Minnesota's Legacy

Targeting Conservation Drainage in the Cobb River Ditch

Project Details by Fiscal Year
2010 Fiscal Year Funding Amount
$39,798
Fund Source
Clean Water Fund
Recipient
Greater Blue Earth River Basin Alliance
Recipient Type
Local/Regional Government
Status
Completed
Start Date
January 2010
End Date
December 2011
Activity Type
Planning
Research
Technical Assistance
Counties Affected
Freeborn
Freeborn
2010 Fiscal Year Funding Amount
$39,798
Other Funds Leveraged
$10,000
Proposed Measurable Outcome(s)

The project objective is to develop a 5 -year implementation plan to manage flow and reduce sediment yield. The effort will provide the needed background and process to extend this systematic approach to the rest of the Cobb River watershed.

Measurable Outcome(s)

Freeborn County and SWCD Staff completed a walk through' survey of this entire ditch system during year one (2011) of this process. Eleven (11) sections of Freeborn Township (T 104 N-R 23 W) or Manchester Township (T 103 N-R 22 W) were visited. Approximately one hundred and forty-eight (148) corrugated metal or plastic surface water outlets, inlets, and culverts were located, identified, and mapped with GPS equipment. Pictures were taken of water clarity, eroded banks, severe slopes, and broken outlets to note areas in need of repair. A Cobb
River Ditch Summary was completed and distributed for GBERBA review during August 2011.

Project Overview

Turbidity and sediment yield from the Le Sueur River watershed to the Minnesota River is a problem. Studies have shown that 200,000 tons/yr come from non-field sources and 25,000 tons/yr come from field sources. With this grant we will develop strategies to reduce sediment yield from the Freeborn County Cobb River Ditch subwatershed.
The Cobb River Ditch drains 30 square miles in the headwaters of the Le Sueur River watershed. The drainage basin has a rolling topography and is dominated by row crop agriculture. At the downstream end of the Cobb River Ditch, moderate sized ravines have formed however small ravines are also evident along the upstream reaches of the ditch. These ravines, as well as the upland crop fields, are sources of suspended sediment load from the Cobb River Ditch.

The project objective is to develop a 5-year implementation plan to manage flow and reduce sediment yield. The effort will provide the needed background and process to extend this systematic approach to the rest of the Cobb River watershed. It is anticipated that transferability of this application from this subwatershed to the other subwatersheds of the Cobb River will be done more efficiently and with greater expectations for outcomes. The information gathered from this area may also have practical application to other similar subwatersheds in the Blue Earth and Le Sueur River basins.

Project Manager
First Name
Kay
Last Name
Clark
Organization Name
Greater Blue Earth River Basin Alliance
Phone
(507) 831-1153 x3
Email
kay.clark@windomnet.com
Competitive Grant Making Body
Conflict of Interest Disclosed
No
Conflict of Interest Contact

Nicole Clapp