Long term sediment research project in South Central Minnesota concludes

The Collaborative for Sediment Source Reduction (CSSR) in the Greater Blue Earth River Basin project was a five-year effort to evaluate strategies for reducing sediment making its way into the Minnesota River via the Blue Earth River. The goal of the project was to incorporate the best available science to develop a decision-making model to reduce sediment pollution through a strategy that is effective, cost-efficient, fair and supported by all stakeholders.

Through a series of nine meetings, stakeholders considered various sediment sources, sediment delivery mechanisms and actions that may reduce sediment transport downstream. Sediment sources were categorized into three primary areas- uplands, ravines and bluffs- each with its own associated reduction strategies.

Overall, the primary sediment reduction target identified by the project was reducing peak flows. This could potentially be accomplished by increasing temporary water storage through strategic wetland restorations, settling ponds, drainage design and increasing the water holding capabilities of soils. These practices provide the greatest benefit when water management can apply the principal of “catch and release,” in contrast to catch and hold strategies. The water holding capacity of soils can be improved by increasing infiltration, often associated with reduced tillage intensity and higher organic matter levels, along with increasing soil health by reducing the duration of saturated soil conditions, often associated with improved drainage.

One example of a multi-faceted project that could potentially address peak flows and sediment levels came to fruition in parallel to the CSSR project. Led by a group of local landowners, with the support of professional engineers and funding from the Legislative- Citizen Commission on Minnesota Resources (LCCMR), changes were made to Blue Earth County Ditch 57 that enhanced crop production through improved tile drainage, helped protect city infrastructure, and provided increased water quality treatment of drainage water. You can find more information about this project, including monitoring data, here- http://www.is-grp.com/project/blue-earth-county-ditch-no-57/.

2 Responses

  1. Todd Prill
    | Reply

    Can you give some examples of traditional “catch and hold” strategies?

  2. Warren Formo
    | Reply

    Some examples would include wetland storage or constructed sediment basins, though the length of time water is held before release would vary. Increasing the water holding capacity of soils themselves by increasing infiltration and organic matter content can also help hold onto water. The idea is to reduce peak flows, which is when most sediment movement occurs. Total flow over longer periods of time may change very little.

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