Effort launched to develop protective assessment tools for California streams

SCCWRP and its partners have begun developing a suite of tools to help managers identify the specific stressors that present significant ecological risks to California streams that are in good health – a new frontier known as stream protective assessment that will complement causal assessment.

The protective assessment tools, which researchers began working to build in late October, will use stream monitoring data to shed light on how much risk different environmental stressors pose to the health of the stream’s biological communities.

The tools will focus on a range of common stressors, such as altered flow, altered habitat and elevated conductivity. Each stressor will be rated either a high, medium or low risk.

The protective assessment tools are being designed to illuminate the most serious ecological threats facing streams that are presently in good health, enabling managers to take informed actions to prevent these streams from experiencing ecological degradation. Proactive management steps could include stream restoration projects and/or implementing stormwater BMPs (best management practices) to remove contaminants in runoff.

As with causal assessment, these protective assessment tools will provide site-specific insights about vulnerabilities facing individual streams, as opposed to general statements about how biological communities respond to stressors.

The tools, which will be developed over the next two years, also will evaluate how future land-use changes and climate change will affect how much of a risk each stressor will likely pose to stream health in the future.

The protective assessment tools are being built to complement a set of causal assessment tools for Southern California streams that was first unveiled in 2019.

The causal assessment tools include the Rapid Screening Causal Assessment (RSCA) tool, a screening-level tool for rapidly identifying which specific stressors are most likely responsible for ecological degradation in streams that are in poor health; the RSCA tool is complemented by two other tiers of tools – Detailed and Confirmatory assessments – that are designed to provide increasing levels of confidence about the causes of stream degradation.

Protective assessment, which can be viewed as the inverse of causal assessment, will consist of two tiers of tools – Assessment of Present Risk and Assessment of Future Risks – that are designed to extend the time horizons of analyses and help in planning preventative actions.

Significantly, protective assessment has the potential to help direct more management attention to protecting streams that are in good ecological condition. Although protection of high-quality waters is a cornerstone of state and federal environmental policy, stream managers typically focus more of their resources and time on remediating ecologically degraded water bodies.

Researchers envision both the protective and causal assessment tools working in concert to guide managers in identifying how human activities are affecting the ecological health of streams. The tools are designed to promote transparency and consistency in how managers analyze stream data, whether for protective or causal assessment purposes.

Like the interactive Rapid Screening Causal Assessment (RSCA) tool, the protective assessment tool will be housed on a publicly accessible, interactive web dashboard that presents users with a range of analysis capabilities, from summaries to detailed outputs about the threats that different stressors pose to individual streams and stream segments.

For more information, contact Dr. David Gillett.