"It could be blue-green algae that is the problem, or it could have been hemorrhagic virus, bluetongue," said Craig Endicott, the northeast regional supervisor for the Oklahoma Department of Wildlife Conservation.
http://www.tulsaworld.com/news/article.aspx?subjectid=11&articleid=20120810_25_A11_Verdig790298
http://www.tulsaworld.com/news/article.aspx?subjectid=11&articleid=20120810_25_A11_Verdig790298