Water Well Construction Related Wastewater and General Permit #6

NOTICE: Renewal of General Permit #6

General Permit #6 - Well Construction and Well Service Discharges (also known as GP6) was renewed on March 1, 2015 for a second five year period.  The changes that are part of the new general permit are minor and include the start and end dates listed on the permit cover and a number of changes in the permit language that do not alter the intent of the permit or the manner in which the permit is managed.

About General Permit #6

The 82nd State General Assembly passed a statute which required the Department to write new rules and a provide issuance of a General Permit to authorize well construction and well services related wastewater discharge when that discharge reaches a Water of the United States.  Beginning on March 17, 2010, all well construction, well related service and GHEX loop borehole drilling related wastewater that reaches a Water of the United States is regulated by National Pollution Discharge Elimination System permit (NPDES) General Permit #6 (GP6).

What is well construction wastewater?

Well construction wastewater is the wastewater generated by any well drilling related activity in our state.  These activities include new well construction, existing well rehabilitation and renovation, pump installation, test pumping, geothermal borehole drilling, water observation well installation, water well test hole and test well drilling, and other types of drilling that access or utilize the groundwater for a specific purpose. The wastewater generated during these activities can be made up of drilling fluids, groundwater or a combination of both, can be very turbid to nearly clear and can contain geologic materials and chemicals used to enhance drilling.  If the well drilling related discharge leaves the construction site it becomes wastewater discharge.

Anytime the wastewater generated by well related construction and services discharges off the well construction site and reaches a Water of the United States, the wastewater falls under the requirements of GP6.  GP6 requires the wastewater to comply with the treatment standards and discharge requirements stated in GP6.  If the well construction or well services related wastewater does not reach Waters of the United States, the discharge is not subject to GP6.

Why is well construction and well service related wastewater regulated?

Many well sites are located in close proximity to waterways or other conveyances that allow the wastewater to reach a Water of the United States.  The well wastewater normally consists of drilling fluids and/or groundwater, and contains particles of natural materials like sand, silt, colloids (clay), limestone and dolomite, and possibly various chemical drill fluid enhancements.  When allowed to flow untreated, the wastewater will eventually reach a stream, river or a lake.  This can result in turbidity that can affect aquatic life and sedimentation that can create long term changes to the stream or lake bed.

In addition, drilling fluid additives and other products used in borehole construction and well servicing may contain substances that are acutely toxic when released in a water body.  These products can chemically and physically alter the receiving water and cause additional problems, such as killing aquatic life and inhibiting the life processes for all species that depend on the water.  In addition, untreated well related wastewater affects the use and enjoyment of adjoining property owners and any citizens who can access the water.

Well construction discharge </center data-verified=
at the point of stream entry." src="/portals/idnr/uploads/water/wells/gp6a.jpg" longdesc="Photo of a stream near a point of well construction discharge" unselectable="on" >="" <="" center="">
Well construction discharge after mixing - downstream 200 feet.
Well discharge near point of discharge. Well discharge after it mixes downstream.

What well services are included in GP6?

  • All types of new water supply well construction including:
    • Private and public water drinking water supply wells, observations wells, test wells and test drilling 
    • Non-potable use wells such as irrigation wells, plant process water supplies and dewatering wells
    • Geothermal use water supply wells
    • Groundwater injection return wells (geothermal injection wells)
    • Geothermal loop borehole construction
    • Compressed air/gas injection well construction
  • All types of services performed on existing wells, like renovation or rehabilitation services
  • All types of well pump repair on all types of water wells when the well will be pumped to waste
  • Development, rehabilitation and test pumping on new or existing water supply wells

What types of well discharges are not included in GP6?
  • The actual production pumping and on-going operation of dewatering wells - please contact your local Field Services Office for additional information on discharge standards for these types of activities.
  • The construction of oil and gas test wells and production wells - please contact IDNR staff listed at the bottom of the page for more information on these discharges.

How do I comply with GP6?

Iowa's NPDES General Permit No. 6 requires the development of a well site specific well water pollution prevention plan (WWPPP or Plan) for the each well construction site where the discharge reaches a Water of the United States.  When an engineer is used to develop the well plans, an engineer must also develop and create the WWPPP for the permittee. For wells that do not require the services of an engineer, the WWPPP can be developed by the well/landowner (permittee) or by a contractor or agent retained by the permittee to manage the WWPPP.

The WWPPP must be designed to address the anticipated volume and treatment needs for the wastewater generated during the well construction project. It shall include specifications for adequate Best Management Practices (BMPs) to treat the wastewater and guidance for the implementation, inspection and maintenance of the BMPs or controls used for the project. The Plan shall be written and implemented to adequately treat the wastewater before it enters streams, rivers, and lakes where is can create watery quality problems. As the work on the well project is about to begin, the local regional IDNR Field Services Office must be notified using the Field Office Notification Form (FON). For your convenience, the FON is now available in both Word and PDF formats.

The Well Water Pollution Prevention Plan shall take into account items that will influence how the wastewater is managed, such as:

  • The location of the well on the landscape;
  • the potential protections or limitations that the landscape may provide for natural wastewater treatment;
  • the potential quantities and anticipated qualities of wastewater that may be generated during each phase of the well construction or service work;
  • the best management practices (BMPs) used both on and off of the construction site to treat the wastewater;
  • the type of BMPs that will be applied to the site and strategic locations of all BMPs used;
  • any adjustments or changes made to the BMPs after the initial installation;
  • who inspects the BMPs, how often the inspections are performed, and what is found during the inspections;
  • and certification that all permittees and co-permittees fully understand what is required under GP6.

What resources are available?

Who should I contact if I suspect that a stream, river, or lake is being impacted by water well related wastewater discharge?

You should contact your local IDNR Field Services office if you suspect a body of water is being impacted by a well discharge. Please use the link below to find the nearest Field Office and their contact information.

Useful web links:

Please this site occasionally to obtain the latest information regarding well discharge wastewater. You can also subscribe to the well discharge wastewater listserv.

Who can I contact to obtain additional information about GP6?

Russ Tell - phone: 515-725-0462, russell.tell@dnr.iowa.gov
Iowa DNR Water Supply Engineering, 502 E 9th Street, Des Moines, IA 50319


Wendy Hieb - phone: 515-725-8405, wendy.hieb@dnr.iowa.gov
Iowa DNR NPDES Wastewater Permits, 502 E 9th Street, Des Moines, IA 50319