Yahara River Sediment Removal Project

Multiphase Project to Reduce Flooding and Improve Water Flow

Yahara River under the Lower Yahara River Trail
Currently, water comes into the Yahara Lakes faster than it goes out.  Therefore, after repetitive and heavy rainfall events, the lake levels increase and can lead to flooding.  The efficient movement of water through each lake is undermined by sediment build-up in the Yahara River.  While sediment movement is a naturally occurring process, the accumulation of sediment in the Yahara River and Lakes is greatly increased by human activity, including urban development and winter sand operations. 

Today, two inches of rain takes over two weeks to leave the Yahara Lakes system due to its sluggish nature.  This project will remove sediment in the Yahara River in five phases with a goal to improve water flow so that the delivery of two inches of rain that normally takes two weeks to travel through the Yahara Lakes system will take half as long, or one week.

 

Yahara River Sediment Removal PhasesProject Phases

Dane County’s sediment removal project in the Yahara Lakes system will take place in five phases, with each phase carried out as Dane County secures permitting - see Phase Map (PDF). The benefit to reduce flooding for all lakes is realized when sediment accumulation has been removed along the Yahara chain, thus it is critical that the phases are planned as timely as possible.  

Several factors were considered for a five phase plan including:

  • Readily available sediment and bathymetry data for developing engineering plans
  • Presence of contaminated sediment that would impact permitting timelines
  • Proximity of dewatering locations to the river
  • Existence of culturally sensitive features

 

Phase 1

The first phase, between Lakes Monona and Waubesa, is expected to be completed in 2020.  The project will involve removal of approximately 40,000 cubic yards of sediment which equates to over 3,000 dump truck loads of sediment. The sediment will be removed hydraulically by suctioning the sediment from the river bottom and transferring through a pipeline to a dewatering basin.  The sediment will be separated from the water at the dewatering basin and reused for other projects such as roadways.

Schedule

Phase

Sediment Testing

Bathymetry Collection

Engineering Plans and Specifications

Permit Submission

Request for Bids

Construction

Phase 1
Monona to Waubesa

Complete

Complete

Complete

Complete

Complete

In Progress.  Please see the Construction Updates tab for the latest updates.

Phase 2
Waubesa to Lower Mud and Kegonsa to Hwy B

Complete

Complete

In Progress

Fall 2020

Fall 2020

Spring 2021

Phase 3
Lower Mud to Kegonsa

Complete

Complete

 

 

 

 

Phase 4
Hwy B to Stoughton

Complete

In Progress

 

 

 

 

Phase 5
Mendota to Monona

Complete

In Progress

 

 

 

  •  

Construction Updates
 

August 5 2020 - Sediment removal has progressed.  Currently dredging has been completed for about 1,000 feet of the Yahara River.  The dredging work is currently located just downstream of Hwy 12/18 (upstream of Gilligan's Island).  

July 16, 2020 - Sediment removal has started upstream of Upper Mud Lake (near Gilligan's Island).  The dredge is starting at the downstream end of the project and they will be working upstream.

June 11, 2020 - Installation of approximately half of the pipeline (1.5 miles) has occured.  Currently, the dewatering basin where the dredged material will be piped to is being constructed.  Depending on weather, sediment removal is expected to start in July.

June 29, 2020 - The installation of  pipeline and construction of the dewatering basin is planned to be completed this week.  Then the dredge will be connected to the pipeline and testing of sediment removal will commence.  We are anticipated dredging to start later this week or beginning of next week.

Yahara River Sediment Removal Update #2

 

Yahara River Sediment Removal Update #1

Contact Information

Dane County Land & Water Resources Department
(608) 224-3730
lwrd@countyofdane.com