September 9-15, 2013

What happened? Over a 7 day period, a record amount of rain fell over the Front Range region of Northern Colorado As a result, rivers and streams overflowed their banks causing widespread flooding across Northern and Northeastern Colorado

How much rain fell? According to different weather stations, various amounts of precipitation were recorded during the storm

How much rain fell? (cont.) Locally, various amounts of rain were reported Boulder = 17.15” Estes Park = 10.77” Drake (on Hwy 34 between Loveland and Estes Park)= 10.68” West Loveland = 5.19” East Loveland = 4.69” Johnstown = 3.63” Milliken = 4.51” West Greeley = 2.9”

How much water is that? Calculate how many gallons of water fell in Estes Park ” of rain fell in Estes Park Surface area of Estes Park = 5.9 mi 2 12 in x 12 in x in = in 3 of water/ft 2 1 gallon = 231 in 3 so… in 3 x 1 gallon = 6.71 gal of water/ft 2 ft in 3 1 mi 2 = 27,878,400 ft 2 so… mi 2 x 27,878,400 ft 2 = 164,482,560 ft 2 in Estes Park mi 2 Therefore…… gallons x 164,482,560 ft 2 = 1,103,677,978 gallons!!! ft 2

So really, how much water is that? Water capacity is measured in acre feet Acre foot – equals one acre of ground covered in 1 foot of water 1 acre is roughly equal to the size of a football field

So really, how much water is that????? (cont) So, if 1,103,677,978 gallons of water fell on Estes Park, how many acre feet is that? 1,103,677,978 gallons x 1 acre foot = 3387 acre feet! 325,851 gallons That’s 3387 football fields covered with 1 foot of water!

So where did that water go? Water that falls either is absorbed into the ground or becomes run-off that filters into streams and rivers What do you think happened to the water in Estes Park?

Big Thompson Watershed The Big Thompson Watershed is the area that drains into the Big Thompson River This region extends from up in the mountains west of Estes Park down to where the Big Thompson merges with the South Platte River east of Milliken Covers 900 square miles (576, 000 acres!) Contains 173 lakes and 975 miles of river

Big Thompson Watershed (cont.) All the rain that fell in Estes Park and the surrounding areas funneled into the Big Thompson Watershed

So why did it flood? There are several reservoirs built along the front range for controlling flood waters Ex: Lake Estes, Carter Lake Reservoir, & Horsetooth Reservoir Lake Estes has a water capacity of 3068 acre feet 3387 acre feet of precipitation fell in Estes Park (which doesn’t include everything that fell outside Estes Park and made its way into the reservoir from other feeder streams and rivers!) Can you see a problem developing here?

So why did it flood? (cont.) The amount of rain that fell in and around Estes Park was too much for Lake Estes to contain so water was released downstream to keep the dam from giving way!

So why did it flood? (cont.) As the rains kept falling, rivers collected run off and water went downstream To save dams, water was being released from reservoirs All that combined = LOOK OUT BELOW!

“1000” Year Event – What does that mean? Natural disasters are categorized on the likeliness that they will occur A “1000” year event means that there is a 0.1% chance of that happening during that year A “100” year event means that there is a 1.0% chance of that happening during that year The flooding that was experienced in Northern Colorado was categorized anywhere from a “1000” year event to a “100” year event depending on location

Where did flooding occur? Several regions were affected by the flooding Boulder – Boulder Creek Lyons/Longmont – St. Vrain River Loveland – Big Thompson River Greeley/Evans – Cache la Poudre & South Platte Rivers Locally, Johnstown and Milliken were affected by the Big Thompson, Little Thompson, and the South Platte rivers

Johnstown/Milliken

As the waters continued to go downstream, more communities were affected by them Fort Morgan, CO Sterling, CO And farther east along the Platte River

So what does this mean for our future? You have been hired as an environmental consultant to assess the damages caused by the Colorado Flood of 2013 and report on the long term effects that the floods will potentially have on this ecosystem Are you ready for the challenge?