The city of Sherman, for whatever it lacks, does not lack for water. Scratch that — the city of Sherman does not lack for water rights. The city has spent $10.8 million over the past 22 years to purchase the legal rights to 33,400 acre-feet of Lake Texoma water each year, or roughly 29.8 million gallons a day. To put that number in perspective, on its peak of peak days, the city uses about 17 million gallons.

The city of Sherman, for whatever it lacks, does not lack for water. Scratch that — the city of Sherman does not lack for water rights. The city has spent $10.8 million over the past 22 years to purchase the legal rights to 33,400 acre-feet of Lake Texoma water each year, or roughly 29.8 million gallons a day. To put that number in perspective, on its peak of peak days, the city uses about 17 million gallons.


And due to the efforts of former Sherman Mayor David Sprowl and others, Sherman even has the ability to access that water, in the form of the 12-mile-long, 72-inch-diameter pipeline that connects the city’s water system to the lake. Combined with 24 groundwater wells the city can operate when needed, it all means Sherman can use about 41 million gallons of water on any given day.


In theory.


But between theory and reality lies a rather particular problem: the city’s water treatment plant, which can treat and desalinate only about 10 million gallons of lake water in a 24-hour period.


It’s a problem for a growing city that Sherman City councilors heard all about on Wednesday, as Director of Utilities Mark Gibson laid out the town’s water needs and the money that will be required to meet them. The meeting was the third in a four-part series on the city’s infrastructure needs orchestrated by Mayor Cary Wacker prior to the annual budget session this summer.


Gibson submitted a proposal to Council Wednesday to double the capacity of the treatment plant by implementing new and expanded filtration technology, with costs estimated at $15 million. Gibson said he projects the upgrade would meet the city’s needs through the next two decades. A full monty upgrade of the plant to 60 million gallons per day capacity — a move that would put Sherman in position to become something of a clean water exporter for North Texas — would cost approximately $130 million, plus costs associated with adding a second pipeline to the lake.


"Our demand on peak days is approaching our capacity," said Gibson. "The main thing to take away is, no matter how you slice it, we’ve got about three years … from the time we decide we’re going to start doing something and the time that water comes out of the plant. So we’re at 2014 right now, if we decided to start now, it’s going to be 2017 before we get any water out of that (upgrade)."


At the heart of Gibson’s proposal were two new technologies that would allow the city to clean multitudes more water with only a minimal increase in the plant’s footprint. Gibson explained that membrane filters — essentially pipes filled with cleaning cords, similar in appearance to a fiber-optic cable — would replace the current technology which uses a flocculator and sediment basin to tease out large, particulate impurities, and a series of media filters to handle finer material.


A second upgrade would ditch proprietary EDR technology for more efficient, generic reverse osmosis trains in order to desalinate the brackish lake water. Because EDR is owned wholly by General Electric, the costs associated with replacement and maintenance are higher than reverse osmosis, for which numerous companies make competing parts, said Gibson. Further, the RO tubes are easily replaceable when things go awry. In contrast, EDR uses stacks of electrodialysis membrane layers which must be peeled-back one-by-one in order to be repaired.


"The filaments, the fibers that are used in (reverse osmosis) filter the water so much that you take out bacteria and viruses," explained Gibson. "So it’s a better, a more thorough treatment process than an EDR unit."


Councilors seemed on-board with the proposal, with several members suggesting that spending more money now on a larger upgrade could save the city funds in the long run. But very few fiscal decisions at the local government level are made in a vacuum, which means desires to upgrade water treatment capacity will have to be weighed against competing infrastructure priorities such as a new fire station and flood mitigation projects.


On that front, however, Sherman will have one new arrow in its quiver when it comes time to take aim at the city’s needs. The nearly completed Panda natural gas power plant on the city’s south edge will require 5 million gallons of untreated lake water each day to provide steam for its turbines, and each of those gallons will put a few more cents in Sherman’s coffers. A rough estimate provided by the Greater Texoma Utility Authority of Sherman’s cut of the Panda money was in the neighborhood of $1 million each year.


When asked if the new Panda revenue stream could help pay for the water treatment upgrades, Assistant City Manager Robby Hefton said simply "Yes," sparking laughter among the Council before he elaborated.


"We have a water services agreement with Panda that spells out what the rate is; there are certain guarantees of providing ‘X’ amount of water at certain pressures, so the short answer is yes, we do get revenue from that," said Hefton. "Can that revenue be used to leverage things like expanding the plant? Yes, but in the larger context of everything else that’s going on in the (city)."