Mojave National Preserve - Springs and Seeps

Water is a scarce and precious resource, extremely important to the flora and fauna that call the desert home. Seeps and springs constitute the majority of surface water in the Preserve and are a critical source of water for wildlife. Springs have a visible flow of water, whereas a seep may be evident only through the riparian vegetation that it supports. Seeps and springs in the Preserve generally appear where groundwater is forced to the surface by geologic features such as faults or fissures, and the majority of seeps and springs are found along the principal mountain chain of the Granite- Providence- Mid Hills- New York Mountains. Seventy-eight percent of the over 200 known seeps and springs occur between 4000 and 6000 feet in elevation but most have an average flow of less than 5 gallons per minute

The flow of water to seeps and springs is greatly dependent upon precipitation. On average, two-thirds or more of the annual rainfall of the Preserve falls in the winter, with the remainder produced by short, localized summer monsoon storms. Intense flash flooding sometimes occurs as a result of these summer storms, but most of the water is lost to evapotranspiration and is largely inaccessable to wildlife. Precipitation in the Mojave Desert is highly unpredictable, and there is great variation in monthly and yearly annual averages. The main source of groundwater in the Preserve is runoff from the mountains, where precipitation tends to be higher than the surrounding valleys. Nearly all of the Preserve’s watershed have headwaters within the Preserve.

Other sources of surface water is rare in the Mojave Desert. There are only 2 other significant sources of surface water for wildlife in the preserve: Piute Creek and Cornfield Spring. Piute Creek, located in Piute Gorge, runs above the surface for approximately a mile and has an average flow of 42 gallons per minute. Cornfield Spring is in the Providence Mountains and supports a much smaller stream. Occasionally water may collect in bowls or depressions in hard rock areas. These pools are called tinajas and may remain for up to a few weeks. Playas, such as Soda Dry Lake, may also contain standing surface water in wet years. Playas have their own unique ecology and host of organisms which thrive in these relatively short-lived bodies of highly saline water.

Over the last 100 years most of the springs in the Preserve were altered and drained for ranching purposes. The modifications include the installation of retention tanks, pipelines, and troughs. Guzzlers are devices that catch surface runoff during storms and provide it to game animals during drier periods. Cattle and other wildlife use guzzlers as well. Wells, powered by windmills, have also been constructed to benefit cattle. There are over 100 livestock tanks, troughs and guzzlers in the Preserve. It is a policy of the National Park Service to protect and restore the natural consition of ecosystemswithin its management purview. Interest abounds to restore springs at various locations throughout the Preserve. Some springs will return to good condition merely by removing the drainage systems, but others will require more active efforts. Restoring the natural flow of water at springs will provide a more sustainable condition for wildlife than what exists today.

The main threats to the springs and seeps of the preserve are tamarisk and burros. Tamarisk, or salt-cedar ( Tamarix ramossissima ), is an invasive exotic shrub commonly found in riparian areas. It can put down very deeps roots to reach groundwater and competes with native vegetation for available water while providing little value to native fauna in terms of forage or cover. Although it is unclear whether tamarisk uses more water than native vegetation, but it is still important to eliminate tamarisk wherever it is found within the Preserve. Burros ( Equus asinus ) are known to pollute water with their feces, making the water unpalatable to bighorn sheep. Burros also damage spring sources by trampling and can eliminate native vegetation through overbrowsing. Burros also drink considerably more water than bighorn sheep, approximately 5 gallons per day versus 1 gallon per day, respectively.

Some data exist on the water quality of groundwater in the preserve. Water quality is a mix with high levels of many metals in the vicinity of Soda Dry Lake and Soda Springs and high nitrate levels in Lanfair Valley. A two year study to inventory the springs and do water quality testing in the Preserve is currently underway and is expected to be completed June 2004. As a part of the spring inventory, scientists will photo document and map all known water features. Documentation of the diversions and alterations will also take place, and lab testing will be conducted on water from selected springs.