PUB00048

• Year: 1992
• Title: Systems Integration as a Water Supply Source for the Denver Metropolitan Area
• CWCB Section: Water Conservation & Drought Planning
• Author: Hydrosphere Resource Consultants
• Description: Overview of water supply alternatives and suggestion for process to address future water supply needs of the Denver Metro Area
• Publications - Doc Type: Historical

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DRAFT 8/24/92, Page 30

C. Maximize Use of Alluvial Aquifer Storage

It has generally been assumed that there is no additional tributary water available for
development in the Upper South Platte River Basin except for water storage projects capable of
carryover-storage from unusually wet years under relatively junior water rights. However,
some metro area water users have successfully developed reliable tributary groundwater
supplies under augmentation plans using the alluvial groundwater aquifer for storage of water
developed under junjor surface water rights by means of artificial recharge. When available
under junior decrees, water is diverted to aquifer recharge ponds which are located so that
return flows enter the stream over a period of several months to years from the time the
recharge takes place. These return flows provide the augmentation necessary for the pumping
oftributary wells under junior decrees. The tributary aquifer is thus used in much the same
manner as would be a surface water storage facility.

This approach to conjunctive use of surface water and tributary groundwater has been
developed extensively along the South Platte River below Denver. Within the metro area of
Denver, it has been assumed that such opportunities are limited by lack of sufficient recharge
sites in the proper locations for augmentation purposes. The Metropolitan Denver Water
Supply EIS assumed that recharge projects would be difficult because the points for stream
depletion (the wells) and augmentation (the return flows) would have to be very close together
because of the high number of diversion points along the South Platte through Denver.

However, the potential for development of this alternative may be increased through the
integration and cooperative management of metro area water supply systems and the
consideration of alternative sources of augmentation. This would provide the potential for
water users to meet the demands from alternative sources of supply and points of diversion.
Augmentation sources for the consumed portion of waters pumped could include the following:

1. Recharge using junior surface water rights that can be utilized in most years for
diversion to recharge ponds. The recharge facilities could be developed in open
space areas, highway rights of way, tributary and mainstem floodplains, and
possibly in conjunction with abandoned gravel quarries as well as those currently
under development.

2. Recharge or direct augmentation using water stored for water supply purposes in
Chatfield and Bear Creek Reservoirs (see discussion above under Water Supply Use
of Flood Control Facilities). This concept could mitigate the need for development
of conveyance facilities to deliver water directly from the reservoirs to treatment
facilities.

3. Recharge or exchange to alluvial wells from transmountain effluent return flows at
metro area wastewater treatment plants.

4. Recharge using storm water runoff from urbanized areas. This particular source of
augmentation water would probably be the most difficult to implement because of
physical, institutional, and regulatory complications. However, it deserves further
consideration because of the potential for multiple benefits, in addition to water
supply, including water quality improvements and flood control.

5. Recharge or direct augmentation using nontributary groundwater that is not of high
enough quality for use in municipal water supply systems.

Developing alluvial storage and recharge opportunities within the metro area would
involve water supply, water quality, urban drainage and flood control, parks & recreation,