5 Things You Should Know About Colorado's '1,000 Year Flood' (with Jaw-Dropping Photos)

Colorado’s Front Range has been ravaged by heavy rain and flooding since last week, with 15 counties now impacted: Boulder, El Paso, Larimer, Adams, Arapahoe, Broomfield, Clear Creek, Denver, Fremont, Jefferson, Logan, Morgan, Pueblo, Washington, and Weld counties. Updates on the number of fatalities and missing is being updated but the latest reports are eight dead. More than 11,000 people have been evacuated and many thousands more are waiting for help.

Here’s what else you should know.

1. It’s really, really, big.

Rainfall totals across impacted counties vary, but there's been enough precipitation that the event is being called a 1,000-year flood. Andrew Freedman writes for Climate Connection that the “average yearly rainfall in Boulder is 20.68 inches.” A map of rainfall in the Denver Post shows that from Monday, September 9  to Sunday, September 15, over 15 inches of rain has fallen in the Boulder area. 

It’s possible that when all the numbers come in, that areas like Boulder will have more rain in a week than they usually record in a year.

2. History of flooding.

Cally Carswell wrote for High Country News that “the Front Range has always been flood prone.” She writes: 

According to the Boulder Area Sustainability Information Network (BASIN), when it comes to flooding, "the Boulder Creek drainage is considered among the most hazardous in the entire western United States." The city sits smack at the mouth of Boulder Canyon, and because its floodplain is so developed, the risks to human safety and property are especially high here.

Fort Collins experienced a devastating flood in 1997 that dumped 10 inches of rain in a matter of hours, killing five people and causing hundreds of millions of dollars in damages.

The rainfall and flooding has impacted more areas than Boulder and Fort Collins that are immediately downhill from the steep slopes of the Rockies. It’s believed that a 200-mile swath from north to south has been impacted, with flooding in communities in the flatlands east of the mountains, too. 

3. The hand of climate change?

While it is too soon to tell what role climate change may have played in this particular flooding event, it’s important to look at it in the context of global patterns. As Freedman writes for Climate Connection: 

An increase in the frequency and intensity of extreme precipitation events is expected to take place even though annual precipitation amounts are projected to decrease in the Southwest. Colorado sits right along the dividing line between the areas where average annual precipitation is expected to increase, and the region that is expected to become drier as a result of climate change. That may translate into more frequent, sharp swings between drought and flood, as has recently been the case. Last year, after all, was Colorado's second-driest on record, with the warmest spring and warmest summer on record, leading to an intense drought that is only just easing. 

4. It’s all connected.

The amount of precipitation isn’t the only climate change-related impact that should be considered; there are other contributing factors that may be making this massive flood event even more dangerous. Subhankar Banerjee writes for ClimateStoryTellers about the connection between climate change, forest health, wildfires, and floods:

In the last decade and a half Colorado (and its neighbor New Mexico) has gone through three major assaults—massive tree deaths, massive wildfires, and now massive floods—each in turn has been called “the worst natural disaster” the region has seen. Each in turn has also made the next one worse—millions of dead trees made the wildfires worse, and we are now learning that the wildfires are making the floods worse. 

Several species of bark beetles have ravaged forests all across the American West—Alaska, Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, South Dakota, Utah, Washington, and Wyoming. The black spruce, white spruce, ponderosa pine, lodgepole pine, whitebark pine, and piñon have all been devastated by recent bark beetles epidemic. When healthy trees become stressed from severe and sustained drought, they become subject to attack: the beetles drill into their bark, lay eggs along the way, and kill their host. 

Climate change may be aiding the devastation of bark beetles on forest ecosystems—which in turn is aiding catastrophic wildfires, which is contributing to dangerous floods. It's a vicious cycle.

5. Damage to oil and gas wells, infrastructure.

The extent of the damage caused by the floods won’t be known for some time, but some residents are worried about damage to oil and gas wells and pipelines that could be creating other hazards and environmental impacts. Bruce Finley at the Denver Post reported: 

One pipeline has broken and is leaking, Weld County Emergency Manager Roy Rudisill said. Other industry pipelines are sagging as saturated sediment erodes around the expanding river.

Industry crews "are shutting in the lines, shutting in the wells," Rudisill said.

In a statement, Gary Wockner, of Clean Water Action, said "Fracking and operating oil and gas facilities in floodplains is extremely risky. Flood waters can topple facilities and spread oil, gas, and cancer-causing fracking chemicals across vast landscapes making contamination and clean-up efforts exponentially worse and more complicated."

Weld County, where the South Platte River has flooded, has been an epicenter of oil and gas drilling in recent years. A website for the county says, "Horizontal drilling has brought new life to energy industry in Weld County, and today, Weld has more oil and gas wells than any other county in the state; approximately 20,000."

Carl Erickson, a resident of Greeley in Weld County, has seen well sites flooded and condensate tanks floating in the Platte River. He is worried about the release of oil products and uncombusted waste gases, as well as possible release of chemicals from companies that store chemicals and are located in the flood zone.

In addition to oil and gas infrastructure, flooding may also cause the risk of spills from other sites with hazardous materials, as well as sewage treatment plants, sewer systems, and feedlots.

Here are some photos taken by resident Robert Winkler in the Greeley/Evans area of oil/gas well sites and infrastructure.

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