IWP&DC takes a look at some of the hydro projects cited for environmental accomplishments in the National Hydropower Association’s 2001 Outstanding Stewardship of America’s Rivers report. The report provides examples of how hydroelectric power producers are caring for rivers in North America
Deerfield river – PG&E National Energy Group
PG&E National Energy Group’s project, the Deerfield river hydroelectric system, is located on the Deerfield river which spans 104.6km from Southern Vermont into Northwest Massachusetts.
The system,which consists of eight hydro power developments generating 85MW of power, has been recognised for land conservation efforts, endangered species protection and safeguards for wildlife habitat.
With the system, river flows and reservoir operations are regulated to protect Atlantic salmon and smallmouth bass, and to restore native brook trout to a portion of the river. In 1998 and 1999, approximately 2000 wild trout per year were introduced. Electrofishing surveys conducted in 2000 indicate that trout populations have become self-sustaining, with counts of around 2700 fish per km, exceeding fish and wildlife agency expectations. In addition, reservoir levels are also maintained for waterfowl during critical nesting periods.
The project has seen over 500 orchid plants relocated within two bypass reaches to prevent their inundation from newly required flows instituted in 1997 as part of the re-issuance of the project’s operating licence. The Vermont-listed threatened Tubercled Orchids (Platanthera flava var herbiols) are being monitored for five years using global positioning satellite systems and manual field surveys, to determine if this approach to species and habitat protection is viable.
French Broad river – Tennessee Valley Authority
Tennessee Valley Authority’s (TVA) Douglas project is located on the scenic French Broad river in Sevier County, Tennessee. The French Broad originates in the mountains of North Carolina and merges with the Holston river near Knoxville – 51km downstream from Douglas dam – to form the Tennessee river.
The Douglas project is operated for multiple purposes, including hydro power production, flood reduction, augmentation of flows for navigation, water supply, recreation and aquatic ecology. It includes a single power house with four turbines with a total capacity of 146MW.
Through the project, TVA has significantly improved conditions for aquatic life in the lower French Broad river, using a combination of technologies to add oxygen to the water released from its Douglas project and to improve minimum flows. These technologies, implemented as part of a five-year, US$50M programme to improve water quality below TVA dams throughout the Tennessee Valley, include auto-venting turbines, surface water pumps and an oxygen diffuser system. In addition, TVA operates the turbines at Douglas for 30minutes once every four hours to provide minimum flows and improve riverbed habitat. Before these systems become operational, dissolved oxygen (DO) levels of one milligram per litre (mg/l) were routinely measured in the Douglas tailwater. Now TVA is able to maintain life sustaining DO levels of four mg/l with very few exceptions.
State and federal wildlife agencies have also identified the Douglas tailwater as a suitable site for the re-introduction of several threatened and endangered freshwater species. Thousands of non-endangered mussels (16 species in all) have been transplanted to the tailwater over the past three years, and it is now also home to several protected species, including spiny riversnails and pink mucket mussels.
Osage river – AmerenUE
The Osage river basin extends from eastern Kansas to central Missouri. The 176.2MW Osage power plant is located at Bagnell dam, which forms the Lake of the Ozarks.
AmerenUE, the owner and operator, worked with the Missouri Department of Conservation to enhance fisheries and improve water quality. A common problem in deep warm water lakes is that the water stratifies during the hottest summer months – with layers of warm water rising closer to the surface and layers of colder water sinking to the bottom. Since the intakes for the Osage plant’s turbine generators are located about 18.3m below the surface, the plant discharges water with a low dissolved oxygen (DO) content into the river, reducing the already-low levels that exist downstream and putting stress on fish populations.
In the mid 1990s, AmerenUE developed new operating procedures and an improved turbine venting system which doubled the amount of DO in water released from the plant. The enhancement has been so successful that levels are sometimes higher than those naturally occurring in reservoir surface water.
Madawaska river – Ontario Power Generation
On Canada’s Madawaska river, Ontario Power Generation (OPG) operates seven major storage and hydroelectric generation facilities (611MW), while the Ontario Ministry of Natural Resources (MNR) operates 16 dams on the Mada-waska and its tributaries, primarily for flood control.
A water management plan has been completed for all sites regulated by OPG and some key Ministry of Natural Resources dams. The main challenge was to balance competing interests in a way that allowed all users to understand the interconnections of the river system whereby limits placed at one site have implications for others.
Savannah river headwaters – Duke Energy
The Jocassee Gorges area encompasses approximately 23,473ha of land in a mountain landscape with steep-sided gorges and more than 20 headwater tributaries of the Savannah river.
In 1973, Duke Power, a Duke Energy business unit, completed construction of the 3035ha Lake Jocassee and the 610MW Jocassee pumped storage station at the Jocassee dam. In 1991, the company completed construction of the Bad Creek reservoir and the 1200MW Bad Creek pumped storage station, which uses Lake Jocassee as its lower pool. Today, these two stations are a major portion of Duke Power’s generation mix serving 2M customers.
In the mid 1990s Duke Energy worked with its environmental partners to develop a conservation plan for the overall 23,473ha tract around Lake Jocassee. The resulting plan was called the Jocassee Gorges Conservation Project.
The project protects some of the most wild and beautiful lands and coldwater streams in the eastern US. At Jocassee, many of these streams drop from 914.4m to 338.3m in less than 4.8km, passing over waterfalls up to 121.9m in height and crashing through the Jocassee Gorges. The conservation project provides protection to major segments of more than 20 named streams which range in size from small first order streams, some of which support wild brook trout populations to larger rivers which include the Whitewater, Thompson, Toxaway and Horsepasture rivers.
The Clark Fork river – Avista Corporation
The Clark Fork river projects, operated by Avista Corporation, are located on the Clark Fork river which originates at the confluence of Silver Bow and Warm Springs creeks (near Butte, Montana), and winds 547.1km through western Montana to northeastern Idaho.
The projects consist of the Cabinet Gorge and Noxon Rapids hydroelectric developments, which are located along the lower Clark Fork river in northern Idaho and northwestern Montana. The projects generate on average nearly 3M MW/hr per year, enough power to meet the annual energy needs of 235,000 households.
To provide additional habitat for salmonids, including westslope cutthroat trout, rainbow trout, brown trout and mountain whitefish, Avista increased the minimum flows between the Cabinet Gorge and Lake Pend Oreille by two-thirds in 1999. The Aquatic Implementation Team is in the midst of a ten-year evaluation programme to monitor the effects of these flows on the various populations.