Managing storm drainage is an integral component of a comprehensive package of public services. Stormwater runoff is a valuable resource if handled wisely, with increased water supply volumes and enhanced open space quality being just two of the benefits. Inadequate stormwater management can result in flooding, infrastructure and property damage, excessive soil erosion, degraded open space, unacceptable water quality in potable water supply reservoirs and other water bodies with decreased recreational and/or fish and wildlife values, and excessive financial burdens placed upon the City of Greeley due to flood damage repairs or increased operation and maintenance costs.

The primary function of storm drainage systems, including natural channels, is the collection, conveyance and storage of stormwater runoff. In a watershed-based approach to urban stormwater management, the municipal stormwater drainage system, sometimes called MS4, including both structural (e.g., pipes, inlets and outlets) and natural drainageways, is a critical structural component. The stormwater drainage system serves multiple functions, such as storm drainage facilities and for open space and biodiversity conservation. While all of these aspects are important and need to be addressed as part of a comprehensive stormwater management program, the hydraulic function of the overall stormwater drainage system takes precedence.

The City of Greeley is committed to taking a proactive role in managing stormwater runoff in the city as part of the overall goal of providing quality services to its citizens. Based upon legislation by the U.S. Environmental Protection Agency (EPA), through the National Pollutant Discharge Elimination System (NPDES) Program requirements of the Federal Clean Water Act, and regulations promulgated by the Colorado Department of Public Health and Environment (CDPHE) - Water Quality Control Division (WQCD) in their Stormwater Phase II Program, the City of Greeley is a Stormwater Phase II permittee (which began in March, 2003) and, as such, must take the lead role in stormwater and drainage management within the city limits.