Coconino County Flood District lays out conceptual flood‑mitigation plan for Muns Park, seeks federal funding

Coconino County officials and engineers briefed Muns Park residents on a countywide, long‑term flood mitigation planning effort and presented two leading conceptual projects for Muns Park: a flood‑retarding structure upstream of the community and a short containment levee at Pinewood Boulevard. The Flood Control District said both concepts are early, would require feasibility studies, federal and Forest Service approvals and tens of millions of dollars in construction funding.

The briefing opened with District 3 Supervisor Tammy Ontiveras and Flood Control District Administrator Lucinda Andreani, who said the district has launched a countywide evaluation of five unmitigated FEMA floodplain areas and is prioritizing projects by risk, cost and expected economic benefit. "Wehave launched an overall long term flood mitigation planning process for the entire county," Andreani said, describing a process that will feed recommendations into the districtboard and the county budget cycle.

Engineer Scott Ogden of J.E. Fuller Hydrology reviewed technical findings and alternatives. He described a proposed flood‑retarding structure — effectively a regulatory dam that does not permanently store water — at a narrow upstream bottleneck and said early modeling suggests it could reduce hundred‑year discharges in the downstream canyon by roughly 50–65 percent. "Flood retarding structure is essentially a dam," Ogden said, adding that the structure's flood pool might be in the 500–600 acre‑foot range. Ogden cautioned those numbers are conceptual and require further modeling, geotechnical study and Forest Service agreement.

Ogden also summarized a Pinewood Boulevard containment levee concept intended to keep flows in the main channel and remove many residential lots from the FEMA 100‑year floodplain. He told the audience that a previously studied alternative that routed more water through the I‑17 outfall was dropped after a no‑adverse‑impact review showed it would raise base flood elevations downstream (Oak Creek area) by about half a foot to a foot in places.

District staff emphasized that federal and state grant programs typically require a benefit–cost analysis (BCA) that demonstrates benefits exceed costs. Ogden explained the BCA logic: "You got to save more than you're going to spend." Andreani said the district's revenues are limited and that successful projects will likely require federal matches and partner contributions from ADOT, the Pinewood Sanitary District and others. She urged residents to support future funding requests with letters to congressional and state officials when feasibility studies are ready.

Residents asked detailed questions about private property work, dredging Odell Lake and the risks of dam failure. Andreani responded that small‑scale, individual property fixes would have "almost 0 impact" on the large volumes arriving via Frog Tank and cautioned the district cannot legally fund measures that benefit single property owners because of Arizonagift law. Ogden said dam designs would be built to managed overflow standards (likely below a 100‑year design level) and noted that even well‑engineered structures cannot eliminate risk for extreme events.

On public‑health and infrastructure risks, Ogden said the Pinewood sanitation lagoons are threatened by roughly a 50‑year event (he cited an earlier 8,100 cfs measured peak as an example). The district also committed to providing attendees with the adopted no‑adverse‑impact criteria and any legal references on its website.

Next steps: staff said the county will seek feasibility funding (examples cited ranged from $1 million to $2.4 million depending on scope), perform geotechnical and environmental studies, and pursue partner letters and grant applications. Andreani and Ogden said the conceptual projects will be vetted in upcoming Flood Control District board discussions and the county budget process.

The meeting closed with staff offering follow‑up contact information and promising to post the presentation and recording on the Flood Control District website.