Borrego Valley Groundwater Basin facts for kids

The Borrego Valley Groundwater Basin is in the southern part of California. It is one of the driest water basins in the state. People are worried about how much water is being used. They wonder if there will be enough water in the future. This is especially true with climate change happening.

The basin has natural and man-made parts. These help experts study how water has been managed over the years. This information helps plan for the future of water use.

What is the Borrego Valley Groundwater Basin?

The Borrego Valley Groundwater Basin is a large underground water storage area. It sits beneath the Borrego Valley. This valley is in both San Diego and Imperial counties in southern California. It stretches from the San Ysidro Mountains in the west. It goes east into Imperial County.

In 2016, the California Department of Water Resources divided this basin. They split it into two smaller parts called sub-basins. These are the Borrego Springs and Ocotillo Wells sub-basins. The whole basin covers about 150,000 acres (240 square miles). It holds water in three main underground layers called aquifers.

What the Land Looks Like

The land in this area is mostly dry. You will see many shrublands and rocky areas. There are also some sandy and dusty spots. Only a few trees grow here. The land's height changes a lot. Some parts are 30 feet below sea level. Other parts in the San Ysidro Mountains are over 4,500 feet high.

The Borrego Valley basin gets very little rain. It usually gets less than 5 inches each year. The weather is mostly dry and hot all year. Winters are only a little cooler.

Understanding the Aquifers

The valley has three main aquifers: the upper, middle, and lower.

• The upper aquifer is closest to the surface. It is made of sand, gravel, and other loose materials. These were left behind by ancient rivers and winds. This layer can be up to 1,000 feet thick. It is the main source of water for the Borrego Valley.
• Below the upper layer are the middle and lower aquifers. These layers have older, more packed sand, gravel, and rocks. The middle aquifer is thickest in the center of the valley, about 700 feet deep. The lower aquifer goes even deeper, reaching 1,800 feet in the southern part.

Borrego Springs Sub-Basin

This part of the basin is only in San Diego County. It is bordered by mountains and fault lines. A fault line is where the Earth's crust has broken. Coyote Creek flows into this area. It collects water in a spot called Borrego Sink. Sometimes, this sink overflows into the San Felipe Wash.

Water does not easily flow between the sub-basins. This is because of large rock formations. This means that pumping water from one area does not affect the other area much.

Ocotillo Wells Sub-Basin

This sub-basin is different. It is in both San Diego and Imperial counties. It gets its water from the mountains to the northeast. This is similar to how the Borrego Springs sub-basin gets its water.

Fun Things to Do in the Area

This beautiful area offers many fun activities. You can go hiking and enjoy nature. Many people also like to play golf here. The nearby Anza-Borrego Desert State Park is a great place to visit. You can also find many places to go camping. It's a wonderful spot to see wildflowers and wildlife.

How Groundwater is Used

Even though this is a desert, a lot of water is used.

• Farming: Water is used to grow crops.
• Golf Courses: It is also used to water green golf courses.
• Homes: People use water for their homes and for septic systems.

From 1945 to 2010, the water levels dropped. They went down by up to two feet each year. This happened mostly in the northern Borrego Valley. This is where most of the farms are.

In 2010, there were 50 wells used for farming. Eight wells served golf courses. Fourteen wells were for homes. More wells exist or are planned. However, only 20 of the current wells are checked regularly.

The amount of water used is a big problem. Farms, recreation, towns, and even Anza-Borrego Desert State Park use four times more water than the basin can naturally refill. Because of this, the U.S. Geological Survey and Borrego Water District are working together. They want to understand the water system better. This will help them plan for future building projects.

Water Availability and Quality

How Much Water is Available?

The amount of water available in Borrego Valley is a big worry. Water levels have dropped over 100 feet in some areas. A special computer model was made to study the water. It helps experts understand how water moved in the past. This helps them guess what might happen in the future.

Groundwater becomes available when rain and stream water soak into the ground. Streams like Coyote Creek flow from the mountains. They help refill the underground water. It was once thought that the Borrego Springs sub-basin could hold 5,500,000 acre-feet of water. An acre-foot is the amount of water needed to cover one acre of land one foot deep. But too much water has been taken out. So, the actual storage space might be smaller now. The Ocotillo Wells sub-basin was estimated to hold about 6,250,000 acre-feet. It faces a similar problem.

How Good is the Water Quality?

Water quality is very important here. It is the only source of water for farms, fun activities, and people. When water levels drop, the quality can get worse. This is because dissolved solids become more concentrated.

Sometimes, as water levels change, it affects how water flows to wells. This can cause the levels of harmful substances to go up or down. A study by the U.S. Geological Survey looked at past water quality data. They found that some substances were too high. These included total dissolved solids (TDS) and nitrate in the upper aquifer. TDS and nitrates can vary a lot across the basin.

The study also found that very little new water is soaking into the basin. This is due to changing weather patterns. Instead, water is soaking into the ground near the mountains.

How the Community Manages Water

The Borrego Water District was created in 1962. The community wanted to protect their water. They did not want it sent to the Salton Sea area. The Borrego Water District helps about 800 customers. They provide water, treat sewage, control floods, and manage gnats.

The Sustainable Groundwater Management Act is a law in California. It requires areas with important water basins to form a Groundwater Sustainability Agency (GSA). The Borrego Valley Groundwater Basin is one of these areas. These agencies must make sure that water levels, storage, and quality do not get worse. They also need to prevent the land from sinking. All this needs to be done by July 2019.

In 2015, experts estimated that about 13,000 acre-feet of water are taken out each year. This is more than what naturally refills. This is about 70% of all the water used in the basin. So, the GSA for Borrego Valley wants to reduce water use. They aim to cut yearly water use from 19,100 acre-feet down to 5,700 acre-feet. This will help the basin be sustainable.