Flooding of Mill Creek

From the City regarding recent flooding:

The Earthworks Park Dam did work as it is intended. The most significant amount of rainfall that we received was on Wednesday and the dam was holding back water that evening. The rainfall let up around midnight and the dam was drained out by morning. The storm event was a large one, but not extremely large, which is why the dam didn’t completely fill, and why it drained out before morning. The dam improvements that were done this past summer will serve to hold additional water during larger storm events such as the twenty five to one hundred year events where we would receive three to four inches of rain in a 24 hour period. The local rainfall this past Wednesday, Jan. 7th was approximately two inches.

The Dam does not, by itself, control the flooding on Mill Creek. There is a larger dam on the top of the hill which also holds water, and the City’s Green River Natural Resource Area along the Green River also holds flood water from Mill Creek during storms. These facilities were functioning during this storm as well.

The City does have areas of improvement needed in its flood protection system. Changes over the years in land use and environmental regulations have created many of these needs, and the City has recently adopted a new Drainage Master Plan with capital improvement projects to deal with those. Much of the flood protection work in the Drainage Master Plan is focused on Mill Creek, including enlarging the Upper Mill Creek Dam, enlarging and restoring the Mill Creek channel through the valley and improving the Green River Natural Resource Area to function more efficiently during storm events. These improvements, many of which are very significant in size, will be going into construction over the next ten years with the highest priority going first.