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Lake Thunderbird
Credit: Mark Hancock

Up to
$10,000 a day in penalties eventually could be assessed on watershed
cities if a 75 percent reduction of pollution in Little River and Hog
Creek is not achieved, according to state Department of Environmental
Quality officials.

At a
public meeting in Norman last month, DEQ representatives said that
figure represents how serious the watershed pollution problem is at Lake
Thunderbird, which long has been designated a “sensitive water supply”
by the U.S. Environmental Protection Agency.

Little
River is one of the primary watersheds flowing into Lake Thunderbird,
which provides 70 percent of Norman’s drinking water, plus drinking
water for Midwest City and Del City.

About
40 percent of the Little River and Hog Creek watersheds are in Moore
and Oklahoma City, with the balance in Norman city limits. Each city has
a five-year stormwater permit from the EPA to discharge into Lake
Thunderbird. The 75 percent reduction would affect suspended solids and
pollutants, including phosphorus, sediment, nitrogen and other organic compounds.

In
2007, the agency entered into an agreement with the Central Oklahoma
Master Conservancy District (COMCD) to do a study of the lake’s total
maximum daily load, or TMDL, but fell behind partially because of lack
of federal funding. TMDL is the amount of pollutants a water body can
receive without violating water quality standards. The TMDL study is two
years overdue, and in 2011 the COMCD and the Oklahoma Homebuilders
Association sued the agency in district court to force its completion.

“We
have been in negotiations with COMCD,” said Mark Derichsweiler,
engineering manager of DEQ’s water quality division for watersheds. “We
were put in a very awkward position.”

The new completion date is Nov. 30, with the study then to be forwarded to the EPA for review with a public comment period.

“This
end result of this process means that there would be some regulation
for Norman, Moore and Oklahoma City,” said Derichsweiler. “EPA will
insist that we have some outline of what cities are to do.”

Lake
Thunderbird is impaired by high turbidity, or murkiness; low dissolved
oxygen, which increases mortality in fish and other aquatic life; and
high chlorophyll, which has a direct relationship with algae presence.
High amounts of algae make it more difficult to meet Clean Water Act
standards.


What’s next

Next steps for DEQ
include refining pollution-flow models and simulating the limited number
of treatment scenarios, including water flow, sediment losses and
nutrient movement.

“The point is we look at all these sources that could be contributing,” Derichsweiler said.

DEQ
water quality engineer Andrew Fang said ideally the agency would like
to know how to get the pollutants’ reduction in the most cost-effective
ways.

“You have urban development. You
fertilize your lawn, that’s one thing,” he said. “You put more
concentration on the land. That will basically change the hydrological
process of your watershed. That creates a lot of erosion on your land.”

Andy
Stoddard of Dynamic Solutions of Knoxville, Tenn., a company contracted
to help with the study, said the model can be used to do “what if”
scenarios. He said Lake Thunderbird’s “sensitive water supply”
designation means it has additional protections “over and above.”

“The
model matches physical observations in the lake. … Oxygen from the air
doesn’t make it to the bottom layer,” he said. “One big piece of the
puzzle is when you get oxygen low, it triggers a big release of
phosphorus and ammonia into the lake.”

Experts
caution that when the watershed cities implement best practices such as
building wetlands in the watersheds, it will take time for those to
work.

“How long might
it take for the lake to attain compliancy?” said Stoddard. “You’re
talking in the order of a few years. … It may seem hopeless at first,
but it can be achieved.”

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