The Michigan General Industrial Storm Water permitting program has changed over the past 2 years and many companies have not adjusted their SWPPP.
Under the old program the general permits required the semi-annual comprehensive storm water inspections be performed. For many locations, the new general permits issued in 2010 and 2011 have changed this requirement to QUARTERLY. To make matters worst the MDEQ do not provide any notification of this change and they stopped sending copies of the general permit and ask the permittee to download it from the Internet.
Take a minute to download your new general permit and verify whether your inspection frequency has changed from semi-annual to quarter.