Five trillion gallons of water has fallen on our region. What’s that look like?

I saw that about five trillion gallons of water have fallen throughout our region in the last couple of days, leading to, obviously, catastrophic flooding.

So, what does five trillion gallons of water look like? Some rough visuals to an unfathomable number:

• Five trillion gallons is 15,500,000 acre-feet, which is equivalent to about two Lake Roosevelts behind the Grand Coulee Dam.
• Five trillion gallons is SIX.POINT.FIVE Lake Washingtons.
• Speaking of Grand Coulee Dam, which I must say is a pretty damn cool piece of Washington infrastructure, when operating at full capacity generating 6,800MW of electricity (9,200,000 horsepower!) uses 273,000 cubic feet per second (CFS) through 33 turbines. Those five trillion gallons is enough water to power the GCD for nearly three days.
• The Columbia Basin Project irrigates 671,000 acres of farmland with 2,500,000 acre-feet per year provided by the Grand Coulee Dam’s pumping facility. Five trillion gallons is enough to irrigate the entire CBP area for six years.
• Based on Seattle City Light’s seven dams generating a combined ~2,500MW and GCD’s power output (~0.025MW/CFS), five trillion gallons is enough water to power Seattle for about a week.
• Five trillion gallons is 66,810,000,000 cubic feet, the equivalent of nearly three days of the average discharge of the Columbia River into the Pacific Ocean near Astoria.
• Five trillion gallons is 2,475,000,000 cubic yards, the equivalent of filling up 25,000 U District or Capitol Hill Stations (each area about 100,000CY) or ~13,000 UW Stations (it’s a much bigger station box because of the crossover). Unfortunately, I don’t know how many obligatory Seahawks Stadium units that is.
• If we covered Seattle’s 84 square miles with all that water, it’d be 290 feet deep, which is about half-way up the Space Needle.
• Any other ridiculous units of measure to add??

Yes, I certainly got some things wrong up above as I’m doing the best I can with a rough-order-of-magnitude kinda exercise based off a big honking estimate of five trillion gallons. My old hydraulics professor used to have these “Fermi problems” where we took really big concepts and converted them into estimated units limited to only a couple significant figures, which is an important skill in engineering. One fun quiz was estimating the volume of water in the ocean based on just what we know in our heads, where the answer isn’t relevant, it’s the thought process that matters. You were awesome, Dr. B!

Also, doing this exercise was also an interesting lesson in AI’s accuracy. There were sure a lot of wrong answers when I asked it various facts and figures, then double-checked against a primary source such as the Army Corps of Engineers, USGS, or Bureau of Reclamation, who have a really sweet logo as the dam folks.

Hope you enjoyed these random factoids from your local civil engineer. Please stay safe out there and follow all emergency instructions, especially road closed signs!