Las Vegas, A History of "Gambling with Water in the Desert," Groundwater

The entertainment capital of the world, located in Clark County, Nevada was established in 1905 and incorporated as a city in 1911. With a population of about 2 million residents and over 30 million visitors a year (Census 2010, Las Vegas Metropolitan Area), Las Vegas is the most rapidly growing metropolitan area in the United States. Las Vegas Valley, aka Las Vegas Metropolitan Area, covers an area of 600 sq miles. (Fig 1)

Fig 1. Las Vegas Metropolitan growth between 1950 and 1990. (Photo courtesy of Southern Nevada Water Authority)

Once famous for its running springs and vast meadows, now this city is facing degrading water resources and aquifers. It is expected that the current water supplies won’t answer the water demand in the Valley. By all indications, global warming will lead to less precipitation in the region. The federally mandated limits on transferring water from Lake Mead (the Las Vegas Valley's local reservoir that supplies 90% of the Valley’s needs) increase the reliance on groundwater resources. Decades of overdraft the groundwater and compaction of the aquifers has led to 6 feet of ground subsidence and numerous land fissures around the Valley with potential hazards for the environment.

Geography, Climate and Precipitation in Las Vegas

Fig 2. Average Temperature and Precipitation in the Las Vegas Valley. 
(Photo courtesy of Western Resource Advocates)

Fig 3. Average Annual Precipitation, 1951-1980.
(Photo courtesy of USGS)

Las Vegas Valley is located in southern Nevada between the Great Basin and the Mojave Desert. It stretches from the city of North Las Vegas to Lake Mead and is surrounded by mountains in all directions. With an average annual rainfall of 4.49in. and an annual average temperature of 68 degrees Fahrenheit, Las Vegas Valley is considered an arid environment. This Valley has one of the highest evaporation rates in the US at 120 in. per year. 

History of water in Las Vegas 

For centuries life in the Las Vegas Valley was sustained by the springs running to the surface. These springs supplied water for human residents for 13,000 years; Native tribes were amongst the earliest users. The steady flow of water made it a perfect stopping point for the union Pacific Railroad to refill the steam locomotives. By 1905 the railroad created the town of Las Vegas. 

Fig 4. Fremont Street, Las Vegas, looking west, 1910 (Photo courtesy of USGS)
(http://pubs.usgs.gov/circ/circ1182/pdf/08LasVegas.pdf)

The Las Vegas land and Water Company was established in 1905 to build and operate the first piping system in order to transfer water from the springs to the City. Although the United States suffered from economic depression of 1930s, the City of Las Vegas flourished economically in this decade. Construction of Boulder Dam (later named Hoover Dam) and Lake Mead (the largest handmade lake in North America) in 1932 attracted more industries and initiated a new period of growth in the region.

Fig 5. A view of Hoover Dam and Lake Mead.
(http://www.skiwirentals.com/LakeMeadAbout.php)

The water resources attracted industries, military and specifically gambling businesses (gambling was legalized in Nevada in1931) to the Valley in the 1940s and ‘50s. 

Fig 6. Population growth in Clark County from 1900 to 1995. (Photo courtesy of USGS)
(http://pubs.usgs.gov/circ/circ1182/pdf/08LasVegas.pdf)

The Las Vegas Valley Water District (LVVWD) was founded in 1947. This initiative acquired the assets of the Las Vegas Land and Water Company and soon became the water supplier for Las Vegas and Clark County.

By 1950, Southern Nevada’s population reached more than 40,000; groundwater use increased up to 35,000 acre-feet per year (AFY) - An acre-foot is the amount of water serves a family of five in a year. - in the Las Vegas Valley. The first pipeline was constructed in 1942 to import the surface water from Lake Mead to the Valley in order to supplement the ground water. Construction of the second large pipeline in 1970 greatly expanded the amount of imported water into the Valley. Over the next 20 years, population growth increased almost threefold. In 1990, almost750,000 people resided in the Las Vegas Valley and land use exceeded 71,000acres, more than 10 times than in 1950.

SWNA and Las Vegas Groundwater Management Program 

The Southern Nevada Water Authority (SNWA) was created in 1991 with the aim of acquiring and managing water resources, construction of water facilities and promoting water conservation plans in order to meet future water demand in Southern Nevada. 

In 1996, the SWNA formed the groundwater management citizenadvisory committee to address the issues related to the groundwater management. In order to get direct input and feedbacks from stakeholders, the 21 members of this committee were selected from well-owners and groundwater-user citizens. As a result of this action, the Las Vegas Valley Groundwater Management Program was created in 1999 to control the overdrawing of the local groundwater basin and protect the aquifer system from the potential sources of contamination. Since the advent of the program in 1997, numerous public meetings have been held around the Valley. Public outreach efforts included establishing a groundwater information line and distributing brochures and guidelines on groundwater conservation among the residents.

Groundwater decline and land subsidence

The Valley witnessed a 1foot/year decline in the groundwater level between 1912 and 1944. This drop increased to 90 feet for some parts of the Valley between 1944 and1962.  Since 1970 most water (between 60,000 and90,000 feet) has been pumped from northwest of the Valley that caused more than 300 feet of groundwater level decline in this area.

Fig 7. An evidence of land subsidence in Las Vegas.
(Photo courtesy of USGS),
(http://geochange.er.usgs.gov/sw/impacts/hydrology/vegas_gw/)

 Land subsidence in the Las Vegas Valley was first reported in 1948 based on the land survey records. Land subsidence in the Valley is usually caused by a combination of decline in the groundwater level and the presence of compressible sediment in the aquifer system. Interestingly, the areas of maximum subsidence are not necessarily the areas of maximum groundwater drop. 

Fig 8. Land fissures have displaced the pavement and have damaged the buildings in Las Vegas.

(Photo courtesy of USGS),
(http://geochange.er.usgs.gov/sw/impacts/hydrology/vegas_gw/)

    



    
     
    Land subsidence and aquifer compaction have had various adverse impacts on the Las Vegas Valley’s lands including:

• Reduction of the aquifers storage capacity by about 187,000 acre-feet between 1907 and 1996. (enough water to supply 100,000 households in the Valley for 20 years.)
•  Ground failure (The land surface displacement has caused damage to 240 homes in north central part of the Valley.)
• Reduction in the natural drainage capacity and creation of a flood-prone area.
• Creation of land fissures and connecting the surface contaminated water to the aquifer. 

Previously, the aquifer’s water was supplied from the infiltration of part of snowfalls on the Spring Mountains to the west and on the Sheep and Las Vegas Mountains to the northwest. Nowadays, recharge from the urban runoff transfers contamination to the shallow near surface reservoirs while the capacity of main aquifers has been decreased because of the water depletion and compaction. 

Preventive programs and measures 

Many initiatives in collaboration with the City of Las Vegas have tried to manage the groundwater resource consumption and run projects to protect the aquifer system from overdrawing and contamination.

In 1988 City of North Las Vegas in contribution with LVVWD developed a plan to artificially replenish the aquifer system. Since then, over 40recharge wells have been injecting the surplus urban water into the principal aquifer. Through this process, dual purpose wells inject treated surface water imported from Lake Mead into the aquifer system. Recharging is usually done during winter when water demand is at the minimum level and the additional water can be used during dry seasons. Stabilizing or even increasing water levels should lessen pumping costs and minimize the need to deepen wells.

Fig 9. A dual-purpose well in the Las Vegas Valley. (Photo courtesy of SNWA)
(http://www.snwa.com/apps/photo/index.cfml?gid=18)

SNWA continues its collaboration with the Groundwater Management Program. Through this collaboration the Groundwater Management Program has participated in SNWA artificial recharge program and paid for the permanent recharge of up to 5,000 acre-feet per year. They also continue working on increasing public awareness where groundwater conditions are critical to ensure the aquifer protection. Furthermore, they have cooperated with state engineers to allow plugging of the abandoned wells at a lower cost, and to establish financial mechanism to assist those individuals who have to abandon their wells and connect to a municipal system. 

Before the formation of the Groundwater Management Program, the number and location of wells and the groundwater basin were not sufficiently documented. The SNWA in collaboration with Nevada's State Engineers has been conducting a well inventory in the Las Vegas basin since 1996. Using GPS equipment, the exact location of more than 4800 wells has been specified and recorded. Also, the water level in each well is monitored and tracked throughout the year. 

 
Hopefully, the continuing work of citizens, SNWA and other entities to address the long-term management issues related to the groundwater system in the Las Vegas Valley area will preserve this natural resource for current water users and ensure water availability for the future generations.