The largest capital cost in new land-based aquaculture ventures is the construction of facilities in a suitable location with reliable access to clean water - features in demand by a variety of other users that compete with aquaculture interests. Dwindling availability of appropriate sites and rising costs have led to proposals to repurpose defunct municipal water treatment facilities for aquaculture in a practice known as Reclaimed Water Aquaculture (RWA). Implementing RWA in the U.S. could offer new avenues for industry expansion, offset capital costs, and utilize facilities that are often demolished at great cost to local municipalities.

A concern regarding RWA is bioaccumulation of metals and endocrine-disrupting compounds (EDC) to unsafe levels in fish tissues despite water treatment and disinfection processes. This study assessed contaminant levels in Hybrid Striped Bass (HSB) reared in RWA under two disinfection regimes (UV and UV/Ozone) and quantified changes in concentration. HSB fingerlings were stocked in eight decommissioned water treatment tanks at the Winchester Water Reclamation Facility (WWRF) for 150 days before the first sampling event in November 2014.  Half of the tanks received treated municipal water with UV as the final disinfection step and half received water with an additional ozone treatment step.  Fingerling and yearling tissue samples were sent to the Arizona Laboratory for Emerging Contaminants for metals and EDC analyses.

Preliminary metals data show levels of copper, zinc, arsenic, cadmium, tin, antimony, and lead to be within international tolerance levels for fish meant for human consumption, and except in the case of arsenic, to meet the strictest of these standards. Furthermore, tissue levels of each of these metals except for arsenic decreased between stocking and sampling, suggesting that metal levels at the WWRF did not contribute to accumulation. Sampling scheduled for October 2015 will provide additional basis for determining assimilation or clearing of contaminants in HSB tissue. Within the current data set, there were no significant differences in metal concentrations between the UV and UV/Ozone treated groups (P > 0.05). Upon receipt of additional metals and EDC data, we will revisit these relationships and analyze EDC data for presence, accumulation, and disinfection effects. At that time, further scrutiny will be applied to arsenic levels to quantify and mitigate potential sources. Based on the relatively low tissue concentrations of heavy metals so far analyzed, we do not anticipate that additional metals analyses will reveal tissue concentrations outside international or domestic action levels.