Inverse condemnation is a term used to describe a legal situation in which the government takes and/or damages private property using the power of eminent domain, but fails to pay the compensation that is required (according to the 5th Amendment of the Constitution). The same Amendment provides government agencies with the power of eminent domain, or the "right to take." Additionally, the California Constitution provides a basis for the same proceedings reflecting the federal law.
The Constitution allows the government to "take" private property if it is needed in order to complete certain types of public projects. They do so through formal condemnation proceedings. Projects that can result in this type of action are widening of public roads/freeways, the building of public transportation systems, etc. This "right to take" is established by the 5th Amendment and Article 1, Section 19 of the California Constitution. The official term for this type of action on the part of a government agency is eminent domain.
Environmental contamination is a serious problem throughout California. In fact, it's a serious problem throughout the nation. Not only does it pose dangerous health risks, but it has a decidedly negative impact on property values. One particular instance in which it becomes pointedly relevant is when government agencies are attempting to obtain a piece of private property by eminent domain.