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LTE: Lesson from Flood is Set Development Back

" Hopefully our city council will not fix what is not broken"
Pelican Squared
Pelicans in St. Vrain Creek (Photo by Matt Maenpaa)

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September 12th is the 10th anniversary of the devastating 2013 flood. In Longmont, all waterways were flooded with development situated near St. Vrain and Left Hand Creeks experiencing the worst damages. Where open spaces and agricultural areas were impacted, the land was able to absorb the flood waters in a way the built environment wasn't.

A big reason areas like Sandstone Ranch and the adjacent Peschel property were able to withstand the flood is due to their having a healthy riparian area. Riparian areas serve a number of crucial functions such as filtering runoff, slowing down flood waters, and preventing erosion. In addition, while riparian areas are estimated to make up less than 2% of the area of Colorado, over 80% of species in the state depend on them at some point in their lives.

Longmont’s reach of St. Vrain Creek is particularly important as it has been identified by Colorado Parks and Wildlife as having the highest diversity of native fish in the Front Range. St. Vrain Creek also plays host to 63 species of special concern listed in the Environmental Resources Element of the Boulder County Comprehensive Plan. It also provides a critical movement corridor for wildlife traveling between the mountains and the plains. The deer and bobcats at Sandstone came through our St. Vrain and Left-hand Creek corridors.

In 2006, recognizing the importance of protecting our riparian areas and, by extension, the wildlife dependent upon them, Longmont City Council established a 150-foot riparian conservation setback for certain water bodies within the city in the Municipal Code. Current development closer than 150 feet from these water bodies was grandfathered in, but future development would be required to adhere to the setback to protect against flooding and maintain ecosystem functioning. In 2019, the Development Code was updated to strengthen the requirements for developers who wanted to pursue a  variance to build within the riparian setback. These updates were codified in 2020 after an extensive public process.

Following the 2013 flood, Longmont embarked on an ambitious and very expensive flood mitigation project designed to remove land surrounding St Vrain Creek from the 100-year flood plain. This land includes 800+ acres of private land that was previously undevelopable. Owners of these properties are understandably anxious to start developing and making big profits from our public investment in flood mitigation. However, the extreme damage the 2013 flood caused to developments abutting St. Vrain Creek that were built before the establishment of the setback tells a cautionary tale of building too close to waterways. That's why any and all future development along this and other waterways needs to be set back. 

According to the Army Corps of Engineers, there have been 11 floods along the St. Vrain corridor in the last 140 years. Expert data on climate change supported by current events this summer, show floods and other disasters happening with more severity and frequency. Rivers are unpredictable and even with the best engineered mitigation measures, it is almost certain this corridor will flood again. Much as we might like to, we can’t mitigate Mother Nature. Advocates for housing, attainable and otherwise, believe we can have both protections and residential development along our St. Vrain and other waterways. Perhaps we can have both, but only if development is considerably set back from the banks of creeks and other waterways.
Our 2013 flood was a wake up call. Now, ten years later, it appears we may go back to sleep unless we continue to honor our riparian conservation setback. Property owners and developers have lobbied some City council members and staff to revisit the process for variance applications to make it easier to build within the 150-foot protection setback. Because of the importance of riparian areas, not least of all as natural flood protection, which is infinitely cheaper than engineered solutions (Longmont has spent well over $200 million and counting for recovery from the 2013 flood and mitigation of future flooding), it SHOULD be hard if not impossible to build within the setback. Hopefully our city council will not fix what is not broken and leave the well-thought-out and publicly-supported variance process and criteria in place.