RBI has been selected by the Central Valley Clean Water Association (CVCWA) and it member agencies to lead the Phase IIa eDNA Pilot Study to evaluate the use of eDNA for determining the presence/absence of freshwater mussels in receiving waters for Central Valley POTWs. The USEPA's recent 2013 ammonia criteria, which are used by the Central Valley Water Board to establish effluent ammonia limits for each POTW's NPDES permit, requires a determination of whether freshwater mussels are present or absent in the POTW's receiving waters to determine the appropriate effluent ammonia limits. Environmental DNA (eDNA) is a revolutionary, accurate, and highly cost-effective approach that has been demonstrated by numerous recent scientific studies to be highly effective for detecting rare or cryptic species, such as freshwater mussels, that are difficult to detect using traditional visual survey methods. The presence or absence of a given species is determined by analyzing receiving water samples, using real-time quantitative polymerase chain reaction (PCR) methodology, for trace amounts of genetic material that all aquatic organisms release into the water column. As lead consultant, RBI is responsible for developing the study plan, overseeing all field data collection, and preparing a report to summarize the findings. Data collection will be conducted in October 2015. The findings from this pilot study will be used to develop guidance for conducting eDNA assessments to determine presence or absence of freshwater mussels in POTW receiving waters throughout the Central Valley. The Central Valley Regional Water Quality Control Board will use the mussel presence/absence determinations for developing NPDES permit ammonia limitations for each POTW.