GP6 - Water Wells

Topics:

Wastewater Permitting

Iowa DNR Wastewater General Permit #6 (GP6) for Well Construction and Well Service Discharges was renewed on July 1, 2023 and is effective through June 30, 2028. Download General Permit #6.

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GP6 Renewal

The DNR is hosting an informal stakeholder meeting on March 3, 2026, regarding the proposed five-year renewals of NPDES General Permits #5, #6, and #7 (GPs #5-7). The purpose of this meeting is to accept comments and answer questions on possible changes to the GPs. The DNR is specifically seeking comments on the clarity, feasibility, and potential impact of the proposed changes. Formal rulemaking to renew GPs #5-7 is expected to begin in mid 2026.

The meeting will be held on Tuesday, March 3 at 11:00 am.  The meeting is open to the public and will be held virtually via Google Meet. 

Questions and comments regarding the draft renewals or the meeting may be directed to Wendy Hieb at wendy.hieb@dnr.iowa.gov. Comments will be accepted until Tuesday, March 10th.

Redline-strikeout version of the draft renewal of GP #6 (2026-1-30)

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What is GP6?

The GP portion of GP6 is an abbreviation of the term General Permit. The number 6 is the order in which the General Permit was developed; GP6 is the sixth of nine National Pollutant Discharge Elimination System (NPDES) general permits developed by the DNR.

General permits are developed and used by the DNR when the type and quality of wastewater generated by an activity is similar, regardless of where in the state the activity takes place. The characteristics of well construction discharge wastewater meet this criteria. This type of discharge normally consists of groundwater mixed with coarse and fine geologic materials like clay, silt, sand, or bedrock fragments. In addition, there may be limited quantities of drill fluid enhancement products used during the drilling process to stabilize the borehole walls and carry borehole cuttings to the ground surface.

General Permit 6 (GP6) is a statewide discharge permit that authorizes the discharge of water well related wastewater into Waters of the United States as long as the wastewater meets the general water quality standards. Discharges under GP6 are temporary and limited only for the time that water well related services are taking place.

The general water quality standards can be met by using one or more best management practices (BMPs) to slow, retain, and filter the wastewater, and allow the geologic materials contained within the wastewater to settle out before the treated water reaches a Water of the United States.

If your well related wastewater will not reach a Water of the United States, you do not need to meet the requirements of GP6.

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GP6 Well Siting Tool

The DNR developed an online GP6 Well Siting Tool to assist landowners, well contractors, and engineers in performing desk evaluations of well sites and determining if a well location will require discharge management through GP6. It also helps define which locations likely cannot support well construction discharge due to close proximity of Outstanding Iowa Waters (OIWs).

Users can access map layers that will help identify distances to surface waters and OIWs, locations of sinkholes, karst areas, land slope, and more. Users can also print the  generated maps to use as a resource.

The GP6 Well Siting Tool works with Google Chrome and Mozilla Firefox browsers. Currently, it is not compatible with Internet Explorer. The tool is available at: https://programs.iowadnr.gov/maps/gp6/.

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How to Comply with GP6 (WWPPP and Inspections)

First, determine if the well construction wastewater will leave the well construction site and reach a Water of the United States. If the answer is yes, then you are legally obligated to follow the requirements of GP6. If the answer is no - your water will not reach a Water of the United States - then you do not need to follow GP6 (but you still need to manage your discharge responsibly).

For all discharges that require GP6, you must to create a well water pollution prevention plan (WWPPP) for the site before any discharge to Waters of the United States takes place. The WWPPP is the water treatment model you use to control and treat the wastewater generated during your well services.

The WWPPP shall accont for all items that will influence how the wastewater is managed, such as:

  • the well location on the landscape;
  • potential protections or limitations that the landscape may provide for natural wastewater treatment;
  • potential quantities and anticipated qualities of wastewater that may be generated during each phase of the well construction or service work;
  • the types, quantities, and locations of best management practices (BMPs) used both on and off of the construction site to hold, filter, treat, and meter the wastewater before it enters Waters of the United States;
  • any adjustments or changes made to the BMPs after the initial installation;
  • who inspects the BMPs, how often inspections are performed, and what is found during the inspections; and
  • whether or not you have co-permittees that need to be part of your WWPPP (and have them sign your WWPPP as a co-permittee).

Provide a Field Office Notification Form (FON) to the local DNR Field Office up to 5 days before your planned discharge, but no later than 24 hours after the discharge starts.

During the times that you discharge, you must:

  • inspect your BMPs at least once every six hours to make sure they are adequate for the discharge you generate;
  • inspect the receiving waterbody and determine if your BMPs are adequate; if not, add additional BMPs to further refine the wastewater treatment; and
  • document your inspection on an inspection form as proof that you are monitoring the discharge and taking steps to meet the conditions of GP6.

Record all issues and comments about your discharge, WWPPP, co-permittees, or inspections on your inspection form.

If you find that any BMPs are inadequate or that the discharge is in violation of Iowa's general water quality standards, you must take corrective action immediately. This includes stopping the discharge until you can increase the BMPs to improve water treatment and notifying the DNR. After addressing any water quality issue(s), you can resume the discharge, monitor the BMPs and discharge water quality, and follow-up with additional inspections. You must update your WWPPP to reflect any additional BMPs. 

For more details on the requirements, please review "A brief Guide to Developing a Well Water Pollution Prevention Plan and Using Best Management Practices".

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GP6 Prohibited Waters

Not all Waters of the United States can be used as a discharge point under the conditions of GP6. Iowa has a class of waters called "Outstanding Iowa Waters" (OIWs) that require the discharger to apply for and obtain an individual NPDES permit from the DNR before any discharge can take place.

OIWs are streams or lakes that have been designated as high quality waters that constitute an outstanding resource to our state and its citizens. These waters have such an exceptional recreational or ecological significance that their water quality is strictly maintained and protected. For more information on OIWs, please visit the Antidegradation webpage.

The map of Outstanding Iowa Waters can help you locate the areas of the state that have more stringent permitting and discharge requirements. You can also use the new GP6 Well Siting Tool to determine if the area where the planned well will be constructed in in an area that includes one or more OIWs. 

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If You Suspect a Discharge

Contact your local DNR Field Office if you suspect a body of water is being impacted by well construction or well service related discharges.

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Available Resources

The following resources provide additional information on the topics related to GP6.

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