Hydrology

Hydrology

Exploring the desert’s water.

Precipitation

In the Mojave, precipitation is common throughout the winter, with little rain during the summer. Depending on where you are in the desert, perception levels vary. Commonly the Mojave receives less than 5 inches (12 cm) of precipitation a year, from November to April. But higher elevations often receives more precipitation, including snow. Sudden rains in the Mojave often leading to flash floods. During the summer, monsoonal showers may fall in July and August. 

During our time in the Mojave Desert it rained once, on Thursday while at the Mitchell caverns. The rain was cold and came down heavy. The sky was foggy and clouds surrounded the tall mountains. Our tour guide at the caverns gave us a “smell test” of the vegetation along the walking path, claiming that with the rain, it was the perfect time to smell the desert scents.

On Monday, on the road to the boron mine, there was a severe weather alert for a hydrologic outlook.  The weather app stated “heavy rainfall and rapid snowmelt leading to a threat of flooding in the Sierra Nevada foothills and the Sierra Nevada below 8000 ft.” 

Rivers

There are three rivers that run through the Mojave desert, the Mojave River, the Colorado river and the Amargosa River. These rivers are the main sources of surface water within the region. All three rivers are exotic rivers, meaning they start outside of the desert and flow within it.

Mojave River

The Mojave river is 110 miles long, covering an area of 4500 square miles. The Mojave river flows from the San Bernardino Mountains, flowing  north through Barstow, and into Afton Canyon. The river receives its water mainly from meltwater from the mountain ranges in the spring and summer.

Colorado River

The Colorado river is 1,450 miles long, covering an area of 244,000 square miles. It starts within the rocky mountains and flows out into the gulf of California. It has two tributaries, the Muddy and Virgin Rivers. The Colorado RIver Water Compact (1922) divides the river into 2 basins among 8 states. However, this compact is based on a wet period, leading to over usage of water and drought conditions. The Colorado River has 3 lake impoundments, lakes Mead, Mohave, and Havasu. All three lakes are created by dams, including the Hoover Dam, Davis dam, and Parker dam.

Amargosa River

The Amargosa river is 185 miles long, covering an area of 1622 square miles. It begins near Pahute Mesa and drains south. Along its path it drains into theream springs near Shoshone and Tecopa. The water in the river is high in salinity and is calcium rich, with many limestone and dolostone deposits. The water supplies for Death Valley, rural towns and communities and wildlife. 

The Amargosa River at sunset.

Runoff

Runoff in the desert helps recharge its rivers, lake basins and groundwater. Yet can also cause flooding, especially with monsoonal showers.

Springs

Historically, springs in the Mojave desert were mapped along major roads for travelers by Native Americans, these springs were important for trading and provided a reliable source of water during long journeys. Without these streams, there would be little human presence today with no roads, mines, or settlements.

         Soda Springs, also known as Zzyzx Mineral Springs, has a rich history. In 1944, Curtis Springer filed mining claims on the springs. He claimed to be mining, but built a health resort. The resort featured mineral baths, special diets, and other health attractions. The resort was closed in the 60’s by the BLM. It is now the site of the Desert Studies Center.

Another spring in Death Valley is the Shoshone Springs, located in Shoshone, California. This spring is located just north of Tecopa Springs. Shoshone springs is the primary water supply for the local town. The geology of Shoshone Springs is like that of Tecopa, as it is located near fault lines. The springs are heated geothermally. There is less information available on Shoshone Springs, likely due to a focus on ecotourism in the area. The main water source is the Amargosa River, which the spring is located directly next to. It is a regional spring. The springs are also fed by aquifers and groundwater sources, likely the same ones as Tecopa (Spring Mountains). Shoshone springs is known for its ecotourism, RV park, and birdwatching. Similarly to the other springs mentioned, Shoshone springs has its own endemic species of pupfish.

         Saratoga Springs lies at the southern end of Death Valley National Park, on the southwestern edge of the Saratoga Hills, along the Death Valley fault zone and the Garlock Fault. The groundwater for this spring has two suspected sources. The first source is the Black Mountains to the west. The second source is the Spring Mountains to the east, which is suspected due to the water chemistry. This would mean that Saratoga springs have the same source as the Tecopa and Shoshone springs, but the exact water path from the mountains is unknown. Saratoga springs is a warm spring, at around 28 ℃. It has one of the highest discharge rates in the region, up to 1000 L/min has been recorded. Similarly to the other springs, Saratoga springs has its own endemic pupfish species. Flora includes common reeds, bulrush, and saltgrass. This area is known as a desert wetland. We were able to see the endemic Saratoga pupfish when we visited this site.

Enjoying the hot water at Tecopa Springs.

The Tecopa springs includes Grimshaw springs, Isolated springs, and the springs at Bath. All of these springs appear to have the same chemical composition, but differ in temperatures, due to varying underground paths and distance from the water source. During the Pliocene era, the Tecopa springs experienced a much wetter climate. Local fault lines led to the formation of a deep lake basin, Lake Tecopa. Roughly 0.5 mya, an outlet opened near the China Ranch Beds, creating a deep canyon on the southern end of the basin.We got to visit the China Ranch Date farm, near Tecopa springs, to see the Amargosa River flowing through and take water samples. Changing climate and increased evaporation led to the disappearance of Lake Tecopa. Deposits were associated with lacustrine mudstone, conglomerate, volcanic ash, and shoreline tufa (Calcium-Carbonate, CaCO3) accumulations. Some Calcium-Carbonate accumulations were found to be associated with Quaternary deposits from Yellowstone, or volcanic activity, even though it was a great distance away. The local aquifers are heated geothermally, due to their location along/near fault lines. There are four main groundwater discharge sources in the Tecopa basin; regional carbonate-rock springs and seeps, Tecopa Hills springs and seeps, thermal springs and seeps, and Amargosa Canyon hillslope springs and seeps. Some recharge is from the Amargosa river, as the Tecopa hot springs are located directly next to it. Other recharge sources include carbonate-rock aquifers, local recharge in the Spring Mountains, and from the Nopah and Resting Spring Ranges.

         One interesting aspect to the Tecopa Springs is the Stauffer Chemical Borehole. This man-made spring was an exploratory drill hole that was started in 1967 by Stauffer Chemical for mineral exploration. Water was found at 360 feet. They tried to plug the boring, but discharge under artesian conditions around the well seals had the effect of creating a large void at depth. They stopped attempting to fill the void. There is no obvious source of the water and no trace of the original well. The spring now is a series of connected pools (and non-connected pools). The water is hot, with the hottest pool being farthest from the road. In this pool, small streams of bubbles can be seen emanating from an area on the bottom, which is likely the source point. The water in the connected pools is hot, has a greenish tint, is relatively deep (3+feet in areas) and contains fish. The water in the disconnected pools is much cooler, reddish in color, very shallow and contains no fish. The water flows toward the road through a large expanse of three-square bulrush, reeds and grass, At the road, a culvert directs the water under the road and into Grimshaw Lake. Flow is monitored by the USGS and can be altered.

We visited the Tecopa Hot Springs on our first full day at the Mojave, Sunday March 5th. We drove north on highway 127 for roughly an hour, going from Baker to the small town of Tecopa. We parked on the side of the road and walked to the springs. It was very windy that day, there was even a wind warning issued. However, most of us had been looking forward to visiting the springs and we were determined to get into the water. The water was warm, and the bottom of the spring had soft clay sediments. The water was colder and more shallow as it approached the road. It was deep enough to almost fully submerge oneself. We got to meet some locals who visited the hot springs frequently. Some people put the clay on their faces, but most of us just floated and enjoyed the warm water. Getting out of the water, it felt very cold due to the strong winds, but the unique experience was worth the trouble. 

Lakes, Playas, and Groundwater

Lake Mead

Lake Mead is the largest reservoir in the United States. It serves as a municipal water source for Las Vegas and Nevada, much of southern California, Arizona, and adjacent Mexico. It is formed by the Hoover Dam. The Hoover Dam generates an average of 4 billion kilowatt-hours of power per year. Roughly 23% of the power goes to Nevada, 19% to Arizona, and 15% to Los Angeles. The Colorado River and two tributaries drain into Lake Mead. The current water level of Lake Mead is 1,045.98 feet. That is roughly 183 feet below the original full pool level. We visited Lake Mead on the last day of our trip. We were able to drive over the dam, from Nevada into Arizona, and experience a time zone jump.

Soda Lake

Soda Lake, also known as Lake Mojave, is a playa. It is fed by groundwater and episodic stream discharge. It is part of a greater system that includes dry lakes, including Soda Lake and Silver Lake.

Lake Manix

Lake Manix, located in Barstow, CA. It was fed by the Mojave River.

Groundwater

         There are two major groundwater basins. The Mojave basin in the north, and the Morongo basin in the southeast. Hydrographs show recharge in January, February, and March. The overall head level seems to be decreasing among most hydrograph sites. Water quality tests in groundwater have detected heavy metals such as lead and chromium, arsenic, and of course boron. 

The declining water level in Lake Mead at Hoover Dam.