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| Taum Sauk Pumped Storage Plant | |
|---|---|
| Name | Taum Sauk Pumped Storage Plant |
| Country | United States |
| Location | Reynolds County, Missouri |
| Status | Operational |
| Owner | Ameren Missouri |
| Operator | Ameren Missouri |
| Construction began | 1960s |
| Opening | 1963 (original), 2010 (reconstruction) |
| Reservoir upper | Upper Reservoir (Reconstruction) |
| Reservoir lower | Lower Reservoir (Rolla) |
| Plant capacity | 450 MW |
| Plant type | Pumped-storage hydroelectricity |
Taum Sauk Pumped Storage Plant The Taum Sauk Pumped Storage Plant is a hydroelectric pumped-storage facility in Reynolds County, Missouri near Garden of the Gods (Missouri) and the Ozark region. It pairs an upper reservoir on Proffit Mountain with a lower reservoir at the Rolla, Missouri area to store and generate electricity for the Midcontinent Independent System Operator footprint and the grid served by Ameren Corporation and Ameren Missouri. The site has been central to discussions involving flood control, energy storage, infrastructure resilience, and regulatory action by the Missouri Public Service Commission.
Taum Sauk operates as a closed-loop pumped-storage hydroelectricity system employing reversible pump-turbines to move water between an upper reservoir on Proffit Mountain and a lower reservoir in a valley near Johnson’s Shut-Ins State Park. The facility contributes to regional load balancing, ancillary services, and peak shaving for utilities like Ameren Missouri and markets administered by MISO and the Midwest Reliability Organization. Its location in the Ozark Plateau places it adjacent to conservation areas such as Mark Twain National Forest and geological landmarks like Taum Sauk Mountain and Johnson's Shut-Ins.
Planning for pumped storage at Taum Sauk began amid post-war expansion of the United States power grid and regional development led by utilities that later became part of Union Electric Company and then Ameren Corporation. Construction occurred during the late 1950s and early 1960s, contemporaneous with projects such as Burr Oak and other midwestern hydro projects influenced by federal policies and state permits from the Missouri Department of Natural Resources. The plant entered service in 1963 and became integrated into regional power operations alongside coal-fired plants like Labadie Power Station and nuclear projects such as Callaway Plant.
The plant uses a high-elevation upper reservoir formed by an earthen/rockfill dam and a reinforced concrete upper ring, paired with a lower reservoir and a penstock-fed powerhouse containing reversible Francis pump-turbines. Original installed capacity was approximately 450 MW with two reversible units capable of rapid mode switching for frequency regulation and load-following, similar in function to units at Bath County Pumped Storage Station and Raccoon Mountain Pumped-Storage Plant. Civil works accounted for geology of the Saint Francois Mountains and proximity to Proffit Mountain, necessitating foundations tied to Precambrian igneous formations and design reviews by firms and regulators with expertise in dam engineering such as entities that consult for U.S. Army Corps of Engineers projects.
Operationally, Taum Sauk cycles daily to store excess generation from baseload resources and intermittent imports, providing spinning reserve and peaking energy to support utilities including Ameren Illinois affiliates and entities trading in PJH markets and MISO schedules. Performance metrics historically included round-trip efficiency, response time, and ramp rates, with comparisons often drawn to other pumped-storage assets like Dinorwig Power Station and Pumped-storage hydroelectricity in the United States. Maintenance, reservoir management, and spillway control have been coordinated with state agencies including the Missouri Department of Natural Resources and emergency responders such as Reynolds County Emergency Management.
On December 14, 2005, the upper reservoir experienced a catastrophic breach, releasing a large volume of water that caused downstream flooding, property damage, and environmental impacts within Johnson’s Shut-Ins State Park and riparian corridors of Black River (Missouri). The incident prompted investigations by the Federal Energy Regulatory Commission and litigation involving AmerenUE (now Ameren Missouri), leading to settlements, fines, and a comprehensive reconstruction program. Reconstruction included redesign of the upper reservoir with modern concrete containment, breach analyses influenced by case studies such as the Teton Dam failure, and compliance upgrades informed by dam safety standards from organizations like the Association of State Dam Safety Officials. The rebuilt plant returned to service after extensive testing, commissioning, and oversight from the Missouri Public Service Commission and federal entities.
Environmental concerns from the 2005 breach and routine operations involved impacts to aquatic habitats, sediment transport, and riparian vegetation, prompting remediation efforts coordinated with the Missouri Department of Conservation and U.S. Fish and Wildlife Service. Regulatory scrutiny extended to licensing under the Federal Power Act and enforcement by the FERC Office of Energy Projects, as well as state permitting with the Missouri Department of Natural Resources and compliance with laws administered by agencies like the Environmental Protection Agency. The project intersects with regional conservation priorities associated with Mark Twain National Forest, Ozark Highlands, and recreational sites such as Johnson's Shut-Ins State Park and has spurred dialogues involving environmental advocacy groups and utility regulators.
Ownership and operation transitioned through corporate reorganizations from Union Electric Company to Ameren Corporation, with current operations by Ameren Missouri. The plant provides economic benefits through grid reliability, ancillary service markets in MISO and associated cost savings relative to peaking thermal units, and local employment and contracting during construction and reconstruction phases. Economic analyses consider avoided costs relative to natural gas peaker plants, market revenue streams from capacity markets similar to those in PJM Interconnection and ISO New England (as points of comparison), as well as long-term asset valuation within Ameren’s utility portfolio and state utility oversight by the Missouri Public Service Commission.
Category:Hydroelectric power stations in Missouri Category:Pumped-storage hydroelectric power stations in the United States