Abstract
Storm water discharges associated with industrial activities must be characterized for effective analysis of pollutant loads in urban watersheds. Regulatory compliance lists and inventories developed for other purposes may be poor estimators of discharging facilities. This research evaluated usefulness, flaws, and limitations of multiple forms of existing databases; then demonstrated methods to assess, combine, and correct databases to refine estimates of potentially discharging facilities in a given region. A commercial database showed few facility listings in common with inventories developed by regional agencies under municipal storm water NPDES permits or with compliance lists maintained by other regulatory agencies (wastewater treatment authorities, fire departments, and others). Comparison to lists of known discharging facilities—self-identified as covered by regulations—showed none of these resources alone captured a large proportion of the facilities. A more intensive approach, tested for part of the Los Angeles region, composited six databases and identified only 75% of known facilities. Results were validated by phone and field verification for selected regions, showing correct location information for about 60% of the listings in two voluntary reporting systems (Toxics Reduction Inventory, and state Air Resources Board); about 65% of the listings in the commercial database; and over 80% for two local regulatory agencies (fire department and wastewater authority). Results were combined to estimate the number of facilities potentially covered by storm water regulations, suggesting the Los Angeles County total may be 100% larger, and the California total 70% larger, than estimates using U.S. Census data.