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Lower Colorado River Population

The 2000 Census populations for each basin and Indian reservation, from highest to lowest, are listed in Table 7.0-3. The most populous basin is the Yuma Basin with 79% of the total planning area population in 2000.  Three basins have population totals less than 100 residents. The 2005 estimated population of the Yuma Basin was 181,600 and Arizona Department of Economic Security (DES) population projections forecast 305,900 residents by 2030. Historic, current and projected basin populations are shown in the basin cultural water demand tables (Sections 7.1-7.11).

The planning area is growing rapidly with a 44% population increase between 1990 and 2000.  Census data for 2000 show about 194,100 residents and DES population projections forecast that the population will double by 2030, to about 388,400 residents (Table 7.0-4).

Table 7.0-3 2000 Census population in the Lower Colorado River Planning Area

Table 7.0-3

Table 7.0-4 Communities in the Lower Colorado River Planning Area with a 2000 Census population greater than 1,000

Table 7.0-4

Listed in Table 7.0-4 are incorporated and unincorporated communities in the planning area with 2000 Census populations greater than 1,000 and growth rates for two time periods.  Communities are listed from highest to lowest population in 2000.  As shown, there are a number of rapidly growing communities in the planning area. San Luis, along the international border, had the most rapid growth rate during both time periods.  Fortuna Foothills, an unincorporated community east of Yuma is also growing rapidly with a 165% growth rate between 1990 and 2000 and a 29% growth rate between 2000 and 2006.  Yuma, Fortuna Foothills and Quartzsite experience a large population increase in the winter when seasonal residents arrive to enjoy the relatively warm climate.  This seasonal population is not accounted for in the population estimates and projections unless these communities are listed as the primary residence.

Population Growth and Water Use

Arizona has limited mechanisms to address the connections between land use, population growth and water supply.  A legislative attempt to link growth and water management planning is the Growing Smarter Plus Act of 2000 (Act) which requires that counties with a population greater than 125,000 (2000 Census) include planning for water resources in their comprehensive plans.  Of the five counties in the planning area, four fit the size criteria in 2000; Maricopa, Pima, Yavapai and Yuma.  Only Yuma County is entirely within the planning area.  The Yuma County 2010 Comprehensive Plan provides a general overview on the quality and quantity of water in the county, including information on drinking water and distribution and wastewater management (Yuma County, 2000).

The Act also requires that twenty-three communities outside AMAs include a water resources element in their general plans.  In the Lower Colorado River Planning Area this requirement applies to Yuma, Quartzsite, San Luis and Somerton and all communities have complied.  Plans must consider water demand and water resource availability in conjunction with growth, land use and infrastructure.

Beginning in 2007, all community water systems in the state were required to submit Annual Water Use Reports and System Water Plans. The reports and plans are intended to reduce community water systems’ vulnerability to drought, and to promote water resource planning to ensure that water providers are prepared to respond to water shortage conditions.  In addition, the information will allow the State to provide regional planning assistance to help communities prepare for, mitigate and respond to drought.  An Annual Water Use Report must be submitted each year by the systems that includes information on water pumped, diverted and received, water delivered to customers, and effluent used or received. The System Water Plan must be updated and submitted every five years and consist of three components, a Water Supply Plan, a Drought Preparedness Plan and a Water Conservation Plan. By January 1, 2008, all systems were required to submit plans.

Fortuna Foothills

Development in Fortuna Foothills, Yuma Basin

Plans have been submitted by 37 community water systems in the planning area including the City of Yuma, Town of Parker, Ajo Improvement Company/Phelps Dodge Corporation, City of Somerton, and Town of Gila Bend and were used to prepare this document. Annual water report information and a list of water plans are found in Appendix B.

The Department’s Water Adequacy Program also relates water supply and demand to growth to some extent, but does not control growth.  Developers of subdivisions outside of AMAs are required to obtain a determination of whether there is sufficient water of adequate quality available for 100 years.  If the supply is inadequate, lots may still be sold, but the condition of the water supply must be disclosed in promotional materials and in sales documents.  Legislation adopted in June 2007 (SB 1575) authorizes a county board of supervisors to adopt a provision, by unanimous vote, which requires a new subdivision to have an adequate water supply in order for the subdivision to be approved by the platting authority.  If adopted, cities and towns within the county may not approve a subdivision unless it has an adequate water supply.  If the county does not adopt the provision, the legislation allows a city or town to adopt a local adequacy ordinance that requires a demonstration of adequacy before the final plat can be approved. To date, only Yuma County and Cochise County have adopted the provision.

Subdivision adequacy determinations (Water Adequacy Reports), including the reason(s) for inadequate determinations, are provided in basin tables and maps and are summarized for each basin in Table 7.0-5.  As listed on the table, a high percentage of lots have been determined to have an adequate water supply and only basins with relatively few subdivided lots have a high percentage of inadequacy determinations

Table 7.0-5 Water adequacy determinations in the Lower Colorado River Planning Area as of 12/2008

Table 7.0-5

Also shown in the basin sections are approved applications for an Analysis of Adequate Water Supply (AAWS). This application is typically associated with large, master planned communities.

The service areas of two water providers in the planning area, Town of Parker and City of Yuma, have been designated as having an adequate water supply for their entire service area.  If a subdivision is served by one of these designated water providers, a separate adequacy determination is not required.


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