Phase I MS4s conduct ambient monitoring of surface waters, such as lakes, streams, and rivers, during normal (non-storm) events to establish baseline conditions, i.e., water quality without direct effects from stormwater runoff. While these conditions are considered normal, that is not to say impacts are not identified. In fact, several of the parameters measured and identified during ambient sampling events can only be a direct result of human impacts and are examples of residual impacts from stormwater runoff. The data also provide a reference point for wet weather conditions, i.e., a baseline to compare pre- vs. post-runoff water quality. The parameters discussed are by no means intended to be an all-inclusive list; instead, they are examples of commonly sampled parameters used to establish the presence/absence of chronic stormwater contamination or water quality impairment. Specific parameters vary based on individual watersheds.

About the author

Erin Rothman

Stormwater Scientist

Talk stormwater with With more than 15 years of environmental consulting experience, Erin observed so many opportunities for innovation in the stormwater industry. With those in mind, she founded StormSensor to enthusiastically embrace new technology to help solve the problems of an age-old industry.