The National Weather Service issued a Flood Warning today, April 20th for Boise River at Glenwood Bridge Idaho, USA.
The current Flood Statement states that the “flow is 8495 cfs (cubic feet per second -rate of flow) however, the forecast is that the river will continue to flow at around 8500 cfs with high flows continuing for the foreseeable future. The expected impact is that large sections of the green belt will be submerged and severe bank erosion will occur. Flooding will occur in low areas close to the river in Boise, Garden City, Eagle and Caldwell, but the water should remain below the level of most residential areas. Water will begin seeping into the Garden City warehouse district. Persons with interests near these flooded rivers should continue to take action to protect property.”
Most of the concern is in highly-populated southwest Idaho along the Boise River due to a giant snowpack and dwindling space in three reservoirs currently preventing destructive downstream flooding.
Water managers said on most days water is coming into the Boise reservoir system faster than the Army Corp of Engineers is letting out. Over time it’s eaten into the remaining capacity, which the Corp says is at 32 percent; only half of what they have normally at this time.
“We have made a very calculated decision to this point to keep the flows at where they’re at, we absolutely could have released enough water to match up with those record run-offs, but the result would have been absolutely flooding Boise,” LTC Damon Delarosa with the Army Corp of Engineers said.
The U.S. Army Corps of Engineers says plans are to run the river at high flows over a longer period of time and into the summer to avoid even larger releases that could flood residential areas.
One of the challenges emergency personnel have faced is the amount of snow that was in the low-lying areas; as we’ve started to see these warming trends, it’s resulted in anywhere between 200 and 350 percent of normal run-off. Also, not helping the situation is the recent spring snow storms that some areas have seen in recent weeks.
The Idaho Office of Emergency Management says the initial damage estimates from flooding, avalanches, and mudslides from all across the state are in the excess of $62 million.