Fish Out of Water
With all the competition for water among humans, who’s looking out for the fish?
By Larry D. Hodge
In the long history of competition for water, the fish that live in lakes and streams have generally been overlooked. Future competition for water may become so fierce, however, that failure to consider the needs of fish may be their death sentence. Texas Parks and Wildlife Department fisheries biologists, along with reservoir controlling agencies, constantly look for new ways to manage water levels in reservoirs and stream flows in rivers to try to balance the needs of people and fish.
The job is far from simple.
Two facts of geography make it so. One: Texas is a vast table with its top tilted downward from the Panhandle toward the Gulf Coast. Two: Average annual rainfall decreases as one travels westward in Texas, from about 55 inches near the Louisiana border to 10 inches or less in West Texas. Texas rivers run the wrong way, from arid West Texas to humid East Texas. West Texas reservoirs are almost always short of water, and East Texas reservoirs can drop dramatically during extended droughts.
The drought in East Texas in 2005 and 2006 sent a wakeup call to fisheries biologists and reservoir operators alike. Dave Terre, TPWD’s Inland Fisheries regional director for East Texas, says: “We are used to fairly stable water levels in East Texas, and lately we’ve seen lakes where low levels meant we didn’t have boater access. As long as there is water, the fish will be there, but we need to help anglers have access. If we don’t have boat ramps in the water, we won’t sell fishing licenses.”
The Sabine River Authority manages Lake Fork, along with Lake Tawakoni and Toledo Bend Reservoir, and general manager Jerry Clark fears the recent drought presages things to come. “The weather does not always cooperate with us on its timing on inflows to these lakes. We have to manage between weather systems, whether it be flooding or drought. As the population of Texas and especially the Dallas-Fort Worth Metroplex grows, we will see increased demand on Lakes Fork and Tawakoni. Lake levels will vary more than they have in the past.”
Fluctuating lake levels worry people in charge of supplying water for municipal and other human needs, but fisheries biologists prefer a more dynamic system. “What fisheries biologists would like to see,” says TPWD Inland Fisheries district biologist Todd Driscoll, “is lake levels slowly drawn down during the summer to allow terrestrial vegetation to grow in the fluctuation zone. Then in December and January, let the lake rise to flood all that growth to provide spawning habitat and cover for young fish. To maximize the survival of fish, maintain water levels as high and stable as possible through mid-summer, then start the whole process again.”
Historically, East Texas has had rainfall in the patterns that seem to work for fisheries. “Most East Texas lakes have some aquatic vegetation, so even when they get low, they still have habitat that can protect young fish,” says Terre. “When they come back up, the fish spawn and grow like crazy. In West Texas the droughts are generally longer, but when the lakes rise, they are like new lakes because of all the vegetation that grew up while they were down. Then — wow — you have some of the best fishing in the state.”
SRA’s Clark points out: “We can’t control the rainfall. The public needs to understand that more storage capacity — more reservoirs — is the only way we can spread demand around to help maintain existing reservoirs and the fish and wildlife habitat. In the longer term, there is some potential for the reuse of water and the storage of reused water.”
Many Texas reservoirs were financed by cities for water supply or by power companies for the generation of electricity, and reservoir managers are contractually bound to supply their needs first. “We have to meet the terms of those contracts,” says SRA operations manager Donnie Henson. “Then we can start looking at the recreational and wildlife habitat needs. We think those are very valuable things to Texas and the rest of the nation. But the first thing we have to do is operate to keep the contracts valid.”
Reservoir managers and fisheries biologists both are caught between a lake and a hard place — but there may be some wiggle room. Experience gained from the management of several reservoirs suggests that sometimes lakes can be managed for the best interests of both people and wildlife, or at least to minimize negative impacts on both.
“In the future, I think we need to look at water usage by people who already own the water,” says Bill Provine, chief of management and research for TPWD’s Inland Fisheries Division. “For example, take Lake Fork, the premier bass fishing destination in Texas. It has a big pipe in it leading to Dallas. They have not used it yet, but someday they will. We need to be able to tell them, ‘We understand you need this water, but this is what its economic value is to fish and wildlife.’ It may influence them to let us help them manage their strategies for using it. Draw-downs have short-term impacts on reservoirs like Lake Fork, and it’s totally within our expertise to figure out when those impacts need to occur. If a city is drawing water from four lakes, it could avoid drawing all four of them down during the spring spawning season every year. Lake Fork could be left alone during the spring, then drawn down in the fall to let vegetation grow that, when reflooded, would release nutrients into the water for fish to use. Using the economic value of recreation and fishing on reservoirs to help negotiate these strategies is going to be very important.”
Fishing regulations are another way to minimize the impacts of varying water levels on fisheries, says Bobby Farquhar, West Texas regional director for Inland Fisheries. “Reservoirs were built to supply water for municipal or other uses, and we have to be realistic about the fact that fisheries management needs are going to be secondary. Water must be used for people first, and we have to work around that through stocking and regulations to protect fish. For instance, if a lake has been down a long time and then fills up, you can stock it and then put a restrictive limit like an 18-inch minimum length on it. That buys you some time when the lake starts back down, because you protect your brood fish. It’s boom and bust in West Texas, and you have to ride the waves.”
Lake B.A. Steinhagen near Jasper is an example of the fact that in rare instances, the best way to heal an ailing lake is to remove the water. A shallow lake maintained at a high level for 60 years to aid in hydropower generation, Steinhagen silted up and became clogged with both living and dead aquatic vegetation, much of it invasive exotics like hydrilla and water hyacinth. Fishing, duck hunting and other recreational uses were severely impacted. “The lake was in the primary stages of becoming a peat bog,” says Howard Elder, a TPWD aquatic vegetation biologist. “The controlling authority, the U.S. Army Corps of Engineers, suggested draining the lake to dry it out and allow the vegetation to freeze, then decay. We are hoping to show that well-timed draw-downs can put invasive aquatic vegetation under stress and perhaps help control it. The lake is now covered with grass five to six feet high, and when it refills, nutrients from those plants will go back into the system and make it very rich, which will be good for fish and other wildlife.”
An unwelcome aspect of reservoirs is that their construction can result in the loss of bottomland hardwood habitat. “We do have to mitigate for that when we build a reservoir,” points out SRA’s water resources manager, Jack Tatum. Mitigation involves creating a like amount of similar habitat as close to the area impacted as possible. “We work with the Texas Parks and Wildlife Department to try to minimize impacts on fish and wildlife. In addition, we feel the reservoirs don’t get enough credit for the fish, duck and other wildlife habitat they create.”
Sometimes the habitat created is in the stream below the reservoir. “Across the South in the 1940s and 1950s, a lot of hydropower dams were built, and it was found that cold-water releases from those dams caused major losses of the historical fisheries in the rivers below,” says David Schroeder, a former member of the board of directors of the world’s largest chapter of Trout Unlimited, Guadalupe River Trout Unlimited, whose home water is the Guadalupe River near New Braunfels. “So the federal government started a mitigation program that replaced the loss of native fishes with rainbow trout. The original plans for Canyon Lake called for a trout fishery in 10 miles of tailwater supported by a consistent 200 cubic feet per second (CFS) flow, but the reality was that the releases from the lake usually diminished to much less than that over the summer. The habitat was never uniform enough to support either a warm-water or a cold-water fishery.”
Working with the Guadalupe-Blanco River Authority, GRTU secured a contract that provides for a 200 CFS release of water from Canyon Lake from May through September in years when the lake is at conservation level after January 1. (“Conservation level” or “conservation storage” is the water level reservoir managers try to maintain on a given lake; it is considered “full” at this level. Reservoirs often are designed to hold flood waters in storage above the conservation level. That level is called “flood storage” or “flood pool.”) “Canyon Dam happens to be the only one in Texas that releases water from the bottom of the dam, where it’s coldest,” explains GRTU president Mick McCorcle. “That keeps the water cold enough to keep trout alive year-round up to 10 miles downstream.” As a result, the Guadalupe has been voted one of the top 100 trout streams in America.
It’s not just about trout, says Schroeder. “About six inches of water from the full lake is what it takes to fulfill the contract,” he says. “The Guadalupe is one of Texas’s premier recreational rivers, and tubers, businesses in New Braunfels and fisheries downstream all benefit. And GBRA still owns that water — they can pick it up downstream and sell it if they want to. That six inches of water yields tremendous benefits.”
“Water is a valuable resource in this state, and its value up to this point has been mainly based on its commercial value for municipal, agricultural and industrial use,” says Provine. “Recreation didn’t really have a value placed on it. We have started looking into the value of our fisheries. One of the first economic studies we did was on Lake Fork, where it was found that fishing yields $27 million a year in direct expenditures. That’s a huge benefit to the community, and knowledge of that is a huge benefit to anglers. We no longer have a sport that’s just nice to do — it’s one that brings a significant amount of money to our state. There are a lot of people at the table wanting their water — for rice farming, for cities, for industry. We can say, ‘Wait a minute. That water is worth this much to anglers, and we want some of it, too.’”
Aldo Leopold, the father of the modern conservation movement, titled one of his essays “Round River,” using a mythical circular river flowing around and back into itself to illustrate the idea of ecology. A cooperative project between the Tarrant Regional Water District and TPWD creates a “round river” using Trinity River water (See also “Washing the Water,” July 2006).
Water from the Trinity is routed through a wetland on TPWD’s Richland Creek Wildlife Management Area before being pumped into Richland-Chambers Reservoir and from there upstream to Fort Worth, where it flows through the city’s water mains and then begins its journey anew. The week-long trip through the wetlands improves the river water, which is as much as 95 percent treated effluent, to the point that it is cleaner than the water in the lake. “TRWD gets improved water quality, and TPWD and the people of Texas get high-quality wildlife habitat for a variety of species,” says WMA manager Jeff Gunnels.
“The cost of treating water using wetlands is about half the cost of building a new reservoir — and you don’t have to go through a 20-year permitting process,” says TRWD project manager Darrel Andrews.
Hot Topic: Power Plant Lakes
Lakes in Texas often provide more than one service. For example, the state currently has more than 40 steam-electric power plant lakes that serve as sources of cooling water necessary for the production of electricity. Many of these lakes, located mainly in central and northeast Texas, provide excellent fishing, especially in the cooler winter months. Warmer water temperatures help fish remain active during the winter and early spring, attracting anglers in search of action. But there are also potential negative impacts to fish and wildlife.
Steam-electric power plants can use enormous quantities of water for cooling in the production of electricity. Current cooling water use in Texas is about 75 million acre-feet per year, expected to increase by almost 10 times by 2060.
Steam is produced either through burning of fossil fuels (i.e. coal) or by nuclear reaction. Steam spins turbines that produce electricity. Steam is cooled by lake water and warmed water is returned to the lake. During this process, fish and other organisms may be drawn into the power plants and killed when larger individuals become pinned on the intake screens or other parts of the intake structure (a process called impingement) or when smaller organisms like fish eggs and larvae pass through the intake screens into the station (a process called entrainment). The warm water that is discharged can also be detrimental to wildlife.
To help guard against unnecessary loss of life, Section 316(b) of the Clean Water Act requires that the location, design, construction and capacity of cooling water intake structures reflect the best technology available (if the facilities were completed after December 2001). Existing electric generating plants that use large amounts of cooling water and at least 25 percent of their withdrawn water for cooling purposes are also subject to the new rules.
TPWD staff often review and comment on development proposals that may affect fish and wildlife resources. During these reviews the impacts expected to occur are assessed, and if they are determined to be excessive, measures are recommended to minimize adverse environmental impacts. For example, minimum mesh sizes for intake screens may be recommended to minimize entrainment of eggs and larvae and minimum intake velocities may be recommended to reduce the potential for impingement of fish on intake screens.
Several power plant lakes in Texas have been the target of fish consumption bans or advisories for human health risks. The Texas Department of State Health Services may issue bans or advisories to protect public health if concentrations of harmful contaminants exceed certain risk levels. For example, a fish consumption advisory was issued in 1992 for Martin Creek Lake in Rusk and Panola counties. Fish tissue samples indicated excessive levels of selenium. The mineral is good for you in small amounts, but high doses can cause neurological problems. TDSHS has since rescinded the advisory, based on results from a new risk assessment.
— Cindy Loeffler