Clean, fresh water is integral to every aspect of life in the Shenandoah Valley. The North Fork of the Shenandoah River provides drinking water, wastewater, and irrigation for towns, households, and farms throughout the region. As one of the region’s most precious and utilized natural resources, the North Fork is under especially high demand during the normal low flow summer season. When flow rates drop, the river becomes susceptible to myriad threats to water quality and ecosystem health.
Learn about how and where the river is used, and how small changes in our individual daily routines can make a big difference for the river’s health.
North Fork: Municipal Water Supply
The North Fork of the Shenandoah provides water to multiple municipalities in the region. The city of Winchester’s water supply is pumped from the North Fork, and the city, in turn, provides all of Middletown’s water, and portions of Fredrick County and Stephens City’s supplies. The towns of Strasburg and Woodstock also use the North Fork for their municipal water supply.
North Fork: Agricultural Irrigation Supply
In general, most agriculture in the Northern Shenandoah Valley relies on surface water pumped from streams for irrigation. In 2017, an estimated 14,630,760 gallons per month were used on Shenandoah County farmlands, and 8,264,880 in Page County, according to the 2017 Census of Agriculture. These estimates do not include cropland irrigation, because usage varies greatly with climate conditions.
Meteorologic Conditions Affecting River Flow
The Shenandoah Valley sits between the Allegheny mountain system to the west, and the Blue Ridge Mountains to the east. As moist air, from either east or west, is forced to rise over these mountains, moisture condenses as it cools, and much of the precipitation falls on the mountain faces outside of the valley. This process, called orographic lifting, on both sides of the valley, produces a double “rain shadow” effect, which makes the Shenandoah Valley the driest area in Virginia, and one of the driest locations in the Eastern United States.
While the Shenandoah Valley does not have distinctively “dry” or “wet” seasons, evapotranspiration rates raise in the summer, leading to an overall loss of moisture. Evapotranspiration is the sum of water evaporating from the ground and water being used and released from plants, both of which increase with the summer’s higher temperatures and stronger sunlight. Groundwater and deep soil reserves are replenished during the colder months.
Low Flow Health Risks for the River
Low flow conditions pose a number of risks to river health. Low water levels aggravate the effects of pollutants. Because there is less water to dilute them, concentration levels of pollutants rise. Also, lower water levels lead to increased effects from winds, bank storage, spring seepage, tributary streams and the warming effect of the sun. The exaggerated impact of these factors can present additional stressors for river life.
The summer algal blooms in the North Fork are one important example of how low flow conditions compound the impacts of pollution, and pose a threat to the health of the river, river life, and the general public. Click here to read more about algal blooms, and how and why they happen.
What You Can Do to Conserve Water
While surface runoff from rain contributes largely to the North Fork’s flow, groundwater is also vitally important to stream and river flow, especially during times of little to no precipitation. Whether your water comes from the river or a well, simple changes in your daily routine can help to keep the river healthy and flowing throughout the Shenandoah Valley’s dry summers. Click here to read about simple actions you can take to conserve water in your home and yard.
Northern Shenandoah Valley Regional Water Supply Plan, 7/26/2011. The Draft Regional Water Supply Plan was prepared by the Northern Shenandoah Valley Regional Commission and Technical Advisory Committee members from the twenty jurisdictions participating in this Plan.
USGS.gov: Evapotranspiration and the Water Cycle