Overview and Issues of the High Overview and Issues of the High Plains Aquifer, Oklahoma, 2010Plains Aquifer, Oklahoma, 2010

Mark F. Becker

U.S. Geological SurveyOklahoma City, Oklahoma

Outline of PresentationOutline of Presentation

Issues (addressed throughout presentation) Location and Setting Oklahoma Water Law Hydrology and Water-Quality

Water-Uses and Effects of Withdrawal Future of Irrigated Agriculture

Conclusions

Issues

1. Long way from State Capitol

2. Sparsely Populated (Small Legislative Representation)

3. Oklahoma Water Law

4. Groundwater Level Declines

5. Future for Irrigation

Issue #1: The Central High Plains and Oklahoma

Kansas

Oklahoma

Texas

New Mexico

Colorado

Issue # 2: Sparse Population

Estimated Population of Panhandle in 2009 was 30,035

Setting

Overlies approximately 7,100 mi2 in OklahomaTexas County is Largest Ag Producer in OKMean annual precipitation around 19-in/yrTemperature range: -25o F to +110o FAverage lake evaporation = 62-in/yearAverage runoff (pre-1970) = 0.2-in/year

Land Use (Oklahoma Portion)

56% rangeland

40% dry cropland

4% irrigated cropland

Harvested Acres (Oklahoma Portion)

Wheat 2,600,000 acres

Corn 800,000

Sorghum 700,000

Hay 300,000

Other 65,000

Livestock (Oklahoma High Plains)

620,000 cattle in 1992 750,000 cattle in 1997

20,000 swine in 1992 > 2,700,000 in 1999

Issue #3: Oklahoma Water Law

Oklahoma has a “mining” based regulatory approach to groundwaterProperty RightAllows for depletion over timeAllocations are for high capacity wells and until

determined set at 2 acre-ft/ac/yr for land ownedDoes not recognize hydraulic connection to surface waterNo effective monitoring

Kansas has highly regulated sustainable based lawTexas has essentially no jurisdiction over groundwater

Hydrogeology

Series of coalescing alluvial fans consisting of sand, clay, and gravel that can exceed 500’ in thickness

Well yields can exceed 2,000 GPMDirection of groundwater flow is from west to eastRecharge is distributedRecharge is relatively rapidWater-level declines from irrigation withdrawals

Center-pivot Irrigation began in the early 1960’s in Oklahoma

Center Pivot Technology Changed Center Pivot Technology Changed Irrigation Practices Irrigation Practices

Land with rolling topography could be irrigated

Circles are 0.5 mile in diameter

Each well pumps about 1,500 gpm

Percent Ground-Water Use in the Central High Plains in 1992

Per

cen

t W

ater

Use

Water Use in 2005

252Mgal/d

Groundwater Flow

Saturated Thickness (1998)

>300

100-300

<50

50-100

Issue #4: Water-Level Declines

Long-term effects on streamflow EcosystemsTreated municipal wastewater

Increased pumping costsPotentially reduces irrigated agricultural opportunitiesCreates acrimony (whiskey’s for drinking, water’s for

fighting)

Water-Level Changes to 1980

Declines more than 100 Declines more than 100 feet in Kansas, Oklahoma, feet in Kansas, Oklahoma,

and Texasand Texas

Declines of 10-50 feet Declines of 10-50 feet widespreadwidespread

Rises more than 25 feet in Rises more than 25 feet in NebraskaNebraska

Large areas of little on no Large areas of little on no changechange

Water-Level Changes to 1997

Areas of declines have Areas of declines have expandedexpanded

Areas of rises have Areas of rises have expanded, especially in expanded, especially in

Texas and OklahomaTexas and Oklahoma

Large rises in Nebraska Large rises in Nebraska continuecontinue

Water-Level Change from Predevelopment to 1998

10-25

± 10

Rise

>50 25-50

Near Guymon 07232500

Stream Gaging Station

Ground Water Well

Optima Lake

Canton Lake

At Beaver 07234000

At Woodward07237500

Near Seiling07238000

Well

A Lesson in Planning: The Beaver/North Canadian River Basin

Upstream face of Optima Dam in 1990

Aerial Photo by Dale Boyle, U.S. Geological Survey

Increases in Numbers of Large-Capacity Irrigation Wells in the Oklahoma Panhandle

1930 1940 1950 1960 1970 1980 1990 2000

YEAR

0

500

1000

1500

2000

2500

NU

MB

ER

OF

WE

LL

S

Depth to Water in a key Oklahoma Well in the High Plains Aquifer

Percentage of no-flow days for theBeaver River near Guymon, Okla.

1930 1940 1950 1960 1970 1980 1990 2000YEAR

0

20

40

60

80

100

PE

RC

EN

T O

F D

AY

S W

ITH

NO

FL

OW

Annual Precipitation (bars) and 10-year moving average (line) for western Oklahoma

Annual flow volume (bars) and 10-year moving average (line) near Guymon (07232500)

Annual Peak Discharge (bars) and 10-year moving average (line) near Guymon, OK (07232500)

Recharge

Myth #1: Recharge comes from snowmelt in the Rockies

Myth#2: Aquifer receives little or no rechargeReality: Distributed recharge from precipitation

Estimated Depth to Water in Feet

Tri

tiu

m

Un

its

18O/16OVSMOW ‰

Deu

teriu

mV

SM

OW ‰

Predevelopment Recharge

4.0% of precipitation in sand-dune areas. Averaged 0.69 inches per year. 139,000 acre-feet per year. 14% of model area.

0.37% of precipitation in other areas. Averaged 0.07 inches per year. 85,000 acre-feet per year. 86% of model area.

Cultivated Dryland Recharge

Extra recharge due to dryland cultivation

3.9% of precipitation over area in dryland; about 0.65 inches per year

345,000 acre-feet per year

Dryland Recharge

30

40

50

1940 1990

De

pth

to

Wa

ter

Constituent Minimum Maximum Mean Median

Temperature oC 14.3 17.4 16.2 16.5 Specific Conductance

470 782 600 595

Dissolved Oxygen * 5.2 7.9 7.6 7.7 pH 7.3 7.9 7.6 7.7 NO2 + NO3 as N* 1.81 12.3 5.30 3.43 Calcium* 27 110 62 60 Magnesium* 4.5 51 26 27 Sodium* 8.9 46 29.4 31.5 Potassium* 0.76 6.2 4.03 4.35 Chloride* 2.1 66 33.3 30.0 Sulfate* 10 180 56 42 Alkalinity* as CaCO3 171 273 207 195

* mg/L

Summary Statistics for Common Ions and Field Parameters

Issue # 5: Future of IrrigationIssue # 5: Future of Irrigation

Tied to prices of fuel and crops New technologies allow exploitation of

lower well yieldsGenetically modified cropsLow/No Till methodsEconomy of scale; larger farms, less

farmers

Conclusion

Politically, not well represented but recognized by the economic value.

Contrasting water management strategies on bordersDeclines in water levels

Increased costsLoss of surface water

Potential for technological advances to keep irrigated agriculture a component

The End

OWRB Sites

ConclusionsConclusions

NO3 is elevated in most wells

NO3 is found at all well depths15N indicates the presence of animal wastesChanges ahead as more data is evaluated

NO

2 +

NO

3 m

g/L

as N

Estimated Depth to Water in Feet

OWRB Data

15N

Air ‰

NO2 + NO3 mg/L as N

Fertilizer

Mixed Animal, Fertilizer, or Soil

Animal

Types of Water-Quality Data (OWRB)

Field measurements (temperature, pH, alkalinity, O2, specific conductance)

Chemical analyses (common ions, metals, nutrients, 15N, 18O, and deuterium)

Age dating (tritium, tritium/helium, and 14C)

Location of Central High Plains NAWQA Study Area

New Mexico

Colorado

Kansas

Oklahoma

Texas

Sub Unit Survey

Reconnaissance

Public Supply

NO2 + NO3 mg/L as N

Trit

ium

Water-quality Data Collected in 1999

Oklahoma water resources board (OWRB)- 12 Wells

NAWQA Sub Unit Surveys- 94 wellsNAWQA Regional Transect - 5 well clusters

(15 Wells)NAWQA reconnaissance - 5 wellsNAWQA Public Supply Survey- 15 wells

Outline of PresentationOutline of Presentation

Describe Oklahoma setting and similarities to the entire Central High Plains

Describe Oklahoma High Plains study and High Plains NAWQA

Water-quality in Oklahoma High PlainsConclusions

15 N

Air ‰

Estimated Depth to Water in Feet

Fertilizer

Mixed Animal, Fertilizer, or Soil

Animal