Why is Oxboro Lake so shallow?
Oxboro Lake was originally a wetland like much of the surrounding area and has always been somewhat shallow.
As the area was settled, many of the wet areas were drained so the land could be farmed. The farming practices of the day were not geared toward soil conservation and much of the topsoil from the surrounding area ended up in Oxboro Lake reducing the depth of the lake. The area developed into what it is known today. Storm sewer was built to convey runoff to (and from) Oxboro Lake with a focus on flood protection and sediment from the storm sewer further filled in portions of the lake.
What's the problem?
Since Oxboro is so shallow, it provides less water quality benefit than it did in the past. It will always be a shallow lake, but over time sediment has filled in portions and made it significantly less shallow. With this, sediments and nutrients remain suspended in the water instead of settling out. The water that flows into the lake almost immediately continues downstream. By restoring the lake volume, incoming water will be held for a longer period of time so that sediment and nutrients have time to settle out.
What kind of work will be done?
Water will be drained from Oxboro to expose the lake bottom to facilitate the removal of accumulated sediment using excavators and other heavy machinery.
Why are so many trees being taken out?
The trees will interfere with access to the lake and the removal effort. There is also new research that suggests that the natural mixing caused by wind is beneficial in reducing nutrients in storm water ponds. All of the vegetation being removed are low-value trees such as cottonwoods, box elder, and buckthorn. Once spring comes, we will be planting a native prairie seed mix that will prevent volunteer tree growth.
Won't the lake just fill in again?
The lessons learned in the last 50 years have led to better construction practices and maintenance approaches, so the sediment accumulation rate will much slower than in the past. It is estimated that this level of work will not be needed for at least another 50 years, most likely longer.
When will the project happen?
You may see activity as early as August 2021 and the project should wind down in spring 2022. Due to the size of the project and the variability of our warming winters, the project may need to be extended through the spring of 2023. Restoration work will be completed as soon as there are favorable growing conditions. Check back here for schedule updates.
How long will the lake be empty?
We may start draining water from the lake as early as mid-August 2021. The lake will stay mostly empty until the beginning of March 2022 when the lake will start refilling. Check back here for schedule updates as project plans are finalized.
Why will the lake be empty for so long?
The surrounding area has been disturbed in various ways for over 85 years. This has resulted in a lot of sediment accumulated in Oxboro Lake. In order to remove this much sediment, a significant effort is needed. We estimate over 4,000 truckloads could be hauled out of the area.
Will trails be added around Oxboro Lake?
No, the area surrounding Oxboro Lake is mostly private property and the upland area on City property is not wide enough to construct a trail and provide the needed shoreland buffers.
I live around the lake; what should I expect?
This fall, you should expect there to be less water in the lake than you are used to and trees down by the water will be removed. After water is drained from the lake, the contractor will build access roads down to the lake bed and then begin removing sediment. There will be higher-than usual truck traffic along Syndicate Avenue during this work.
Won't draining water from the lake be bad for fish and animals?
The lake is too shallow to support a fishery other than rough fish, possibly. Due to Oxboro Lake’s shallow depth, it typically freezes to the bottom in the winter and likely does not provide overwintering habitat for turtles.
Is there anything I can do to help protect Oxboro Lake?
Yes! Visit www.adopt-a-drain.org to find tips for protecting clean water. While you are there, you can sign up to adopt a storm drain near your house. By adopting a storm drain, you will receive a yard sign that will show your neighbors you care about clean water.
What will the restoration look like?
The restoration will use native seed mixes that will result in a natural prairie-type edge around the lake. The seed mix includes native grasses and flowers meant to attract and provide habitat for pollinators. This approach returns the area immediately around the lake to something close to its original condition prior to the area being farmed.