Fri, Sep 05, 2008
Poncho Villanueva vacuums the million-gallon wave pool at Breakers Water Park in Marana,
where water use by homes is less than that of the farms they are replacing
.
Photos by Jim Davis / Arizona Daily Star
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VALLEY PROTECTIVE SERVICES SECURITY OFFICERS Administrative & Professional Pima Prevention Partnership Administrative Assistant Trades/Construction Mechanical Systems, Inc Plumbing/Piping Superintendent Construction Green Valley Heating & Cooling HVAC Service Tech Technical Dynamics Information Technology Systems Engineer Driver/Transportation Pioneer Landscaping Dieel Fleet Mechanic General Preferred Capital Management, Inc Apartment Mgr/Maintenance NorthwestRising water needs> Oro Valley, Marana situations contrast now, but both seek future solutions <
arizona daily star
Tucson, Arizona | Published: 05.24.2007
When it comes to groundwater on the Northwest Side, it's a tale of two towns.
Underground water levels in Oro Valley are dropping at an average rate of 5.6 feet a year, while the water table in Marana is rising 10 feet annually.
The decline of farming in Marana, coupled with efforts to artificially replace underground water, has created the resurgence in Marana.
Oro Valley, which relies heavily on annual rainfall to replenish its groundwater, can't pipe in renewable water and recharge its wells as easily as Marana.
With well levels continuing to decline in Oro Valley, officials are hoping to stave off future losses by treating outside water and sending it directly to customers rather than having it refill underground wells. But doing so would cost the town an estimated $120 million.
Marana will continue to use outside sources, such as CAP water, to increase groundwater levels, but officials caution that groundwater alone won't be enough to handle future growth.
Despite the different situations the towns face, officials in Marana and Oro Valley both agreed that long-term renewable water is needed to provide for area build-out that is expected to climb above 200,000 people. That is more than double the current population of the two towns combined.
And it's going to cost residents, in the form of new fees and possibly higher taxes.
"The days of cheap water are going to be gone," said Brad DeSpain, Marana's utilities director.
To start, officials plan to build a Central Arizona Project storage and treatment facility near Interstate 10 and Tangerine Road that could cost the region $225 million. Other alternatives need to be explored as well.
The high cost of the facility — which officials plan to pay for by levying fees on new homes — is only the beginning of future dramatic cost increases, officials and water experts said, as water becomes more scarce in the desert.
Pumping direct to customers
For Oro Valley, replenishing its wells with water from the Central Arizona Project canal would be an uphill battle — literally.
The town would have to build a pipeline and several pump stations to take the water from the CAP line, which lies just east of Interstate 10 and provides Colorado River water throughout Central and Southern Arizona, up to Oro Valley.
By the time the town paid to install the pipeline and pumps, it would make little sense to put the water back into the ground only to pump it back out later.
That's why the town, along with other regional water suppliers, plans to treat CAP water and send it directly to residents' taps.
"Why bother building a recharge facility?" said Philip Saletta, director of the Oro Valley Water Utility. "We should use it directly and save the groundwater."
Marana has an easier time getting CAP water because the canal runs through town limits, along the western edge of the Tortolita Fan.
The town, which receives about 1,528 acre-feet of water from the CAP annually, mainly uses the water to recharge the Santa Cruz River basin. It later pumps the water back out from area wells.
The recharge effort, along with the decline of well pumping for agricultural use, is responsible for the town's rising water table, DeSpain said.
Oro Valley, which doesn't use any artificial recharge methods, relies solely on annual rainfall to replenish groundwater.
While agriculture is being replaced by residential development in Marana, the water farmers would've used can't be directly transferred into renewable water for households.
Water for farming is dedicated to the land based on deeds and historical agreements. When the land is rezoned for residential development, the water rights don't transfer, said Sharon Megdal, director of the University of Arizona's Water Resources Research Center.
In Marana, a development gets a one-time credit for 3 acre-feet of water when an acre of farmland is converted to residential development. That supply doesn't go very far in ensuring renewable water for the development, DeSpain said.
When farmland is converted to rooftops, people generally believe that the water used by the previous farm will sustain the residential development, said Megdal, who spoke on water issues last week at a forum on Arizona's population growth.
While agriculture has typically been responsible for using 75 percent of the state's water annually, residential use could eventually replace or exceed the needs of farmers, Megdal said.
That will be the case for Marana, according to town projections.
In 2005, farms in Marana used roughly 35,000 acre-feet of water, compared with residential use of less than 5,000 acre-feet.
But as households fill in farm fields, residential use should catch up to agricultural use sometime after 2020, when farms and households in Marana are each expected to use almost 20,000 acre-feet a year.
Ultimately, Marana officials expect residential demand to rise to almost 44,000 acre-feet a year while agricultural use will decline to about 12,000 acre-feet.
Complex, costly project ahead
Establishing the collaboration and funding necessary to ensure a renewable water supply for the growing Northwest Side will be one of the most complex and costly projects ever undertaken by regional leaders, said Marana Town Manager Mike Reuwsaat.
As groundwater becomes increasingly scarce throughout the state, municipalities and water providers will have to work together to make sure residents' needs are met, he said.
Meeting those needs will require funding and cooperation that is more complex than the recent Regional Transportation Authority initiative, which was created in 2004 in an effort to solve Pima County's transportation woes.
The RTA added a half-cent sales tax throughout the county, with the money going to pay for regional road improvements.
Bond money is already being put to use to provide water to Northwest Side residents.
Metro Water began construction in 2005 of a 5 million gallon underground reservoir near North First Avenue and East Magee Road.
When completed in July, the $6.3 million storage site will allow the district to supply water to customers in case of a shortage. It also should help maintain stable water pressure for district residents.
Even with the construction of Metro Water's reservoir and the proposed CAP reservoir and treatment facility — which would provide water to Marana, Oro Valley, Metro Water, Tucson Water and the Flowing Wells Irrigation District — other water sources must be found to support projected growth.
Those solutions are going to have to be paid for by regional users in some fashion, whether it's through bonds or impact fees, Reuwsaat said.
Unlike Tucson, which currently uses about half of its annual CAP allocation of 135,000 acre-feet, Marana can't depend on the canal to provide renewable water for the growth.
Acquiring the needed water could include buying water farms similar to the city of Prescott's recent purchase of the Big Chino Water Ranch. The city plans to build a 30-mile pipeline to bring the water from the ranch to the city.
Other options Marana officials are exploring include floodwater retention and trying to buy water rights from the Cortaro-Marana Irrigation District or other sources. Even importing desalinated water from California could be a possibility.
"We're all being forced to take a look at how we do business as it relates to water," Reuwsaat said.
For Oro Valley, the main focus has always been the regional treatment facility, said Saletta, the town's utility director.
But eventually, the region will need to find other sources of water, and it won't be cheap.
"No matter where you bring water from, it costs money," Saletta said.
Because of the large cost, it's important that regional municipalities and water utilities form a long-term partnership with the goal of providing water to future residents, Reuwsaat said.
That way, costs can be shared, he said. "It's important to have a regional dialogue to meet our long-term growth," Reuwsaat said.
● Contact reporter Aaron Mackey at 618-1924 or amackey@azstarnet.com.
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