AAC R18-9-I652: Drywell Inventory Rules

The core duty is one sentence: "The owner or operator of an injection well authorized by rule under R18-9-I650 shall submit inventory information to the Director." In other words, the person who owns or runs the drywell reports it to ADEQ. Nobody else does it for you.

The rule sets a deadline for wells that already exist: "The owner or operator of an injection well shall submit inventory information no later than one year after the effective date of the Arizona UIC program." The federal rule approving Arizona's program says "The effective date of this program is October 15, 2025." Our reading: one year after that is October 15, 2026. ADEQ's pages don't state that date in so many words, so treat it as our math, not ADEQ's announcement.

The companion rule, R18-9-I650, explains why there's no individual permit. Class V injection is "authorized by rule," meaning owners and operators must comply with all the requirements of the Article "but do not have to get an individual permit." The catch is in the same section: an owner is prohibited from injecting into the well "upon failure to submit inventory information in a timely manner."

The parts, in order:

• Who files: the owner or operator of the drywell.
• What goes in: facility name and location, legal contact, ownership, the nature and type of well, and its operating status (R18-9-I652(B)).
• Where: ADEQ's myDEQ portal. ADEQ's page says wells "must be registered and managed in myDEQ."
• Fee: ADEQ's fee rule, R18-14-111, lists "$200 per well inventory" and "$100 per well transfer," and ADEQ adjusts those flat fees every August 1.
• How long it lasts: ADEQ says "The registration is valid for the life of the Class V well, until it is plugged and abandoned."

• Drywell. A shallow well, usually a settling chamber over a gravel-filled shaft, that lets stormwater soak into the ground below a basin or parking lot. Federal rules list "Drainage wells used to drain surface fluid, primarily storm runoff, into a subsurface formation" as Class V wells (40 CFR 146.5).
• Class V well. The federal catch-all class for injection wells that aren't Class I, II, III, IV or VI. EPA calls most of them "low-tech," draining by gravity.
• Authorized by rule. Legal to operate without a permit of its own, as long as you follow the rules, starting with the inventory.
• Inventory versus registration. ADEQ's page still says "registered." The rule says "inventory." They mean the same filing.
• Primacy. The state, not EPA, now enforces the program. EPA's approval (90 FR 44327) covers Arizona except Indian lands.

It covers anyone who owns an existing or proposed drywell: commercial centers, office parks, industrial yards, churches, schools, HOAs and cities. ADEQ's page says the inventory "is for a person who owns an existing or proposed UIC Class V well."

This does not apply to:

• Golf course drywells used for course maintenance. ADEQ says they "do not need to be registered," unless the well takes stormwater mixed with reclaimed water or groundwater from a golf course, park or neighborhood lake.
• Wells on Indian lands. Those stay with EPA.
• Retention basins with no drywell. A basin that drains only by soaking into its own floor isn't an injection well.

Two things are banned outright, not inventoried: "The construction and operation of cesspools and motor vehicle waste disposal wells are prohibited" (R18-9-I654). A shop floor drain that dumps into a drywell is the classic example of the second one.

A Mesa strip center with four drywells from 2004. The owner has old ADEQ registration numbers in a binder. The statute behind those numbers was repealed, so the owner checks myDEQ. If the wells aren't listed, the owner files the inventory before the one-year mark.

A Phoenix warehouse sale. The buyer's due diligence finds two drywells in the truck court. Under R18-9-I650, transferring ownership takes an inventory plus the transfer fee. The buyer also asks for the site's inspection records, because ADEQ's guidance treats truck areas as heavy-use sites that need a pretreatment interceptor.

An auto repair shop's floor drain. A tenant improvement finds the bay drains tied into a drywell. Here the answer flips: this isn't something to inventory. It's a prohibited motor vehicle waste disposal well, and it has to be disconnected and closed.

1. 1Find every drywell on the site. Grading and drainage plans, as-builts and the grate covers (ADEQ guidance calls for covers cast "stormwater only") show where they are.
2. 2Search myDEQ for the property. ADEQ's page links to it, and the Groundwater Permits line is 602-771-4686.
3. 3File the Class V inventory in myDEQ for any well that isn't listed, with the facility, contact, ownership, well type and operating status the rule asks for.
4. 4Pay the inventory fee shown in myDEQ. The rule's base is $200 per well, adjusted each August 1.
5. 5Transfer the wells when the property sells, and plan closures under R18-9-B614(C), then report them in myDEQ.
6. 6Keep inspection records on site. ADEQ's 2018 guidance recommends inspecting at least annually, and whenever water stands in the basin longer than 36 hours.

• "A.R.S. 49-331 requires drywell registration." Laws 2022, Chapter 177 says "Title 49, chapter 2, article 8, Arizona Revised Statutes, is repealed." Article 8 was the drywell article. The duty now comes from the UIC rules.
• "Old registration means you're done." The old registration came from the repealed statute. ADEQ doesn't say old records carried over, so check myDEQ.
• "Class V means a permit application." Most drywells are authorized by rule. No individual permit, but the inventory isn't optional.
• "Anything that drains can go in a drywell." ADEQ guidance says drywells should take "only stormwater and urban surface run-off." Other discharges can trigger stricter injection well rules.
• "The city handles it." Cities review drywells on grading plans. The inventory is the owner's filing with ADEQ.

R18-9-I650 says an owner is "prohibited from injecting into the well" after failing to submit inventory information on time. For a basin that depends on its drywells, that's a legal problem every time it rains. City and county drainage reviews also ask for proof of ADEQ drywell registration on as-builts.

For how each Valley city sizes retention basins and drywells, see retention basin and drywell rules by city. Plugged drains and standing water after monsoon storms are covered in how monsoon season affects plumbing.

Read R18-9-I650, R18-9-I652 and R18-14-111 on the Cornell LII mirror of the Arizona Administrative Code, ADEQ's UIC Class V Well Inventory page, EPA's approval of Arizona's UIC program, and the 2022 repeal. This page explains the rules; the official text governs.