Environmentally enhanced hydroelectric turbines have been developed to reduce injury and mortality of downstream‐migrating fishes and to improve downstream water quality. Significant progress has been made in the past decade in the development of such turbines and in the methods to evaluate their biological and power generating performance. Full‐scale demonstrations have verified the performance of Voith Hydro's minimum gap runner turbine, which maintains high survival rates for fish while producing more power than conventional designs. Despite a promising pilot study and subsequent design enhancements, similar full‐scale demonstrations of the fish‐friendly Alden turbine have yet to be conducted. Furthermore, the tools with which to predict and evaluate the performance of new turbine designs are available and are continually being improved. This article provides a status update of advances in this field over the past decade.

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Ocean thermal energy conversion (OTEC) is a marine renewable energy technology with the potential to provide baseload power to island communities in tropical regions. Large volumes of warm and cold water are required to drive the electricity-producing cycle. This creates a risk, particularly at the warm water intake, for the impingement and entrainment of organisms. This paper provides an update on the progress of a project funded by the U.S. Department of Energy that seeks to estimate the potential impacts of a warm water intake being considered for a potential OTEC project in Kauai, Hawaii. A 9-month, site-specific biological field sampling program has recently been completed at the OTEC site under consideration in Kauai.The intent of the field sampling program was to generate a baseline characterization of the species and life stages of ichthyoplankton present in the areas where the warm water intake may be located for the potential OTEC facility. This baseline characterization data will aid in the siting, selection, and design of the best intake technology for the warm water intake. It will also provide data useful for estimating the potential impacts of an intake at this location on the organisms present.