MS4 located in an incorporated place with a population of 100,000 or more but less than 250,000, as determined by the latest U.S. Census.
MEDIUM MUNICIPAL SEPARATE STORM SEWER SYSTEM (MS4)
Meaning of MEDIUM MUNICIPAL SEPARATE STORM SEWER SYSTEM (MS4) in English
Environmental engineering English vocabulary. Английский словарь экологического инжиниринга. 2012