5 Colo. Code Regs. § 1003-5-3.3
The overflow gutter when provided, shall extend around the entire perimeter of the pool, except at steps or recessed ladders. The overflow gutter lip shall be level within .3 inch. This gutter shall be capable of continuously removing 100 percent of the recirculated water for return to the filter. All overflow gutters shall be connected to the recirculation system through a properly designed surge system. The gutter, drains and return piping to the surge system shall be designed to rapidly remove overflow water caused by recirculation displacement, wave action or other causes produced from the maximum pool bathing load. Gutters shall be designed to prevent entrance or entrapment of bathers. The overflow outlets shall be provided with outlet pipes which shall in any case be at least two (2) inches in diameter. Outlets shall be a maximum of fifteen (15) feet apart and opening in grating less than 1.5 times cross-sectional pipe area.
5 CCR 1003-5-3.3