SPECIAL EDITION March/April 2014 • ISSUE 10 Our Relationship with a Dynamic Landscape: Understanding the 2013 Northern Colorado Flood The summer of 2013 was drier than normal along the Front Range, so when rain started falling on the northern end on September 9, 2013, some greeted it with enthusiasm. Others tempered their enthusiasm when the five-day forecast revealed an anomalous lineup of raincloud icons. In fact, a stationary low pressure system had developed over the Great Basin, to the west of the Rocky Mountains, and began to pull monsoonal tropical moisture from the Pacific Ocean as well as more moist air off the Gulf of Mexico. This circulation pattern directed and focused these moisture plumes toward the Front Range. The rain showers beginning on September 9th didn’t let up until September 15th, falling most intensely between September 11th and 13th, 2013. According to the Colorado Water from the Big Thompson River washes through a wide landscape in Johnstown, CO. Climate Center, total rainfall for the (Image credit: Jenny Sparks, Loveland Reporter-Herald) week beginning Monday, September 9th measured 16.9” in Boulder, 9.3” in Estes Park, 5.9” in Loveland, and 6.0” in Fort Collins. Because the steep, rocky The destruction and loss of life that This includes an estimated $44 million terrain in and around these communities resulted from the September 2013 in damage to the Arapaho and Roosevelt channels water, the effects of precipitation flood were tremendous. The flood National Forests, where hiking trails can be greatly amplified and lead to affected 14 counties, killed 10 people, and other recreation infrastructure were rapid runoff. The sudden, huge influx damaged 26,000 homes, and entirely washed away. Many mountain roads led to extensive flooding that damaged destroyed 2,000 homes. Preliminary were damaged and remain impassible, infrastructure on the Arapaho and figures suggest $2 billion in housing, and access to public lands and private Roosevelt National Forests and devastated road, and infrastructure damage to the inholdings remains compromised. property, infrastructure, and lives in flood-impacted northern Colorado “Our preliminary flood impact surrounding communities. communities of Boulder, Estes Park, assessment report, compiled in the Evans, Fort Collins, Longmont, weeks following the flood and subject Loveland, Lyons, Jamestown, and others. to change – especially as we anticipate 1 Science You Can Use Bulletin MARCH/APRIL 2014 • ISSUE 10 spring run-off events – indicates that the human communities and environmental decades,” explains quantitative ecologist floods caused over 250 debris slides and risk, being vulnerable is not necessarily Linda Joyce, who lives in the affected damaged at least 382 miles of roads, 236 desirable. One way that scientists area. “As the number of residents in miles of trails, several dozen recreational sometimes think about this “social- many of these mountain and Front facilities [campgrounds, picnic areas, ecological” vulnerability is according to Range communities increases, our parking areas, fishing/boating access the following pieces: human footprint in the form of roads sites, etc.], and four bridges,” says Glenn and buildings expands across the Casamassa, Forest Supervisor on the Exposure + Sensitivity + Adaptive landscape, altering the hydrology of Arapaho and Roosevelt National Forests Capacity = Vulnerability these systems and, over time, increasing and Pawnee National Grassland (ARP). our exposure to risk. In addition, when To put this in perspective, the miles of In this equation, “exposure” is a we build permanent infrastructure such roads damaged on the forest is about measure of how much a system (e.g., a as homes directly on the floodplain, we the north-south length of the state of community) might be in contact with dramatically increase our sensitivity to Colorado. The ARP preliminary flood a threat. “Sensitivity” is a measure of these events,” Joyce notes. impact assessment report evaluated whether and how a system is likely to be 463,000 National Forest acres by affected by the threat. “Adaptive capacity” In some cases, the lessons learned helicopter; 230,000 of these acres are refers to the opportunities that exist to from previous floods have helped to considered to be “most heavily impacted.” reduce exposure or sensitivity, thereby inform the third element – adaptive In addition, 144,000 acres of private mitigating – or reducing – the overall capacity. Prior to 1997, the City of Fort lands interspersed in patchwork fashion threat. Combined, these add up to overall Collins had already taken many flood with public lands were not included in vulnerability. mitigation measures including regulation the estimate of “most heavily impacted” “Unfortunately, we’ve significantly of floodplain development, design public lands. Many owners of these increased our vulnerability to natural criteria for structures in the floodplain, private land inholdings may have once hazards, such as floods, in much of land acquisition, and informational relied on historic mining or timber the Front Range over the past several services. The lessons learned from the roads minimally maintained by the National Forest to access their private lands; however, many of these roads were These images highlight Colorado’s Front Range, which runs north-south from Casper, WY to Pueblo, partially or fully washed away by the CO and has a total population approaching floods. According to Forest Supervisor 4.5 million. Annual rainfall on the Front Range Casamassa, “Working with the public averages 16-20”, while the annual number of days with sunshine averages about 300. (Image credits: and nearby communities, communicating Left, Colorado State University -Werner College of about the changed landscape and the Natural Resource; Right, Wikipedia.) associated heightened risks, and making decisions about how, where, and to what extent to rebuild infrastructure will be a large part of our flood recovery efforts.” As part of this, a better understanding of the future vulnerability to risk will help the Forest make some critical decisions about rebuilding. UNDERSTANDING HOW NOT TO BE VULNERABLE A degree of vulnerability may be desirable in some human relationships. However, when the topic relates to 2 Science You Can Use Bulletin MARCH/APRIL 2014 • ISSUE 10 increased; as a result, much of the built infrastructure – roads, overall vulnerability bridges, trailheads, campgrounds – was is far lower. Indeed, relatively high. This is because peak flows Fort Collins suffered in many streams on the Forest were comparatively little comparatively larger, and infrastructure damage in the was primarily sited close to these rivers recent flooding and and streams. these decisions may have played a role. Many of the roads and access points that However, flooding were recently damaged on the Arapaho along the Cache and Roosevelt National Forests were la Poudre River in first constructed for mining and timber 2013 was not as interests in the 19th and 20th centuries. severe as along the In recent decades, as the Front Range Big Thompson and communities of Boulder, Longmont, St. Vrain rivers, Loveland, Fort Collins, and others where peak flows became more heavily populated and were so large that social values and planning processes optimal floodplain shifted, timber and mining roads were management may repurposed to provide far-reaching have done little to access to a wide variety of recreation and mitigate damage. other opportunities. Now, many of the 3.3 million people who live along the CHARACTERIZING Northern Front Range have a favorite THE RECOVERY trail, hiking or camping spot on the ON NATIONAL Arapaho and Roosevelt National Forests FORESTS: ONE or other adjacent public lands that may The most significant flooding took place within the Big PART SOCIAL, have been affected by the flood. This Thompson and St Vrain watersheds, though the Cache la Poudre ONE PART infrastructure damage has elicited a very and Clear Creek were also affected. (Image credit: Colorado ECOLOGICAL emotional response from surrounding State University, Werner College of Natural Resources.) communities. Due to the scope and scale Unlike in Fort of the flood, many of the public’s favorite Collins, damage on places have been irreversibly changed or the Arapaho and Roosevelt National flooding in 1997 helped to initiate can no longer be accessed. additional activities including stormwater Forests was substantial. Vulnerability of management, flood-proofing, further land acquisitions, community education and outreach, and a fully functioning National Forests and the “Multiple-Use” Mandate emergency notification system. As a According to the Multiple Use Sustained Yield Act of 1960 (MUSYA), the National Forests result, much of the Cache la Poudre and Grasslands are supposed to be managed for the “multiple use” and “sustained river corridor through Fort Collins yield” of a range of renewable resources – including timber, range, water, recreation, and now consists of open space that offers wildlife. For the Forest Service as an agency, this mandate translates into the need to both plan for and balance a wide variety of interests, needs, and objectives, and rarely – if abundant opportunities for recreation; ever – leaves all stakeholders completely satisfied. This is to be expected, however, since it also provides the land area for water, National Forest stakeholders – i.e., the American public – represent a broad and diverse as in the 2013 flood, to