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The original item was published from 3/24/2023 8:43:18 AM to 4/30/2023 12:00:00 AM.

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Posted on: March 28, 2023

[ARCHIVED] Stormwater rate increase effective April 1

The City of Flagstaff has adopted a new stormwater rate, equivalent to a 12 percent annual increase, effective April 1, 2023. The current rate will increase from $3.74 per equivalent rate unit (ERU) to $4.19 per ERU, then increase by 12 percent annually through 2028. Funding from the rate increases will be used to create enhanced flood mitigation and flood risk reduction through improved infrastructure and maintenance services.

Another change included in the rate adoption is the maximum on single-family residential ERUs. The current maximum for a single-family residential property of 5 ERUs is being increased to 10 ERUs effective April 1. Residents and businesses can explore ways to reduce their stormwater bill through implementing certain stormwater controls on their property or education programs, as outlined in the Stormwater Credit Manual.

Stormwater fees are measured in ERUs and one ERU is equivalent to 1500 square feet of impervious surface. For this calculation, impervious surfaces include buildings, asphalt, compacted gravel surfaces, decks, driveways, parking areas, patios, rooftops and sidewalks. ERUs measure the impact of a property to the stormwater system.

It has been over a decade since aerial imagery has been used to update impervious surface measurements. A high-resolution mapping project in 2022 provided better accuracy that identified ERU adjustments to about 50 percent of the customer base, with both increases and decreases in ERU base assessments. Stay tuned for adjustments to be implemented during the year.

For more information on the stormwater rate increase and ERU calculations, please visit For related questions, please contact Ed Schenck, City of Flagstaff Stormwater Manager at


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