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

Jehn Water Consultants, Inc.

Overview of the Denver Basin

Recent focus on water level trends

Data Collection Methods

Results of Accurate Data Collection from the edges of the Basin

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

G G’

Quaternary Deposits

Late Eocene Rocks

Dawson Group Sequence D1

Dawson Group Sequence D2

Laramie Formation

Fox Hills Sandstone

Pierre Shale

South Metro Water Supply (SMWSA) Study, 2003

Colorado Water Conservation Board Statewide Water Supply Initiative, 2004;

SMWSA Regional Master Plan, 2007; Citizen’s Guide to Denver Basin

Groundwater, 2007; Draft SMWSA Regional Aquifer Assessment,

2010; Several Others.

(SMWSA, 2007)

~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

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)

0

200

400

600

800

1000

1200

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Quality of Water Level Data depends on: Method; Measurement

timing/interval; Probe calibration; Time since

rehabilitation.

Airline; Pressure Transducer; Datalogger; Supervisory Control and

Data Acquisition (SCADA).

Infrequent data – incorrect assumptions;

Favorite day approach;

Once a year whether we need it or not;

Twice a day.

4000

4100

4200

4300

4400

4500

4600

4700

4800

Wat

er E

leva

tion

(ft.)

Date

Monthly Readings

Current Pump Setting

Top of the Arapahoe

Bottom of Screened Interval

0

50

100

150

200

250

300

350

400

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

Dept

h to

Wat

er (

ft)

Date

Minute Readings

Pressure Transducer, Datalogger,

1-minute recording interval

Airline, No Datalogger,Monthly recording interval

Reference elevation; Cannot assume that probe sits at

bottom of monitoring tube; Calibrate depth setting with physical

static water level; Conduct diagnostics when equipment is

at the surface.

0

50

100

150

200

250900

1000

1100

1200

1300

1400

15005/1/2002 5/1/2003 5/1/2004 5/1/2005 5/1/2006 5/1/2007 5/1/2008 5/1/2009

Pum

ping

rate

(gpm

)

Dep

th b

elow

sur

face

(ft.)

Dually Completed Arapahoe Aquifer Water Levels, 2002 to 2009

Depth to Water

Pumping rate

Top of Arapahoe

Bottom of Arapahoe

Well Rehabilitation

0

10

20

30

40

50

60

700

200

400

600

800

1000

1200Apr-08 Jun-08 Aug-08 Oct-08 Dec-08 Feb-09 Apr-09 Jun-09 Aug-09 Oct-09

Flow

rate

(gpm

)

Dep

th fr

om s

urfa

ce (f

t.)

Small Town Water LevelsArapahoe Aquifer, April 2008 to November 2009

Water levelFlow rate

Top of Arapahoe

Bottom of Arapahoe

0

20

40

60

80

100

1200

200

400

600

800

1000

1200

1400

1600

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

Flow

rate

(gpm

)

Dep

th fr

om s

urfa

ce (f

t.)

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

Water level

Flow rate

Bottom of Laramie-Fox Hills

Top of Laramie-Fox HIlls

4600

4700

4800

4900

5000

5100

May-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

Elev

atio

n (fe

et)

Sedalia Water and Sanitation DistrictArapahoe Well A-1 Water Levels, 2000 to Present

Top of Arapahoe

Bottom of Arapahoe

4400

4500

4600

4700

4800

4900

5000

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

Elev

atio

n (fe

et)

Private Development, Western EdgeArapahoe Well A-1, 2006 vs. 2010

Water Level has risen 1 ft over 4 years

Top of Arapahoe

Bottom of Arapahoe

0

100

200

300

400

500

600

700

800

900

4100

4200

4300

4400

4500

4600

4700

4800

4900

5000

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

Flow

rate

(gpm

)

Wat

er e

leva

tion

(ft.)

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

Water elevation

Flow rate

Top of Arapahoe

Bottom of Arapahoe

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

Use Judgment Collection of data in the

Denver Basin takes time, patience and networking

Data are not linear

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 agency.