Colorado Water Rights and Discharge Permits: Integrating Water Rights into Wastewater Permitting Strategy

Colorado water rights and discharge permits come from two separate systems, and your wastewater plan has to satisfy both. The discharge permit controls the quality of what leaves the plant. It gives you no right to the water. Water rights, decreed by the water courts and administered by the State Engineer, decide whether you can reuse effluent, move an outfall or stop a discharge that downstream users depend on. Settle those questions before you fix the disposal method.

Why doesn't a Colorado discharge permit settle the water rights question?

Because the law keeps the two systems apart. The Water Quality Control Act may not be applied to impair water rights, and it sends injury questions to the water court.

Under C.R.S. 25-8-501, a point source discharge to state waters needs a permit from the Water Quality Control Division. That permit sets effluent limits. It says nothing about who may use the water.

Water rights run on prior appropriation. The Division of Water Resources' water rights overview calls it "first in time, first in right." Seven water courts, one in each major river basin, decide water rights applications.

The bridge is C.R.S. 25-8-104. Nothing in the Act may cause material injury to water rights. The statute expects some dischargers to choose consumptive treatment to meet water quality limits, and it makes them remedy any material injury, as the water court decides. A disposal method picked for water quality reasons can become a water court case.

Who relies on your treated effluent today?

Possibly every decreed right below your outfall. Once effluent reaches the stream, it is part of the supply other rights draw on in priority.

Not all diverted water is consumed. Part returns through drainage, seepage and treated discharges. A plant that has discharged for decades is part of the stream's supply, and the rights below it may have relied on that water for just as long.

Changing the pattern can be a legal event. A change in the type, place or time of use is a "change of water right" under C.R.S. 37-92-103(5). Under C.R.S. 37-92-305(3)(a), the water court approves a change or an augmentation plan if it will not injure a vested or decreed conditional water right. Water users who file a statement of opposition become parties to the case.

This lands hardest on utilities and municipalities with a long discharge record.

Can you reuse treated effluent instead of discharging it?

Sometimes. It depends on where the water came from and what your decrees allow, and water quality approval is a separate step.

Under C.R.S. 37-82-106, water brought in from an unconnected stream system may be used in succession to the extent its volume can be distinguished. The reuse right for foreign, nontributary or other developed water is personal to the developer. Once released from the user's control, that water becomes part of the stream, subject to the rights on it in priority.

Native stream water is the harder case. Plan as if it is a one-use supply until your water rights attorney shows the decree says otherwise.

The quality side is Regulation 84, the Reclaimed Water Control Regulation (5 CCR 1002-84):

• The treater files a Treater Application and receives a Treater Authorization. Older documents call it a Notice of Authorization.
• Authorized uses are industrial, landscape irrigation, commercial, fire protection, agricultural irrigation, and toilet and urinal flushing (84.4).
• The application must affirm that the reuse will not materially injure water rights (84.6(A)(9)).
• It does not cover effluent released to state waters before later use, or used on the plant site for landscape irrigation or process uses (84.4).

Regulation 84's statement of basis says it plainly: reclaimed water use is subject to Colorado water rights law.

Does moving the outfall change anything on the water rights side?

It can. Return flows reach the stream where you discharge, so a new outfall changes which rights receive that water.

Compare candidate outfalls on water rights as well as effluent limits. For an existing plant, moving the outfall downstream takes return flows away from the rights between the old point and the new one.

Augmentation credits are tied to place, too. A plan must replace water at the time and location a senior right would otherwise be shorted (37-92-305(8)(c)), so returns that land below the senior's headgate may not count. Treat outfall location as a site feasibility question, settled before design.

When does a wastewater project need an augmentation plan?

When it diverts or pumps water out of priority and must replace the depletions. Projects served by wells often need one.

DWR's augmentation plan guidance says a plan lets a junior user divert out of priority as long as replacement water is made available, and that a water court decree must approve it. It warns that in most areas of Colorado you may not get a well permit for a subdivision without one. In the Eastern Plains' Designated Basins, the Ground Water Commission sets the rights, and replacement plans play a similar role.

Wastewater can sit inside that math. Regulation 84's statement of basis notes that some land application operations built their return to groundwater into their discharge permits and augmentation plans. If your plan counts effluent returns as replacement, reusing or moving that water changes the plan. Check the decree before you design reuse.

While a case is pending, the State Engineer can approve a substitute water supply plan under C.R.S. 37-92-308. DWR's substitute water supply plan page calls these temporary approvals, usually limited to one year.

How do CDPHE and the Division of Water Resources split the work?

CDPHE rules on water quality. The State Engineer and the water courts rule on water rights. Neither approval stands in for the other.

• CDPHE: site location and design approval (Regulation 22), the discharge permit (Regulation 61) and reclaimed water authorizations (Regulation 84).
• Water courts: decrees for water rights, changes and augmentation plans.
• State Engineer: administration of priorities and substitute water supply plans.

Run both tracks in parallel, with the same reuse volumes in each. For the CDPHE sequence, see the difference between a site application and a discharge permit application.

Is your Colorado wastewater plan ready for the water rights questions?

Answer yes or no to each item. Any no is your next task.

1. Have you classified each supply that becomes wastewater as native surface water, tributary groundwater, nontributary groundwater or imported water?
2. Have you read the decrees for those supplies, including any reuse terms?
3. Do you know the decreed rights below each candidate outfall?
4. If wells serve the project, do you know whether an augmentation plan is needed and what it counts as replacement?
5. Do the reuse volumes in your Regulation 84 application match your water rights analysis?
6. Is a Colorado water rights attorney on the team before the disposal method is fixed?

Then ask your engineer and attorney: what happens to the return flow math when the plant runs well below design flow, and which approval sits on the critical path?

Scope note: This is general education based on the Colorado Revised Statutes current through 2025, DWR guidance and Regulation 84 as amended effective May 30, 2026. It is not legal advice. Injury to a water right is for the water court to decide.

Frequently asked questions

Does a CDPHE discharge permit give me a water right?

No. The permit authorizes a discharge under C.R.S. 25-8-501. Water rights come from water court decrees, and C.R.S. 25-8-104 says the water quality law may not impair them.

What is an augmentation plan in Colorado?

A water court approved plan that lets a user divert out of priority by replacing the depletions at the time and location a senior right needs the water.

I'm developing a rural subdivision in Colorado with no sewer nearby, and we want to reuse effluent from a small private plant for landscape irrigation. Do we need to worry about water rights?

Yes. If wells serve the homes, you may need an augmentation plan before you get well permits, and it may count your return flows. Landscape irrigation is an authorized Regulation 84 use, but you must affirm the reuse will not injure water rights. Have a water rights attorney read the supply decrees first.

I run a Colorado town's utility, we've discharged to the same creek for decades, and the council wants full reuse. What should we check first?

Where the water comes from. Imported, nontributary or developed water may be reusable to the extent you can account for it. Native water is harder, because rights below your outfall may depend on it. Inventory those rights and read your decrees before you size anything.

How do I find the water rights downstream of my discharge point?

Start with DWR's Water Rights Net Amounts tool. It searches decreed rights by county, division, district or source and lists appropriation dates, priority numbers and decreed uses. A water rights engineer or attorney then works out which ones depend on your return flows.

Related resources

• Plan of Reuse vs. Direct Discharge: Strategic Wastewater Disposal Decisions in Colorado
• Colorado CDPHE Discharge Permit Process: Timeline, Requirements, and How It Differs from Texas
• Colorado Package Wastewater Treatment Plant Permitting: CDPHE Approval, Operations, and Compliance
• Antidegradation Policy in Colorado Water Permits: What It Means for New Discharge Permits

Planning reuse or a new outfall in Colorado?

Water rights decide what you can do with your effluent, so settle them before the disposal method is fixed. MES is licensed in Colorado, has an office in Golden, and designs the wastewater side to fit what your decrees allow.

We specialize in:

• Wastewater disposal alternatives: discharge, reuse and land application
• Package wastewater treatment plant design
• Reclaimed water system design
• CDPHE site location and discharge permit applications
• Collection systems and lift stations
• Construction administration

Modern Engineering Solutions, McKinney, Texas. Contact: (214) 833-6748 or mod-eng.com