If Eagle Road were to flood and had to be shut down, where would traffic be detoured?
Where would students be taken if a flood emergency occurred during school hours, and how would they be reunited with their families?
Who would evacuate people who need additional assistance, such as the elderly or people with physical limitations?
Ada County officials are hoping for the best but planning for the worst — and everything in between — as flooding continues along the Boise River.
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“We have been looking at the different flows, and the impact that would have on the communities,” said Douglas Hardman, director of Ada County Emergency Management.
There are many variables that can change things quickly. A tree with a roughly 10-foot, mud-clogged rootball that got hung up in the river in Garden City on Friday became a defacto dam, sending water into three city streets: 46th, 47th and 48th.
“That’s how quickly things can change,” Hardman said. “The whole system is fragile. Anything like that can make a huge change.”
Garden City Mayor John Evans said the tree has drifted downstream a bit, and the flooding of those three streets has receded. He said he hadn’t heard any reports that the water went into any buildings. Authorities will keep an eye on the tree and fish it out if it approaches the Glenwood Bridge.
Flooding’s Situation Room
The Ada County Emergency Operation Center was set up to handle flood coordination in late March, after county commissioners declared an emergency here.
Representatives from more than 50 public and private agencies — including the American Red Cross, Central District Health, Idaho Power, Suez, Idaho Mountain Search & Rescue Unit and the National Weather Service — have participated in daily meetings at the center to discuss contingency plans. Attendance varies by day.
They’ve looked at a variety of flooding scenarios, considering the impact of impassable roads or bridges. “Anything and everything you can think of,” said Hardman, who in 28 years on the job believes he’s never confronted a situation of this magnitude and with such far-reaching, worst-case implications.
Already, the cost to repair bank erosion, Greenbelt damage and potential bridge issues is likely to run into the millions of dollars, Hardman said.
Development along the river in Eagle over the past 30 years has raised the stakes. Most of the 2,200 homes in the Eagle Island area, with roughly 6,200 residents, were built in that time.
The emergency center is in the basement of the the county’s Public Safety Building, 7200 Barrister Drive. It’s a room full of tables, Chromebooks, phones, ham radio equipment and wall screens that allow anyone in the room to easily see maps, hydrologic data and images from cameras along the river.
After a busy winter with record snow and significant damage around the county, Hardman and his four-person staff expect to be on call 24 hours a day into July for flooding-related issues. There’s no vacation planned, nor time off, and they’ve been working 10- to 12-hour days for the past two months (including weekends).
“Everybody is tired but we have another two months to go,” Hardman said. “We’re just going to power through it.”
What keeps him awake at night is the “perfect storm” this year: The Treasure Valley has had double its normal precipitation. Irrigation water is at its lowest demand in recent memory. Low- and mid-elevation snowpack is at the highest level in three decades, and snow was still accumulating in the mountains well into April. Snowpack in Boise’s watershed is at 165 percent of its usual water content for this time of year, and after record-breaking flows into the Boise River in February and March, 2 million acre-feet or more of water still remains in the mountains, waiting to run off.
There are 21 bridges over the Boise River. The most vulnerable — those that have the least amount of clearance from the surface of the water — are being monitored day and night by local and state agencies.
The Idaho Transportation Department and Ada County Highway District are working with police, fire and other agencies to regularly check important bridges in person.
ITD’s highest concerns are bridges along Glenwood Street in Garden City, Idaho 16 in Star, Interstate 84 in Caldwell and U.S. 95 in Parma, according to spokesman Jake Melder. In addition to looking for any trees and debris caught in bridge supports and girders, crews look for erosion that might have caused damage to the foundation of each road’s approach to the bridge. Excavators are stationed nearby so debris can be pulled out quickly.
The Ada County Highway District or local officials check the Linder Road and Star Road bridges every two hours, district spokesman Craig Quintana said. “They drive across the bridge, get out and look for snags,” he said.
One Greenbelt bridge connecting to Plantation Island near the Western Idaho Fairgrounds was removed in April over worries it would be swept downstream against the Glenwood Bridge, or just collapse “and become a strainer — meaning it could have caught all the trees and limbs coming down, and, in essence, become a dam,” Hardman said.
On Friday, ACHD crews notified Flood Control District 10 about a downed tree in the middle of the river near Artesian Road in Eagle. It turned out to be two trees together, said Mike Dimmick, the flood district’s manager.
“We are watching the trees in the South Channel and don’t feel we can reach them safely at the current flows,” Dimmick said. “We will take them out if they move down to the bridge since we do coordinate with ACHD and ITD for this operation. With the high river flows and saturated banks, it is pretty dangerous to try to use heavy equipment to work in the river.”
Once the river goes down, Dimmick expects his district will remove hundreds of trees in its 35-mile stretch between Plantation Island and Caldwell — many more than usual because the extended high water has weakened the riverbanks.
“Groups of trees are migrating toward the river,” he said. Residents who own backhoes should not try to fish trees out of the river, he said, nor go near soggy riverbanks that could swallow equipment.
ACHD is helping county officials by training a portable camera on the Linder bridge and turning the Five Mile-Chinden traffic camera toward the Sunroc gravel pits that are of great concern. A breach in the wall of the pits “could shift the entire river channel to go down the South Channel,” Hardman said. “It could exceed a 100-year flood.” Just to the west: Boise’s wastewater treatment plant, also a key concern.
The haul road on the wall between the two gravel pits is so precarious — it’s cracking and leaking — that no one is permitted to go on or near it. For safety reasons, officials have done some topography imaging there with a drone.
The county’s emergency management office contracted with the U.S. Geological Survey to install portable stream flow monitors at the Eagle Road bridge, the Linder Road bridge and one of the Sunroc ponds. If there’s a significant change in the water level, Hardman will receive a text alert on his phone.
Anyone who lives in the Eagle Island area is advised to be ready to evacuate, particularly those who live along the South Channel. A pre-evacuation checklist is available online. If the river were to divert into Sunroc, an alert would immediately be sent out to the public via the CodeRED system. Residents might only have hours to get out safely, not days.
Where should I go for updates?
Hardman said one of the challenging things about flood emergencies is that Idaho code doesn’t specify an agency to lead emergency efforts — something he learned during high-water years in the early 1990s.
“There was nobody for the public or dispatch to call,” he said.
Now, Ada County has a 75-page flood response plan, last updated in March and available to the public online.
Each city has a lead agency for flood response — usually public works or fire departments. But the best place for good, up-to-date information is Ada County Emergency Management’s website, which gathers a wide range of information, Hardman said.
One of his staff members monitors social media, including NextDoor, to be sure bad information isn’t circulating.
“Social media is a great tool but, oh my god, can misinformation spread so quickly,” he said. “Things can get cattywampus in a hurry.”
Get emergency alerts, sandbags
▪ See something amiss in the river that authorities should know about? Call non-emergency dispatch: 377-6790.
▪ Looking for sandbags?
Boise: Is not currently distributing sandbags. That will change if the river rises to the point where property is threatened. Limit will be 25 sandbags per property. For more info: Boise Public Works Department, 608-3339 during business hours and 384-4262 on evenings and weekends.
Ada County: Sandbags are available at Expo Idaho. Updates will be posted on Facebook and Twitter by Ada County and Ada County Emergency Management and at https://adacounty.id.gov/. For more info: Ada County Emergency Management, 577-4750.
Star: Star Riverwalk Park, near Star Road and Main Street.
Eagle: Eagle Fire Station #1 parking lot located at 966 Iron Eagle Drive. Limit is 25. For more info: Eagle Fire District, 939-6463.
Meridian: Sandbags are available at 11 E. Bower, off North Meridian Road. Self serve and the limit is 20 bags. For more info: www.meridiancity.org/storm.
Garden City: Garden City Library, City Hall, 6015 Glenwood St. See notaquietlibrary.org for business hours. Maximum of 25 bags per Garden City resident and identification required. Free bulk sand is located outside at 405 E. 48th St. For more info: Garden City’s Facebook page or website, gardencityidaho.org. Or, call Garden City Public Works Operations Center: 472-2949.
Kuna: Kuna has taken down its sandbag station, anticipating minimal threat. Kuna’s sandbag stockpile has been provided to Eagle and Star.
Source: Ada County Emergency Management