BMPs should be considered and implemented in that order: administrative, source control, and then treatment control. Implementing BMPs in this order is the most cost effective and does the best job of protecting stormwater quality. Administratively eliminating pollution sources will almost always be the best solution. Using source control BMPs to eliminate pollutant sources prior to polluting stormwater runoff should be your next option. Your last option is to treat stormwater runoff in an effort to remove pollutants.
Treatment is likely the most expensive and often least effective way to go. Treatment control should be a part of your overall stormwater pollution prevention strategy as a last and final effort to remove pollutants that could not feasibly be addressed through administrative and source control BMPs. Treatment control BMPs should not be used as stand alone BMPs.