BADFISH II
04-16-2002, 09:10 AM
Straight from the Park Services:
Boaters need to be careful this spring as Lake Mead's water elevation drops. Unmarked reefs are exposed or are just below the surface of the water. Boating at night or at faster speeds can be dangerous. Special care also needs to be taken on the launch ramps. They have been underwater for years and have deteriorated.
Why is the water going down?
Lake Mead stores Colorado River water for delivery to farms, homes and businesses in southern Nevada, Arizona, southern California and northern Mexico. About 96 percent of the water in Lake Mead is from melted snow that fell in Colorado, Utah, New Mexico and Wyoming.
Each year, Lake Mead receives a minimum amount of Colorado River water from these states, known as the "Upper Basin" states. And each year, a specific amount of water is released from Lake Mead to users in Nevada, Arizona, California and Mexico. In an "average" year, the amount of water flowing out of Lake Mead exceeds the amount of water flowing into Lake Mead.
In some years, Lake Mead receives much more than the minimum amount of water from the Upper Basin, but the amount of water released from Lake Mead does not vary much from year to year.
The water level in Lake Mead is lower than it has been over the past several years, but not unusual; during the period 1990 - 1996, water levels were at or below the current elevation.
The water is going down because the Colorado River runoff for the past two years has been far below normal.
In 2000, for example, the runoff was only 56 percent of normal. This year, the runoff is projected to be only 66 percent of normal. Because of this decreased runoff, Lake Mead has received only slightly more than the minimum required amount of water from the Upper Basin. But the amount of water going out from Lake Mead has remained at normal levels. So, there has been more water going out of Lake Mead in the past two years than there has been coming into the lake. This causes the elevation to drop a little more each year.
The variation in water flowing into Lake Mead and the water flowing out of Lake Mead causes the lake's water level or "elevation" to fluctuate yearly and over multi-year periods, and has done so throughout the reservoir's 66-year history. This is normal - it is how Lake Mead was designed to work.
Water is released from Lake Mead only to meet downstream municipal and agricultural demands. Consequently, power demands in California, Arizona and Nevada do not impact its elevation.
Lake Mead is typically at its highest yearly elevation in the late fall and early spring months. The lake begins to drop in elevation in the late spring and early summer when the desert heats up and causes a higher demand of agricultural and municipal water needed in the Las Vegas Valley, in Arizona and California, and in Mexico. Some years, the drop is greater than others, depending on how much difference there is between inflow and outflow.
If there are several consecutive years where outflow exceeds inflow, Lake Mead begins each year with lower water levels, and the elevation continues to drop until a "wet year" occurs in the Colorado River. Then, Lake Mead typically receives more water than it releases, and the lake again returns to higher elevations.
This pattern - where the lake periodically fills to capacity then experiences a period of declining levels, only to fill up again - is projected to continue into the future. But no one can predict the weather, so it is not possible to predict when the high and low periods will occur.
Boaters need to be careful this spring as Lake Mead's water elevation drops. Unmarked reefs are exposed or are just below the surface of the water. Boating at night or at faster speeds can be dangerous. Special care also needs to be taken on the launch ramps. They have been underwater for years and have deteriorated.
Why is the water going down?
Lake Mead stores Colorado River water for delivery to farms, homes and businesses in southern Nevada, Arizona, southern California and northern Mexico. About 96 percent of the water in Lake Mead is from melted snow that fell in Colorado, Utah, New Mexico and Wyoming.
Each year, Lake Mead receives a minimum amount of Colorado River water from these states, known as the "Upper Basin" states. And each year, a specific amount of water is released from Lake Mead to users in Nevada, Arizona, California and Mexico. In an "average" year, the amount of water flowing out of Lake Mead exceeds the amount of water flowing into Lake Mead.
In some years, Lake Mead receives much more than the minimum amount of water from the Upper Basin, but the amount of water released from Lake Mead does not vary much from year to year.
The water level in Lake Mead is lower than it has been over the past several years, but not unusual; during the period 1990 - 1996, water levels were at or below the current elevation.
The water is going down because the Colorado River runoff for the past two years has been far below normal.
In 2000, for example, the runoff was only 56 percent of normal. This year, the runoff is projected to be only 66 percent of normal. Because of this decreased runoff, Lake Mead has received only slightly more than the minimum required amount of water from the Upper Basin. But the amount of water going out from Lake Mead has remained at normal levels. So, there has been more water going out of Lake Mead in the past two years than there has been coming into the lake. This causes the elevation to drop a little more each year.
The variation in water flowing into Lake Mead and the water flowing out of Lake Mead causes the lake's water level or "elevation" to fluctuate yearly and over multi-year periods, and has done so throughout the reservoir's 66-year history. This is normal - it is how Lake Mead was designed to work.
Water is released from Lake Mead only to meet downstream municipal and agricultural demands. Consequently, power demands in California, Arizona and Nevada do not impact its elevation.
Lake Mead is typically at its highest yearly elevation in the late fall and early spring months. The lake begins to drop in elevation in the late spring and early summer when the desert heats up and causes a higher demand of agricultural and municipal water needed in the Las Vegas Valley, in Arizona and California, and in Mexico. Some years, the drop is greater than others, depending on how much difference there is between inflow and outflow.
If there are several consecutive years where outflow exceeds inflow, Lake Mead begins each year with lower water levels, and the elevation continues to drop until a "wet year" occurs in the Colorado River. Then, Lake Mead typically receives more water than it releases, and the lake again returns to higher elevations.
This pattern - where the lake periodically fills to capacity then experiences a period of declining levels, only to fill up again - is projected to continue into the future. But no one can predict the weather, so it is not possible to predict when the high and low periods will occur.