[Arya (left) is our newest student intern, and is a Junior at Vintage High School.]

According to the City of Napa, Napa uses 13,000-acre feet of water each year, which is equivalent to 4.2 billion gallons. Most would be appalled by this statistic, understandably. Is it the seemingly endless supply of water to our homes and the long showers that has caused this gross overuse of water? Well, not entirely. According to the Napa Water Committee’s 2023 Groundwater Management report, 72% of Napa County’s water is consumed by agriculture.

To understand anything about Napa’s use of water, we must understand where our water comes from and where it goes. Napa has several main water sources. We take water from Lake Henesey, the State Water Project (the Sacramento Delta), and the Milliken Reservoir. Agriculture, on the other hand, uses well water, which is groundwater. This groundwater comes from several basins, one of them being the Napa Valley Subbasin, which sits on the larger 426 square mile Napa watershed.

Unlike the other basins, the Napa Valley Subbasin is labeled as one of forty-six high priority basins in California. How come? Well, the government’s main concern is overdrafting. Overdrafting, to put it simply, happens when groundwater pumping is increased. The water table, the upper level of underground soil and rocks that are permanently saturated with water, sinks deeper into the earth. This human caused phenomenon has far-reaching consequences for human as well as ecosystem life in Napa.

Before we dive into the effects of overdrafting, let's go back in history, all the way to before humans began doing large-scale agriculture in Napa. (Illustration: Napa River in the 1800s, by Brian Maebius) Rivers ran from mountains on either side of the valley onto the valley floor. Robin Grossinger, the author of the Napa Valley Historical Ecology Atlas wrote, “forest remnants 200 to 400 feet wide can be seen upstream of St. Helena in early 1940s aerial photography”. These rivers were slow, wide, and lazy, and as they approached the valley floor, they spread out, soaking and filtering into the ground. This naturally replenished and enriched the groundwater basin. In addition, there was healthy flooding assisted by beaver ponds and fallen trees, which enabled native flora and fauna to thrive even during the dry season. Oak trees and riparian life used this abundance of water and acted like pumps to direct water down into the earth, further adding to the basin. Due to all these naturally occurring phenomena, Napa had a very high water table, with it rising within a few feet of the ground during the wet season.

However, this is where the problem started. When humans began to start commercial farming, they started thinking of the efficiency of the land. (Photo: Robin Grossinger) To efficiently grow crops, they needed plots of land that could be tilled. For those who don’t know, tilling is when farmers dig, stir, and overturn soil to break up or loosen the soil and prepare it for agriculture. This also involves destroying any pre-existing vegetation. According to the U.S. Department of Agriculture, to till and grow agriculture, you must remove any shallow and standing water because “if left untreated, these issues can make it impossible to grow vegetation or crops”.  Of course, they still needed water, but only in the amounts and locations the farmers thought they were needed for the crops. To solve this issue, farmers channeled the lazy, slow, and shallow rivers away from the farms. Channeling rivers makes them move at a much faster speed, which has devastating consequences. Since the water was moving so fast, it was easily able to catch and carry soil with its rushing currents. Especially since the soil was tilled and loose rather than connected in a complex root system, it was easy for water erosion to occur, dirtying the water quality, carrying excess nutrients into bodies of water, and eroding the land.

Another consequence of getting rid of the shallow water was the impact on beaver populations. Beavers were slowly killed off because they played a crucial role in creating ponds with their well-known “beaver dams”, slowing the water down, which disrupted the farmers from achieving their high agricultural yield. Unfortunately, all of this caused a dramatic reduction in the number of wetlands in Napa. In the mid-1800s, there were 12,996 acres of valley wetland (areas permanently saturated with water). In 2010, there were only 105 acres, 99% less than in the 1800s. (Photo: Rusty Cohen)

At this point in the story, it may seem that the farmers had it all, and had solved all the problems which had stopped them from having productive agriculture and a large profit. However, at first, much of the agriculture suffered as well. Unlike native plants such as the valley oak trees, which were adapted to the high-water table, according to Grossinger, “agriculture plantings suffered due to the extreme variation in water levels during different seasons.” Especially during the wet season, the high soil saturation restricted deep root development in crops, and plant roots often drowned if they tried to push deeper into the ground.

So, many soil scientists recommended a widespread increase in artificial drainage to eliminate the high groundwater problem, which was especially apparent in the lowlands and the south of the valley, near Oak Knoll district. (Photo: Roland Dumas) They suggested that saturated soils could be dewatered by creating ditches or drains that would convey water from the valley floor directly into the river. This new technique, developed and used starting in the mid-1800s, expanded agricultural potential, but had drawbacks as well. By redirecting groundwater to the river, it not only reduced the groundwater recharge but also increased floods from the rivers as more water was dumped there. Even now, the effects of flooding have increased as more urban storm drains have accelerated the conveyance of water to the river.

Napa, as we know it now, is one of the most widely known wine regions in the world. However, Napa was not always like that. When wine grapes and Napa wines were in high demand, farmers were still using dry farming without irrigation. This involved planting each vine and coming back to hand-water them a few times a year in their first year of growth. After this year, the rain would be the only irrigation they received. However, this traditional method was inefficient as it did not allow for higher volumes of crops and was not conducive to the goals of the planters, who wanted bigger and fast-maturing crops. Instead, farmers began switching to drip irrigation, which involved small sprinklers which would slowly irrigate the plant through drops of water. This new form of irrigation allowed planters to grow vines on hills, thus increasing the volume of each harvest.

However, like everything, this irrigation had severe drawbacks as it negatively affected the environment. The water used for irrigation was pumped out of the ground. As Napa’s grape vines increased vastly in popularity, the amount of groundwater used for irrigation also increased exponentially. This phenomenon, as said in the beginning of this article, is overdrafting. But what are these consequences of overdrafting that I keep mentioning? (Photo: Chris Sauer)

Well, firstly, overdrafting can create a financial and energy problem. When we pump groundwater, the water table decreases. However, this results in the need to use more energy to reach the water for future pumping. It is a positive feedback loop that self-perpetuates as we continue to pump more water, lower the table, then use more energy to pump the very same water.

In addition, Napa is at great risk of saltwater intrusion. The United States Geological Survey states that saltwater intrusion occurs when saltwater infiltrates freshwater aquifers, raising the water table and contaminating the freshwater. This is often due to excess water pumping from wells and is a growing risk for farmers. Normally, the seaward movement of freshwater prevents saltwater from infiltrating the underground aquifers. However, when wells pump water from the water table, it makes the freshwater move upwards rather than seaward, allowing the salt water to move in and contaminate the aquifer. Not only does this endanger crops, but it also endangers the livelihood of people who rely on freshwater from the ground for drinking water.

Furthermore, when groundwater is pumped and the aquifer is very dry, nearby streams and lakes can often become disconnected from groundwater, which causes dry periods to be extended and intensified. This is because during the dry periods, the stream or river cannot be replenished by the groundwater underneath, and vice versa: the groundwater cannot be replenished by the body of water above. This leads to dry periods becoming much drier as water sources dry up.

Not only does it affect ecosystems, but it also affects humans. Many people who live in rural areas near large vineyards in Napa use well-water as their main source. However, when nearby vineyards pump water, the water level decreases tremendously in the surrounding area, creating a “cone of depression”. This can reduce and even cut off water supply to those rural residents, creating an economic issue and bringing to light the larger social issue of equality.

Luckily, we live in an age where environmental knowledge and advocacy are a priority for our people and government. So, action has already been taken to change the course of Napa’s future. In 2014, the California government labeled our subbasin as “high priority” due to our population size and water usage. Due to this classification, the subbasin is subject to the Sustainable groundwater management Act, or SGMA. This act requires Napa to have a plan to sustainably manage our groundwater usage. It requires agencies to form groundwater sustainability agencies, (or GSAs). The GSAs help to implement groundwater sustainability plants specific to their basin to avoid and/or mitigate overdrafting within twenty years. Napa already has these aspects, and the people in our county are working hard to save our environment from further damage as well as restore it to its former glory.