Livestock water tanks are covered under the "Livestock Water Tank Act of Colorado" sections 35-49-101 to 35-49-116, C.R.S. These structures include all reservoirs built after April 17, 1941, on watercourses which the state engineer has determined to be "normally dry" and having a capacity of not more than ten acre-feet and a vertical height not exceeding fifteen feet from the bottom of the channel to the bottom of the spillway. Again, as with erosion control dams, the height is measured from the lowest point of the upstream toe to the crest of the spillway. No livestock water tanks can be used for irrigation purposes.
Erosion control dams are governed under Colorado statute (see section 37-87-122, C.R.S. (1990). These types of structures may be constructed on water courses which have been determined by the state engineer to be normally dry (which for our purposes is dry more than 80% of the time). Structures of this type cannot exceed fifteen feet from the bottom of the channel to the bottom of the spillway and cannot exceed ten acre-feet at the emergency spillway level. The height of the dam is measured vertically from the lowest point of the upstream toe to the crest of the dam in contrast to those measured vertically from the centerline pursuant to section 37-87-105, C.R.S. (1990). Note: The structure can be larger than specified under section 37-87-122, however, it then will be evaluated and must be constructed pursuant to section 37-87-105.