Atmospheric River Envy

Last winter after three years of drought California experienced an unprecedented wet winter in Water Year 2023 with a deluge from what were described as 19 atmospherics rivers which made landfall in California. According to the California Department of Water Resources “Statewide the annual precipitation in water year 2023 totaled 33.56 inches, which is about 141% of the long-term (1901-2000)annual average precipitation statewide,” though rainfall varied across the state from 16.99 inches in Fresno to 78.92 inches in the gauge in Miranda and over 45 inches in Piedmont and Eureka.

“According to the April 1 snow survey, the statewide snowpack was at 237% of normal for the date and the deepest on record since the state’s network of snow sensors was established in the mid-1980s. The snowpack was so deep that it contained roughly 30 million acre -feet of water, or more water than 1.7 times the annual average groundwater use (about 18 million acre-feet)in California. The subsequent snowmelt runoff filled surface water reservoirs and caused historic flooding.” Though this was only a single wet winter. The state’s groundwater basins, which supply more than 40% of the state’s total water supply, in an average year, remain seriously depleted despite the wet winter because the groundwater basins require a much longer time frame to recover and through mismanagement of groundwater resources California has experienced land subsidence in many areas and the groundwater basins can never recover.

Here in Haymarket, Virginia we had a relatively dry winter and a very dry summer and fell into drought in August. Besides lawns turning brown (my lawn and my neighbors are either watered by rain or not at all) there were also signs of concern. The Bull Run Mountain Conservancy recorded that the perennial streams: Little Bull Run and Catlett’s Branch were dry. Catharpin Creek, another perennial stream, appeared to have been reduced to a series of puddles. Then September came, and my rain monitoring station recorded a series of intense storms that brought 13.57 inches of rain (and hail) most of it over a 4 day period. Because the area around my home is semi-rural and wooded, flooding was not a problem. The ground just drank up the water. We ended the water year on September 30th at over 45 inches of rainfall above the average of 44 inches per year. I was shocked to realize that Piedmont and I had about the same amount of rain. I experienced it as a dry year. Yet, the intense rains in September were very localized and the region remains abnormally dry, but my lawn is green.

Catlett's Branch from BRM Conservancy, M. Kieffer

Generally, groundwater in the Culpeper Basin is renewed each year through precipitation. The groundwater has always been able to feed the perennial streams during dry periods, but not this year. In the past, the water stored in the watershed has been able to provide adequate water in droughts because historically the withdrawal of water was within the average recharge rate. However, the only nearby US Geological Survey groundwater monitoring well is no longer stable. The fall seasonal lows have been getting lower and the recharge even in 2018, the wettest year on record, did not reach the level of recharge during the drought that occurred in 2007-8.

We appear to have a growing problem in this area. We need information to find out. Prince William County and Loudoun County need to engage the USGS and DEQ to study the groundwater in our region expanding on the study they have been performing for Fauquier County. Little is known about the sustainability of our groundwater basins, but potential problems can still be addressed before it is too late.

Groundwater models and data from more monitoring wells can help develop a picture of the volume of the water within the groundwater basin and at what rate it is being used and at what rate it is being recharged. We need to know if the current and planned use of our lands, groundwater and surface water is sustainable even in drought years. We need to understand how ground cover by roads, parking lots and buildings will impact groundwater recharge and what level of groundwater and surface water withdrawals are sustainable to determine if a proposed change in land use or additional use of water resources is sustainable before it is granted. Without coordinated and proactive management, the aquifers and rivers supplying our region will be depleted. Through mismanagement we can turn ourselves into California.