S8_11-15-04

• Basin: Statewide
• Title: SWSI Phase 1 Report - Section 8 Options for Meeting Future Water Needs
• Date: 11/15/2004
• Author: CWCB
• SWSI - Doc Type: Final Report

Section 8
Options for Meeting Future Water Needs
8.2.5.3 Indirect Potable Reuse
Indirect potable reuse involves the capture of legally
reusable return flows and reintroduction of these
captured flows into the municipal raw water supply. The
return flows that are captured may have been discharged
to a river or stream and mixed with other waters. Other
options include the capture of treated wastewater effluent
and additional treatment. The captured flows are then
reintroduced into the M&I raw water supply system. The
water may require advanced water treatment methods
beyond the existing level of treatment used for the
current water supply before the recaptured water was
introduced into the raw water supply.
Potential benefits of indirect reuse include:
^ Improves M&I reliability.
^ Maximizes use through successive use.
^ Maximizes beneficial use of water.
^ Lesser environmental impacts than a new water
supply project.
^ May not require new diversion structures.
The potential issues and conflicts of indirect potable
reuse are:
^ Can be very expensive. Infrastructure and operations
and maintenance costs will be high.
^ Must have consumable effluent to reuse.
^ Raw water treatment plant and/or pump back station
needs to be constructed. Infrastructure is required to
divert and store return flows, pump back to raw water
supply storage and additional treatment.
^ Existing and future regulatory compliance concerns.
SDWA regulations have to be met at a minimum.
Concerns over disinfection byproducts and pollutants
in captured return flows can result in expensive,
advanced water treatment processes.
^ The disposal of water treatment waste products is
becoming increasingly problematic and costly.
^ Previously unused reusable effluent historically
resulted in reduced or morejunior river calls
controlling the river.
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^ As M&I users develop or expand the reuse of existing
reusable return flows via water rights exchanges less
water may be available to downstream users.
^ River calls may become more senior, impacting all
users.
^ Public acceptance of the reuse of return flows for
drinking water must be achieved.
8.2.6 Control of Non-Native
Phreatophytes
This option would consist of a basinwide or a focused-
area program for the removal and control of non-native
phreatophytes that consume water that could otherwise
be used by any of the basin users: agricultural, M&I,
recreational, or environmental. Non-native phreatophytes
are invasive plant species that consume water. Of
particular concern in Colorado are tamarisk trees.
Methods of removal include: mechanical removal,
prescribed burning, biological control, and herbicide
application. While state and federal programs are
beginning to evaluate phreatophyte control options in
more depth, the costs and benefits (e.g., yields) of
phreatophyte control programs are largely unknown at
this time. Demonstration projects are planned in the Rio
Grande and Arkansas Basins, and USGS is updating
estimates of potential water savings.
Potential benefits of non-native phreatophyte control are:
^ Benefits all users: M&I, Agriculture, Environment, and
Recreation in accordance with water right priorities.
^ Reduces non-beneficial consumption of water.
^ Creates additional supplies without new water storage
or other infrastructure.
Potential conflicts or issues associated with non-native
phreatophytes are:
^ Any water saved would be administered under the
water rights system.
^ Does not benefit specific users and thus funding by
water users will be a challenge.
^ Would require regional cooperation and funding from
a regional, state or federal agency.
^ It is not clear that the vegetation that replaces the
non-native species will use less water.
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