Authorities in northwest Iowa have arrested 21 people in a drug sting after an investigation that ran 18 months. Storm Lake police say “Operation Crystal Ball” was carried out Tuesday along with help from police departments in Newell, Cherokee, Sheldon, Denison and sheriff’s departments in Ida, Buena Vista and O’Brien counties.

Charges filed against the suspects range from delivery of a controlled substance to possession with bonds as high as 250-thousand dollars. 15 of the 21 suspects are from Storm Lake. The others are from: Holstein, Cherokee, Sheldon, Denison and Newell. More arrests are pending.