CO SB183

Requires quantification of historical consumptive use for water rights to be based on analysis of actual historical use during a representative study period that includes wet years, dry years, and average years.

Study period must not include undecreed use of the water right and need not include every year of the entire history of the water right.

Prohibits water judges from reconsidering or requantifying historical consumptive use when an application seeks to change a portion of a water right for which a previous judicial change approval and quantification already exists.

Allows water judges to impose terms and conditions on future use of previously quantified water rights to limit future consumptive use to the previously established historical amount.

Applies to applications pending before water judges or referees or filed on or after the effective date of the act.