C150243 feas study

• Contract/PO #: C150243
• Contractor Name: Aurora, City of
• Contract Type: Loan
• Water District: 0
• County: Adams
• Bill Number: SB 07-122
• Loan Projects - Doc Type: Feasibility Study

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Background and Need for the Prairie Waters Project
Aurora's water supply depends on renewable surface water supplies in the Colorado,
Arkansas, and South Platte Rivers. Yields from these supplies are highly variable because of
weather cycles and because Aurora's water rights are relatively "junior° water rights during
dry conditions. During the relatively wet conditions of the late 20+� century, this system was
capable of ineeting Aurora's demands. However, these conditions are not typical of the
long-term water conditions in Colorado or other arid western states. The variability of these
water supplies has been recently demonstrated by the drought conditions experienced since
2002, with an extreme drought that was estimated to occur once every 300 years. The City's
water storage reservoir levels fell below 26 percent of capacity, to a low storage volume
representing only about six months' worth of water supply. These conditions demonstrated
that Aurora s water system is vulnerable, and can not currently provide the level of
reliability that Aurora needs to safely meet current and future demands.
Aurora Water has implemented highly productive and comprehensive water conservation
programs that will allow it to meet its customers' demands in the near term. However, a
long-term water supply strategy is needed to ensure reliability in the long-term. Thx'ough a
series of water resource planning efforts, water conservation actions, responsible water right
acquisitions, and water leasing agreements, the City identified a strategy to improve
reliability of its water supply system and continue to provide high-quality water to its more
than 300,000 customers. The City developed a plan to deliver a cost effective, responsible,
and reliable water supply to the City for the foreseeable future. The plan included the
development of a new water infrastructure project which is the Prairie Waters Project.
The Prairie Waters Project (PWP) will allow Aurora Water to use its full share of existing
water rights as well as take advantage of future resources. In 2003 and 2004, the project's
sponsor, Aurora Water, assembled a team of professionals to develop the PWP to a
preliminary design level to determine its viability and affordability as the City's next water
resource.
Water Demands
The following three unit water demand rates, based on gallons per capita per day (gpcd) of
water usage in Aurora were evaluated during project planning:
175 gpcd = Average water usage rate during a normal or average year.
160 gpcd = Reduced average water usage rate reflecting a 10-percent decrease in
water usage due to conservation measures implemented during dry years.
140 gpcd = Further reduction in average water usage rate reflecting reductions in
water demand that may be achieved through mandatory water use restrictions
beyond normal dry year conservation measures, such as significant limitations on
outside watering.
The three demand rates include other demands in addition to residential usage, such as
' industrial and commercial demands; therefore, they are blended demand rates
incorporating all water demands. Population growth projections for Aurora were used with
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