Mud, rocks and debris outside of an overmatched culvert after a monsoon storm where Finger Rock Wash crosses under East Skyline Drive near North Columbus Boulevard.
Pima County could wind up owning a few pricey addresses in the Catalina Foothills as a result of recent floods along the Finger Rock Wash.
The Pima County Regional Flood Control District has identified several homes in the path of the wash that are at significant risk of flooding and could qualify to be purchased and demolished.
The district is also scrambling to secure $2 million so it can replace an old culvert that carries Finger Rock Wash beneath Skyline Drive. The 2-foot pipe there is so “woefully undersized,” it could lead to a catastrophic “dam-failure-type scenario,” said Brian Jones, who heads up the district‘s floodplain management division.
On Havasu Road about half a mile north of Skyline, at least 10 homes, including an assisted living facility, sustained damage in a July 31 flood along the wash.
Rural Metro firefighters had to evacuate 10 residents from the assisted living facility, after the residence filled with several feet of water.
Jones said at least three other houses also ended up with water inside of them, and at least four more had their garages flooded.
It was the second time since last year that a significant flood on the Finger Rock Wash has damaged homes in the Coronado Foothills Estates neighborhood at the base of the Catalinas.
Flashy monsoon flows on the normally dry wash have intensified since the Bighorn Fire burned through the upper reaches of the watershed in 2020, but problems there actually go back decades.
The subdivision was mapped out in the early 1960s, before the county established the flood control district and adopted regulations for construction in flood zones, Jones said. As a result, numerous homes were built in places where they would never be allowed today.
“In an ideal world, none of them would exist,” he said of the houses built along the wash. “They’re well within a known floodplain — and it’s a high-hazard floodplain.”
Not many options
Jones said the district is still considering its options, but Finger Rock Wash doesn’t easily lend itself to flood improvements. It’s a natural drainage flowing across private land, and the district is not allowed to spend public funds to make flood improvements on private property, he said.
The only place the district can work on the wash is where it flows over a public right of way, but the road crossings in Coronado Foothills Estates are too shallow and too narrow to accommodate significant flood-control structures.
“There just isn’t enough room to do anything,” Jones said. “Not having people living there is probably the best solution.”
The program was created in response to the devastating floods that hit Tucson in 1983. Since then, the district has purchased more than 14,000 acres, most of it vacant land to prevent future development in flood areas.
Jones said the district buys only from willing sellers and does not use eminent domain or other tactics to force acquisitions.
There are three or four properties on Havasu Road that are at significant enough risk to qualify for FLAP, he said. One homeowner there has already applied for the program, which enables people to sell their property to the district at fair market value, even if it has been flooded.
Jones said FLAP has access to up to $1 million a year to buy land at risk from floods, but that won’t stretch very far in the Foothills. Without an infusion of additional funds, he said, “we could probably buy one house, but not two.”
Any homes the district purchases would be torn down, Jones said.
Buying property in the flood zone would also give the county direct access to the wash so it can make more substantial improvements to the channel that might reduce the risk of flooding downstream.
“But there’s nothing practical that can be done to fully remove the flood risk for these properties,” Jones warned. “Even if there’s only one house left, it would still be in the floodplain. It would still be at risk.”
After last year’s flood, several Foothills residents pooled their money to pay for channel improvements where the wash crosses their properties. Jones said that work — done in consultation with the district — was partially destroyed July 31, but it did help minimize some of the damage there.
The storm last month produced what he called a “deeper, faster flow event,” which plowed down the mountain with considerable force.
“Three- to 4-foot boulders were getting pushed around and moved downstream by this flood,” he said. “We didn’t see anything like that during last year’s flood.”
Lynn Orchard, a chief hydrologist for the district, said both floods were triggered by roughly the same amount of precipitation. Only the timing was different.
On July 23, 2021, the watershed was hit with about 2½ inches of rain over the course of three hours. On July 31 of this year, nearly that much fell in just 30 minutes.
“Very intense rainfall,” Orchard said.
Such a downpour is rare. He said there is only about a 3% chance of so much rain falling so quickly at that location in any given year, based on data from the National Oceanic and Atmospheric Administration.
The surge of water from the July 31 storm eventually reached Skyline Drive, where a single, 2-foot pipe carries the wash beneath an earthen berm that holds the road up.
The pipe was quickly overwhelmed, causing the area just upstream to fill to a depth of about 14 feet, high enough to send six inches of water rushing across the road and down the other side of the berm.
Jones said the water only overtopped the berm for about 30 minutes or so, but it still damaged the guardrail on Skyline and caused some erosion on the downstream side of the slope.
Had the flood lasted longer or crested higher, he said, it could have undercut the road or caused the berm to collapse altogether, potentially sending a 13-foot wall of water downstream.
In September 2020, the district applied for a federal emergency hazard mitigation grant to replace the old pipe with three 12-foot-by-10-foot box culverts that have “massively more capacity than what’s there,” Jones said.
The project is expected to cost about $2.6 million, including engineering and design.
"We planned on this project even before they flooded in 2021," Jones said. "It was a location that we were concerned about before the Bighorn Fire, but the cost of the project meant it was unlikely to happen without outside funding."
He was hoping a grant with the word emergency in its title might come through quickly, but the district’s application is apparently still under review, so Jones and company have turned to the state for help.
The district recently applied for money from the Arizona Department of Forestry and Fire Management’s Post-Wildfire Infrastructure Assistance Program, which was created last year with $10 million available for public and private landowners in need of emergency repairs.
Care home concerns
The flood on Finger Rock Wash might also spur changes to the way assisted living facilities are approved in Pima County.
Jones said district officials are now reviewing their own procedures and those of other county departments in hopes of strengthening the review process for such facilities.
He said that review was already underway before the care home on Havasu Road flooded, but “that particular case really drove the point home.”
The Federal Emergency Management Agency designates care homes as critical services — alongside things like hospitals, police and fire stations and utility providers — and only allows them to be placed in floodplains if they are built to withstand a 500-year flood event, Jones said.
According to the Arizona Department of Health Services, Catalina Foothills Adult Care on Havasu Road was originally licensed in 2003 for up to five residents. Its capacity was increased to 10 in 2009.
State records show the facility is licensed to provide “directed care services” to “persons who are incapable of recognizing danger, summoning assistance, expressing need or making basic care decisions.”
The facility’s current status is unclear. A message left with the home’s operator was not returned.
Jones said that to his knowledge the flood control district was not consulted before the care home received a license and was cleared to open on the bank of Finger Rock Wash.
“If we had been in the loop when this facility was permitted and we had the power to say no, we would have said no,” Jones said.