Water Protection Program fact sheet
Division of Environmental Quality Director: Kyra Moore

The Missouri Department of Natural Resources may establish exemptions from the Missouri State Operating Permit requirements, according to Code of State Regulations 10 CSR 20-6.015(3)(B)14 and the Missouri Clean Water Law and regulations. Specifically, this regulation allows the department to establish permit exemptions, similar to de minimis permit exemptions, within the framework of an industry’s master general permit for an industry.

This MO-G940000 permit exemption is only available for facilities, activities, land application or discharges that would be eligible for coverage under the MO-G940000 permit. Other types of permit exemptions may also apply, like individual or site-specific de minimis discharge permit exemptions, with department approval as authorized in 10 CSR 20-6.015. 

Limitations and Conditions

As this permit exemption is associated with MO-G940000, the same prohibitions in MO-G940000 (applicability) apply. As such, this permit exemption only applies to facilities impacted with petroleum, including gasoline, diesel, oil and similar materials, and does not apply to solvents or PCB-containing materials.

The department is not authorizing a discharge of any pollutants with concentrations exceeding the water quality standards established in 10 CSR 20-7. Based on our knowledge of the traditional pollutants of concern at petroleum impacted sites, the following pollutants must be sampled according to an approved method, sufficiently sensitive, authorized in Code of Federal Regulations 40 C.F.R. Part 136 and the results must meet the water quality standards listed below: 

Water Quality Standards
Pollutant Pollutant Criteria
Benzene 71 µg/L
Total Suspended Solids (TSS) 100 mg/L
Oil and Grease 10 mg/L
pH 6.5-9.0 standard units

The discharge may not create a sheen in, result in foam on, or visibly discolor the receiving waterbody. This permit exemption does not authorize discharge of RCRA-characteristic wastewater (e.g. flammable). 

Maximum discharge for the total project may not exceed 5,000 gallons in a 12-month period. Sampling must occur before discharge and at least every 48 hours if the discharge is longer than 48 hours. Larger discharges may apply for coverage under the MO-G940000 general permit or apply for a site-specific permit.

A permit is also not required for a one-time, on-site land application of less than 500 gallons of impacted stormwater from underground storage tank pit closure activities, provided the closure or remediation project is under the authority of the department’s Underground Storage Tanks section under 10 CSR 26-2.061 through 26-2.082, and land application occurs in the area of the closure, remediation investigation or activities.


Wastewater may not be discharged under this permit exemption:

  1. Into the watershed of a Metropolitan No-Discharge Stream, as defined in 10 CSR 20-7.015(5);
  2. In a way to allow water to be released into sinkholes, caves, fissures or other openings in the ground which could drain into aquifers directly or indirectly per 10 CSR 20-7.015(7);
  3. Within 2 miles upstream of reservoirs or lakes used for public drinking water supplies (class L1) or drinking water supply streams with less than 10 cubic feet per second (cfs) (7-day Q10) low flow, as defined in 10 CSR 20-7.031;
  4. Within 100 feet upgradient or upstream of any well or water supply structure, such as an intake or within a water designated for groundwater or drinking water supply, as defined in 10 CSR 20-7.031
  5. Within 2 stream miles upstream of biocriteria reference locations;
  6. Within 2 stream miles upstream of streams, lakes or reservoirs identified as critical habitat for endangered species;
  7. Into an Outstanding National or State Resource Waters, as defined in 10 CSR 20-7.015(6)(A)1;
  8. Within the watershed of an impaired water as designated in the 305(b) report without prior approval from the department; and
  9. Into a regulated municipal storm sewer system without prior permission from the MS4 operator.

Land application of petroleum-impacted wastewater is not authorized by the department’s Water Protection Program through the MO-G940000 permit or associated permit exemption. However, you can discuss potential authorization or other treatment options with the department’s Environmental Remediation Program as part of an active, ongoing remediation project.    

Nothing in this document may be used to implement any enforcement action or levy any penalty unless promulgated by rule under chapter 536 or authorized by statute.

For more information