Simple Flood Math: 3 X as Much Snow in Mountains Than Reservoirs Can Handle
As the Bureau of Reclamation begins to increase release of water into the Boise River this week, some are asking why, when we already are experiencing closures along the Greenbelt and flooding along the river? Well, it's simple math, and it doesn't look good.
I hope you're prepared for more flooding along the Boise River this week. Already the Boise River has hit the 2nd highest flow in history, since Lucky peak was built and flows are set to increase another 500cfs by this Wednesday (4/12). The reason levels have been so hard to manage, according to the Bureau of Reclamation, is that the March and early April flows into the three Boise River reservoirs — Arrowrock, Anderson Ranch and Lucky Peak — were a record setting 300 percent higher than normal. (Yes, that's not a misprint...300% above normal)
So it’s really pretty simple math right now as to why the flooding is occurring and why water managers are releasing more water even though the Boise River is already 1000cfs above flood stage: Last week according to the Bureau of Reclamation, the flows coming into the reservoir system were at between 10,000 and 16,000 cfs, while damn managers were releasing less than 8500cfs.
The worst-case scenario would be to have a week of really warm weather and heavy rains that turn the heavy snow pack into snow run off very quickly. The reservoirs have just 320,000 acre-feet of space, according to the Bureau of Reclamation.
According to an article in the Idaho Statesman, The Bureau’s supervisory manager said that it’s a balancing act of “trying to release as much water as we can that doesn’t cause a large amount of damage.”
In addition to measures being taken in Eagle to hold off any flooding of homes and property in the area, we've already seen one bridge removed from the river due to a possible collapse.
Check out Before and After video of the Plantation Bridge in Garden City. It was in danger of collapsing into the Boise River due to erosion of the banks, so as a safety measure the city removed it so that it didn't potentially cause a huge disaster if it had fallen into the Boise River.