Redirecting the Rio de Flag
The ever present Rio de Flag, a runoff stream that originates in the southwestern slopes of the San Francisco Peaks, continues to be the nexus of Flagstaff both geographically and culturally. Since settlers from Boston mounted Old Glory on a ponderosa pine, the Rio de Flag has provided opportunity for growth and occasion for destruction.
"It's a serious problem," said Joseph Meehan, a director of the Arizona Historical Society. "It can be a tremendous flood."
In an attempt to curb the flood, the city of Flagstaff is working with the U.S. Army Corps of Engineers to redirect the fluctuating stream.
The diversion is expected to exceed $20 million. Flooding along the Rio de Flag during the last 100 years has swallowed roads and ruined property to a massive extent, although speculation as to the exact amount is purely that, speculation.
Nevertheless, an even more devastating flood could occur, causing hundreds of millions of dollars worth of damage, flooding homes, businesses, the college campus and even city hall.
Even if the "100 year flood" does not happen for several more years - or ever - the city of Flagstaff suffers from the very presence of the floodplain in terms of lack of opportunity of development, renovation, property value and expansion. The subject is broad, and to understand the Rio de Flag takes both breadth and depth.
Bubbling from Leroux Spring on the San Francisco Peaks, the stream we know as Rio de Flag gains volume from other tributaries and springs as it drops into Flagstaff. Depending on snow pack, ground saturation and precipitation, the Rio de Flag can run almost bone dry or become a raging torrent.
In places like the narrows, a region bordering North Fort Valley Road, the current can move at more than 4,500 cubic feet per second, a massive flood gouging the earth and sweeping away anything in its path.
But this stream is mostly a pleasant resident of the Flagstaff area. It supplies a duck pond by Flagstaff Middle School and provides tranquility to Wheeler Park and the public library.
During the late 19th century, settlers built in a 100 year flood plain, and the watershed surrounding the area was extremely prone to flooding.
The 100 year floodplain title does not necessarily mean an epic flood occurs every century. Instead, the title is a gauge for both severity and probability. There is an approximate one in 100 chance of the type of flooding the early 20th century saw every year which can sometimes happen several times a year.
The last major flooding in terms of discharge occurred in 1938. Meehan explains the magnitude of the event.
"The water (on Aspen Avenue) was described by residents as deep enough to swim a horse. People used to take rowboats to cross it," Meehan said. "It was an incredible flood and it showed what the Rio could do."
In response to the problematic runoff, many diversions were constructed through the years. The original flow of the stream bordered Historic Route 66, but business owners along the banks feared damages. Citizens used every means necessary to redirect the natural course of the runoff, including dynamite.
In 1983, the Federal Emergency Management Agency announced the area a flood zone; requiring developers to buy flood insurance or elevate above the FEMA flood zone depth. Development in the area since has come to a stand still.
But years of unregulated building combined with previous redirection had residences backed by a narrow and shallow channel. Many historic buildings lay entirely in the possible flood's path, threatening records of a rich history.
Small culverts blocked frequently and in 1993, waters flooded Continental Country Club, resulting in the biggest volume of floodwater in Flagstaff history. However, the creation of "Lake Continental" was the result of a mere 25-year flood. A bigger flood could cause an estimated $100 million to $500 million worth of damage.
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