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Boxelder Watershed Area

The Boxelder Creek Watershed represents a vast, relatively undeveloped part of northeastern Larimer County. The drainage basins in this watershed cover approximately 260 square miles and extend from southeast Fort Collins north into Wyoming. It contains some of the best agricultural land in the County.

Close to I-25, the area 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, a portion of the City of Fort Collins, and areas adjacent to the towns of Windsor and Timnath are included in this watershed. The lower portion of the watershed is more urbanized and is impacted by many existing man-made structures such as irrigation canals and culverts.

Historical Flooding

The Boxelder Creek Watershed has 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

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 must regulate land uses in the FEMA designated floodplain. More than 5,000 acres of land in the Boxelder Creek Watershed are in the floodplain.

For individuals, this means that if their house was previously built in what is now designated as a floodplain, they could be prohibited from adding on to their house, building a garage, or making substantial improvements. They might even be restricted in a landscape design change.

For farmers and ranchers, a floodplain designation might restrict where a farmer can park his equipment, or a rancher may place a loafing shed.

Flooding concerns in the Boxelder Creek Watershed can impact property values and result in mandatory flood insurance requirements. With approximately 5,000 acres of this watershed located in the floodplain, this is a significant issue for many residents.

Flooding affects everyone, not just the residents directly located in a floodplain. In the event of a flood on Boxelder Creek, the following may occur:

• Roadway overtopping
• Water supply contamination
• Sewer system disruption
• Disruption of emergency services due to impassable roads

In addition to the hundreds of homes located within the current floodplain boundary, there 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. Access to an electrical substation could be cut off in a major storm event and over 18 detention ponds and irrigation storage reservoirs, 4 irrigation canals, and 30 roads are predicted to overtop and likely be damaged during the 100-year flood event.

Addressing the Need

In early 2005, stormwater engineers from various entities began discussing how to address stormwater and drainage needs in the area. The group consisted of representatives from Larimer County, Town of Wellington, City of Fort Collins, Town of Timnath, Town of Windsor, North Poudre Irrigation Company, Boxelder Sanitation District, New Cache La Poudre Irrigation Company, Colorado Water Conservation Board, and a private property group.

The group combined public and private funds to hire a stormwater engineering consultant to complete a Stormwater Master Plan for a portion of the Boxelder Creek Watershed (consisting of those lands tributary to Boxelder Creek, extending from County Road 70 north of Wellington, south about 12 miles to those areas where Boxelder Creek floodwaters join the Cache La Poudre River.) This area is called the "Proposed Boxelder Service Area".

The consultants conducted a study of the Service Area that included various options, a substantial public process, and evaluation of alternatives that resulted in selection of the alternative that best met the needs of the area. This preferred alternative has been adopted by Larimer Coutny as the Boxelder Creek Regional Stormwater Master Plan.

The Master Plan focuses on the concept of storing floodwater within higher portions of the Service Area and releasing it slowly so that no damage is done as it flows downstream.

What's Proposed?

Phase I of the improvements identified in the Master Plan consist of stormwater detention basins at two locations.

The first location, referred to as the Clark Reservoir Diversion and Enlargement, involves creating floodwater retention at the existing Clark Reservoir site. The second component is referred to as the Edson Detention Basin. The two storage sites will be combined with channel improvements in the segment of the creek that is midway between Wellington and Colorado State Highway 14.

These improvements will considerably mitigate flooding that would otherwise occur between Larimer County Road 70 and the natural confluence of Boxelder Creek with Colorado State Highway 14.

Funding the Projects

Funding options for the improvements have been studied and financing would come from local, state and federal sources.

• The local governments have been awarded a $3 million federal grant to help finance the first project in the Stormwater Master Plan, which will add capacity to Clark Reservoir.



• The Authority would accept and administer the grant as well as continue to look for other state and federal funding opportunities.



• Upon creation of the Authority, each local government would be committed to providing an annual monetary contribution to the Authority. The amount of the contribution is based upon the total amount of impervious surface (rooftops, driveways, parking lots etc) that exists within the Boxelder Service Area. Larimer County would meet its obligation in the following manner:

Timing of Improvements

The participating entities recognize that the sooner the major components of the Master Plan can be built, the more benefit they will have to people of the area. It is anticipated that if the Authority is formed construction may begin in the latter part of 2009.

Also, work is underway to look at preliminary engineering, costs, and funding options for the Edson Stormwater Detention Project.

The Possibilities...

Completion of these projects brings many benefits to area residents, including:

• reduce or remove the flood danger
• eliminate the need for mandatory flood insurance for some
• reduce the threat of roadway overtopping, water supply contamination, sewer system disruption, etc. due to flooding
• prevent the disruption of emergency services by keeping roads open and accessible
• reduce the threat to current businesses and homes
• allow thoughtful and safe use and development of vacant lands

The focus of the improvement projects is on flood mitigation, but we realize that there may be an opportunity to incorporate other benefits (whether regional or to adjacent property owners) into the project. We welcome ideas how this might be done and what types of things people are most interested in considering.

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