Plan of Reuse vs. Direct Discharge: Strategic Wastewater Disposal Decisions in Colorado

What is a "Plan of Reuse" under Colorado rules?

It is shorthand, not a permit name. Colorado's reclaimed water rule, Regulation 84 (5 CCR 1002-84), does not issue a "Plan of Reuse." It authorizes two parties: the treater that makes the reclaimed water and each user that applies it.

According to CDPHE's reclaimed water (reuse) permits page, the treater files a Treater Application, and each user files a User Application and Site Management Plan (UASMP) through the authorized treater. The UASMP replaced the older "User Plan to Comply," which may be where the plan language comes from. There are separate UASMP forms for landscape irrigation, industrial uses, commercial uses, fire protection, toilet and urinal flushing, and several kinds of crop irrigation.

Before a treater application, CDPHE asks for a Reclaimed Water Quality Planning Target Application, and its engineering section must review and approve the facility design before it issues a Treater Authorization. So the reuse path has its own front end, not a shortcut around design review.

What does Regulation 84 require of the reclaimed water?

A treatment category matched to the use. Regulation 84 sets three categories of reclaimed water, and Table A in Section 84.10 lists which category each authorized use needs.

• Category 1: at least secondary treatment with disinfection.
• Category 2: secondary treatment with filtration and disinfection, plus turbidity limits.
• Category 3: secondary treatment with filtration and disinfection, with the tightest E. coli standard.

The rule covers only the uses it lists: industrial, landscape irrigation, commercial, fire protection, agricultural irrigation, and toilet and urinal flushing. Any other use is a violation, and recreational use is prohibited outright. Section 84.4 also says the rule does not apply to wastewater treated and released to state waters before it is used. Once effluent goes to the creek, it is a discharge, not reuse.

When does direct discharge make sense?

When the receiving water can take the effluent at limits your plant can meet. A CDPS discharge permit sets effluent limits from the stream's classifications and standards, so the same plant can face very different limits on two creeks a few miles apart.

Discharge tends to win where there is a large receiving water with flow at critical low conditions, no reuse customer for the volume, and limits the planned process can meet every month. It tends to lose on small, cold tributaries and low or zero flow segments. Basin rules matter too, as covered in our post on Colorado's basin specific standards.

How does antidegradation change the comparison?

A new discharge to a reviewable water must avoid significant degradation, or justify it. CDPHE's antidegradation and permits page says new dischargers after a segment's baseline date likely get fairly stringent antidegradation-based limits, typically 15 percent or less of the numeric standards where no assimilative capacity is available.

To degrade a reviewable water, the Division must find it necessary for important economic or social development under Regulation 31, Section 31.8(3)(d). That includes an alternatives analysis showing no economically, environmentally and technologically reasonable option would cause less or no degradation. A practical reuse option is exactly the kind of alternative that analysis has to address.

The same page says temporary dischargers of less than two years, and small discharges diluted 100 to 1 or more at low flow, are generally not significant. Outstanding waters get the highest protection, and typically only short-term construction discharges are allowed in them.

How do water rights affect reuse in Colorado?

Regulation 84 governs water quality, not the right to reuse the water. Whether you may keep effluent out of the stream is a separate water rights question, and it can decide the project on its own.

As a general rule, return flows from native water belong to the stream, and downstream appropriators may depend on them. Colorado statute (C.R.S. 37-82-106) lets a party that lawfully brings foreign water into a stream system reuse it, to the extent its volume can be distinguished. Nontributary and other developed water can also carry reuse rights. The source of your supply, and its decree, sets what you can reuse.

Switching an established discharge to reuse later can be harder than choosing reuse at the start, because others may rely on the flow. Bring a water rights attorney into the comparison early. We go further in our post on water rights and discharge permits in Colorado.

What happens to reclaimed water in winter?

It has to be stored, discharged or sent to a use that runs all year. Irrigation demand stops in the cold months while the plant keeps producing water.

Storage ponds now carry their own rule. CDPHE's reuse page says the 2022 Regulation 84 rulemaking requires reclaimed water impoundments to either meet the allowable seepage rate in Regulation 61.14(9)(a) and get a seepage waiver, or get a surface or groundwater discharge permit, by August 14, 2027. Size the storage, the liner and the paperwork together.

Agricultural and landscape users also have to stay within agronomic rates, and CDPHE publishes guidance for the nitrogen agronomic rate analysis. The land you need depends on the crop, the season and the nutrient load, so it is a site calculation, not a rule of thumb.

Can one plant use both reuse and discharge?

Yes. A plant can hold a CDPS discharge permit for the flow it releases and a Treater Authorization for the reclaimed water it delivers. CDPHE even has a supplemental form for terminating a discharge permit when that discharge is being used as reclaimed water.

A hybrid often fits seasonal demand: reuse in the irrigation season, discharge or storage the rest of the year. Each authorization has its own monitoring and reporting, so plan the operator's workload before you commit.

What should you decide before design starts?

Work through this list before you pick a treatment process:

1. Classify the nearest receiving water and check whether it is reviewable, use protected or outstanding.
2. Ask the Division about likely limits, including antidegradation, for a discharge there.
3. Identify real reuse users, their uses and the Table A category each needs.
4. Have a water rights attorney confirm what part of your supply you may reuse.
5. Size winter storage and confirm the impoundment seepage path.
6. Plan the separate design review a new plant needs, covered in our post on the CDPHE site application and discharge permit.

A note on limits: this is general education on Colorado rules as of October 2026, not advice for a specific site. Regulation 84 and the antidegradation guidance change through rulemaking, so confirm current requirements with CDPHE's Water Quality Control Division and, for water rights, a Colorado water attorney.

Frequently asked questions

Is reuse in Colorado faster to approve than a discharge permit?

Not by rule. Each path has its own applications, design review and conditions, and neither has a guaranteed review time. Which is faster depends on the receiving water, the users and the water rights.

Does Regulation 84 allow reclaimed water for drinking?

No. It covers the uses in its Table A, such as irrigation, industrial, commercial, fire protection and toilet flushing. Any use not listed is prohibited.

I'm planning a small rural Colorado subdivision with its own plant and a hay field next door. Can the farmer irrigate with our effluent instead of us discharging to the creek?

Possibly. Your plant would need a Treater Authorization and the farmer a User Authorization with a UASMP for the crop use, meeting the category Table A requires. You still need winter storage or a discharge, and a water rights review of whether you may keep that water out of the creek.

I run a Colorado district that has discharged to a river for years. What should we check before moving most of that flow to reuse?

Start with water rights: downstream users may rely on your return flows, and native return flows generally belong to the stream. Then check the Regulation 84 category your users need and whether your plant meets it, and plan storage that meets the impoundment seepage rule.

Related resources

• Colorado CDPHE Discharge Permit Process: Timeline, Requirements, and How It Differs from Texas
• Antidegradation Policy in Colorado Water Permits: What It Means for New Discharge Permits
• Colorado Package Wastewater Treatment Plant Permitting: CDPHE Approval, Operations, and Compliance
• Public Notice and Citizen Petition in Colorado Water Quality Permitting: Preparing for Opposition

Choosing between reuse and discharge for a Colorado plant?

We compare both paths on the receiving water, the reuse users, storage and the permit steps before your treatment process is set. Talk with an engineer about your site.

We specialize in:

• Wastewater disposal path evaluation in Colorado
• Regulation 84 reclaimed water system design
• CDPS discharge permit applications
• Package wastewater treatment plant design
• Effluent storage and irrigation system design
• Site civil engineering for land development

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