Design for proposed southern Utah reservoir is poor and poses risk to public safety, geophysicist says

Residents cite concerns about dust and invasive trees for their opposition to the project.

(Robert Bolar) Dry Wash.

Ivins • A $22 million reuse reservoir the Washington County Water Conservancy District proposes to build in the middle of an Ivins residential community is poorly designed and will pose a safety risk to residents.

That’s the assessment Wayne Pennington, a geophysicist and retired dean of engineering at Michigan Technological University, provided to the Ivins City Council about the current design for Dry Wash Reservoir the district plans to build on about 90 acres between Kwavasa Drive and Highway 91.

“We are not bound to the model the district has,” said Pennington, who lives in Ivins and has researched the reservoir on his own time and dime. “In fact, I think the model the district has will not stand up. … Frankly, I think if any professional engineer put their imprimatur on that model [he or she] would lose their license.”

Pennington’s verdict on the district’s reservoir design, which resulted from his own research and report he prepared on Dry Wash, was delivered before an overflow crowd that packed the Ivins council chambers for a work session Thursday. The session was focused on potential problems with Dry Wash Reservoir, which is a key component of water district officials’ plans to amass another 47,000 acre-feet of water by 2042 to keep pace with growth.

By storing treated wastewater for use in outdoor irrigation, district officials argue, Dry Wash would free up culinary water the district would then have on tap to supply new homes constructed in the county over the next two decades. Opponents counter that locating a reservoir in the middle of the Kayenta residential community in Ivins is a bad idea and would be fraught with problems.

Dry Wash’s current design calls for a 1,500-acre foot reservoir with a high-water level of 3,044 feet, which is four feet higher than the maximum level a 2004 Environmental Assessment determined was safe. Moreover, Pennington noted, the current design is much larger than the 1,000 acre-foot reservoir the water district initially agreed to with the city in 2021.

Another concern is that nearby homes are at 3,020 feet elevation, 24 feet lower than the high-water level proposed in the reservoir’s current design which also calls for a 66-foot dam that critics worry might leak and seep into the groundwater and cause flooding.

Dust in the wind

Further exacerbating matter safety and public health concerns, Pennington and others voiced at the work session, is the problem posed by dust. When the reservoir is drawn down to send the water where it is needed during the hot summer months, about 47 acres of the lakebed would be exposed.

“A reservoir with these characteristics would … create problems due to a broad, shallow area on the western flank, creating a mudflat when the reservoir is low, and allowing wind to pick up the dust and other materials, carrying it to populated areas,” Pennington told city officials.

Ivins resident Ginamarie Foglia, an adjunct professor at Rocky Vista University who specializes in internal medicine and infectious diseases, expressed concern about dust clouds spreading valley fever, a fungus prevalent in the dirt and soil of Utah and other states in the American Southwest that can afflict and sicken both people and animals.

(Mark Eddington | The Salt Lake Tribune) Washington County Water Conservancy District general manager Zack Renstrom talks about the importance of Dry Wash Reservoir at a public meeting Wednesday, Feb. 21, 2024, at Rocky Vista University in Ivins. Ivins Mayor Chris Hart is seated onstage to Renstrom’s right.

Washington County has the highest incidence of valley fever, or Coccidioides fungus. Between 2009 and 2015, there were 17.2 cases of valley fever per 100,000 people, compared with 1.83 per 100,000 for Utah as a whole, according to the Utah Department of Health.

“Some people exposed to valley fever may develop some kind of immunity and do OK,” Foglia said. “But the people who really suffer from it and need antifungals or can land in respiratory distress are people who are immunocompromised, people on steroids or who are on oncology medications…”

Pennington and others concerned about Dry Wash are pushing for a smaller reservoir with a different configuration that enhances public safety and mitigates any dust problems by shrinking the size of the lakebed exposed to wind during the summer months.

District officials did not comment on the concerns over the design of the reservoir during the work session. But district general manager Zach Renstrom recently told The Tribune that the current design is sound, has undergone rigorous analysis and has been subject to extensive review from the state and an independent third party. He also said the district has not encountered dust problems at its other reservoirs.

Meddlesome midges, gnarly gnats, biting black flies

Last week’s work session was not a public hearing. Instead, the council took comments from people credited with having some level of expertise or first-hand experience with various problems that might plague Dry Wash. Besides concerns about the reservoir design and dust, residents fretted about the havoc they said could be caused by pesky midges, gnats and biting black flies.

Kayenta developer Terry Marten said homes located at nearby Ivins Reservoir are already plagued by swarms of insects.

“When the lights are on in one of the [homes] close to the reservoir … and if a door is left open, then your house is filled with gnats,” Martin said. “They die relatively soon but then they are on the tables and furniture and chairs.”

Chuck Warren, president of the Desert Preservation Initiative, warned about Dry Wash Reservoir leading to the spread of invasive tamarisk trees, which out-compete native species like cottonwood and willow trees, “kill everything else” and fuel more wildfires.

Ivins officials plan to hold another work session soon to give water district officials and project engineers an opportunity to answer residents’ questions and concerns. Before construction can begin on Dry Wash Reservoir, the city must sign off on the project and grant the district a conditional use permit.

“We need to determine what the severity of these problems are, what mitigation the city of going to be required to provide and what the expense will be to the city so that when a decision on a conditional use permit is made, it is made with an understanding of what the city is committed to do,” Ivins Mayor Chris Hart said.

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