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Aquifer Water Quality Standards Update
Background
The Arizona Department of Environmental Quality was established by the Arizona Environmental Quality Act (EQA) of 1986. The EQA also established the Aquifer Protection Permit Program to protect the State’s aquifers.
The definition of “aquifer” as it appears at A.R.S. §49-201.2 “…means a geologic unit that contains sufficient saturated permeable material to yield usable quantities of water to a well or spring.” An idealized diagram is shown below.
Aquifer Water Quality Standards (A.A.C. Title 18, Chapter 11, Article 4)
A Notice of Final Rulemaking was published in the Arizona Administrative Register on July 4, 2025, effective on August 4, 2025, to update or revise three AWQSs and establish new AWQSs for four contaminants, as follows:
Aquifer Protection Permits – Implementation Rule (A.A.C. R18-9-101 and R18-9-215)
Existing permittees may not be able to immediately comply with the new and adjusted AWQSs because of a need to install additional treatment or initiate other measures. Also, ADEQ does not have the manpower and resources to amend all permits at the same time. A companion rule was issued with the same effective date to implement the process to amend existing individual Aquifer Protection Permits to incorporate the new and adjusted Aquifer Water Quality Standards.
Baseline Monitoring
The implementation rule requires permittees with individual Aquifer Protection Permits to conduct baseline monitoring for the new and adjusted AWQSs. The Baseline Monitoring must commence within three months of the effective date (between August 4 and November 4, 2025) at permit-required groundwater point of compliance, discharge, or other monitoring locations subject to alert levels, discharge limitations, or Aquifer Quality Limits (AQLs).
Baseline monitoring shall be conducted as follows:
- Groundwater monitoring quarterly for two years (8 quarters)
- Discharge monitoring monthly for one year
Individual permittees can request an alternative baseline monitoring schedule than that prescribed in the rule. The request must be submitted to ADEQ no later than November 4, 2025, and must provide a rationale for the alternative schedule.
Baseline monitoring will not be required for permittees who have no ongoing monitoring requirements in their current permits, but may be required to characterize their discharge for the adjusted and new AWQSs using historical data, treatment process, or other information (e.g. pretreatment program). In addition, individual permittees can make a demonstration, prior to the commencement of baseline monitoring, that a pollutant is unlikely to be present in the discharge to reduce the scope of their baseline monitoring.
Analytical Methods
The analytical methods for chemical contaminants can be found in Table 1 of the Preamble to the rules (reproduced below) (also see A.A.C. R18-9-215.E.4).
Monitoring for microbiological contaminants is changing under the new rule. Previously individual permits required analysis for the presence or absence of Total Coliform bacteria. Baseline monitoring for microbiological contaminants will analyze for the presence or absence of Fecal Coliform or Escherichia coli (E. coli). Compliance monitoring under amended permits will require analysis of Fecal Coliform or Escherichia coli (E. coli) for routine and repeat monitoring.
Baseline Monitoring Report (R18-9-215.E)
A baseline monitoring report shall be prepared within three months of receipt of the final sample results required by baseline monitoring. The report should include the following:
- The analytical results of discharge and groundwater monitoring
- A demonstration of the baseline concentration of a new or adjusted AWQS at permit required locations subject to Alert Levels, Discharge Limits, and Aquifer Quality Limits (AQLs).
- Laboratory data for all baseline monitoring.
- A proposal for Alert Levels, Discharge Limits, and AQLs, as appropriate, for the new and adjusted AWQSs.
Individual Permit Amendments
Once the baseline monitoring is completed, the permittee shall prepare an application to amend the Aquifer Protection Permit to incorporate the new or adjusted AWQSs, as applicable. The Baseline Monitoring Report shall be a part of the permit amendment application.
ADEQ estimates that about 500 permits will require amending. A schedule has been established for completing this process.
The permit amendment schedule will be carried out in phases based on what, if any, monitoring is required in the existing permit.
Permit Phase Assignment
- Phase 1 – August 4th through December 31st, 2025:
- No Discharge or Groundwater Monitoring required in permit
- Phase 2 – January 1st through December 31st, 2026:
- Only Discharge Monitoring required
- Phase 3 – January 1st through December 31st, 2027:
- Only Discharge Monitoring required
- Phase 4 – January 1st through December 31st, 2028:
- Only Groundwater Monitoring or Groundwater & Discharge Monitoring required
- Phase 5 – January 1st through August 4th, 2029:
- Only Groundwater Monitoring or Groundwater & Discharge Monitoring required
The goal is to complete all permit amendments by 2030, after which the five year cycle of amending permits will continue from there.
All applications for new permits (i.e. facilities that have never had a permit) will be processed as received and will incorporate the new or adjusted AWQSs, as appropriate.
ADEQ should have already notified all individual permittees of the new rules, effective date, baseline monitoring requirements, and timeframe (i.e. Phase) that their permits will be updated.
ADEQ recommends that individual permittees schedule a pre-application meeting to discuss their specific requirements under this rulemaking.
More information about the Aquifer Water Quality Standards Update rulemaking effort can be found at https://azdeq.gov/rulemaking/awqs-update/resources. The Notice of Final Rulemaking published in the Arizona Administrative Register on July 4, 2025 can be found at https://apps.azsos.gov/public_services/register/2025/27/contents.pdf, pages 2167-2254.
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About The Author
At NJBSoft, we’re proud to collaborate with experts like Robert Hollander, P.E., whose extensive experience in water quality and regulatory compliance allows us to design SAMS in order to meet industry needs. Bob’s leadership and deep industry knowledge supports utilities in staying organized, compliant, and focused on protecting public health every day.
Robert Hollander
- 45 years of experience in water quality, regulatory compliance, and utility management
- President of Hollander Consulting Services
- Held senior roles at the City of Peoria, City of Phoenix, and the Arizona Department of Environmental Quality
- Served as President of the AZ Water Association and the Western Coalition of Arid States
- Licensed Professional Engineer in Arizona with multiple Grade 3 operator certifications
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