Modeling analysis completed in effort to predict biological consequences of ionic stress

SCCWRP and its partners have completed an analysis of where levels of chlorine, sodium and other ions in the Santa Ana watershed have been elevated above background concentrations – a milestone in ongoing efforts to build a modeling tool for predicting how aquatic life are being stressed as these ion levels rise.

The modeling analysis, completed in January, accounts for dynamic climate conditions that cause background concentrations of the ions to vary naturally in response to precipitation, temperature and drought.

The goal of the project, which kicked off 2021, is to help watershed managers protect aquatic life by appropriately applying a set of existing Santa Ana basin objectives that call for capping the concentrations of multiple major ions. Managers also intend to develop prescriptive requirements for related indicators of ionic stress, including water hardness.

Managers have been limited in their ability to effectively use these indicators to manage ionic stress across the Santa Ana region because none of the indicators have been correlated with biological effects in aquatic life.