White Rock’s Second Chance
An expensive dredging project saved Dallas’ popular oasis, but only improved watershed management can prevent it from filling up with silt again.
By John H. Ostdick
On a muggy spring afternoon, J.R. Compton walks deliberately along a greening patch of Sunset Bay shoreline at White Rock Lake, about five miles from the Dallas urban core. Unfazed by large piles of dark clouds portending an approaching storm front, he studies trees above him fluttering with new growth.
“I was hoping to see some woodpeckers that were in these trees yesterday,” he says softly, his curly grey locks mimicking the wind-blown foliage.
Compton, a regular visitor to White Rock since he attended the University of Dallas in the 1960s, began photographing the more than 217 species of birds here about three years ago. His Amateur Birding Journal (www.jrcompton.com/birds) brims with images of both the spectacular and the charmingly mundane of the lake’s feathered life. His daily lake pilgrimages are a constant learning process.
Compton is but one of the thousands drawn to White Rock each week. As he speaks, a woman and her two children flaunt a “do not feed the waterfowl” notice posted awkwardly behind a tree, tossing white bread crumbs to a small army of ducks and geese. A jogger plods by, followed by two whizzing cyclists. Down the shoreline, a fisherman sits languidly in a cheap folding chair, watching his line.
This 1,100-acre lake, constructed as a water source for a growing Dallas in 1911, has been called everything from the city’s fitness epicenter to its soft soul. The urban pressures that tug at it offer insight into the life cycle of a lake and into the effects policy, politics and population growth have on lakes in Texas and across the nation.
The lake and surrounding park — home to a diverse population of mammals, including bobcats, red foxes and minks; reptiles, including rattlesnakes and horned toads; and amphibians — receive heavy recreational use. Its fervent supporters have fostered grass-roots efforts, including the White Rock Lake Foundation, founded in 1989, and For Love of the Lake, formed in 1995. The foundation was a critical force in a $9 million bond package that helped dredge what was a clogged lake in 1998, and volunteers with the Love of the Lake have hauled hundreds of tons of litter and recyclables from the lake’s shores in more than 100 consecutive months of second-Saturday spruce-ups.
As Richland College professor and unofficial White Rock historian Steven Butler describes in his History of White Rock Lake Park (Poor Scholar Publications, 2004), bison once roamed the creek bottomlands of what would become White Rock Lake as settlers began arriving in the 1840s. A growing Dallas dammed up the valley surrounded by tall rock embankments in 1911. People ventured “out in the country” by carriage to watch the reservoir fill, which it did by 1914. When White Rock became inadequate to meet Dallas water demands, Lake Dallas (now Lewisville Lake) was impounded in the late 1920s, and in 1929 the area received city park designation under the auspices of the Dallas Park Board. The lake underwent its first dredging operations in 1937. President Franklin D. Roosevelt’s Civilian Conservation Corps undertook several permanent lakeside improvements between 1935 and 1942. Subsequent dredging in 1955 and 1974 served as temporary band-aids for the lake. (For more history, see www.watermelon-kid.com/places/wrl/wrl.htm.)
Silting problems at White Rock are easy to understand. The lake’s watershed is a narrow 100-square-mile band along the 30-mile-long White Rock Creek that stretches from its upper reaches in Frisco through Plano, Richardson and North Dallas into the lake — the Dallas-area growth corridor of the past 30 years. Water escaping the lake’s spillway travels another eight miles south before emptying into the Elm Fork of the Trinity River.
As an urban watershed is developed, vegetation and land are stripped off to build houses, roadways and shopping centers. When it rains, that ravaged soil washes into creeks and flows into the lake.
In the early to mid-1970s, the area around Interstate 635 (LBJ Freeway) in North Dallas started to explode. In 1970, Plano had a population of 17,872; it doubled in size every five years into the 1980s. By 1990, the city of 72 square miles had grown to 128,713. About 25 years ago, Frisco had a population of 2,000; by 1990 that number had only grown to 6,000. The population growth rate since 1990 has been phenomenal, with a 400 percent growth rate over 10 years, making it the fastest-growing city in Texas and one of the fastest in the nation.
Although it is about 23 miles from the Bath House Cultural Center on the north side of White Rock Lake to the Frisco Texas League ballpark that opened in 2003, the explosive growth from the top of White Rock’s watershed to its heart has had an enormous impact. And although environmental impact practices have improved in recent years, the countless wooded areas, farms and ranches scraped and developed to the north in the past 25 years contributed significantly to the sediment flows, nutrient runoffs and erosion problems in the creeks feeding the lake.
In 1990, the Environmental Protection Agency instituted storm water regulations that attempted to clamp down on unregulated storm water flows, but they were too late to help prevent the clogging of White Rock. When a watershed is built out, the runoff can increase, which causes higher velocities that eat away at its tributary banks, accelerating silt loading. The City of Dallas has begun armoring the creek banks to curtail erosion problems.
“Whether it is in an urban or rural situation, watershed management is critical to water quality,” explains Pat Radloff, Water Quality Program Leader for TPWD. “It’s not just what happens on the shores of the lake — the quality of the water body depends on what goes on in its tributaries, and their tributaries.”
A 1988 U.S. Geological Services study offered a comprehensive look at the sediment entering White Rock. By the 1990s, the lake’s sediment build-up had reduced the depth at its north end to less than a foot. Some ecologists were predicting that White Rock Lake would be completely filled with sediment and debris by 2034.
In 1994, the City of Dallas utilized an EPA grant to hire Carter & Burgess, a Fort Worth–based architecture/engineering/ construction management company, to do a Clean Lakes Study of White Rock to determine its overall condition.
The study verified the lake’s high sediment levels and found that during certain summer periods its dissolved oxygen could drop, threatening the fish population. Tests for a whole host of contaminants required under the Clean Lakes Study found none above action level, however.
A grassroots effort led by White Rock–area groups won a bond issue to address the lake problems. It raised half the money needed to do the project, and the city committed to provide the other half out of its operating budget.
An ensuing study involving where to put the dredged material involved 72 sites all over the city and some highly vitriolic public meetings. “We found a site 17 miles south of the lake that was a series of old gravel pits dug out in the 1970s to acquire dirt for highway projects to the north,” says Burt Weatherbee, manager of the company’s water infrastructure unit and project manager. “They were ripe for being filled up.”
In an ironic environmental circle of life, silt and sediment that streamed from northern expansion into White Rock would be pumped back to the gravel pits that had previously yielded materials used to build the infrastructure that supported that growth.
A hydraulic dredge, basically a big vacuum cleaner, sucked up 90 percent water and 10 percent sediment, and pushed the slurry mixture down a 24-inch steel pipeline to the pits, where it was discharged. After about 72 hours, the sediment settled out and the cleaner water off the top was removed and discharged via pipeline into a South Dallas creek. “We ended up filling 200 acres of pits with four or five feet of sediment,” Weatherbee says.
The dredging company kept a collection of items recovered during the project, including three handguns, two bowling balls, a ski pole, skateboard parts, and a host of different house and auto parts used as fishing weights.
“We determined we could only dredge about 3 million of the 5 million cubic yards of sediment in the lake and stay within the budget,” Weatherbee explains. “Our goal was to try and make as much of the lake as we could at least eight feet deep. Sunlight can’t penetrate that depth, which limits the vegetation growing on lake bottom and provides a cooler layer of water for fish during the summer months. We backed into a dredging area, from about halfway up the lake. We dredged up to six feet deep of sediment in some areas.”
The construction and dredging process took about nine months, from January to September. Although his company hopes that the dredging process will last 20 years, it’s impossible to predict, Weatherbee says.
Re-testing conducted a couple of years ago found that the lake isn’t re-silting quite as quickly as expected. “In a small lake, re-silting could happen in 10 years,” Weatherbee says. “On a larger lake like White Rock, we hoped it could be 20 or more before it needs to be done again. Now that development has been completed in the watershed, the rate of sedimentation is slowing down.”
Business is good for Weatherbee’s company, which has completed about 17 other projects in the state since White Rock.
“We can repair some damage, as was done at White Rock Lake, but at what expense?” says Cindy Loeffler, water resources branch chief of TPWD’s Coastal Fisheries Division. “We need to look at the bigger concept of watershed management and brush control: If we had a little preventative medicine going in, taking care of the watershed to prevent the heavy sedimentation, maybe it (clogging of White Rock) could have been avoided.”
White Rock is but one puddle in the state’s lake system, and each faces a continuing battle of how, and for what and whom, they are used. The state did most of its heavy lifting in reservoir construction after the severe drought of the late 1950s, with projects ebbing by the 1970s.
“The big water storage lakes in Texas have a silt build-up factor planned into them, but many times that is a 50-year sediment life,” Weatherbee says. “A lot of those lakes are reaching that 50-year point now, so you are going to have issues as sedimentation starts to infringe on the water supply portion of the lakes.”
Whether dams are constructed primarily for water storage, power generation or recreation, however, every lake will follow the same general life cycle. As years go by, aging effects cause a lake to get shallower and more nutrient-rich until, left uncorrected, it turns into a marsh, wetland or bog.
In Texas recreational lakes especially, many water quality, silting and bank erosion problems are linked to the lack of stabilizing vegetation on the shore.
“If the body of water is in a state park, we encourage them to leave the habitat and vegetation around the shore as a buffer for water quality and soil stabilization purposes, but also for wildlife habitat,” explains Kathy Boydston, a wildlife management specialist with TPWD who reviews a wide range of the state’s development projects for environmental sensitivity. “We recommend that when reservoirs or lakes are built a vegetation buffer is maintained around the lake’s edge. It stabilizes the soil and cleanses some of the pollutants out of the runoff, and helps create good fish habitat.”
Other local conditions may also impact a lake’s life cycle. Cities and industries often dump materials into lakes that accelerate the growth of plankton. One such material is point-source pollution, such as discharges from municipal wastewater treatment plants; although the waste is cleaned up, some pollutant loadings remain in it. Another is non-point source pollution, untreated or less-treated water that makes its way into the state’s water systems. In an urban environment such as the White Rock Lake area, urban storm water runoff is a smorgasbord of animal feces, fertilizers, and oil and grease from cars. In a rural setting, non-point source pollution could come in the form of agricultural animal waste and fertilizers.
“Probably the biggest unresolved pollutant issue right now is what we call nutrient loading, the nitrogen and phosphorous loads that give rise to algae blooms in lakes,” says TPWD’s Radloff, a chemist formerly of the Texas Commission on Environmental Quality’s wastewater regulatory program. “The trick is finding a happy medium in managing water sources for both recreational and consumer use. For fishery managers, it’s good to have a certain amount of algae bloom because it is the primary food source in a lake. Too much algae, however, affects the amount of money spent in treating the odor and taste problems in drinking water drawn from a lake.”
Despite White Rock’s age and urban location, the fish population is abundant and generally free of pollutants, notes Tom Hungerford, a TPWD fisheries biologist for lakes in Dallas, Denton, Rockwall and Tarrant counties (except Lake Ray Roberts). Motor horsepower restrictions limit the amount of boat fishing here.
Hungerford’s office conducts rotating fish samples from lakes in its district every four years. State health services personnel also identify lakes they want to test fish from each year.
“The biggest threat to fish populations today is water demand, and how it leads to unstable water levels that upset spawning patterns,” he notes.
Texas lakes are highly managed for various uses, be it for public water supply, fisheries management or other recreational use. Texas has many power plant lakes, originally created to provide once-through cooling waters at power plants. Variances in use can influence how rapidly a lake matures and what measures are possible for a variety of ills, from heavy sedimentation to elevated mercury levels.
“Reservoirs are manipulated water bodies, and the lake cycle depends a lot on how the reservoir is operated,” explains biologist Dave Sager, a 19-year TPWD veteran with the Inland Fisheries Division. “In Texas, we have some reservoirs that rarely fill up, and everything that comes into it stays in it, and others that have a great deal of water released, which can come from down in the water column or at the surface.”
State agencies watch and manage the fisheries in Texas reservoirs. The process of producing Goldilocks’ just-right porridge is a lake-management balancing act: They try to make sure that nothing cuts off nutrients that enter the lake naturally or oversupplies nutrients, manage wastewater treatment plants, ensure people fertilize lawns in a reasonable manner, and effectively manage runoff of silt and sand loads from construction.
“Urban lakes are much more of a challenge because things can change so quickly,” Sager explains. “Construction projects far out into the watershed can have a great effect on the reservoir, as do fertilizing practices. Many of us fall into the trap of thinking that if a little is good, more is better. With fertilizers, that only works to a point without having ramifications. Things done individually can have drastic effects in an urban situation when looked at in the aggregate.”
Making certain that urban lake enthusiasts — from joggers to birdwatchers — appreciate the importance of individual initiative is critical to the reservoirs’ survival, even if the particulars of the biology involved may not be easy for everyone to understand.
“I was photographing a green heron on the far side of the bridge at the Boat House recently,” Compton recalls. “A runner came by, stopped, looked, and said, ‘Wow, I’ve never seen one of those before.’ There are 40 or 50 of them in trees there. I know he runs by them all the time, but he just never noticed them before.”
In protecting the health of Texas lakes, getting more people to stop and notice is a large part of the battle.