At the upper end of the Watershed District, Clear Lake is the first lake the Clearwater River flows through. As part of the District's efforts to increase the water quality in this lake, a Notch Weir was installed on the southern tributary (County Ditch No. 44) to the lake, along 355th Street. The purpose of this weir is to temporarily impound water during rain events over a 24-48 hour period. By doing so, this allows any water-born sediment a chance to settle out of the water column before entering Clear Lake. In conjunction with this weir, a sand/iron filter was constructed. The sand/iron filter provides a filter media to remove soluble phosphorus from the water column before entering Clear Lake.
An easement for this project was secured in 2011. The project was constructed in 2012, and monitoring of its effectiveness continues. The project is estimated to provide 588 lbs. per year of phosphorus reduction.
Another notch weir is located on the northern tributary to Clear Lake. Learn more here.
Permit Application for Installation of Clear Lake South Notch Weir and Sand/Iron Filter
View Project Photos