CO HB1172

Adds water efficiency improvements to Colorado's list of conditions that prevent abandonment of water rights due to nonuse, protecting water rights holders who reduce consumption through efficiency projects or methods.

Requires water right owners to submit written notice of efficiency improvement projects to the division engineer on a prescribed form within one year of implementation to qualify for nonuse tolling.

Limits nonuse tolling from efficiency improvements to a maximum of 20 years, after which the water right may be subject to abandonment provisions.

Clarifies that efficiency improvements cannot be used to increase or expand consumptive use under a water right, preventing circumvention of water use restrictions.

Takes effect August 5, 2020, unless subject to a referendum petition, in which case it requires voter approval at the November 2020 general election.