Rebirth of a River
The Big Wood River Better the Second Time Around
Photography: Courtesy of the Wood River Land Trust
A view of Boxcar Bend after spring flooding created a new pond.
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Anglers from around the county, as well as locals, fish the Big Wood River, making it one of the economic drivers that create and sustain the tourist economy in the Valley. But it is also a dearly loved neighbor to the communities that reside along its banks. Families enjoy hot, summer days swimming the Big Wood’s waters; cyclists travel the bike path that winds along its banks, and many a local has nurtured a passion for stalking the trout that dart between its pools and riffles.
In May of 2006, the Big Wood River unleashed its highest ever recorded volume, peaking at 7,500 cubic feet per second (cfs) on May 21. An unusually heavy snowpack, warm temperatures, and precipitation during the week before the flood contributed to the water’s historic rise. The river remained above flood stage for just under a week, transforming the river channel with swiftly coursing high water. What local communities learn from this flood and how they respond to the river in the coming years can positively influence the river and the communities it sustains. The powerful flood of 2006 shows, above all, that living with the river and learning to accommodate its changes will improve our local communities and the health of the river. And as a major factor in the purity and amount of the water in our aquifer, the river’s health directly relates to the public health of our local communities.
High flows leave a healthier river behind.
Like a child entering adolescence, the river expressed itself in surprising ways this spring. Local floodplain residents experienced flooding in their yards, basements and neighborhoods; cities also experienced flooding of parks, streets and other infrastructure. This spring’s convergence of weather, snowfall and timing allowed flooding to reach a level that Jim Bartolino, a hydrologist with the U.S. Geological Survey calculates as “having a 0.5% chance of occurring in any given year,” according to USGS data for the period of record since 1915. The high water left behind a new and healthier river system as well as a unique opportunity to build on this newly invigorated river by shaping future policies. Previous restoration efforts on the Big Wood leave a few clues as to how local communities can learn to live with this new river and better prepare for future flooding. Learning to live with the new river—allowing it to change and evolve in its floodplain—will mean a healthier river and possibly an easier high water season for floodplain property owners in the future.
What makes a river healthy?
Rivers rebuild themselves each year as high mountain snows melt and course through the system to create new habitat for fish and bring other benefits to the river and its floodplain. The floodplain is the relatively flat land along the river that is often filled by water during high water events. Spring runoff builds new areas along the river, encouraging cottonwood seeds to take root; scours old algae off the riverbed to allow new populations of insects to thrive; fells cottonwood trees that become in-stream wood; picks up debris; and revives old side channels that are critical for trout spawning and rearing. Additions of in-stream wood and the movement of the river form new pools for fish. Shallow, slow-moving water in the floodplain (known as sheet flooding) is filtered by plants and recharges the aquifer for local drinking water supplies. Sheet flooding allows dirt and fine sediment in the stream to settle in the floodplain and the riparian area bordering the river, which enhances the growth of the native plants. Flooding and the changes associated with high water are part of a natural process that keeps the entire river system more healthy and productive. >>>