Evan Hansen: Dissolved Solids Standard Would Protect Drinking
Water, Aquatic Life
OP-ED Charleston Gazette
5 February 2011
CHARLESTON, W.Va. -- Legislators are now considering a new total
dissolved solids (TDS) standard to protect West Virginia's streams and
rivers. TDS includes substances that impact the odor and taste of
drinking water, deposit scale in pipes and harm aquatic life.
Here in north-central West Virginia, TDS problems have recurred since
2008, when high levels in the Monongahela River fouled drinking water
supplies in Pennsylvania. High TDS levels again in fall 2009 led to a
toxic algae bloom and a massive fish and mussel kill in Dunkard Creek.
Our state Department of Environmental Protection is concerned, and has
proposed a new standard of 500 milligrams per liter (mg/L). This
standard matches that of Pennsylvania, but is twice as lenient as the
250 mg/L recommended by the federal Environmental Protection Agency.
The proposed standard fills a gap in our state rules, because we have
no enforceable TDS standard to protect rivers and streams as sources of
drinking water. It is critical to understand the difference between
drinking water standards under the Safe Drinking Water Act and public
water supply standards under the Clean Water Act. A federal TDS Safe
Drinking Water Act standard of 500 mg/L is already in place, but this
standard applies at the tap and is an unenforceable guideline that
public water systems strive to achieve. This standard does nothing to
ensure that our rivers and streams provide clean source water.
While the new standard is intended to protect rivers and streams as
sources of drinking water, it would also begin to protect the life in
those streams. DEP has proposed the TDS standard to ensure that
stream water can be efficiently treated for drinking. If the standard
is applied to all of the state's rivers and streams as proposed, it
would, as a side benefit, protect fish and other aquatic life
everywhere across the state. But if it is applied only at intake pipes
for public water systems, as some are proposing, the aquatic life
protection would be significantly weakened. While a TDS level that
truly protects aquatic life can be debated in future legislative
sessions, this standard is a solid first step toward preventing future
nightmare scenarios like the fish kill on Dunkard Creek, where there is
no public water intake and where TDS reached levels more than thirty
times the proposed standard.
The 500 mg/L limit would be an instream standard; dischargers would not
necessarily have to meet it at their discharge pipes. The new TDS
standard, like all instream standards, would be used to calculate
permit limits for dischargers such as wastewater treatment plants,
industrial facilities, and coal mines. Some dischargers have expressed
concerns that their water pollution control permits would be
strengthened to the point that limits may not be achievable. In
reality, however, TDS discharge limits would be site-specific and would
depend on the flow coming out of the pipe as well as the flow and TDS
level that already exists in the receiving stream. A wastewater
treatment plant, for example, that discharges to a major river would
generally be permitted to discharge at levels higher than 500 mg/L if
the river is relatively clean. This is because of the dilution that
such a river provides. There are certainly some situations in which
dischargers' permit limits would need to be strengthened in order to
ensure that the new standard is met in the stream. But even if the 500
mg/L standard were assigned at end-of-pipe, permits would still allow
maximum daily concentrations to exceed 500 mg/L.
It is important for legislators to be clear about what is being
proposed: a Clean Water Act instream standard to protect source water
used by public water systems. No such standard exists now. Legislative
action is necessary to fill this gap in our regulations.
Hansen is founder and president of Downstream Strategies, an
environmental consulting firm in Morgantown.