Illinois American Water is finishing improvements to a water tank located near the cross streets of Birch and Oak Streets in Mokena. The work to the 200,000-gallon ground storage tank in Mokena is expected to be completed by the end of September. The investment included an overcoating on the outside of the storage tank and spot welding and coating on the interior floor. New logos were also added to the exterior of the tank. The total investment is over $450,000.