Gillette-Madison Well Field Project

Project Update, November 20, 2017

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. 

Next Steps

Once data from both the DEQ Lab and Energy Laboratory has been validated, DEQ will provide the information to landowners for their wells and offer to meet with them to discuss what the results indicate.  The public will also be updated through the electronic mailing list (link above) along with updates to this website.  

An advisory group consisting of an Executive Committee and four (4) working groups has been established to facilitate and oversee the development of plans and schedules to implement preferred options that address the overall objective to investigate the cause of impacts to private wells in the study area.  The Executive Committee consists of one representative from DEQ, Water Development Office, State Engineers Office, Oil and Gas Conservation Commission and the City of Gillette.  The DEQ representative is the chairperson of the executive committee.

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.

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 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 Lee at or 307-777-7072.

Program Resources

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