Sherman pipeline back in service, zebra mussels and all

After relying exclusively on well water for nearly a month, the city of Sherman brought its Lake Texoma pipeline back into use late last week. The pipeline, which typically supplies about half the city’s drinking water, was out of commission for the last three weeks to accommodate a railroad construction project near Pottsboro.

“We put it back on line last week, on Thursday or Friday,” said Sherman Sherman Director of Engineering and Utilities Mark Gibson. “The pipeline was closed primarily because they were installing casing under a future rail line — they’re going to build another rail line between Pottsboro and Denison — and they had to re-case the pipe under this future rail line.”

The City used the downtime to perform an annual inspection of the pipeline necessitated by a zebra mussel infestation in the lake that was first discovered in 2009. Inspectors with the U.S. Geological Survey walked the 72-inch pipeline to check for signs of the invasive creatures, the spread of which authorities are attempting to curtail.

“It was just kind of a routine type thing,” said Gibson. “The USGS comes up and inspects it — just looks inside it to see. They’ve been doing it every year for several years to see how the interior looks in relation to the zebra mussels. We haven’t heard and reports are not back from that yet.”

The fast-reproducing mollusks have been known to clog and damage water infrastructure and negatively affect endemic species. The USGS estimates that economic costs associated with zebra mussels are approaching $1 billion per year.

“There was some aspect of the visual inspection where (the inspector) did see zebra mussels, as (were also seen) in 2011,” said USGS spokeswoman Lynne Fahlquist. “They collected some samples, and they’re processing information, so we do not have the results yet. I don’t have any information beyond that — if there was anything different from 2011 — but (zebra mussels) were seen in this most recent inspection.”

Gibson explained that the City has been fortunate thus far that the mussels haven’t impeded water treatment operations.

“At this point in time it really doesn’t affect us; we’re not yet seeing any zebra mussels at the treatment plant,” said Gibson. “The City and the North Texas Water District would clean the pipeline if there were any accumulation. That’s just standard for all utilities that have zebra mussels, they have to clean their pipes, their intakes, when zebra mussels become a problem.”

The city of Sherman draws approximately 4-million gallons of water each day off the lake during the winter months, but has the rights to take much more. Major growth in the City would require local officials to pursue an upgrade of the Sherman Water Treatment Plant, located near Grayson College, which opened in 1993 with a nominal treatment capacity of 11-million gallons per day.

The City’s wells tapping the Woodbine and Trinity Aquifers are expected to dry up as water levels recede in the coming decades, making the Lake Texoma pipeline an increasingly valuable commodity for the City.


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