Wildlife habitat and water quality
In the City of Bend survey in 2015, 77% of residents considered these values "extremely important".
Dredging has a negative impact on wildlife habitat and water quality. Technical details are well summarized in Comments to Oregon DSL by Ryan Houston, then Executive Director of Upper Deschutes Watershed Council, July 5,2017
Increase depth of water: a time limited benefit.
In a City Club forum in 2013 a panel of 3 hydrologists opinioned that 80% of sediment will reaccumulate within 10 years, 90% after 20 years. So, if depth is increased by 5 feet as currently proposed, increased depth would only be 1 foot after 10 years, and 6 inches after 20.
Impact on weed beds and mud flats: a minimal benefit.
Kayakers and paddle boarders complain of the weeds in lower Mirror Pond. But experience after the 1984 dredge documents how time limited this benefit would be. Problematic weed beds recurred only 3 years after the 1984 dredge (The Bulletin, August 13, 1987).
Mud flats are exposed when pond levels drop when dam repairs are made or when irrigators do stock runs during winter low water conditions. As for weed beds, this was a recurrent issue only 3 years after the 1984 dredge. (The Bulletin, November 17, 1987).
Project execution: During the dredge recreational use of the pond will be disrupted, city roads will carry hundreds of heavy trucks, and county landfill, already near capacity, will be stressed.
Dredging will not improve the iconic view of Mirror Pond
Photo taken January 12, 2019
Mirror Pond today - how can dredging improve on this historic view?