By Adam Wilmoth Energy Editor awilmoth@oklahoman.comThree environmental groups on Tuesday sent a letter to the Environmental Protection Agency, asking the new leadership to address what they say appears to be preferential treatment shown to three Oklahoma City-based oil and natural gas companies. The Oklahoma companies said they are continuing to work with the EPA, and the agency said the environmental groups' letter contains "significant factual errors and omissions.Read more on NewsOK.com