BOULDER FLOODS: PAST, PRESENT AND FUTURE (PART 1)
Between September 11 and 15, 2013, Boulder received over 15 inches of rainfall (Daily Camera, 2013 Floods) resulting in severe flooding that destroyed 345 and damaged 557 houses, damaged 150 miles of county roads, and killed 4 people. Experts have claimed that this particular event was a 1000-year rain and a 100-year flood. The reality, however, is that floods are not new to Boulder (Static BoulderColorado).
Floods have been recorded in Boulder and the surrounding areas since 1844. Between 1844 and 1900, 10 floods were reported, of which 3 occurred in 1864 alone. Despite the frequency of floods, flood mitigation only entered public consciousness after the 1894 floods, during which peak discharge was estimated between 7,400 and 13,200 cubic feet per second and floodwaters destroyed building, roads, and bridges. Mitigation measures taken at this time included raising the ground up to 3 feet in certain areas and rebuilding the railroad on higher ground.
The next 60 years, however, were marred by a lack of action. The Boulder City Council appointed dozens of consultants to suggest flood mitigations, but most of the reports were shelved due to a supposed lack of funds. Despite this, Boulder still did not take action when federal funds were made available through the Flood Control Act. The main issue at hand was a lack of public interest in flood mitigation. After all, floods had not occurred between 1939 and 1964, likely causing people to forget the effects of floods and/or become complacent. Many also had a false sense of security that the Barker Dam, constructed in 1910, would protect them from future floods. In addition, many felt that the risk of building in a floodplain was theirs to take without interference from the City.
Public interest in flood mitigation was ignited in 1965, after floods in nearby Denver resulted in the loss of 2,500 homes and 750 businesses, and again in 1969 after a 25-year flood in Boulder. Yet, although flood awareness had increased, people were unwilling to support changes in zoning and building codes and stricter floodplain regulation. Therefore, the Council implemented less ‘invasive’ measures such as requiring buildings in certain areas to be flood-proofed and disseminating drainage information.
In the late sixties and early seventies, national conversation on flood mitigation changed with the establishment of the National Flood Insurance Program (NFIP). Communities participating in the NFIP were eligible for federally backed flood insurance provided that they incorporated flood mitigation into planning and development. It was with this shift in the national mood and major floods in South Dakota in 1972 and Big Thompson in 1975 that the Boulder Council began to take significant action. They defined the floodway, revised floodplain regulations and permits, assessed flood risk of tributaries, produced detailed flood plain maps, and joined the NFIP.
In terms of mitigation, the public was and continues to be against structural solutions such as concrete floods walls and lining the creeks. Consequently, since the 1970s the Council has largely focused on non-structural solutions such as early warning systems, stricter building codes, and multi-purpose structural solutions such as creek-side bike paths.
In light of the recent, severe flooding, what will happen? How will discussions concerning flood mitigation change and/or progress? What must be remembered, as discussions continue, are the following lessons learned from the history of flood control in Boulder:
Flood mitigation was only taken seriously after major flooding events and with a change in the national conversation about flood mitigation.
When floods don’t occur for long periods of time, people forget/become complacent.
Public support for flood mitigation initiatives tends to focus on soft solutions such as open space, greenways and multi-use paths that double as floodways.
Seen through this lens, the September 2013 floods provide a window of opportunity that many players in the City and County of Boulder are considering how to best leverage to build resilience.