Public and private developers and planners often encounter environmental contamination caused by leaking underground storage tanks (LUSTs) when redeveloping previously used urban lands(brownfields). This article addresses the process by which underground storage tanks (USTs) are regulated, how leaks are discovered, and the proportion of serious leak incidents with groundwater contamination. Empirical case-study evidence of 429 leaking tank sites in Cuyahoga County, Ohio, describes the severity of leaks, how they were discovered, and the effect of a No Further Action status, which was minimal. Programmatic failure of the state regulatory agency may be partly responsible for this lower transaction rate and may partially contribute to many closed tank locations and inadvertent loss of jobs. Trends in liability reduction for USTs may change this in the near future.