General Permit 6 and Well Construction Discharges

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What is General Permit #6?

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.

General NPDES permits are statewide discharge permits 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. 

Why GP6 Was Created

Well contractors approached the State Legislature seeking a uniform and defined rule that authorized discharge of well construction wastewater from well construction sites. In response to this request, The 82nd State General Assembly passed a statute requiring the DNR to write new rules and develop a General Permit to authorize well construction and well services related wastewater discharge when that discharge reaches a Water of the United States. Read the bill history here.

The department worked with well industry professionals from our state to develop GP6, along with guidance documents to inform contractors and engineers on how to meet the permit conditions. Since March 17, 2010, all well construction, well related service, and groundwater heat exchange (GHEX) loop borehole drilling related wastewater that reaches a Water of the United States has been regulated by GP6.

Why Well Construction Regulations Exist

Many well construction sites are located near ditches, waterways, or subsurface drainage inlets that may allow well construction related wastewater to reach a Water of the United States.

When allowed to flow untreated, water well construction related wastewater may eventually reach a stream, river or a lake. This can result in turbidity that can affect aquatic life and deposit sediments that create undesirable changes to the stream or lake bed. 

In addition, when released in large quantity, drilling fluid additives and other products used in drilling and servicing wells may contain substances that are acutely toxic to aquatic life. These products can chemically and physically alter the water body and cause additional problems like killing aquatic life and inhibiting the life processes for all species that depend on the water.

Untreated discharges also impact the manner in which the water is used or enjoyed by adjoining property owners and citizens who have access to the water.

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Examples of GP6 Wastewater

Water well construction wastewater is the wastewater generated by any of the water well drilling related activities. Well construction related wastewater normally consists of groundwater mixed with coarse and fine geologic materials like clay, silt, sand, and bedrock fragments. It can also contain limited quantities of drilling fluid enhancement products designed for use in drinking water wells to enhance drilling by stabilizing borehole walls and carrying borehole cuttings to the ground surface. The wastewater can be very turbid to nearly clear.

If well drilling related activities create a discharge that reach Waters of the United States, it falls under the category of GP6 controlled wastewater which requires the site to follow the conditions set by GP6. The following activities commonly fall under GP6.

  • New water well construction
  • Existing water well rehabilitation and renovation
  • Water well pump installation
  • Water well test pumping and capacity testing
  • Geothermal heat exchange borehole drilling
  • Groundwater observation and monitoring well construction for sites that will not generate contaminated water
  • Water well test hole drilling
  • Water well test well construction
  • Potentially other types of drilling that access or utilize the groundwater for a specific purpose, fall under the definition of "well" or water well" in Iowa rules, and discharges well construction related wastewater into Waters of the United States.

Anytime the wastewater generated by well related construction and services is discharged off the well construction site and reaches a Water of the United States, the wastewater falls under the requirements of GP6. 

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Well Services Not Included In GP6

The following services are not covered under GP6:

  • The actual production pumping and on-going operation of dewatering wells. Dewatering discharge is now managed under General Permit 9 - please see the information on dewatering found on the General Permit 9 webpage.
  • The construction of oil and gas test wells and production wells - please contact the Iowa DNR staff listed at the bottom of the page for more information on these discharges.
  • The discharge of wastewater from gas reservoir production or injection wells.
  • Recreational well pumping and discharge into a water feature.
  • Horizontal drilling associated with underground utility work.
  • And any other discharge that is not directly associated with construction, reconstruction, rehabilitation, or service/repair of water supply well, geothermal borehole systems, test boreholes or test wells, or uncontaminated groundwater monitoring and observation wells.

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

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Available Resources

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

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GP6 Well Siting Tool

The DNR GP6 Well Siting Tool assists landowners, well contractors, and engineers with the evaluations of well sites, and the tool helps determine if a well location will likely 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 to map layers to identify distances to surface waters and OIWs, locations of sinkholes, karst areas, land slope, and more. Users can also print the map to use as a resource.

The GP6 Well Siting Tool works with Google Chrome and Mozilla Firefox web browsers. Currently, it is not compatible with Internet Explorer. 

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How to Comply with GP6

GP6 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. Meeting the general water quality standards can be achieved 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. Discharges under GP6 are temporary and limited only to the time that water well related services are taking place.

GP6 requires dischargers to comply with certain treatment standards and discharge requirements.

  • 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 - the well construction wastewater leaving the well construction site 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 create a Well Water Pollution Prevention Plan (WWPPP) for the site before any discharge to Waters of the United States takes place. The WWPPP will be the water treatment model you assemble and use to control and treat the wastewater that is generated during your well services.

The WWPPP 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 types, quantities, and locations of best management practices (BMPs) used both on and off of the construction site to hold, filter and 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 the inspections are performed, and what is found during the inspections
  • Determine if you have co-permittees that need to be part of your WWPPP and have them sign-on with your WWPPP as a co-permittee
  • Provide a Field Office Notification Form (FON) to the local DNR Field Services Office up to 5 days before the 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 body of water and determine if your BMPs are adequate, if not, add additional BMPs to further refine the wastewater treatment
  • Document your inspection on an inspection form as proof that you are monitoring the discharge and that you are taking the necessary steps to meet the conditions of GP6

If you find that any of the BMPs are inadequate and that the discharge is in violation of Iowa's general water quality parameters, you must take corrective action immediately. This includes stopping the discharge until you can increase the BMPs and improve water treatment, and notifying the DNR.

All issues and comments about your discharge, WWPPP, co-permittees, or inspections, should be recorded on your inspection form. You must also update your WWPPP to reflect the additional BMPs. 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.

For more details on the requirements, please review our guidance document, 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 by following 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 National Pollutant Discharge Elimination System (NPDES) Discharge Permit through Iowa DNR before any discharge can take place.

Outstanding Iowa Waters (OIWs) (OIWs) are streams/stream segments or lakes that have been designated as high quality waters that constitute an outstanding resource to our state and its citizens. These waters are such an exceptional recreational or ecological significance that the water quality of these features shall be strictly maintained and protected. The DNR has a map of OIWs that will help you locate the areas of the state that have more stringent permitting and discharge requirements. For more information on OIWs, please visit the DNR's Antidegradation page.

You can also use the 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 of the OIWs. 

If your discharge will reach an OIW, or you have questions about applying for an individual NPDES Discharge Permit, please contact Wendy Hieb for more information at 515-808-3039 or by email at wendy.hieb@dnr.iowa.gov.

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Contact your regional 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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