Session A7 - Estimation of Turbine Passage Survival for Atlantic Salmon Entrained at Penobscot River Hydroelectric Projects
Session A7 - Estimation of Turbine Passage Survival for Atlantic Salmon Entrained at Penobscot River Hydroelectric Projects
Abstract
The National Marine Fisheries Service (NMFS) is in the process of developing a population model for endangered Atlantic salmon to assist in determining acceptable levels of incidental "take" at hydro projects on the Penobscot River in Maine. Salmon smolts and kelts migrating downstream will pass the project through a bypass (if available), over the spillway, or through the turbines. To assist with the assessment of overall project impacts, survival of smolts and kelts passing through each of 65 turbines installed at 15 Penobscot River dams was estimated. As the projects located within the basin are considered low head (<100 ft), the primary injury mechanism leading to mortality was assumed to be blade strike. Utilizing an established blade strike probability model and blade strike mortality test data, estimates of turbine passage survival associated with strike were developed for each turbine. Required turbine data associated with estimating strike survival included parameters such as runner diameter, rotational speed, number of blades, leading edge blade thickness, wicket gate angle, wicket gate trailing edge diameter, and wicket gate height. As some of this information was not always available from project owners, unknown turbine features were estimated using trends derived from available information on similar projects, as well as professional judgment. Turbine diameters ranged from about 2 to 16 ft, while the fish lengths evaluated ranged from 130 mm (about 5 inches) to 800 mm (about 31 inches). For some projects, the fish length evaluated was relatively large compared with the turbine diameter. Therefore, additional analysis was completed to estimate the impacts on survival associated with fish passing through narrow wicket gate openings and blade spacing. Final survival estimates for each turbine were completed over a range of flows and are a function of the strike probability analysis and the physical interactions with various turbine components.
Type
article
event
event
Date
2012-06-07