Underground Rivers / Federal, State Researchers Are Looking into Ancient Ones on Northern Neck

Two great rivers surround the Northern Neck. But seven other ancient rivers – slow-moving, unseen and vital – also flow under the peninsula.

These aquifers are the source of practically all the drinking water for the region. Some of the water may be 40,000 years old. Will there be enough to drink in years to come?

To help answer that question, a rig on a hill in Northumberland County has recently been drilling deep to find facts about the aquifers beneath the Northern Neck.

Since March 1, drillers from the U.S. Geological Survey and the Virginia Department of Environmental Quality have brought up core samples of soils going down more than 1,000 feet below the surface. The cores reveal the layers, depths, thicknesses and other characteristics of the aquifers in all their colorful, sandy, clayey, gritty, even fossilized-fish-poop detail.

State and federal hydrologists will use the data to install wells to monitor the levels and water quality of the various aquifers. In years to come, the science may help set public policy, such as possible restrictions on industrial uses of groundwater or the need for reservoirs or other new sources of water if the aquifers dry up.

This month, the drillers laid out 101 boxes, or 808 feet, of the fresh core samples on 11 tables at a Heathsville museum. They extracted the cores from Surprise Hill, a 100-foot-high rise near the Chesapeake Bay end of the Northern Neck at Reedville.

T. Scott Bruce, a DEQ groundwater geologist, took a visitor on a 15-minute tour of the samples that formed over a period of 140 million years. Bruce’s first stop was the shallowest aquifer.

Called the surficial aquifer, this water supply is found to about 95 feet below the surface. Frequently tapped by shallow wells, the aquifer is renewed by rainwater seeping down from the surface.

At 115 feet, Bruce pointed out the marine shell deposits that identify the Yorktown Eastover Aquifer. Bruce is well acquainted with this aquifer from his work south of the York River and on the Eastern Shore.

At Surprise Hill, however, the layer is just 12 feet thick. Bruce said he was not exactly sure what the drillers found from 280 to 340 feet below the surface. “It’s either a sliver of the St. Mary’s Aquifer or a leaky confinement layer,” he said.

Another “little wrinkle” shows up at 532 feet.

“The geology up here in the Northern Neck isn’t quite the same as it is south of the York. I may have an extra aquifer here. I’ve got to figure out what to do with it,” he said.

Two aquifers that supply much of the drinking water to southern Maryland show up next: a 40-foot-section of the Piney Point Aquifer 440 feet below the surface and “a little speck of the Aquia Aquifer” between 670 and 695 feet.

The granular material that identifies the Aquia Aquifer is surrounded by green glauconite, the geological term for fossilized fish feces dropped on the ocean floor for millions of years millions of years ago. From 704 feet on down is the Potomac Aquifer, the largest source of artesian groundwater available to the Northern Neck. The Potomac Aquifer is also a major source of water for southern Maryland to the north and the Middle Peninsula to the south.

This fall, Bruce said, seven monitoring wells will be dug in a cluster around the bore hole at Surprise Hill, one well into each aquifer. Equipment at the wells will report water levels via satellite. The wells will also be sampled occasionally to check salinity, fluoride and other elements of concern to groundwater users in the Northern Neck, said Bruce.

DEQ, USGS and the Northern Neck Planning District Commission are sharing equally in the cost of the $90,000 project, he said.

Gayl Fowler, founder of SAIF Water Wells Inc., called the aquifer study “a major scientific advance.” The knowledge will ultimately yield facts instead of guesses about groundwater usage and aquifer declines, she said.

Fowler, whose organization has provided hundreds of Northern Neck families with safe water and septic systems, said the time may come when the region will need a groundwater management plan.

“Right now, any new industry could come in and start taking millions of gallons a day. A groundwater-management plan would require a permit for that type of use,” she said.

Lynton Land is a retired geology professor who lives a few miles away from Surprise Hill. Land continues to study groundwater issues and serves on state and regional groundwater panels. He said the rural Northern Neck consumes 78 million gallons of artesian water from the aquifers each day. Southern Maryland withdraws 43 million gallons and a paper mill at West Point uses 20 million gallons a day, he said.

Land said the current study is “absolutely necessary.” He would also like to see a similar groundwater-analysis project at Coles Point in Westmoreland County. Coles Point is 4 miles across the Potomac River from Maryland.

“We need to spy on the profligate water users in Maryland. That’s where a lot of our water is going,” he said.

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