7:00 a.m. to      7:00 p.m. to  
  Zone            next 7:00 p.m.   next 7:00 a.m.  

  
  Residential         55 db(A)      50 db(A)

  Commercial         60 db(A)      55 db(A)

  Light industrial      70 db(A)      65 db(A)

  Industrial         80 db(A)      75 db(A)

   (2) In the hours between 7:00 a.m. and the next 7:00 p.m., the noise levels permitted in subsection (1) of this section may be increased by ten db(A) for a period of not to exceed fifteen minutes in any one-hour period.

   (3) Periodic, impulsive, or shrill noises shall be considered a public nuisance when such noises are at a sound level of five db(A) less than those listed in subsection (1) of this section.

   (4) This article is not intended to apply to the operation of aircraft or to other activities which are subject to federal law with respect to noise control.

   (5) Construction projects shall be subject to the maximum permissible noise levels specified for industrial zones for the period within which construction is to be completed pursuant to any applicable construction permit issued by proper authority or, if no time limitation is imposed, for a reasonable period of time for completion of project.

   (6) All railroad rights-of-way shall be considered as industrial zones for the purposes of this article, and the operation of trains shall be subject to the maximum permissible noise levels specified for such zone.

   (7) This article is not applicable to the use of property for purposes of conducting speed or endurance events involving motor or other vehicles, but such exception is effective only during the specific period of time within which such use of the property is authorized by the political subdivision or governmental agency having lawful jurisdiction to authorize such use.

   (8) For the purposes of this article, measurements with sound level meters shall be made when the wind velocity at the time and place of such measurement is not more than five miles per hour.

   (9) In all sound level measurements, consideration shall be given to the effect of the ambient noise level created by the encompassing noise of the environment from all sources at the time and place of such sound level measurement.

   (10) This article is not applicable to the use of property for the purpose of manufacturing, maintaining, or grooming machine-made snow. This subsection (10) shall not be construed to preempt or limit the authority of any political subdivision having jurisdiction to regulate noise abatement.

   (11) This article is not applicable to the use of property by this state, any political subdivision of this state, or any other entity not organized for profit, including, but not limited to, nonprofit corporations, or any of their lessees, licensees, or permittees, for the purpose of promoting, producing, or holding cultural, entertainment, athletic, or patriotic events, including, but not limited to, concerts, music festivals, and fireworks displays. This subsection (11) shall not be construed to preempt or limit the authority of any political subdivision having jurisdiction to regulate noise abatement.    Source: L. 71: p. 648, § 1. C.R.S. 1963: § 66-35-3. L. 82: (10) added, p. 424, § 1, effective March 11. L. 87: (11) added, p. 1154, § 1, effective May 20.

   Am. Jur.2d. See 61A Am. Jur.2d, Pollution Control, § 267.

   Residential development of property is not precluded when noise emanating onto property exceeds limits set forth in this section. Einarsen v. City of Wheat Ridge, 43 Colo. App. 232, 604 P.2d 691 (1979).

   Trier of fact to determine mode to use in measuring noise. Davis v. Izaak Walton League of America, 717 P.2d 984 (Colo. App. 1985).

   Applied in City of Lakewood v. DeRoos, 631 P.2d 1140 (Colo. App. 1981).