Following is a summary of the rule. To review the rule in the Arizona Administrative Register, visit the Arizona Secretary of State website | View R18-9-A215 >
- Upon the effective date of a new or adjusted AWQS, Baseline Monitoring or sampling is required for individual Aquifer Protection Program (APP) permits with ongoing discharge or groundwater monitoring.
- In the case of these seven new or adjusted AWQS, Baseline Monitoring or sampling (for all seven parameters) is required to be initiated between Aug. 4, 2025 and Nov. 4, 2025.
- Data from Baseline Monitoring or sampling establishes baseline conditions and, through the Baseline Monitoring Report and permit amendment, assists with the determination on whether new or adjusted limits are necessary in the permit.
- Baseline monitoring or sampling duration and frequency varies depending on whether the permit has ongoing discharge or ongoing groundwater monitoring:
- Permits subject to ongoing discharge monitoring are required to sample monthly for 12 months.
- Permits subject to ongoing groundwater monitoring are required to sample quarterly for eight quarters.
- Permits subject to both ongoing discharge and groundwater monitoring are required to conduct Baseline Monitoring at both locations for the durations and frequencies listed above.
- Permittees with ongoing groundwater monitoring are required to conduct Baseline monitoring or sampling for each permitted point of compliance (POC) well in the permit.
- Permittees may request an alternative baseline monitoring commencement, duration and/or frequency.
- Permittees may provide a demonstration that a parameter with a new or adjusted standard is unlikely to be present in discharge.
- Submission of a demonstration results in removal of the parameter from the scope of the otherwise required Baseline Monitoring.
- Upon the conclusion of Baseline Monitoring, a Baseline Monitoring Report must be submitted to ADEQ through a permit amendment application.
- New or Adjusted AWQS permit amendment applications are required to be submitted during the assigned submission time frame or “phase” to help regulate the workload.
- In June 2025, ADEQ sent emails and physical mailers to permittees notifying them about the new or adjusted AWQS, Baseline Monitoring requirements, permit amendment submission phase assignments and other information.
- See Key Resources section on this web page for phase assignment information.
- The assigned phase should align with each facility’s sampling requirement timelines (later phases are extended past the sampling timeline).
What Changes on Aug. 4, 2025
Seven new or adjusted AWQS will become effective in the Arizona Administrative Code (A.A.C.). Those standards are for the following parameters:
- arsenic
- bromate
- chlorite
- haloacetic acids
- microbiological contaminants
- total trihalomethanes
- uranium
Table of changes to AWQS through this rulemaking | View Table >
In addition, a rule for the implementation of new or adjusted AWQS into existing individual APP permits also takes effect on Aug. 4, 2025.
What Permit Holders Need to Do
Most Individual APP permit holders with ongoing discharge or groundwater monitoring requirements must begin Baseline Monitoring within three months of the effective date of a new or adjusted standard; in the current case — by Nov. 4, 2025.
To check applicability, review the implementation rule | View Rule >
Visit our Frequently Asked Questions page to learn more | View FAQs >
Purpose of Baseline Monitoring
The data collected from the baseline monitoring will help ADEQ determine if new or updated:
- Alert Levels
- Discharge Limitations
- Aquifer Quality Limits
... need to be incorporated into existing APP permits through an amendment.3
This process helps protect Arizona’s groundwater and aligns regulatory requirements with current science and best practices.
Key Resources
The AWQS implementation rule requires applicable permittees to submit a permit amendment application during a specified time period (phase). In most cases, the application will contain a report on the baseline monitoring.
AWQS Permit Amendment Schedule of Phases
- Phase One | View P1 >
- Phase Two | View P2 >
- Phase Three | View P3 >
- Phase Four | View P4 >
- Phase Five | View P5 >
Phase 1 permittees should schedule a meeting with ADEQ as soon as possible to discuss implementation of the new or adjusted AWQS using one of the following forms:
- AWQS Alternative Baseline Monitoring Timeframe, Duration and/or Frequency Request | View ABM Form >
- AWQS Pre-Application Meeting Request Form | View PA Form >
To submit an Alternative Baseline Monitoring Request or an Unlikely to be Present in Discharge Demonstration, please utilize the following Guidance Documents and submit by email | Email >
- Alternative Baseline Monitoring Request | View ABM Guidance >
- Unlikely to be Present in Discharge Demonstration | View Demo Guidance >
Questions?
Visit our Frequently Asked Questions page | View FAQs >
Contact ADEQ | Email >
1Per Arizona Revised Statutes (A.R.S.) | View § 49-223 >
2Per A.R.S. | View § 49-224(B) >
3Pursuant to A.A.C. | View R18-9-A205 >