalt aquifer with interbedded sands
• The 3 aquifers are hydrologically connected either
through natural pathways or through wells
completed into more than one aquifer.
• Depths and screen intervals were known for about a
third of the wells sampled by EPA.

11. Regional Hydrogeology

12. Source Tracking
• Better study design:
• Use monitoring wells or existing
wells with completion
information to characterize the
aquifer and groundwater flow
direction in particular

13. Source Tracking
• Source tracking with aquifer
knowledge - still have multiple
potential upgradient sources
• Need:
o Upgradient monitoring wells
o Monitoring wells downgradient from
potential sources

14. Proper Monitoring Well
Completion
• Casing extends above
ground surface and is
protected by a large
concrete pad and bollards
• Concrete pad sloped away
from well
• Monitoring well is locked
• Screen straddles the top of
the water table

15. EPA’s Improper Monitoring
Well Surface Completion
• Well is located in bar ditch
– a depression where
water will accumulate
• Water will accumulate
around well head
• No well surface pad
• This type of well head
completion is for
urban/gasoline/chlorinated
hydrocarbon type
monitoring on asphalt or
concrete – not agricultural

16. Improper Monitoring Well
Surface Completion

17. Improper Monitoring Well
Surface Completion

18. Sampling Design
It is crucial for any study examining nitrate sources to
have knowledge about:
• Well completion information
• Depth, degree of interconnectedness, and extent of
aquifers
• Groundwater flow direction
• Aquifer parameters (k, S or Sy, T)
If this information is not available, potential source
identification or pathways cannot be accurately
determined.

19. Sampling Design
Analytical methods that have been employed are:
• Relationship between chloride and nitrate-N
concentration:
o Synthetic fertilizer has little to no chloride
o Dairy lagoons tend to have high chloride concentrations
o Septic systems tend to have intermediate concentrations
o Complicating factors
• Sources overlap
• Different geochemistry of source water
o Shallow ground water
o Deeper ground water
o Surface water sources

20. Chloride vs. Nitrate-N
McQuillan, 2004

21. Sampling Design
Methods that have been employed are:
• Relationship between chloride and nitrate-N
• Nitrogen and oxygen isotopes:
o Synthetic nitrate fertilizer has lower d15N values than organic sources
o Synthetic nitrate fertilizer has higher d18O than organic sources
o Problem – nitrogen may undergo numerous biological
transformations, which change the isotopic signature detected in
groundwater
o Problem – sources overlap
o Problem – greenwater has a wide range of d15N so the nitrogen
isotope analysis requires a dairy-specific approach

22. Nitrogen and Oxygen Isotopes
Kendall, 2004, USGS

23. Sampling Design
Data sets that have been used to distinguish different
different sources of nitrate in groundwater:
• Relationship between chloride and nitrate-N :
• Nitrogen and oxygen isotopes:
• Isotopes in water:
o Water in lagoons evaporates, enriching the lagoon and groundwater
beneath if the lagoon is leaking significantly
• Boron isotopes:
o Boron is present in detergents and fertilizers – both have unique
range of d11B

24. Isotopes in Water
-110
-100
-90
-80
-70
-60
-50
-13 -12 -11 -10 -9 -8 -7
d 18
O, o
/oo
d
2
H,o
/oo
Global MWL (Craig, 1961) Dairy 1 Dairy 2 Dairy 3 Dairy 4
Downgradient from lagoon –
falls well below MWL
Upgradient from lagoon
– falls close to MWL

25. 0
2
4
6
8
10
12
14
-5 0 5 10 15 20 25
δ18O(‰)
δ15N (‰)
MW- Baseline
MW- Land Application Area
MW- Lagoon
MW- Flood Irrigation
Lagoon
Manure
Fertilizer
Dairy Area IsotopesDowngradient from corral,
near pecan flood irrigation

26. Nutrient Management
• Manage nutrients to insure nitrogen in applied at
agronomic rates
• By maintaining agronomic rates, nitrogen will not
leach beneath the root zone
• Sample irrigation and other production wells as
part of nitrogen loading calculations
• Maintaining good ground water quality and soil
health retains the value of the CAFO facility for
future generations
• Informed decision lead to optimal use at the
CAFO, insuring “wastes” are converted to assets
or worth

27. Dairy Sampling, Monitoring & Reporting
with CAFOweb™ integration
Sampling:
(Performed by consultants and/or Dairy)
Monitoring wells
Lagoon
Soils
Manure
Plant tissue
Laboratory
Analysis
Consultants and/or Dairymen
Lab Report
Monitoring:
(Data collected by Dairy and/or consultants)
Effluent meter readings
Crop planting & harvesting
Crop Irrigation
Record Keeping
Track Data Trends in
Reports:
Discharge, MW, Lagoon, Soils,
Manure, Yields, Irrigation,
Nitrogen application
Predict:
Effluent & manure solids
application
Fertilizer application
Freshwater application
Data Entry

28. Case Study:
Nitrogen Tracking

29. Conclusions
• Overall the Report provides a significant lack of supporting
technical information for EPA to arrive at the conclusions
presented in the report.
• Locally the ground water flow direction may be modified by
geologic structures and by irrigation practices, drains, ditches,
canals, and other hydrologic features.
• Very limited data on well completion, screened intervals, pump
setting, casing diameter, presence or absence of surface/sanitary
seals is presented.
• Lack of well completion information severely limits EPA’s ability to
verify if the wells identified as upgradient and downgradient of
potential sources produce water from the same water bearing
zone.
• No water levels were measured and converted to ground water
elevations with which to construct seasonal potentiometric surface
maps in each aquifer to determine temporal changes in both
localized and valley-wide ground water flow directions.
• The dairies and other sites are located in a matrix of farming and
septic systems, which makes source tracking impossible without
detailed knowledge of aquifer and well properties.
• EPA did not produce enforcement-quality data from this study.

30. Always Know Where the
Recharge Originates

31. Questions/Discussion
Glorieta Geoscience, Inc.
PO Box 5727
Santa Fe, NM 87502
(505) 983-5446
www.glorietageo.com