In the latest effort by municipalities seeking to hold fossil fuel companies liable for their alleged contribution to climate change, the city and county of Boulder, Colorado, and the county of San Miguel filed suit against two companies on April 17, 2018. Board of Commissioners of Boulder County et al. v. Suncor Energy (USA) Inc. et al., (District Court, Boulder County, Colorado). This is the first such lawsuit by noncoastal communities against the fossil fuel industry. Other similar lawsuits filed last year by coastal municipalities and counties in California and New York City seek to hold those companies liable for the costs to be incurred by them in dealing with climate change impacts in their jurisdictions, including sea level rise. Those all remain pending in different courts in various procedural postures (see "Federal Court in California Denies Remand of Climate Change Litigation" and "Another Federal Court in California Grants Remand of Climate Change Litigation"). No decision on the merits has been issued in any of those cases. 

The Colorado suit asserts claims of public and private nuisance, trespass, and unjust enrichment, as well as violations of Colorado consumer protection laws. The suit asserts, among other things, that the defendants, through the production, promotion, marketing, and sale of fossil fuels, knowingly contributed to climate change generally and, more specifically in the case of the Colorado communities, impacts to fragile high-altitude ecosystems, increased wildfires, and increased flooding and drainage. The suit also alleges various climate change-related impacts affecting roads and bridges, parks and forests, buildings, farming and agriculture, the ski industry, and public open space. The municipalities seek, among other things, past damages as well as future damages and costs to mitigate the impact of climate change.

Whether the Colorado action will be followed by other allegedly similarly situated municipalities in other parts of the United States remains to be seen. However, given press reports indicating that certain municipal entities have received authorization to retain outside counsel to investigate the possibility of filing such suits, it is likely that more can be expected in the future.