Providing a whole-picture biological survey using eDNA technology

VenturaWaterPure eDNA Survey

The VenturaWaterPure program aims to recycle and beneficially reuse tertiary-treated water at a new advanced water purification facility. This effort will augment the City of Ventura’s potable water supply while enhancing the Santa Clara River Estuary’s ecosystem by reducing amount of treated effluent discharged there. To support this, the City engaged our team to conduct baseline ecological monitoring of fish populations within the estuary.

A critical challenge in this effort involves monitoring special-status species—particularly the Southern California steelhead trout—without causing harm or “take” of these protected fish. Traditional survey methods are often limited in detecting the presence of cryptic species, especially if they are present in low abundance.

To overcome this, we’ve incorporated environmental DNA (eDNA) sampling, an approach that detects genetic traces organisms leave behind in their environment, whether from skin, scales, mucus, or other biological materials. eDNA metabarcoding allows us to characterize the full fish and amphibian community of the Santa Clara River Estuary, and quantitative polymerase chain reaction (qPCR) analyses focus in on special-status species. Together, these techniques provides a cost-effective, non-invasive way to track population changes without the physical handling of sensitive species.

By using eDNA, this process not only complies with State regulatory constraints but also equips the City with supplementary ecological insights beyond those of more traditional fish sampling. If anticipated ecological benefits are observed following the initial reduction of tertiary treated water to the estuary, then the City may further reduce their discharge to a scientifically-recommended level. However, if take of listed species are detected or anticipated, decision-makers may remain at the initial discharge level or adjust effluent management practices.