Rainwater Harvesting in Colorado Fact Sheet

• Year: 2007
• Title: Rainwater Harvesting in Colorado
• CWCB Section: Water Conservation & Drought Planning
• Author: CWCB
• Description: Rainwater Harvesting in Colorado
• Publications - Doc Type: Fact Sheets

COLORADO WATER CONSERVATION BOARD

Departtnent of Natural Resources
Bill Ritter, Jr., Governor
Harris D. Sherman, DNR Executive Director
Dan McAuliffe, CWCB Acting Director August 2007

RAINWATER HARVESTING IN COLORADO

The following information has been taken from
the final report of the Holistic Approach to
Sustainable Water Management in Northwest
Douglas County study from January 2007.

Background:

Currently, rainwater harvesting is being practiced in at
least 7 other western states. It is practiced in various
forms in numerous other arid and semiarid states
surrounding Colorado. Rainwater Harvesting has
been overlooked in Colorado primarily for two
reasons: 1) historically, relatively abundant and low-
cost alternative water supplies have been available and
2) current law requites 100010 replacement of any
precipitation captured, thereby requiting the user to
find an equal amount of replacement water.

The study objectives were to research existing studies
and apply identified algorithms to show:
The potential precipitation as a water supply

The potential water savings from rainwater
harvesting for existing developments that
currently rely on non-tributary groundwater
supplies.

Study Findings:

With rainwater harvesting, outdoor water
demand is reduced by approximately 65010
with moderate conservation and
approximately 88010 with water wise
conservation.
For existing well users, rainwater harvesting
provides an opportunity to reduce
withdrawals from non-tributary aquifers with
declining water levels and to provide a

supplemental supply, especially for itrigation
and flte suppression.
Rainwater harvesting does have potential as a
sustainable water management approach in
northwest Douglas County, particularly when
paited with outdoor water demand
management practices.

Legal Roadblocks to Rainwater Harvesting:

Current Colorado law does not allow
rainwater harvesting to be utilized to its full
advantage as one source of a sustainable water
supply.
All water that falls as precipitation is assumed
to ultimately contribute to flows in the stream,
and is deemed to be part and parcel of the
water that existing water rights are entitled to
use in accordance with theit decreed priorities.
Intercepting precipitation that would have
otherwise migrated groundwater or surface
water might interfere with the full allocation
of existing water rights.
Colorado law requites 100010 of any
precipitation captured-out-of-priority for later
beneficial use to be replaced to the stream
system in like time, place and amounts.

Statutory Exceptions to the Law:

C.R.S. ~3 7 -84-11 7 (5) & C.R.S. ~3 7 -80-120(5)
concerning on-stream reservoit evaporation &
~37-92-305 (12)(a) concerning gravel pit pond
evaporation, expressly recognize that not all
precipitation is a supply to existing water
rights.
These statutes allow "credit" to be taken
against the amount of water that would

For more information contact Veva McCaig at the CWCB at [phone].
1313 Sherman Street, Room 721, Denver, CO 80203
Phone: [phone]. Fax: [phone]
Website : www.cwcb.state.co.us