History and Overview of the Boxelder Authority
The Boxelder Creek Watershed is a vast, relatively undeveloped part of northeastern Larimer County. The drainage basins in this watershed cover approximately 260 square miles and extend from extreme southeastern Wyoming into southeast Fort Collins with flooding continuing extending past Timnath toward the southeast. The Lower Boxelder Valley is irrigated and it contains some of the best agricultural land in the County.
The Lower Boxelder Basin, close to I-25, has developed into an agribusiness and agri-research corridor which includes a major brewery, the Colorado State University Horticultural Research Center, and the Colorado State University Agricultural Research, Development, and Educational Center.
The entire Town of Wellington and a sizeable portion of the City of Fort Collins are included in the Lower Boxelder Basin. The lower, southerly portion of the Basin is more urbanized and is impacted by many existing man-made structures such as streets and buildings.
Boxelder Creek and its tributaries have a long history of flooding. A Soil Conservation Service report documents that in a 65 year period from 1904-1969, on average there was a damaging flood every 1-3 years somewhere in the watershed. In addition to the 24 major storm events documented within this timeframe, there were numerous localized storms occurring over the irrigated land causing flooding, sediment and erosion damages as well.
In 1947, a Coloradoan newspaper headline read, "Violent Rainstorm Floods Large Area; Crop Losses Heavy." In this storm, as much as five inches of rain fell northwest of Wellington, damaging nearly 1,000 acres of grain, alfalfa and corn as well as washing out bridges.
In 1967, heavy rains again flooded the area, causing Boxelder Creek to overtop roads which resulted in the death of a mother and her three daughters on a county road southeast of Wellington. Seven times that summer county bridges in the Watershed were destroyed by flooding.
Need for Improvements to Mitigate Flood Hazards
Since 1976, the Boxelder Creek Watershed, along with other parts of Larimer County, has been included in the National Flood Insurance Program. As part of that program, Larimer County, the Town of Wellington, and the City of Fort Collins are required to regulate land uses that exist within the designated floodplains of each respective community. More than 5,000 acres of land in the Lower Boxelder Creek Watershed are designatedas floodplains by FEMA.
Owners of buildings within flood hazard areas are required to purchase flood insurance. For individuals, this means that if their house is in a FEMA designated floodplain, they must purchase flood insurance, which has become quite expensive in recent years. With approximately 5,000 acres of this watershed now identified by FEMA as floodplain, this is a significant issue for many residents.
Potential Flood Damages
Flooding affects everyone, not just the residents directly located in a floodplain. In the event of a flood on Boxelder Creek, or its tributaries, the following may occur:
- Roadway overtopping
- Flood damage to stream crossings
- Water supply contamination
- Sanitary sewer system disruption by overloading
- Disruption of emergency services due to impassable roads
- Damages to schools, homes and businesses
- Loss of use of schools, homes and businesses
- Disruption of traffic
In addition to the hundreds of homes located within the floodplain are two schools, two gas stations, a liquid propane storage facility, numerous business and commercial facilities, sanitary sewers, electrical lines, water transmission lines and other critical infrastructure that could be impacted or damaged by flooding from Boxelder Creek and its tributaries. Access to an electrical substation could be cut off in a major storm and 4 major irrigation canals, and 30 roads will overtop and be damaged during a 100-year flood.
Often, in times of emergencies, schools are used as an emergency shelter and gathering point. In this case, two of the three schools in Wellington are in locations subject to flooding.
FEMA Adopted Study of Boxelder Creek and its Tributaries
In late 2006, the Federal Emergency Management Agency adopted a revised floodplain map for the Lower Boxelder Basin. The revised floodplain maps were based on a hydrologic study of the Boxelder Watershed produced by Anderson Consulting Engineers in 2001. The revised study takes into account the existence of the SCS Flood Control Dams that were constructed in the late 60’s and early 70’s as part of the Boxelder Watershed Project. The revised hydrologic study of the Watershed was based on rainfall standards for the area that were prepared and adopted by the City of Fort Collins and Larimer County.
Addressing the Need
In early 2005, stormwater engineers began studying stormwater needs in the Boxelder Watershed. A group was formed that included representatives from Larimer County, the Town of Wellington, the City of Fort Collins, the Town of Timnath, the Town of Windsor, North Poudre Irrigation Company, Boxelder Sanitation District, New Cache La Poudre Irrigation Company, Colorado Water Conservation Board, and a private property owners’ group.
The group completed a Regional Stormwater Master Plan in 2006 for the Lower Boxelder Creek Watershed (consisting of those lands tributary to Boxelder Creek, extending from County Road 70 north of Wellington, south about 12 miles to the locations where Boxelder Creek floodwaters join the Cache La Poudre River.)
The Master Plan focuses on the concept of storing floodwater at strategic locations within higher portions of the Lower Basin and releasing it slowly so that peak flows are not additive as they progress downstream. In this case, the upstream improvements reduce flows regionally. Computer models were used to compare the flows resulting from different upstream storage volumes and locations.
Phase I improvements recommended by the Master Plan will operate together as a system to reduce flows over a wide area. They lessen damages and flood hazard from the North Poudre Canal downstream some 20 miles to those points where Boxelder Creek floodwaters enter the Cache La Poudre River. The improvements include stormwater detention facilities at two locations and channel improvements at a third location:
The first stormwater detention facility, referred to as the Coal Creek Flood Hazard Mitigation Project, will use the existing Clark Irrigation Reservoir three miles north of Wellington as a combined facility for irrigation and flood control. The second detention facility, referred to as the Indian Creek Floodwater Storage Facility is planned for construction on Indian Creek at an as-yet undetermined location generally east of Wellington. The flood mitigation effects of the two storage sites will be complemented by a berm to be built in a segment of Boxelder Creek that is midway between Wellington and Colorado State Highway 14. These master planned improvements will considerably mitigate flood damage potential that exists in developed areas between Larimer County Road 70 and the locations at which Boxelder Creek floodwaters flow into the Cache La Poudre River.
Phases II and III of the master planned improvements involve construction of improvements that benefit local areas and construction of roadway crossings of Boxelder Creek and its tributaries. Those improvements will be built by developers and local governments.
Implementation of the Master Plan
Implementation of Phase I of the master planned improvements will be completed by and through the Boxelder Stormwater Authority. This new governmental entity, created through an intergovernmental Agreement among Larimer County, the Town of Wellington, and City of Fort Collins, will design, construct, operate, and maintain the Phase I regional improvements identified in the Master Plan.
Funding to build and maintain these facilities will come from State and Federal sources including a $3 million dollar grant from FEMA, one-time development fees for new buildings or developments, and stormwater user fees charged to owners of developed property within the Service Area of the Authority.
Timing of Improvements
The first regional project, the Coal Creek Flood Mitigation Facility at Clark Reservoir north of Wellington should be completed in September 2012. The East Side Detention Facility and the Middle Basin Improvements are currently in conceptual design and undergoing a fatal flaws analysis. Construction of these projects will be dependant of loan application and the review process.