Colorado CDPHE Discharge Permit Process: Timeline, Requirements, and How It Differs from Texas

A CDPHE discharge permit is a Colorado Discharge Permit System (CDPS) permit from the Water Quality Control Division. A new domestic wastewater plant also needs Regulation 22 site location and design approval, and the permit application is due at least 180 days before discharge. For Texas developers, those two approvals are the biggest change.

Who issues a CDPHE discharge permit, and who sets the standards behind it?

The Water Quality Control Division issues the permit. The Water Quality Control Commission adopts the rules and standards the Division applies.

Under Regulation 61, the Colorado Discharge Permit System Regulations, no one may discharge a pollutant from a point source into state water without a Division permit. Its water quality based limits come from Regulation 31, the Commission's basic standards for surface water, and the basin regulations (Nos. 32 to 38) that classify each segment. Changing a standard is a Commission rulemaking, not a permit negotiation.

Texas puts both jobs in one agency: TCEQ develops the Texas Surface Water Quality Standards in 30 TAC Chapter 307 and issues TPDES permits.

What approvals does a new Colorado plant need besides the discharge permit?

Two more, under Regulation 22: site location approval and design approval. Both must be in hand before construction starts.

Regulation 22, the site location and design approval rule, covers domestic wastewater treatment works designed to receive more than 2,000 gallons per day, including plants and lift stations. The site location application carries an engineering report covering flows, alternative sites and treatment options, Division planning targets, consolidation, floodplain and geotechnical conditions, site control, and the owner's financial and management capability.

Local reviewers see it first. For an unincorporated site, the county, any city or town within three miles, the local health authority and the 208 planning agency get 60 days to comment, and a sign stands on the site for 15 days before you submit. The Division's goal is a decision within 60 days. Approval expires in 18 months if construction has not started, unless the Division sets another date.

Design approval follows: a Process Design Report stamped by a Colorado-registered engineer, then a self-certification of the final plans. Construction cannot start until the site location, the report and the self-certification are all accepted.

Texas differs. Under 30 TAC 217.6, plans need no approval before the permit, and a project filed with a sealed summary transmittal letter is conditionally approved if TCEQ does not announce a review within 30 business days. In Colorado, fix the plant site and discharge point during site feasibility and due diligence, because the local sign-offs and planning targets hang on them.

How long does the CDPHE discharge permit process take?

No rule promises a total. Regulation 61 sets clocks, and most stretch when an application is incomplete or the public gets involved.

1. Apply at least 180 days before discharge.
2. The Division starts review within 45 days and rules on completeness within 90.
3. The applicant gets 14 days to flag errors in a preliminary draft.
4. Public comment on the draft permit typically closes in 30 days, or 60 with a public meeting.
5. The Division issues or denies after EPA review; an issued permit normally takes effect 30 days later.

If the Division has not acted within 180 days of receiving the application, Regulation 61.6 calls for a temporary permit, unless the applicant waived or extended the deadline. Your time answering information requests, plus 15 days each, and 30 days for a public meeting extend that clock.

TCEQ says to submit a complete application at least 330 days before the proposed discharge begins. In both states your lever is a complete first submittal, so book the pre-application conference Regulation 61 strongly encourages.

How do Colorado water quality standards set your permit limits?

Water quality based limits protect the classified uses of the receiving segment, so the segment's classification drives those numbers.

Regulation 31 splits Class 1 aquatic life into cold water and warm water. Dissolved oxygen is a 6.0 mg/L minimum for cold water biota, 7.0 during spawning where the permit sets it, against 5.0 for warm water. Tier I cold water streams carry a June to September chronic temperature criterion of 17.0 °C.

The Division's planning targets may come from preliminary effluent limitations (PELs), which Regulation 22 defines as limits for the proposed design flow that keep the plant from causing a standards exceedance. Get them before you pick a process. On a cold water segment, ammonia, oxygen and temperature limits can decide it.

When does Colorado require an antidegradation review?

When a new or increased discharge may degrade a reviewable water, one the Commission has not designated outstanding or use protected.

Under Regulation 31.8, the Division first asks whether degradation is significant. It is not if, among other tests, the discharge is diluted 100 to 1 or more at low flow or uses less than 15 percent of the baseline available increment. If it is significant, the degradation must be necessary for important economic or social development, with no reasonable alternative that degrades less. That alternatives analysis is where design time goes, as our post on antidegradation policy in Colorado water permits explains.

This is not a Colorado-only step. 30 TAC 307.5 applies antidegradation to Texas discharges, with the same economic or social development test in its Tier 2.

Who can challenge a Colorado discharge permit, and when?

The applicant or anyone affected or aggrieved can demand an adjudicatory hearing within 30 days of the final decision, but only on issues raised in public comment or not reasonably ascertainable from the draft.

It binds your team too. If you disagree with a limit in the draft, put it in a written comment. Anyone can request a public meeting within 30 days of notice. Site location and design decisions have a separate appeal to the Commission, due within 30 days of the Division's bulletin notice.

In Texas, 30 TAC 55.201 sets a 30-day window after the executive director's decision and response to comments, and for applications filed since September 1, 2015 an affected person's request must rest on that person's timely comments. Per TCEQ's public participation guide, it asks the commissioners to refer the case to the State Office of Administrative Hearings.

When does a Colorado permit make you plan an expansion?

At 80 percent of design capacity, when the permit carries the Regulation 61.8(7) conditions. Construction must start at 95 percent.

Under that section, a municipality at 95 percent that has not started construction must stop issuing building permits that add wastewater flow until it does. Texas uses 75 and 90 percent, each over three consecutive months, under 30 TAC 305.126. If you run a utility or municipal system, track throughput against design capacity so 80 percent is not a surprise.

Is your Colorado project ready to apply?

If you can answer yes to all six, start the site location application. Any no is your next task.

1. Do you have design flows for each phase, with unit counts behind them?
2. Do you know the receiving segment's classifications and whether it is reviewable?
3. Has the Division issued planning targets for your discharge point?
4. Is the service area consistent with the regional water quality management plan?
5. Do you control the plant site for the life of the project?
6. Does your schedule file the CDPS application at least 180 days before first discharge?

Then ask your engineer: What limits do the targets imply, does antidegradation apply, and which approval sits on our critical path?

Scope note: This is general education on Colorado Regulations 22, 31 and 61 as in effect in October 2026 and the Texas rules cited, not a permit determination for your site. Confirm your path with the Division and your engineer.

Frequently asked questions

What is a CDPS permit?

Colorado's discharge permit under Regulation 61, issued by the Water Quality Control Division. Any point source discharging pollutants to state waters needs one, apart from a few listed exceptions.

Does a small package plant in Colorado need Regulation 22 approval?

Yes, if it is designed to receive more than 2,000 gallons per day of domestic wastewater. Above that line, Regulation 22 treats even an onsite absorption system as a treatment works.

I've permitted package plants in Texas and I'm starting my first Colorado subdivision. Can I reuse my Texas engineering report for the CDPHE application?

Use it as source data, not as the submittal. Regulation 22 also asks for alternative sites, a consolidation analysis, regional plan consistency, local agency signatures and proof of financial and management capability, and the design report needs a Colorado-registered engineer's stamp.

I manage a small Colorado sanitation district and our plant just averaged 82 percent of design capacity. What does our permit expect now?

If your permit carries the Regulation 61.8(7) conditions, start engineering and financial planning for expansion now; construction must start at 95 percent. If one storm or a broken line caused the jump, you can instead submit a report showing it is extremely unlikely to recur.

Related resources

• CDPHE Site Application vs. Discharge Permit Application: The Two-Step Process Colorado Developers Often Confuse Into One
• Colorado Water Quality Control Commission Basin Specific Standards: Why the Same Discharge Limit Does Not Apply Statewide
• Public Notice and Citizen Petition in Colorado Water Quality Permitting: Preparing for Opposition
• The 330 Day Timeline: Why Texas Wastewater Permits Take Longer Than Developers Expect

Planning a Colorado discharge after permitting in Texas?

Colorado's siting, planning target and antidegradation questions are easiest to settle before the site plan is fixed. MES has an office in Golden, Colorado, is licensed in Colorado and Texas, and handles the wastewater side from feasibility through construction administration.

We specialize in:

• Site feasibility and wastewater due diligence
• Package wastewater treatment plant design
• Collection systems and lift stations
• Site location applications and CDPS permit applications
• Construction administration

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