Swim beach monitoring

What is a natural swimming area?
A natural swimming area (swim beach) is a specific part of a body of water that is for swimming, bathing or wading. You are charged a fee to use the area. The area is typically separated from the surrounding water by rope or buoys to prevent other activities, such as boating, from occurring within the swimming area. An example of a natural swimming area is a designated swimming area in a state park where a park visitor pays a daily or yearly use fee. Areas that are free to use, such as Confluence Park do not meet the definition of a natural swimming area, and are not monitored. 
Why might a swimming area close?
Natural swimming areas in Colorado are required to report water quality data to us on a regular basis during the swimming season to ensure public health and safety. Water quality samples are analyzed for the fecal matter, or E. coli​. If a laboratory result indicates an E. coli concentration above 235 organisms per 100 milliliters, the natural swimming area must be closed. The swimming area will remain closed until E. coli results return to a safe level. We monitor natural swimming areas as outlined in Regulation 5 CCR 1003-5.
What causes elevated E. coli concentrations?
Elevated concentrations may result from:
  • Waste from swimmers, pets or wildlife.
  • Improperly disposed dirty diapers.
  • Excessive runoff from rain or flood.
  • Runoff from urban, suburban or rural areas.
  • Malfunctioning septic systems.
Information documents for swimming area monitors
Fillable/electronic reporting forms
Swim beach closures

No closures at this time

Colorado Parks and Wildlife logo drawing of bighorn sheep on mountain background

Find a swim beach near you using the park finder link above.