Frequently Asked Questions


How was Tempe Town Lake filled and how is it kept full?

Tempe began filling the 220 surface-acre lake on June 2, 1999, and declared it officially full on July 14, 1999. The City purchased water for the initial fill from the Central Arizona Project, which delivers water statewide from the surplus in the Colorado River. This water was delivered through the Salt River Project canal system. Using technology, the City of Tempe has minimized the amount of water lost to seepage. A flood levee forms an impenetrable wall around the sides of the lake. This levee was covered with a structural and aesthetically attractive lake edge. Underground, a clay wall connects to bedrock underground at the west end. On the east end, a seepage recovery system recovers almost 100 percent of the water that seeps into the ground. Water is recaptured by 10 wells around the eastern portion of the lake and pumped back into the lake. Eight bladders form two inflatable dams that contain the water on the east and west ends of the lake and can be deflated or inflated in 45 minutes to release overflow water or catch flood tail water. Water released during storms is replaced with the tail waters from water released from the lakes upstream. Water from evaporative losses will be be replaced primarily with Central Arizona Project water and recharge water exchanges.
 

Why is Rio Salado important to Tempe?

Unlike most cities in the metropolitan Phoenix area, Tempe does not face issues of urban sprawl; rather it has to creatively use the land that exists within its borders. Rio Salado reclaims over 800 acres of once undeveloped land from the flood plain, making it possible for river land to be developed which enhances the quality of life of Valley residents. Rio Salado provides increased recreational opportunities for residents, tourist attractions for visitors and economic growth for employment and stability. The Tempe Town Lake, which is between 800 to 1,200 feet wide and two miles long, is the closest lake available to the largest population residing in Arizona. The scale of this project is larger than San Diego’s Balboa Park, the San Antonio (Texas) River Walk, the Boston Waterfront and New York City’s Central Park. The scope of the project is a combination of all of these attractions and more.
 

Who pays for Rio Salado?

Rio Salado is a cooperative effort accomplished through public and private partnerships. The channelization of the river, completed in early 1996, cost $40 million and was paid for by the Flood Control District of Maricopa County and the Arizona Department of Transportation. Construction of the Tempe Town Lake cost just less than $45 million, $27 million of which will be absorbed by private developers who will also assist in long-term operational and maintenance funding. Additionally, a lake assessment fee is structured into the cost of the land around the lake. Some City-owned property surrounding the lake will be leased for development, creating immediate revenue. Development is expected to generate up to $3 million annually in sales revenue to be reinvested into the lake. State and federal grants have been used to help fund public art features, lake trails and landscaping. 
 

What about water flows?

Throughout the Valley's history, the Salt River has taken lives and destroyed buildings with its deceptively strong currents (200,000 cubic feet per second). Through channelization, these floodwaters are contained within an 800-foot floodway, allowing for the creation of parks and structures in areas once subject to flood damage. This channel consists of eight-foot thick soil cement walls, combined with the lake edge, to form a 100-year flood lower levee and rock gabions forming a nearly 500-year flood upper levee. The Tempe Town Lake is designed to minimally impede the flow of floodwater. Dams at both ends of the lake can be lowered partially or be completely deflated depending on the size of the water releases from lakes upstream. By restricting the placement of structures within the channel, potential damage due to flooding can be limited to minor landscape maintenance and cleanup.
 

Highest recorded Salt River flows
Tempe Town Lake is built to handle floodwaters of 250,000 cubic feet per second. The highest recorded flows in the Salt River to date are:

  • 200,000 cfs          Nov. 27, 1905
  • 170,000 cfs          Feb. 16, 1980
  • 143,000 cfs          Feb. 23, 1890
  • 130,000 cfs          Feb. 23, 1920
  • 129,000 cfs          Jan. 8, 1993
  • 126,000 cfs          Dec. 19, 1978
  • 122,000 cfs          March 2, 1978
  • 115,000 cfs          April 13, 1905

 

What about preserving wildlife and the native environment?

By concentrating water in an urban lake, more people will be able to enjoy the environment it creates. Balancing the preservation of desert plant materials and providing park environments for people to use is critical to Rio Salado. The desire for green public parks is being fulfilled in larger areas conducive to picnicking, playing games and sightseeing. Drought-tolerant plants are being used in appropriate areas (this is known as xeriscaping). These plants are not limited to cactus: many trees and flowering shrubs from climates similar to Tempe's are being used to create a beautiful park environment. These plants are not native and are selected carefully to avoid species that would impact surrounding native landscapes. Some 80 percent of the plant species in Rio Salado are native. A 13-acre Mesquite Bosque, maintained by volunteers, has been planted at the northeast end of Rio Salado providing refuge for wildlife, educational opportunities for students of all ages and a natural tie to the history of the Salt River.

A feasibility study completed by the United States Army Corps of Engineers identifies the possibility of creating habitats at both the east and west ends of the project and in the Indian Bend Wash outlet. These sites would be in the river channels and would be designed to attract native animals back to the area and to discourage migratory birds who might want to relocate to this area. Papago Park is currently being revegitated with native plants after years of scarring from cactus harvesting, four-wheel driving, horseback riding, mountain biking and hiking. Papago Park remains the only area in Tempe with significant saguaro and creosote growth.

 

Is the Tempe Town Lake a threat to aircraft safety?

BIrd in Habitat Phase IIThroughout the years, the City of Tempe has been a leader in promoting aircraft safety. Like the hundreds of other airports located on or around water, Tempe Town Lake is located about 12,000 feet beyond the runways of Sky Harbor International Airport. While it is rare to find flocks of migratory birds in the state of Arizona that commonly interfere with airplanes, the City of Tempe has taken several steps to ensure that Tempe Town Lake does not become a threat to airline safety. In addition to following Federal Aviation Administration (FAA) rules and regulations, the Tempe Town Lake design team took great care in ensuring that the lake would not become an attraction for birds and other wildlife. For example, the lake has no places for birds to nest or roost as evidenced by the steep sloping walls and the deepness of the water. Additionally, Rio Salado park areas have a strict policy against feeding birds and wildlife and food and beverage vendors are restricted from serving items that attract fowl, such as popcorn and peanuts. Special wildlife habitat areas are planned near the lake, where birds can fly with no threat to airline safety. The City's Wildlife Management Plan addresses numerous issues related to the removal and relocation of birds and other wildlife from areas that could be deemed unsafe for their habitat. This plan also outlines the City’s ongoing commitment to monitor the situation and make changes as necessary.
 

What about Transit?

In September 1996, Tempe citizens passed a transit improvement plan which provides significantly increased transit service throughout the city. Connections to the Rio Salado Project area include: additional bicycle facilities and pedestrian amenities, expanded FLASH (Free Local Area Shuttle) service and seven-day-a-week local/regional bus and dial-a-ride service. The City also participates in major investment studies that explore fixed guideway transit options throughout the region. Three corridors have a potential effect on the Rio Salado area.