The Mississippi Lock and Dam No. 2 Hydroelectric Project is located at the U.S. Army Corps of Engineers’ (USACE) Lock and Dam No. 2 on the Mississippi River in Hastings, Minnesota, approximately 15 miles downstream of St. Paul. The existing project consists of (1) a powerhouse containing two generating units rated at 2,200 kW each; (2) transmission facilities consisting of (a) 6.6-kV generator leads; (b) two 3-phase, step-up transformers; (c) a 1,000-foot-long transmission line; and (3) appurtenant facilities.
The City of Hastings (City) proposes to install two hydrokinetic turbines rated at 35 kW each, suspended below a floating barge, in the tailrace of the existing project. The floating barge or platform, which would measure 65 feet wide by 50 feet long, would be tethered to the existing dam structure and anchored for stability.
Hydrokinetic turbine technology is new, and few, if any, studies of the effects of hydrokinetic turbine operation in any large river are yet available. Recent workshops (e.g., National Renewable Energy Laboratory, 2006), white papers (e.g., EPRI, Inc., 2006), and publications (e.g., Cada et al., 2007) have identified a range of potential effects, but these would be expected to vary a great deal, depending on turbine design, physical and biological conditions at each site, and other factors that might interact with hydrokinetic turbines to produce inter-related outcomes.
The City consulted with federal and state resource management agencies to identify and focus on the potential effects of installing and operating the hydrokinetic turbines at the existing project. Based on this consultation, the City proposes to monitor water quality for 1 month following installation of the turbines and to evaluate fish survival through the turbines using the HI-Z Turb’N Tag (balloon tag) tag and recapture methodology (Heisey et al., 1992). The City would protect native freshwater mussels, including the listed Higgins’ eye pearlymussel, if encountered during anchoring of the turbine/barge. The City would document non-native zebra mussels if encountered during anchoring, and would follow standard procedures to prevent the spread of this invasive species.
Staff’s recommendations include the City’s proposals, with additional water quality monitoring, a broader approach to evaluating fish entrainment and survival, systematic mussel surveys, development of a control plan for zebra mussels, and development and implementation of a bird monitoring plan. We also recommend immediate modification of turbine operation or removal of the turbine/barge, if monitoring results show adverse effects on water quality, fish, or diving birds.
Based on our independent analysis as described in this EA, the Proposed Action, with our recommended measures, does not constitute a major federal action significantly affecting the quality of the human environment.