In 1912 and with a population of about 1,000, settlers drew about 22,000 acre feet of water per year from the springs. As the town grew, people drilled wells and often didn't cap them, allowing water to gush out at an enormous rate.

By the late 1920s, drought and heavy demand for water began to take its toll on the valley's principal aquifer. In 1935, major water shortages began to occur and residents were encouraged to save water. By 1940, with a valley population of about 10,000, water use was about 21,000 acre feet per year.

Unfortunately, the huge waste of water depleted the groundwater table quickly and by the early 1940s, the Nevada State Engineer declared the valley overdrawn.

In 1955, the Nevada Legislature authorized the State Engineer to issue temporary (revocable) permits with the express understanding that these wells would be abandoned when municipal water became available. These temporary permits were issued so that the Las Vegas Valley could continue to grow.

As the natural springs and artesian flows from wells declined, many people installed pumps. New wells were installed near existing wells. By 1960, about 3,000 wells had been drilled in the valley. However, more than half of the groundwater production still came from less than 25 wells located within a mile of the Las Vegas Springs.

By then, the population had increased to about 119,000 and about 48,000 acre feet of groundwater was used each year. Increased overdraft resulted in water level declines of two to four feet per year. The springs flows, once a hallmark of the valley's geography, eventually stopped altogether by 1962.

By 1970, about 4,700 wells had been drilled. New housing developments increased the acreage of irrigated landscapes, thus increasing the amount of secondary recharge. Water applied to landscapes that's not absorbed by plants and that reaches the aquifers is known as secondary recharge. Over time, this secondary recharge created a shallow aquifer in the basin. The shallow aquifer holds low-quality water and is still present in the valley today.

By 1990, groundwater use had declined to 62,000 acre feet, despite a population increase to about 700,000. Water level declines returned to the 1940-to-1960 rate of two to four feet per year. Well drilling continued and the total number of wells had increased to about 7,800. Artificial recharge -- the injection of treated Colorado River water into the groundwater system -- began on a small scale in 1988.

While the water level rose in some parts of the valley during the 1990s, it continues to decline on the peripheral parts of the metropolitan area, the site of many domestic and community wells.

The Southern Nevada population reached 1.2 million in 1998. The growth brought a surge of new residents, many of whom have grass lawns. In the hot summer months, residents use as much as 90 percent of the drinking water supply to irrigate their lawns, contributing to an increase in the shallow aquifer.

Total pumping from the groundwater basin is about 75,000 acre feet per year. However, water recharged into the aquifers by both natural and artificial processes as well as secondary recharge of the shallow aquifer is still greater than the total water pumped out, helping stabilize the groundwater supply.

Today, Lake Mead remains our valley's main source of water, with groundwater supplementing that source and helping to meet peak demands in the summer. The Southern Nevada Water Authority is committed to finding and implementing long-term solutions to our area's water resource needs. The Las Vegas Valley Groundwater Management Program is part of a comprehensive effort to protect the valley's groundwater supply and ensure its availability to users for years to come.