So let's take a look at total dissolved gas and Lake Roosevelt. The Columbia River originates in Canada and flows into Lake Roosevelt at the border. On the Canadian side, there are four large dams and six smaller dams that are either on the Columbia or feed into the Columbia.

In addition, the Pend Oreille River flows from the United States into the Canadian portion of the Columbia. As a result, dams on and upstream of the Pend Oreille River also contribute to TDG that comes into Lake Roosevelt.

The net result is that water flowing across the border into Lake Roosevelt exceeds the 110% TDG water quality standard about five to six months of the year.

The Spokane River also feeds into the southern part of Lake Roosevelt. There are six relatively small dams on this stretch of the river, with Little Falls being the closest to Lake Roosevelt.