Colorado Pesticide General Permit - What you need to know
What You Need to Know to Get Started
The Pesticide General Permit (PGP) covers pesticide discharges to the state's surface waters and was renewed, effective on July 1, 2025. The permit, which first became effective in Colorado in November 2011, is in response to the 6th-Circuit court ruling that identified pesticide discharges as point source discharges, all requiring permits under the Clean Water Act. The following guidance should help you decide if you need coverage under this permit or not. Contact information for staff at the Water Quality Control Division is provided at the end of this document.
Do you need permit coverage?
The Colorado Water Quality Control Division regulates the discharge of pesticides to surface waters of the state, including intentional and unintentional applications to surface water. The use of pesticides and the resultant residues thereof, when not in or adjacent to a drainage-way, ditch, canal, stream, wetland, creek, or other surface water, does not require permit coverage under the Colorado Pesticide General Permit. Also, federal facilities in Colorado are not covered by the Colorado permit and must contact EPA Region 8 for the different requirements imposed by that permit.
The following guidance identifies some key information you must consider to determine your eligibility for permit coverage. However, the guidance is not comprehensive, and all operators covered by the permit must read and understand the permit.
Find more information on the pesticide permit website.
The 2025 General Permit and Fact Sheet are available at the links below:
Will your discharge conform to one of the following use patterns as defined on page 3, Part 1.A.1, of the permit?
- Mosquito and Flying Insect Control
- Weeds and Algae
- Forest Canopy Pest Control
- Animal Pest Control
If no, you do not qualify for permit coverage under the PGP and may need an individual permit for your discharge.
If yes, you are automatically authorized to proceed with the application of pesticides to state waters, in accordance with the requirements of the permit.
If you’re the one in charge of deciding to make an application of pesticides to the Waters of the State, and you have day-to-day control of those decisions, you are the Decision Maker and the legal contact for the permit.
If you are the person in charge of deciding to make an application of pesticides to Waters of the State but you want to hire someone to perform the application, you are the Decision Maker and the person you hire is the Applicator. The Decision Maker is the person responsible for reporting to CDPHE where required.
If you make the decisions AND apply the pesticide, you are both the Decision Maker and the Applicator.
If the discharge is to an irrigation ditch or canal, the guidance in this section does not apply, since none of these waters are classified as impaired in Colorado. For discharges to all other surface waters, the operator must review the information in the Colorado regulation to determine the status of the water, as follows:
Impaired waters
You need to determine if the water body to which you plan to discharge is impaired (has poor quality) for any of the ingredients in your product or any degradates of the ingredients in your product. If so, you may not use that product on that water body. For example, if you plan to use copper sulfate but the stream is impaired for copper or sulfate, you may not use that product. Degradates of a product can be difficult to determine and consultation may be needed. CSU Extension programs are good resources. You may contact Troy Bauder at CSU with your questions.
To determine impairments in a water body, you must look in Regulation 93 and see if the water body to which you intend to apply pesticides has impairments for any of the ingredients in your product. The Regulation 93 dashboard can be used to search by stream segments in Colorado.
Segment ID - To identify your stream segment, you may view the column, entitled “Attainment Portion Description.” You also may search by Segment ID. The first two letters of the segment ID are CO. The next two letters represent the River basin, followed by the subbasin. The numbers at the end represent the segment of stream/river described in the attainment portion description. For example, for COARFO02a,
- CO: Colorado
- AR: Arkansas River
- FO: Fountain Creek
- 02a: Fountain Creek from Hwy 47 to the Arkansas River
This map may also help identify the Segment ID.
EPA Category - This column refers to monitoring and evaluation (M&E) of a particular parameter, meaning that the stream segment is borderline impaired. If the segment is M&E for an ingredient in your product, you are not prohibited from discharging to that segment, but you will be contributing to the impairment. Further impairment of a segment generally leads to a listing on the 303(d) list which in turn would prohibit you from using your product in the future on that stream segment.
Analyte - Parameters listed here are prohibited from being discharged to the stream segment under the Colorado Pesticide General Permit. If your product contains any of the ingredients, or degradates of those ingredients, that match what’s listed in this column, you may not apply. In this case, you could not apply a pesticide with copper to this segment. Pay attention to this column!
You need to determine if the water body to which you plan discharge is an Outstanding Water. Discharges to outstanding waters are not allowed under the Colorado Pesticide General Permit unless the discharge is meant to restore or maintain water quality or to protect public health or the environment. These discharges must either not degrade water quality at all or, if they will degrade water quality, they may only be applied on a short-term or temporary basis. Operators discharging to outstanding waters are required to submit an Annual Report.
There are no outstanding waters east of I-25 in Colorado. For discharges located west of I-25, this map can be used to determine whether or not a water body is an Outstanding Water.
If it appears that you may be discharging to an Outstanding Water, you need to verify the information from the map by looking up the water body in the Numeric Standards Tables for the basin to which the application will occur. More information can be
found on the water quality control commission regulation website.
- Open the applicable basin regulation (e.g. Regulation 38 for the South Platte basin)
-The tables you’ll need are the appendices - Find the stream segment applicable to your discharge
- Outstanding Waters will be identified as “OW” in the lower left corner of the table as shown below:
An operator that meets ALL of the following criteria is required to prepare and maintain a Pesticide Discharge Management Plan, or PDMP. The operator must:
- be a Decision-maker, AND
- be required to submit an annual report (Table 2 of the permit), AND
- be a Large Entity, which is defined in the permit as either a business that exceeds the Small Business Administration size standard as identified at 13 CFR 121.201, or a local government that serves a population of greater than 10,000).
Part I.E. of the permit identifies the requirements for the completion and maintenance of a PDMP.
There is a single reporting mechanism for certain operators to provide data concerning where, when, and how much product is used. Special Districts, certain agencies that are considered land stewards, and those operators that apply pesticides beyond a given threshold are required to submit reporting forms (see Table 2 of the permit) by February 1 of each year. The report will summarize discharges made over the previous calendar year.
Please use our annual report template.
Please note
The information contained in this guidance is in no way comprehensive and cannot be substituted for a thorough reading of the permit document. Please contact John Nieland if there are additional topics you would like to see included in this guidance or if you have specific questions about permitting and your discharge of pesticides.