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AGRICULTURAL AND GROUNDWATER An Overview of Current Issues
Mike Wireman
National Ground Water Expert - US EPA Region 8 Chair- US Chapter – International Association of Hydrogeologists
2011 Ground Water Protection Council Annual Forum
Atlanta, Georgia
What are the issues??
• Sustainability “development & use of gw in a manner that can be maintained for an indefinite time without causing unacceptable environmental, social or economic consequences” (Alley, et. al) – Water quantity – Water availability – Water quality
Sustainable Use of Water 1. World Population
1950 – 2.5 billion 2000 – 6 billion 2010 – 7 billion 2050 – 9 billion USA -3rd most populous country- 300 million +
2. No longer possible to feed people without irrigated farming 3. Agricultural water use - % of all withdrawals
• USA – 41 • World – 70
Does 1 + 2 + 3 = Crisis!
Global Groundwater Use Annual withdrawals have increased
from approximately 100 million af/year in 1950 to approximately 790 million af /yr in 2000 (1 AF = 325,000 gallons)
Supports annual output valued at $210 - $230 million / year – approx. $0.23 to $0.26 / m3
Increase due primarily to
agricultural water demand
Irrigated area supplied partially or wholly by groundwater increased from 74 million acres to 247 million acres
Supplemental irrigation in Syria
One of key reasons for reduced poverty, better food security, improved livelihoods in Asia, India, Africa –groundwater is a local irrigation source
From –Water for food –Water for life – International Water Management Institute, 2007
China, USA, Iran, India, Bangladesh, Pakistan account for 80 % of global GW use
Water footprints of various crops
Crops Water footprint -gallons
1 apple 19
1 orange 13
1 pound of barley 156
1 pound of soybeans 216
1 pound of wheat 156
1 pound of corn Products
108
1 pound of cheese 600
1 gallon of milk 1000
1 pound of butter 2044
Source – Water footprint.org – EPA OPEI (2009)
3000 liters required (converted from liquid to vapor) to produce one persons daily food need
Drinking water – 2-5 liters per person per day
Water use for food production increased by 200% in last 50 years- due to population increase AND change in human diet
Today’s food requires much more water
1 kilo of peanuts needs 2x as much water as 1 kilo of soybeans 1 cup of orange juice needs 5x as much water as 1 cup of tea
Water Footprint
From –Water for food –Water for life – International Water Management Institute, 2007
Long-term average groundwater recharge (millimeters per year)
Intensive groundwater use in agriculture
0-2 2-20 20-100
100-300
300-1000
A USA example Blue dots - wells in USGS NWIS where water level difference is = or > 40 ft Red areas > 500 mi2 - Water level decline > 40 ft in confined aquifer or > 25 unconfined Ogallala (174,000 mi2 ) – 27% of irrigated land in US – 94% of gw used for irrigation –water level declines of > 100ft
What is the water quality issue? CONTAMINATION OF WATER RESOURCES / FOOD BY
AGRICULTURAL CHEMICALS - PRIMARILY PESTICIDES AND NUTRIENTS
Approximately 20,000 PESTICIDE products registered for use in the USA
Approximately 12 million tons of NITROGEN applied by US farmers as fertilizer
in 2000 More than 200,000 Animal Feeding Operations in USA– AFOs and CAFOs Environmental issues
♦ Pesticide toxicity -humans and animals ♦ Nitrogen
Drinking water – methemoglobenemia (blue baby), bladder & ovarian cancer, treatment costs
Nutrient loading to surface waters - hypoxia, eutrophication Mobilization of selenium by nitrate
Herbicides3 1870 37 553 46 30
Insecticides 1232 24 105 9 9
Fungicides 475 9 73 6 15
Other4 1469 29 472 39 32
Total 5046 100 1203 100 24
WORLD MARKET US MARKET
TYPE MILLION LBS. OF A.I.2
% MILLION LBS. OF A.I.
% USA % OF WORLD MARKET
2001 WORLD AND USA AMOUNT OF PESTICIDE USE(1) (ACTIVE INGREDIENT)
1. Source – EPA estimates based on Croplife America annual surveys, USDA/NASS & EPA proprietary data
2. A.I. = active ingredient
3. Includes herbicides & plant growth regulators
4. Includes nematicides, fumigants, rodenticides, mulluscicides, aquatic & fish /bird pesticides plus other chemicals used as pesticides (oil, sulfur)
Nitrogen in groundwater – Agricultural Sources
Animal feeding operations Nitrogen fertilizers
Nitrate in groundwater - What is the problem?
Human health problem
PWS /private well contamination (MCL = 10 mg/l)
Methemoglobenemia (blue baby)
NO3 reduced to NO2 which restricts bloods capacity to carry oxygen Dangerous for infants due to low pH of infants blood
Linked to bladder & ovarian cancer Treatment costs
Taste and odor problems Possible health effects from algal toxins Organic matter + disinfectants = disinfection byproducts
Nitrate in groundwater - What is the environmental problem?
Nitrate in groundwater is a source of nitrogen loading to surface waters nutrients can stimulate algal growth hypoxia, eutrophication acidified soils and sensitive fresh waters
GW N loading to surface water controlled by complex
physical, hydrologic, bio-geochemical processes where groundwater & surface water mix Denitrification processes greater than nitrification in hyphoreic zone
Mobilization of selenium by nitrate
Nutrient Impacts to Water Resources
EPA Wadeable Streams Assessment Hypoxia Areas Have Increased Dramatically over the Last 50 Years Source: Science/World Resources Institute.
USA - Nutrients impacts – 10,000+ 303(d) listings = third largest cause of impairment
– Over half (80) of U.S. estuaries suffer harmful low oxygen events – 49 states have section 303(d) listings for nutrients or excessive algal
growth. – Over 5,000 completed TMDLs for nutrients, oxygen depletion, or
excessive algal growth
What is the problem?
0 10 20 30 40 50 60 70 80
E
NE
E
NE
E
NE
E
NE
E
NE
E
NE
E
NE
GROUNDWATER
• Since 2003 69 PWS systems in EPA Region 8 in violation of nitrate MCL (63 are ground water systems)
• Excessive nutrients leads to problems for drinking water treatment:
• Algal and moss growth • Taste, odor, color and
treatment problems • Possible health effects
from algal toxins • Bacterial and other aquatic life • Excessive organic matter =
disinfection byproducts
WY
UT
SD
ND
MT
CO
% stream length
Red –exceeds reference site values
Green – does not exceed
SURFACE WATER
Primary sources INORGANIC FERTILIZER Application of fertilizers to cropland is most common &
widespread source of nitrate in GW (Rupert, M.G., USGS, 2008)
ANIMAL FEEDLOTS – ESPECIALLY CAFOS Can be significant concentrated source
URBAN – variable and local
SEPTIC TANKS – local scale
RESIDUAL NITROGEN IN SOIL / VADOSE ZONE Uncommon – can be significant source in arid areas (San Pete
Valley- Utah)
NATURAL SOURCES – very uncommon –some shales, saltpeter
Nitrate in ground water
Fertilizer Use for Corn - USA
0
20
40
60
80
100
120
140
160
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
Year
use
-lbs/
acre
0
50
100
150
200
250
300
350
cost
-dol
lars
/ to
n
Use Cost
Fertilizer Use – USA
Nitrate concentrations in groundwater have increased greatly since the 1940s in response to N fertilizer use & irrigation
Fertilizer use has increased significantly with development of new genetically enhanced varieties of corn, which require more N to maximize yields
Approximately 12 million tons of NITROGEN applied as fertilizer in 2000 –
Fertilizer costs approx. 40% of total operating costs of corn production
2007 – 57 million acres irrigated in US Fertilizer applied to 65% of all cropland
Food –Energy nexus
Increase in corn production due to ethanol market- is this consistent with sustainable management of groundwater??
AFOs / CAFOs
Animal Feeding Operation Approx. 240,000 in USA Confines animals for 45
days in 12 months Sustains no vegetation in
confinement area Concentrated Animal
Feeding Operation Approx. 20,000 in USA
Number of animal feeding operations
in USA has increased significantly over past 25 years
# of animals - large CAFO Dairy cows - 700 Veal Calves - 1000 Beef Cattle -1000 Swine
o 2500 (55 lbs / more) o 10,000 (< 55 lbs)
Horses -10,000 Sheep /lambs -10,000 Turkeys -55,000 Chickens liquid manure -30,000 Chickens other
o 82,000 (laying) o 125,000 (non-laying)
Ducks o liq. Manure - 5000 o non-liquid -30,000
Broilers18%
Layers: Wet2%
Ducks0%
Hogs43%
Turkeys3%
Horses2%
Dairy13%
Heifer2%
Beef Cattle12%
Layers: Dry5%
Beef Cattle
Veal Calf
Heifer
Dairy
Hogs
Broilers
Layers: Dry
Layers: Wet
Ducks
Turkeys
Horses
CAFOs in USA
Hogs + Cattle = 70%
USEPA, National Pesticide Survey, 1990
Sampled 783 rural domestic wells in 38 states and 566 PWS in 50 states An estimated 4.5 million people were served by PWS or domestic wells that exceeded
the MCL
Rupert, M., 2008 495 wells (24 well networks –primarily in ag areas) Sampled 1988-1995 and again 200-2004 Significant increase in NO3 concentrations in whole data set 7 of 24 networks showed significant increase in NO3 concentrations Median NO3 concentrations in 3 networks increased above MCL
Dubrovsky, et. al. 2010
Nutrient concentrations in streams /groundwater in areas of agricultural and urban development are significantly greater than background concentrations
Median concentrations of total N and P in agricultural streams – 6 times greater than background
More than 20% of water samples from shallow domestic wells (< 100 ft below water table) exceeded the nitrate MCL
NITRATE TRENDS IN GW
Big Sioux Aquifer Underlies 1000 mi2, 11 counties ; depth to water table < than 25 ft ; 21-25 inches / yr precip High use - municipal / domestic drinking water, irrigations, commercial / industrial ------------------------------------------------ 2009 - 1.3 million acres planted in corn in 11 County area - 95% fertilized @ 140 lbs/acre 2009 production - 208 million bushels 1989-2009 - more than 1840 nitrate samples from 54 monitoring wells
•18% exceeded MCL – 10mg/l •36% exceed 5 mg/l •Ave. annual NO3 concentrations are increasing in 9 of 11 counties
Wireman, 2011- unpublished data
Effects of intensive gw use for agriculture
Aquifer / stream depletion Groundwater /surface
water contamination Increased treatment costs Global scale perturbation
of N cycle Increasing competition
from other uses Equity issues
“It is probable that today’s food production & environmental trends, if
continued, will lead to crisis in many parts of the world” (Water for food –water for life, 2007)
Can we avoid this?
Source - Global Climate Change Impacts in the United States, 2009, US Global Change Research Program
Predicting water related crisis
What are the solutions? Combine supply side with demand side measures
Better integrate water and land use planning Differential / adaptive management
• Example - recharge areas need to be managed differently than discharge areas
• Will need to adapt management to climate change conditions • Acknowledge uncertainty in model results
Need to plan for large increase in GW use required to produce energy from new sources (shale oil / gas, oil shale nuclear)
Improve water resource monitoring /data collection Need better science re: groundwater contribution of total
maximum daily loads (TMDLs) Recognize socio-economic aspects of water supply
Land & water management LAND USE CONTROLS
• Delineate vulnerable areas -
recognize hydrogeologic constraints
• Apply SWP strategies to catchment scale
• Apply Sole source aquifer concepts
to allocate water
HOW TO USE LESS WATER Precision irrigation
Reduce agricultural subsidies
Full cost pricing applied to ground-
water development and use
Promote water saving crops & technologies
Conservation • reduce loss from conveyance,
conservation tillage, rotate crops
Best Management Practices Are they effective for reducing nitrogen loading/ conserving water If not –why? Poor design? Poor implementation
• Conservation tillage • Crop nutrient
management • Pesticide management • Conservation buffers • Irrigation management • Grazing management • AFO management plans • Erosion /sediment control • NRCS – Conservation Effects
Assessment Program
Increased Regulation? Fertilizer use is not regulated –should it
be? Tax fertilizers – using hydro-economic
models to look at economic incentives Regulate residual nitrate concentrations in
soil Numeric vs. narrative nutrient standards Groundwater classification –in-situ
standards Moe effective regulation of AFOs / CAFOs
• EPA currently promulgating new CAFO rule
