Most facilities are required to conduct visual monitoring of stormwater discharges. This typically requires collecting a sample of stormwater discharge within the first 30 minutes of discharge.

Given the 30-minute requirement, most facilities need to have their staff trained to conduct visual monitoring

Chemical monitoring is an extension of visual monitoring - instead of visually describing the samples, they are sent to a lab for analysis.

Many States have included "benchmark values" to compare the results of chemical monitoring, and to determine if corrective action is needed.

Caltha provides monitoring kits to facilities to collect and ship samples.

In some areas, each outfall must be inspected periodically to determine if non-stormwater water is being discharged.