WQD | ER | Nitrogen Management Areas (NMAs)

Groundwater

Nitrogen Management Areas (NMAs)

Posted On: Mar. 18th, 2026 - 04:39 pm

Protecting Drinking Water with an NMA

ADEQ protects Arizona’s groundwater and surface waters so families have access to safe drinking water and a healthy environment. In some communities, onsite wastewater treatment facilities (OWTFs), commonly known as septic systems, are polluting groundwater, Arizona’s primary drinking water source, and causing nitrate levels in drinking water to rise above the safe limit of 10 milligrams per liter (mg/L). This is more likely to occur where many homes with septic systems are located close together.

Nitrogen is essential for all life, but in excess this becomes a serious pollutant harmful to our health, particularly for infants under six months, who can develop methemoglobinemia, or “blue baby syndrome.” This life-threatening condition occurs when high nitrate levels prevent the infant's blood from carrying enough oxygen.

Treating water polluted by nitrate can be very expensive. In addition to contaminating groundwater, septic systems can also contaminate nearby surface waters. When groundwater interacts with surface water, nitrate can damage rivers and lakes by fueling algae growth.

To address this problem, Arizona rules (R18-9-A317) authorize ADEQ to designate certain areas in the state as Nitrogen Management Areas (NMAs). An NMA is a region designated by ADEQ where too much nitrogen is polluting the groundwater and causing the water to be unsafe to drink without costly intervention. In an NMA, any new or replacement OWTFs must include nitrogen-reducing technology or homeowners can choose to connect to a sewer system, if one is available.

Frequently Asked Questions (FAQs)

Why would ADEQ propose an NMA?

ADEQ will propose to designate an NMA to protect community health from the harmful effects of consuming drinking water impacted by high nitrate levels. In some communities, many homes use septic systems instead of public sewers. When these systems release more nitrogen than the ground can absorb, the wastewater can reach and contaminate the water people use for drinking. By designating an NMA, ADEQ can:

Protect drinking water and reduce health risks for families, especially babies
Stop pollution before it spreads or becomes more expensive to clean up
Require new or replaced septic systems to use technology that reduces nitrogen
Encourage homeowners to connect to a public sewer system when it’s available

What are the benefits of an NMA for me, my family and my community?

An NMA helps:

Protect drinking water wells — both public and private
Keep groundwater and surface water safe
Maintain property values and community health
Prevent expensive water treatment in the future

By addressing nitrogen at the source, NMAs make long-term water protection easier, and more cost effective.

How does ADEQ decide to propose a designated NMA?

The process typically begins when ADEQ detects high nitrogen levels in groundwater or drinking water. ADEQ investigates the issue by collecting and testing water samples for indicators of human wastewater, such as the artificial sweetener sucralose. These results help ADEQ understand where the nitrogen is coming from and how it may affect local drinking water.

A proposed NMA designation must be based on a review of several criteria, including:

The number and density of septic systems
Population growth trends
Nitrate levels in drinking water wells
Whether sewer service exists or could be added
How quickly nitrogen moves through local soils and rock

Can the public participate in this process?

Yes, when ADEQ identifies an area of concern and proposes that area to be a designated NMA, ADEQ first will engage local officials to discuss the potential designation, which will be followed by additional informal and formal public participation activities including:

Posting the proposal to the ADEQ website,
Seeking input from local officials through a 120-day formal comment period, and
Soliciting community input through the formal public comment period and hosting an informal public meeting during the comment period.

After the comment period has closed, the ADEQ Director will evaluate all comments received and make a determination as to whether to designate or modify an NMA, or withdraw the proposal. This determination, including ADEQ’s responses to the comments received, will be posted to ADEQ’s website and provided to all commenters.

What happens if ADEQ designates an NMA?

Property owners must comply with any special provisions established for that specific NMA. These requirements help reduce nitrogen pollution at its source and protect local drinking water.

If ADEQ designates an NMA:

New or replaced septic systems must use technology that reduces nitrogen
Homeowners may choose to connect to a public sewer system if one is available

Can ADEQ remove or change an NMA designation once it is established?

Yes. ADEQ can amend or remove an NMA designation if new data show that groundwater quality has improved. Any change would follow a public process, including opportunities for community input.