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Local Reservoir Gets Clean Bill

Charlottesville's Rivanna reservoir has
been given a clean bill of health in all but
the official formalities for reuse after a
15-day precautionary shutdown because
of a persistent pesticide in waters
upstream.

A State Water Control Board biologist
said yesterday that for the last several
days, daily tests on the reservoir for the
pesticide, endrin, consistently had shown
levels of only one-tenth or less of the amount
permitted by board standards for raw water
intakes.

Official Clearance

The State Health Department must give
official clearance for the city to resume using
the supply for drinking water. The notice will
go out as soon as the control board's written
report reaches the department, J.R. Sutherland,
assistant director of the department's bureau of
sanitary engineering, said.

Mr. Sutherland explained that there is no
great urgency since Charlottesville has ample
alternate sources of water. It is one of the few
places so well fixed in the state, he said.

The city had switched off its Rivanna supply
Dec. 1 when the control board notified it that a
pesticide was suspected to have washed into the
Mechum River from an orchard-spraying
operation when a rainfall hit the area.

The Mechum's flow enters the South Fork
of the Rivanna River several miles upstream
from the reservoir.

On Dec. 3 the board confirmed that the
potent chemical was endrin, used to control
rodents in orchards, and said it had been
detected from the headwaters of the reservoir, a
stretch of about 22 miles.

David S. Bailey, the board's chief biologist,
said dilution and settling would likely take care
of the problem in the big reservoir and below.

Board Standard

The board standard permits up to one part
per billion (ppb) of endrin in the raw water
intake of drinking water supplies. The
subsequent reservoir samples tested one-tenth
of 1 ppb or less, Bailey said yesterday. That
amount approaches the detectable limit or
accuracy of the laboratory equipment-it can't
read below 0.1 ppb precisely, he noted.

In the Mechum itself, levels of 2.1 ppb, or
twice the board standard, were found. That was
the highest concentration detected in the
incident, he said.