Last Updated 07/20/2026
The City of Flagstaff has enacted a Stormwater Ordinance in order to establish minimum stormwater management requirements and controls to protect and safeguard the general health, safety, and welfare of the public residing in watersheds within this jurisdiction. The City of Flagstaff is the permitting authority for all land disturbing activities and requires the land owner to maintain all on-site stormwater control facilities and all open space areas (e.g. parks or “green” areas) required by the approved stormwater control plan. The City of Flagstaff will only provide construction permits to projects that establish a plan to manage stormwater runoff occurring during the construction process. The City of Flagstaff, under the NPDES program, also has the authority to inspect properties for noncompliance and can issue a notice of violation (NOV) for any deficiency or infraction onsite. Property owners are responsible for the maintenance of any stormwater facilities or practices located on the property. The City of Flagstaff has the authority to inspect stormwater facilities and practices in order to ascertain that they are properly maintained and functioning.
Flagstaff Stormwater Laws and Regulations
The City of Flagstaff requested coverage under the 2016 MS4 by submitting a Notice of Intent (NOI) to ADEQ. ADEQ posted a public notice and proposes to issue Water Quality (AZPDES) Small MS4 General Permit (AZG2016-002) coverage to the City of Flagstaff. The City of Flagstaff is subject to provisions of the Federal Clean Water Act and the requirements of the Arizona Pollutant Discharge Elimination System (AZPDES) program, pursuant to Arizona Revised Statutes (A.R.S) Title 49, Chapter 2, Article 3.1, and Arizona Administrative Code (A.A.C.) Title 18, Article 9.
Excerpt from General Permit For Stormwater Discharges From Small Municipal Separate Storm Sewer Systems Permit Number AZG2016-002:
6.4.5 Post-Construction Stormwater Management in New Development and Redevelopment Permittees shall develop, implement, and enforce a program to address post-construction stormwater runoff from new development and redevelopment projects that disturb one (1) or more acres of land (or less than one (1) acre if part of a common plan of development) that discharge into the permittee’s MS4. The post-construction stormwater management program must include a combination of structural and/or non-structural best management practices, as well as the components identified in this section.
6.4.5.1 Regulatory Mechanism for Post-Construction Stormwater Controls The new development/redevelopment program shall include an ordinance or regulatory mechanism to address runoff from new development and redevelopment projects. The regulatory mechanism must specify that owners or operators of new development and redevelopment sites discharging to the MS4, design, install, and maintain post-construction stormwater controls that reduce or eliminate the discharge of pollutants from the site after construction activities are completed. Permittees must evaluate existing ordinance or other regulatory mechanism(s) to address post-construction stormwater runoff from new development and redevelopment projects. If it is determined existing ordinances or other regulatory mechanism(s) must be modified, the permittee must develop, adopt and implement a revised ordinance or other mechanism within the timeframes(s) specified in Part 3.1. The permittee’s new development/redevelopment program shall have procedures to ensure any stormwater controls or management practices for new development and redevelopment will prevent or minimize impacts to water quality from stormwater runoff.
6.4.5.2 Site Plan Review The permittee shall design, implement, and maintain a site plan review process to evaluate and approve post-construction stormwater controls. 6.4.5.3 Post-Construction Stormwater Control Inventory Within the first year of the effective date of this permit, the permittee shall implement and maintain an inventory system of all post-construction structural stormwater control measures installed and implemented at new development and redeveloped sites, including both public and private sector sites located within the permit area that discharge into the MS4. The inventory must be searchable by property location (either on paper or electronic) or other relevant criteria. 6.4.5.4 Operation and Maintenance of Post-Construction BMPs The permittee shall establish processes, procedures, and other such provisions necessary to ensure the long-term operation and maintenance of postconstruction stormwater BMPs.
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Frequently Asked Questions
What permit governs stormwater discharges in Flagstaff?
Flagstaff operates under Small MS4 General Permit AZG2016-002, issued by the Arizona Department of Environmental Quality. The city requested that coverage by submitting a Notice of Intent to ADEQ, and the permit ties Flagstaff’s local requirements back to both the federal Clean Water Act and Arizona’s own AZPDES program under state statute.
What size project triggers post-construction stormwater requirements in Flagstaff?
Any new development or redevelopment disturbing one acre or more of land that discharges into the city’s storm sewer system. Projects under one acre aren’t automatically exempt, though. If a smaller project is part of a larger common plan of development, the same post-construction requirements still apply.
Does Flagstaff require ongoing maintenance for post-construction stormwater controls, or just installation?
Both. The city’s permit requires owners and operators of new development and redevelopment sites to design, install and maintain post-construction stormwater controls that reduce or eliminate pollutant discharge after construction wraps up. That maintenance obligation doesn’t end when the certificate of occupancy is issued.
Does Flagstaff keep records of stormwater controls installed on private property?
Yes. The city maintains a searchable inventory of post-construction structural stormwater control measures at both public and private sites that discharge into the MS4. That means a property’s controls are tracked by location once they’re installed, which is worth knowing if a future inspection or ownership transfer comes into play.
Do I need city approval before installing stormwater controls on a new development in Flagstaff?
Yes. Flagstaff maintains a site plan review process specifically to evaluate and approve post-construction stormwater controls before they go in. That review sits alongside the general construction permitting process the city already requires for any land-disturbing activity.
How does Flagstaff make sure stormwater controls keep working after construction?
The city’s permit requires it to establish processes and procedures ensuring the long-term operation and maintenance of post-construction BMPs. That obligation is on the city to set up the system, but in practice it flows down to whoever owns or operates the property where the BMP sits.
How can AQUALIS help my property stay compliant with Flagstaff's stormwater permit?
AQUALIS helps Flagstaff property owners design, install and maintain the post-construction BMPs the city’s MS4 permit requires, and supports properties through the site plan review process before construction begins.
The information on this page is provided for general informational purposes only and is not legal advice. Regulations change frequently — AQUALIS makes no warranty as to the accuracy or completeness of this content, and any reliance on it is at your own risk. Consult a qualified professional or your local regulatory authority to confirm requirements applicable to your specific property.
