Although it wasn’t until August 1, 1923 that the new Chippewa Flowage crested only 19 inches below normal full pool, it’s interesting to note exactly when the reservoir first began filling. With the original surface level of the Chippewa River where the dam is now located hovering around 1279 feet above sea level, the waters would have to rise some 34 feet before normal full pool of 1313 feet could be reached in the Flowage.
During most of 1922 (while the dam was being constructed), a large coffer dam was in place around upriver side, the west side, and the downriver side of the project site to divert the flow of the river. The three spillways of the dam were constructed so that their sills at the base would be at an elevation of 1287 feet… perhaps as much as 14 feet above the dry river bottom.
However, beneath the east spillway a temporary sluice gate had been created – with its base at an elevation of 1277 feet – to allow the river to pass through the dam after the coffer dam which was diverting the river was removed. It was during this later phase of the project when the Tainter gates were to be installed into the three spillways.
Consequently, while the coffer dam was still in place and the river could flow around the project site, the river bottom on both the flowage side & downriver side of the dam was virtually bare ground. (See Photo #1) However, once the upriver portion of coffer dam was removed and the river was allowed to follow its original path towards the dam, the river began to be backed up by the dam. This most likely occurred on either November 9th or 10th of 1922 and marks the precise moment of inception of the Chippewa Flowage.
Once the water level reached an elevation of 1277 feet, it began passing through the sluice gate and excess water slowly began backing up into the new reservoir. This is documented by Photo #2 taken on November 12, 1922 and serves as the earliest photographic record of the Chippewa Flowage’s origins.
After the work was done installing the Tainter gates into the three spillways, the sluice gate was sealed and the water level of the reservoir eventually rose to the 1287 foot level, at which time it began spilling over the sills of the bases of the three spillways.
On March 15, 1923, the three Tainter gates were closed allowing the water in the reservoir to continue rising: reaching an elevation of 1293.6 feet by April 1, 1923, an elevation of 1302 feet by May 1, 1923, an elevation of 1306 feet by June 1, 1923, an elevation of 1309.2 feet by July 1, 1923, and peaking at an elevation of 1311.4 feet by August 1, 1923.
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