Colorado Revised Statutes Title 30. Government County § 30-28-403. Cluster development

(1) A cluster development is any division of land that creates parcels containing less than thirty-five acres each, for single-family residential purposes only, where one or more tracts are being divided pursuant to a rural land use process and where at least two-thirds of the total area of the tract or tracts is reserved for the preservation of open space. No rural land use process as authorized by this section shall approve a cluster development that would exceed one residential unit for each seventeen and one-half acre increment.

(2) As a condition of approving a cluster development, a rural land use process shall require that the cluster development plan to set aside land to preserve open space or to protect wildlife habitat or critical areas not permit development of such land for at least forty years from the date the plan is approved.