UNT Resource : Water Wisdom

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UNT Resource magazine >> Water Wisdom

Lakes have always been magnets for college students. But when University of North Texas students and professors from the Institute of Applied Sciences head to Lake Lewisville, they have something other than swimming in mind. Working on projects developed by the IAS, they are examining critical natural and human resource issues facing Texas, the nation and the world. Among the most pressing of these issues are water quality and quantity.
    Tom LaPoint, professor of biological sciences and director of the IAS, gets right to the point. Within 15 to 20 years, he predicts, water use in the region will have caught up with water supply.
    "That means it will start controlling economic growth, and that is getting people's attention," he says. "Water has to be managed well because it's going to affect economic growth and economic well-being in North Texas."
    Area lakes like Lake Lewisville, he says, are the objects of competing interests. They serve as water supply, recreation area and wildlife environment. Each use must be taken into account in the development of a water management plan.

Team for streams
That's where projects like LaPoint's Stream Team come in. This and other IAS programs are providing relevant data to local governments so that people can make informed choices when dealing with water quality problems.
    The Stream Team, headed by LaPoint, is made up of a group of UNT students and other faculty members, along with city of Denton employees. Their project, the Stream Research Facility, assesses the condition of the water flowing into Lake Lewisville — a major source of drinking water for Denton and Dallas counties.
    Located at the municipal sewage treatment plant on Pecan Creek, the facility is made up of 12 artificial streams that mimic the natural streams of the region. Each stream is 16 feet long and two feet wide, with a gravel bed similar to that found in natural streams. The streams are stocked with aquatic creatures such as insects, larvae, snails and fish.
    Researchers are able to examine the effects of chemicals that are commonly found in the lake, such as the gasoline additive MTBE (methyl tertiary butyl ether) and herbicides and pesticides such as atrazine and diazinon. By noting how the chemicals react with one another and with the aquatic life, the Stream Team can determine which chemicals are of concern and gauge the effectiveness of the city's water treatment system.
    IAS projects like these are successful, LaPoint says, because they involve aquatic biologists as well as chemists, geographers, GIS (geographical information systems) landscape analysts, sociologists and even members of UNT's environmental philosophy and environmental journalism programs. This interdisciplinary approach provides a "big-picture" assessment to the public officials who establish and implement policies related to water use.

Water problems
What are some of the issues facing the North Texas area? Pesticides, herbicides and compounds like MTBE are obvious, says LaPoint. But another issue that many people don't think about is sediments.
    "That's a big problem in reservoirs in the West and in Texas," LaPoint explains. "Suspended sediments — small particles — get into water from construction sites or are washed off roads or agricultural sites. When sediments move into a lake like Ray Roberts or even Lake Lewisville, they start to fill it up. The basin isn't as deep as it used to be, and the capacity for water storage decreases. It's become a serious problem at Lake Texoma (on the Texas/Oklahoma border)." To help decrease the incoming sediments, standard soil conservation measures are being applied to agricultural lands near the lake.
    Another issue worthy of public attention, says LaPoint, is the connection between surface water and groundwater.
    "Where groundwater aquifers are depleted, the surface water tends to disappear because water is moving to refill the aquifer. So you can have disappearing streams. Water that should be moving downstream moves down into the aquifer to try to replenish that."
    The influx of people into Denton and Collin counties poses a twofold problem, says LaPoint. "We're increasing the need for available water, and we're paving over ground that absorbs water. Research shows that the incidence of flash flooding is directly proportional to the degree of building in a watershed. We're taking away permeable surfaces with all this growth, so water can't percolate down to replenish groundwater supplies."

Public knowledge
The increase in public awareness of the issues surrounding water supply and use is a hopeful sign.
"People are beginning to think about this," says LaPoint. "We've always been able to open a tap and draw water. Now we have to learn how to manage water, and that includes managing wastewater."
Clearly, research universities such as UNT can play an important role in managing water quality and quantity. "The interesting thing for us is that we're not just looking at the toxicity and hazards of MTBE and other chemicals," LaPoint says. "We're working in a broader sense with economists, managers, public officials and others about how to manage the overall problem. And that, I think, is a good focus for the university."

MTBE is uninvited guest at Party Cove

"To MTBE or Not to MTBE: That Is the Question!" Such was the light-hearted title of a Spring 2000 environmental science seminar conducted by Ken Dickson and graduate student Anne Lee. But to Dickson, Regents Professor of biological sciences and former director of the Institute of Applied Sciences at UNT, the MTBE issue is a serious one.
      Methyl tertiary butyl ether, or MTBE for short, is a gasoline additive that acts as an oxidant. It makes gasoline more volatile, enhancing combustion and thereby cutting down on emissions into the atmosphere.
      But what's good for the air is not necessarily good for the water. For more than two years, Dickson, Lee and other graduate students have been looking at the levels of MTBE in Lake Lewisville - especially at a spot known as Party Cove, close to the intake for the city of Denton municipal water supply. Gasoline leaking from boats tied up at the popular spot and from two-stroke engines in recreational vehicles such as jet skis increased MTBE to such levels that city officials have placed a boom across the cove to block boats from entering.
      The additive poses an even greater problem in groundwater than it does in surface water. When it is present in surface water, the compound reacts with oxygen and evaporates into the atmosphere. If the supply can be cut off, the water will eventually clean itself up. But because MTBE cannot react with oxygen and evaporate when it is underground, it remains in groundwater. Leaks in gasoline delivery pipelines and underground storage tanks are the biggest culprits in groundwater contamination.
      Although current concentrations of MTBE are not considered to be a threat, officials at all levels of government are closely watching the build-up of the potential carcinogen.
      "There are a lot of unknowns about MTBE," Lee says. "We hope this project may lead to wiser ecological and economical management of recreational activity on lakes."

Clams speak eloquently about water quality

When Tom Waller's clams clam up, people listen. Waller, professor of biological sciences and director of the Aquatic Toxicology Laboratory at UNT's Institute of Applied Sciences, and doctoral student Joel Allen are using the Asiatic clam as a sentinel in the Texas Elm Fork watershed, which includes Lake Lewisville, Lake Ray Roberts and Grapevine Lake.
    Testing water for the presence of individual chemicals, says Waller, does not necessarily give an accurate or complete picture of its quality. "Living material is the best measure of toxicity because it integrates the totality of its environment," he says.
    When clams sense that the water in which they live is toxic, they protect themselves by closing their shells. The distance that a clam's shell is open, known as gape, can tell Waller and his fellow researchers when the water in the Elm Fork tributary, which flows into Lake Lewisville, is contaminated. Changes in gape, picked up by small sensors to which the clams are attached, are transmitted via cellular modems to a lab on the UNT campus. There the information is processed and posted on the project web site, www.ecoplex.unt.edu.
    The clams are part of a much larger monitoring program that involves geographical information systems, satellite imagery, hydrology, land use and other methods, says Waller.
    "Access to the data is one part of understanding what is going on in a watershed," he says. "Interpreting the data is another part. Through education, we hope to help the public interpret the data." To that end, teachers in the Denton Independent School District are developing curricula designed to teach K-8 students about watersheds.
    "Anything that goes on in the watershed has a potential impact on the reservoirs and hence our drinking-water supply," Waller explains. "Ultimately we hope to monitor the entire watershed in a way that will help us understand potential trouble spots and manage them to maximize the benefits to the animal and plant populations as well as the humans."
    The study, a joint effort by UNT and the city of Denton, is funded by the Environmental Protection Agency's EMPACT (Environmental Monitoring for Public Access and Tracking) program.

Waller and graduate student Joel Allen paddle out to the Water Quality Monitoring Platform at Lake Lewisville (top) to check the clam housing (middle). By the distance that their shells are open, the clams (bottom) can tell the researchers when the water in the Elm Fork tributary is contaminated.