Guest column: Dredging Mirror Pond is not a sound idea
Dec 20, 2018
BY JOHN R. ANDERSON
Based on my knowledge of rivers, I believe Mirror Pond should not be dredged again — even if costs can be totally funded from private sources. From an ecological perspective, the most logical and practical solution to what will be a continuing pond dilemma is to return this reach of the river to its natural hydrology. By nature, the flow of rivers constantly transports sediment and organic matter downstream until particles drop out in areas where the current declines — such as in an artificially excavated pond. This fundamental fact means that deposition of sediment and the subsequent natural wetlands transition process, called eutrophication, will recur each time Mirror Pond is dredged.
Proponents of dredging Mirror Pond should be aware that, in future years, dredging will need to be done at more frequent intervals because of the greatly increased population of Bend since the pond was last dredged. This has resulted in many more people wading into and out of the river while engaged in tubing/floating, kayaking, paddleboarding and surfing between Farewell Bend and Drake parks. The foot traffic associated with these activities consequently dislodges a greater volume of sediment that is transported downstream and fills in the pond. The predicted continued increase in Bend’s population will only exacerbate the amount of sediment being transported downstream as more and more people wade in the river. The recent development of the surfing area below the Colorado Street Bridge has increased the number of people going into and out of the river and recreational activity here is not just limited to summer months. The increased current velocity and turbulence in (and below) the newly developed surfing area will transport sediment downstream at a more rapid rate and greater volume than previously occurred in this area.
From a biological perspective, the most logical and practical solution to what will be a continuing Mirror Pond dilemma if the pond is dredged is to return this reach of the river to its natural hydrology. This can be done at little or no cost by letting the river proceed through a natural wetlands transition that will border a deeper primary channel. Contrary to alarmist speculation that Mirror Pond will become a “mudflat” if it is not dredged, the long-range sedimentation and natural eutrophication event can be skipped by simply filling in the pond now and extending parkland to the bank of the river. This action will: 1. accelerate re-establishment of the natural hydrology of the river in this reach of the river, 2. likely cost much less than the projected cost of dredging and 3. result in a permanent solution.
There is no evidence that Mirror Pond is an “iconic” tourist attraction, and it is doubtful that most residents (or tourists) benefit any more from this ephemeral artificial pond than from other undisturbed reaches of the river flowing through Pioneer, Sawyer or other Bend parks. As for attracting tourists to Bend, it is more likely that the famous salmon hatch associated with naturally flowing reaches of the Deschutes River attracts many more fly fishing “tourists” to Bend than visitors traveling to view Mirror Pond.
I believe that neither the City Council nor the parks and recreation board should authorize spending any dollars to dredge Mirror Pond when, in my view, money authorized for public use could be better used for maintenance and construction of city roads, supporting and expanding a public transportation system, construction of a performing arts center, etc.
— John R. Anderson lives in Bend.
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