At the request of the U. S. Forest Service on Ogden, Utah, limited water quality investigations were made on the upper Green River by the Colorado River Basin Project in relation to possible effects from the Forest Service Moose Creek Insect Control operation conducted in the summer-fall of 1962, when approximately 5,500 acres of evergreen forest were treated for spruce bark beetle control. It was believed that heavy rains might wash some of the spray material into streams and have an effect on aquatic life or other water quality characteristics. No apparent runoff of the ethylene dibromide spray was found.