One of the key water reservoirs for Napa wine country in California has experienced dropping water levels in 2023. Lakes and reservoirs are essential to residential water supply, especially in places like California where there are frequent droughts.
Here's what to know about Lake Berryessa water levels, what they mean for California residents, and the overall climate impact.
Where is Lake Berryessa and how did it form?
According to the United States Bureau of Reclamation (USBR), Lake Berryessa is a reservoir between Blue Ridge and Cedar Roughs, just east of the Napa Valley. It's part of the Solano Project, which the Bureau of Reclamation owns. Lake Berryessa is 23 miles long, three miles wide, and comprises 165 miles of shoreline.
Lake Berryessa is one of California's biggest bodies of freshwater: at capacity, it can store 1.6 million acre-feet of water. It offers the water supply for irrigation and the cities of Vacaville, Suisun City, Vallejo, and Fairfield. In addition, the Solano Project helps with flood control protection for the city of Winters and other communities.
What is the Morning Glory Spillway?
At Lake Berryessa, the Morning Glory Spillway, also called the "Glory Hole," is a drainage feature for the reservoir, KCRA3 notes. It works as the overflow valve for the lake, and once the Lake Berryessa water levels reach 440 feet, the water spills into the Glory Hole and the Putah Creek below.
In January of 2023, KCRA3 reported that the lake's water levels were at about 412 feet and rising following several weeks of rain beginning in December. The station noted that the Glory Hole had not been used since 2019, the last time water levels were high enough to spill over.
What's the highest Lake Berryessa water level to date?
Wikipedia notes that the reservoir's highest recorded water level is 446.7 feet or 136.2 meters. Lake Berryessa has only overflowed past the 440-foot level a handful of times.
KCRA3 reported that Lake Berryessa showed its lowest water levels in recent years in December of 2022, at 394 feet.
The YouTube channel EveryNews has offered video updates on Lake Berryessa's water levels in spring and summer of 2023. In April 2023, they reported the water levels of the reservoir to be about 415 feet, which was an increase.
In May 2023, another video indicated the water levels had risen to just above 430 feet, only about nine feet from the top of the Glory Hole drain. However, by that point the water had stopped rising. According to Solano County Water Agency, as of June 29, 2023, the water levels were at 428.81.
What impacts Lake Berryessa's water levels?
The reservoir's water levels are directly tied to rainfall, and droughts have certainly impacted the water levels. Droughts in 1976-1978 dropped the reservoir levels to less than 50 percent capacity, according to LakeBerreyessaNews.com. The 400,000 people who use Lake Berryessa as their drinking water source are impacted every time there is a drought.