Living on the Edge in the Denver Basin:Fact or Fiction?

Theresa Jehn-Dellaport, P.G.Matthew J. Welsh

Jehn Water Consultants, Inc.

Introduction

Overview of the Denver Basin

Recent focus on water level trends

Data Collection M h dMethods

Results of Accurate D t C ll ti f Data Collection from the edges of the Basin

Denver Basin Geologic Cross-sectiong

G G’G G’

Quaternary Deposits

Late Eocene Rocks

Dawson Group Sequence D1

Dawson Group Sequence D2

Modified from: Barkmann, P. Denver Basin Field Trip Guide

p q

Laramie FormationFox Hills Sandstone

Pierre Shale

District 8

Recent Studies

South Metro Water Supply (SMWSA) Study 2003 South Metro Water Supply (SMWSA) Study, 2003 Colorado Water Conservation Board Statewide

W t S l I iti ti 2004Water Supply Initiative, 2004; SMWSA Regional Master Plan, 2007; Citizen’s Guide to Denver Basin Groundwater,

2007; Draft SMWSA Regional Aquifer Assessment,

2010; Several Others.

Water Sources in South Metro Area

(SMWSA, 2007)

Denver Basin Use in South Metro Area

~467 000 000 af total in Denver Basin ~467,000,000 af total in Denver Basin ~83,000,000 af total in District 8 ~35,000 af used in District 8 in 2008 556 af injected in 2008

Water Use in District 8

Total Available (af/yr)Total Available (af/yr)

Total Withdrawn 2008 (af/yr)

Injected 2008 (af/yr)

The Sky is Falling

Chicken Little

Aquifers are progressing Aquifers are progressing from confined to unconfined;

Edges of the Denver Basin are considered more vulnerable to water level declines;

Increased demand due to population growth:

(Moore et al., 2007)(Moore et al., 2007)

Pump it Dryp y1200

1000

800

400

600

200

400

0

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Data Considerations

Quality of Water Level Quality of Water Level Data depends on: Method;; Measurement

timing/interval;g Probe calibration; Time since

rehabilitation.

Data Collection Methods

Airline; Pressure Transducer; Datalogger;gg Supervisory Control and

Data Acquisition (SCADA).

Timing of Measurement

Infrequent data –

g

Infrequent data incorrect assumptions;

Favorite day approach;

Once a year whether we need it or not;

Twice a day.

Timing of Measurementg

Minute Readings

Pressure Transducer Datalogger0

50

100

150

t)

Pressure Transducer, Datalogger,1-minute recording interval

Monthly Readings

200

250

300

350

Dep

th to

Wat

er (

ft

4600

4700

4800

Top of the Arapahoe

400

45011/2 11/7 11/12 11/17 11/22 11/27

Date

4200

4300

4400

4500

Wat

er E

leva

tion

(ft.)

Current Pump Setting

p p

Airline No Datalogger4000

4100

Date

Bottom of Screened IntervalAirline, No Datalogger,Monthly recording interval

Probe Calibration

R f l ti Reference elevation; Cannot assume that probe sits at bottom of

it i t bmonitoring tube; Calibrate depth setting with physical static water

level;level; Conduct diagnostics when equipment is at the

surfacesurface.

Time Since Rehabilitation

Time Since Rehabilitation

Dually Completed Arapahoe Aquifer Water Levels, 2002 to 2009

250900

1000

Top of Arapahoe

150

200

1100

gpm

)

ace

(ft.)

100

150

1200

umpi

ng ra

te (g

th b

elow

sur

fa

50

1300

1400

Pu

Dep Depth to Water

Pumping rateBottom of Arapahoe

015005/1/2002 5/1/2003 5/1/2004 5/1/2005 5/1/2006 5/1/2007 5/1/2008 5/1/2009

Well Rehabilitation

Data Which Do Not Support the “W t L l A F lli ”“Water Levels Are Falling”

Water Levels From the Edgeg

Small Town near Eastern EdgegSmall Town Water Levels

Arapahoe Aquifer, April 2008 to November 2009

60

700

200

p q , p

Water levelFlow rate

40

50400

m)ft.

)

30

40

600

ow ra

te (g

pm

rom

sur

face

(f

Top of Arapahoe

10

20800

1000

Fl

Dep

th fr

Bottom of Arapahoe

01200Apr-08 Jun-08 Aug-08 Oct-08 Dec-08 Feb-09 Apr-09 Jun-09 Aug-09 Oct-09

p

Small Town near Eastern Edgeg

Small Town Water LevelsLaramie-Fox Hills Aquifer, 2000 to November 2009

100

1200

200

q ,

Water level

Flow rate

80

400

600

m)ft.

)

60

800

1000

ow ra

te (g

pm

om s

urfa

ce (f

20

401200

1400

Flo

Dep

th fr

o

Top of Laramie-Fox HIlls

0

1600

1800Nov-00 Nov-01 Nov-02 Nov-03 Nov-04 Nov-05 Nov-06 Nov-07 Nov-08 Nov-09

Bottom of Laramie-Fox Hills

Water Levels From the Edgeg

Sedalia Water and Sanitation District

Sedalia Water and Sanitation DistrictArapahoeWell A‐1Water Levels, 2000 to Present

5100

Arapahoe Well A 1 Water Levels, 2000 to Present

Top of Arapahoe

5000

t)

4800

4900

evat

ion

(feet

4700

800

El

4600May-00 Feb-01 Nov-01 Aug-02 May-03 Feb-04 Nov-04 Aug-05 May-06 Mar-07 Dec-07 Sep-08 Jun-09 Mar-10

Bottom of Arapahoe

Private Development, Western Edgep g

Private Development, Western EdgeArapahoeWell A‐1, 2006 vs. 2010

4900

5000

Arapahoe Well A 1, 2006 vs. 2010

Top of Arapahoe

4800

4900

et)

Water Level has risen 1 ft over 4 years

4700

Elev

atio

n (fe

e

4500

4600

Bottom of Arapahoe

4400Apr-06 Oct-06 Apr-07 Oct-07 Apr-08 Oct-08 Apr-09 Oct-09

Bottom of Arapahoe

Castle Pines

Castle Pines Metropolitan DistrictWell A-12 Water Levels from 2002 through February 2010

800

900

4900

5000

g y

600

700

4700

4800

.)

Top of Arapahoe

400

500

4500

4600

low

rate

(gpm

)

ter e

leva

tion

(ft.

200

300

4300

4400

Fl

Wat Water elevation

Flow rate

B tt f A h

0

100

4100

4200

Jun-02 Jun-03 Jun-04 Jun-05 Jun-06 Jun-07 Jun-08 Jun-09

Bottom of Arapahoe

Conclusions and Recommendations

Using data which are not reflective of a true static reflective of a true static water level leads to incorrect conclusions: Use Judgment

Collection of data in the Denver Basin takes time, Denver Basin takes time, patience and networking

Data are not linear

Conclusions and Recommendations

We need to be good We need to be good stewards of the resource

There needs to be one agency for compiling and disseminating water level data.

Well permits need to require that data are recorded and submitted to the agencyto the agency.