Water Management Situation Report for Cumberland River Basin Reservoir System and Associated Waterways

Conditions on Lake Cumberland, Wolf Creek Dam and its Tailwaters

August 2007 was intensely hot and dry across the Cumberland Basin with 100+ degree days becoming commonplace. With the heat came continually drier conditions and management of Lake Cumberland and the tailwater area below the dam became more challenging each day. As inflows into the lake dropped, so did the pool (lake) level, reaching elevation 680.0 on August 29. In order to conserve the Lake Cumberland pool and protect water intakes in the lake and in the Cumberland River downstream from Wolf Creek Dam, a number of sluice release patterns were tried. Management into early fall required reduced flows from the dam because there was a need to conserve water in Lake Cumberland, and no guarantee of any rainfall any time soon. One measure tried with some success was coordinating with Eastern Kentucky Power to obtain generation water from Laurel River Lake. Laurel River Lake is a deep but relatively small reservoir with the only water in storage that was available to help the ever-shrinking Lake Cumberland. Fortunately by late September, the worst of the intense heat had passed and by October some small rain systems began pushing through. However because the land was so dry, it took a number of weather systems to produce noticeable runoff to help lake levels rise. The low point of the Lake Cumberland pool was reached on October 22 when it registered 678.61.

The coolwater fisheries (striped bass, walleye, and smallmouth bass) survived the critical late summer and fall period when temperature and oxygen conditions were the worst. Wintertime will bring cooler weather and more favorable conditions for these fish. As the lake cooled in the fall, the thermocline (the layer of water separating two layers of warmer and cooler water) broke down and the lake eventually experienced turnover, reoxygenating the water column. Water quality in the lake should remain good through the winter and early spring.

At the dam, sluicing which had been maintaining the cold water regime of the upper tailwater (down as far as Burkesville, Kentucky) was helped somewhat when another of the main sluices was outfitted with an orifice gate originally designed for Center Hill Dam. This device was placed on the intake to one of the six sluice conduits and now produces a continuous flow of approximately 260 cubic feet of cold water per second. The orifice gate provides a way to “stretch” the supply of cold water by allowing a continuous though smaller flows giving water managers more options. Indications are that the discharge from the orifice gate aerates to a slightly lower, but still acceptable, degree than an unrestricted sluice discharge. KDFWR has requested that the COE continue the use of the orifice sluice gate through March 31, 2008 during any daily period of no power generation. With two more orifice gates being built, Wolf Creek Dam will have two of the devices and the original will be returned to Center Hill Dam.

View of the orifice gate discharge at Wolf Creek Dam. In left foreground iis another set of sluice openings.

By the end of October, sluice releases were limited to one in each 12 hour time period, augmented by the orifice gate release. This situation continued until December when rising pool levels combined with improving water quality conditions (associated with fall mixing) in the lake allowed resumption of some hydropower generation.

Intensive monitoring of water quality conditions at Lake Cumberland and the tailwater continues. The Corps collects biweekly samples of temperature and dissolved oxygen (DO) at two locations upstream from the dam and does grab sampling in two or three locations to monitor the tailwater. The Kentucky Department of Fish and Wildlife Resources (KDFWR) worked closely with the Corps of Engineers (COE) through the summer and fall 2007 to monitor water quality conditions in the Cumberland tailwater. KDFWR personnel deployed temperature loggers at five locations in the tailwater (Winfrey’s Ferry, Big Willis, Bakerton, Cumberland Co. Water Plant, and Cloyds Landing) to record hourly water temperatures. Data from the loggers showed suitable water temperatures for trout (<68 F) existed in the upper 30-35 miles of the tailwater throughout the summer; however, lower portions of the tailwater were often too warm for trout. Fortunately, no fish kills occurred during the critical summer/fall period and water temperatures have cooled sufficiently in the fall.

Grouting and stablization work continues on the long embankment section of Wolf Creek Dam.

During the summer, adequate DO existed in the top 35 feet of the lake. By late November, as the waters mixed, adequate DO levels had only reached down 65 feet, thus limiting the ability of the Corps to generate power. The most recent data collected in mid-December indicates mixing down to 85 feet of depth. This is still well short of complete turnover but enough to permit the generation of hydropower. Turnover is also important to life in a lake as it mixes nutrients and oxygen more deeply in the lake. Monthly water quality monitoring trips are planned to keep tabs on conditions in Lake Cumberland. Over winter data collection is vital for managers to determine the “set up” conditions for the next warm season. Water conditions in the tailwater should remain favorable throughout the winter and early spring. Temperature and oxygen levels will be suitable for trout throughout the Kentucky portion of the tailwater. Also, the increased rainfall in the fall should allow adequate flows in the tailwater. Wade fishing opportunities should remain good. As usual, the big unknown is the weather.

Pictured is a "redd" or salmon nest in the Cumberland River downstream from Wolf Creek Dam. Redds were observed at numerous locations in the Wolf Creek tailwater.