canals of Fredericksburg used for powering mills in 1862, with water diverted by 1855 crib dam on Rappahannock River
Source: Library of Congress, Map of Fredericksburg, Va., and vicinity
After the Rappahannock Navigation Company failed, the Fredericksburg Water Power Company purchased the company's rights on the Rappahannock and Rivanna River. The transportation rights were useless, but the company had acquired the land adjacent to the Rappahannock and Rivanna rivers that might be flooded by proposed dams.
The Fredericksburg Water Power Company built an 18' high dam at Fredericksburg in 1855, plus a canal system through the countryside outside the town. The canals carried the water to mills downstream, where the falling water turned waterwheels that powered the machinery inside.
The Fredericksburg Water Power Company became part of the Spotsylvania Water Power Company in 1910, one year after it had built a concrete dam 4' higher than the wooden 1855 dam. The extra height allowed the new 22' tall dam to supply 8,000 horsepower, compared to the 5,000 horsepower provided by the earlier dam.1. The Virginia Electric and Power Company (VEPCO) acquired the Spotsylvania Water Power Company (along with most other private utilities and built a hydropower plant to generate electricity from the falling water.
The City of Fredericksburg acquired the Embrey Dam from the local electrical utility in 1968, after VEPCO closed the small hydropower plant because it was inefficient compared to larger facilities (especially nuclear power plants). Until 1999, the city maintained the VEPCO canal that runs through Fredericksburg in order to bring water to the municipal water treatment plant. The city now relies upon a new plant upstream on Motts Run, and removal of the Embrey Dam started in 2004.
Until 2004, Embrey Dam blocked passage of anadromous fish such as American shad and striped bass. They could not spawn in the main stems of the Rappahannock and Rapidan and in tributaries to those rivers upstream of Fredericksburg, because the fish could not jump over a 22' high wall. Those species are essential to restoring the health of the Chesapeake Bay. By some estimates,2 170 miles of suitable habitat were blocked by the dam. Repairing or reconstructing Embrey Dam to meet current safety and environmental requirements would have cost Fredericksburg $10 million - 25% more than the estimated cost of removing the dam. Thanks to the efforts of Senator john Warner, the US Congress agreed to fund the dam removal.
One challenge - what to do with the sediment that had been trapped by the dam? The dam was 22 feet high when first built, but by 1998 perhaps 500,000 cubic feet of sediment had acummulated and water depth behind the dam was only 6-8 feet.3
There has been little industry in the Rappahnnock River watershed upstream of Fredericksburg, so the level of toxic chemicals in the sediments was very low. They did not need to be handled as hazardous waste, but removing the dam and allowing a slug of sediments to wash downstream would have caused a substantial short-term impact on the aquatic vegetation and fish.
The developer of the Celebrate Virginia project offered to use the sediments as fill material, reducing the cost of transport for the Corps of Engineers and increasing the amount of flat land that the real estate developer can create. The City of Fredericksburg finally purchased the disposal site, so the city would own the valuable real estate that would be created.
Estimates of the volume of sediment ranged from 270,000 cubic feet to over 500,000 cubic feet. The Corps of Engineers decided to dredge about half of the estimated volune for disposal on land. The hard-to-access remainder was spread out in a thin sheet on the river bottom, so that half was left behind the dam for natural river flows to disperse downstream towards the Chesapeake Bay. In the end, the Corps was unable to dredge all the planned sediment before the deadline for dam removal, which had to occur before the springtime fish runs. 4
As a result of incomplete removal or miscalculate volume, excess sediment plagued the Rappahannock River for years after removal of the Embrey Dam. In 2011, the local Fredericksburg paper called for the Corps to return and complete the job - at no expense to Virginia or local communities - to prevent future flooding from the barrier of sediments still remaining in the Rappahannock River.5
 old location of Embrey Dam (note I-95 in upper left) Source: US Geological Survey Fredericksburg 7.5 minute topo map (1994) |
 Rappahannock River, flowing free (now) between I-95 and old location of Embrey Dam |
