Gillette-Madison Well Field Project

Project Update, February 21, 2018

To view the Gillette Madison Wellfield Project Status Summary- Click Here


Wyoming Gillette-Madison Electronic Mailing List

The Wyoming Department of Environmental Quality (DEQ) recently created an electronic mailing list specifically for the Gillette-Madison Well Field Project.  The mailing list will allow us to more easily send updates and let individuals add or remove themselves as they wish. You can manage your subscription here


The Wyoming Department of Environmental Quality received notification of water quantity and quality issues on August 11, 2017 for two existing and two deeper, replacement private domestic wells located 18 miles northeast of the Town of Moorcroft, Wyoming.  The two existing domestic wells which had previously produced a good quantity of water had gone dry and the two deeper replacement wells had identified low pH (< 4 s.u.) in them. 

A public meeting was held on October 12, 2017 in the Town of Moorcroft to answer questions on the recent water quality/quantity issues.  In addition, a survey was distributed to identify well owners that may have noted potential water quality issues and to solicit access to sample those wells.

Study Area and Sampling

The study area is shown on the “Study Area” figure at the link below.  The study area encompasses the majority of private domestic and stock wells and several springs that DEQ identified for sampling. 

The WDEQ mobilized water sampling crews to the study area on October 25, 2017. As of November 17, 2017 a total of 53 water sources have been sampled. Collected samples have been sent to the DEQ Water Quality Lab in Cheyenne and Energy Labs in Gillette and will be analyzed for the analytes identified in the Gillette Madison Well Field Private Water Well Sampling List (Click here to view)

The DEQ Lab has completed laboratory analysis of 32 private wells and it is anticipated that all remaining samples will be analyzed by the end of the month.  The DEQ Lab is also conducting fingerprinting analysis as to the speciation of the type of acid identified in the low pH wells.

A total of five wells have been identified as having low pH (<4 s.u.).  An additional three wells and one spring have been identified as having pH levels slightly below the state standard for domestic water wells of 6.5 s.u. 

Questions regarding this effort can be directed to Nicole Twing at or 307-777-8275. 

For a list of Fact Sheets regarding Common Contaminants found in groundwater, please click here.

Next Steps

An advisory group consisting of an Executive Committee and three (3) working groups have been established to facilitate and oversee the development of plans and schedules, to implement preferred options that address the overall objective, and to investigate the cause of impacts to private wells in the study area.  The Executive Committee consists of one (1) representative each from WDEQ, Water Development Office, State Engineers Office, Oil and Gas Conservation Commission, and the City of Gillette.  The WDEQ representative is the chairperson of the executive committee.  In addition, the working group has hired an independent consultant to assist with the data review and investigation of the cause of impacts.

The structure of the working groups, members of the Executive Committee and Working Groups and the task for the specified working group can be downloaded here.

The following are meeting agendas for each working group:

Working Group #1–     December 21st, 2017

                                    February 16, 2018

Working Group #2 –    January 23, 2018

Working Group #3 –    December 22nd, 2017

Working Group #4 –    Not yet active

Interested 3rd parties may attend working group and executive committee meetings (including conference calls) and will be provided, during the meeting or conference call, an opportunity for comment prior to the working group and executive committee votes on recommendations and, at the discretion of the working group or Executive Committee chairperson, prior to adjournment.  Questions regarding this effort can be direct to Lily Barkau at or 307-777-7072.

Program Resources

File Date