15.50 - Article VI - Subsection IV

Section 280: Standards for Water Quality, Stormwater, Drainage, Bogs, and Wetlands

280.1 Intent

The intent of this Section is prevent water that leaves a property from contributing to and/or creating a deterioration in quality or impact to other uses and/or other waters unless explicitly allowed (and within the conditions of) State or Federal approval and after it is shown to be entirely necessary as part of the regular operation of the use.  Included is the control of stormwater on-site so that waters can be managed via catchments, gravel beds and other best-management practices.  Drainage is to be incorporated into the design of developments to prevent erosion and resulting sediment, and land and/or water deterioration.  In addition construction on lands that are moist or collect waters such that they can be considered bogs or wetlands may have limited building potential because encroachment may adversely affect the wetlands’ ability to maintain water quality, provide wildlife habitat, provide flood protection and maintain other critical environmental functions.  When encroachment cannot be avoided mitigation of the impacts resulting from encroachment may be required.

280.2 Water Protection

Development shall comply with all local, state and federal water quality standards including, but not limited to, those regulating erosion and sedimentation, storm drainage and runoff control, solid wastes and hazardous substances.

Addressing water quality impact during design, construction and occupancy phases of development can reduce impact by identifying potential pollution sources and selecting and implementing best-management practices.  When determined necessary by the administrators, applicants for development must submit a Water Quality Management Plan that identifies potential sources of water pollution (including sediment and chemical sources), describes potential best- management practices for minimizing these pollutants, and proposes a plan for implementation of selected strategies to mitigate reasonably foreseeable problems.  Examples of potential best-management practices include minimizing directly connected impervious areas, grass-lined swales, constructed wetlands, landscaping and vegetative practices, fertilizer management, buffers and setbacks from sensitive areas, and maintenance and housekeeping procedures.

Drinking water sources such as the White River, its tributaries and reservoirs must be given the highest achievable level of environmental protection.  Based on a development’s potential to impact water quality, monitoring may be required.  Monitoring of drinking water sources for chemical, biological, and other contamination including sediment transport, and quality management reports addressing the need to know whether a water source is being impacted, can be required as a condition of an approval for development.

280.3 Stormwater and Drainage

Developments and/or subdivisions are responsible for managing stormwater and irrigation drainage so as to not impact surrounding property and uses.  No development is permitted to operate in a manner that creates drainage of stormwaters that endangers life or property of an adjacent use.  As applicable, dedicated facilities for stormwater retention and/or to pass drainage to an acceptable point of discharge are required for all types of development when features are developed that could create excessive water runoff because of rainfall or irrigation.  Unless otherwise determined unreasonable by the administrators, all stormwater shall be maintained on the site of development.  Adequate facilities may consist of natural and/or man-made ponds, drainages, wetlands, channels, or pervious surfaces that do not create standing waters that contribute to nuisance situations such as promoting the breeding of mosquitoes.  To be adequate, facilities must be legally and physically acceptable.

  • Applicants must provide information to determine hydrologic impact of development.  Based on the scale of the development a generalized hydrologic analysis considering both existing and future developments may be required.
  • If generalized hydrologic analysis is required the analysis must define generalized flow paths based on estimates of peak rates of runoff per unit area and each development must provide adequate retention and/or conveyance facilities for the estimated peak rate of runoff coming to and passing through the development;
  • An acceptable legal and physical retention and/or path-of-flow for stormwater moving through the development and down stream to an acceptable point of discharge must be identified for each development, and if applicable it must be consistent with watershed and/or other generalized basin plans.
  • An adequate legal and physical retention and/or path-of-flow for runoff through and from the development to an identified outfall facility consistent with the generalized basin master plan must be available or funded at the time of vesting of development rights, if applicable.
  • Stormwater drainage for streets designed to rural standards may be achieved through the use of roadside ditches on both sides or roadside ditches on the cut side with slope away from the road on the fill side, if this does not create standing waters that contribute to nuisances such as promoting the breeding of mosquitoes.

Water quality impacts during the construction phase of a project or from the open lot areas of industry may include erosion and sedimentation, deposition of wind blown debris, and release of hazardous materials such as fuels or other chemicals used in construction and industrial processes.  Applicants for development must submit the following documents regarding control of water quality impacts.

If the construction project or industrial site will disturb one or more acres, a Stormwater Management Plan prepared in accordance with the current Construction Guidance Document: Preparing a Stormwater Management Plan from the Water Quality Control Division, Colorado Department of Public Health and Environment, is required.  The purpose of a Stormwater Management Plan is to identify potential pollution sources, select appropriate best-management practices and design implementation strategies. Guidelines regarding best-management practices are included in the Construction Guidance document.  The Town shall review and approve the Construction Stormwater Management Plans.

If the construction project or industrial site will disturb less than one acre, the administrators will determine if a Stormwater Management Plan is required based on site considerations such as slope and soil type.

280.4 Erosion

Activities are to be carried out so as to not create hazards or water quality impacts due to excessive erosion of soils by excessive wetting, or building in known hazard areas.  The Town may require adequate erosion control measures to be taken during and post construction.  Erosion control may be required regardless of whether a Stormwater Management Plan is required based on the site and slope.  An erosion control plan may be required.

280.5 Bogs and Wetlands

When review of a development proposal indicates the presence of a bog or wetland, consideration of potential impact of development on such site shall be addressed in the Stormwater Management Plan.  Consideration shall include the impact of construction over the lands (subsidence) and the loss of land as a function in how the broader hydrologic system operates.  If it can be clearly demonstrated that the land is a bog, whereby the wet area can be developed without consequence for the broader area and stormwater and/or there are no reasonably foreseeable structural construction problems, the development can move forward without regard for the wetland.  If the wetland contributes to the areas hydrologic function or will result in a structural problem, a plan of mitigation shall be developed as part of the overall development.