West Tarkio Watershed Inventory and Analysis Continues

Inventory and analysis of the 105,570 acre West Tarkio Watershed by USDA’s Natural Resources Conservation Service (NRCS) continues with a draft watershed plan anticipated mid-summer 2004.

The NRCS is providing planning assistance at the request of nine units of government in southwest Iowa and northwest Missouri. These sponsoring local units of government include the counties and soil and water conservation districts of Montgomery, Page, and Atchison, and the cities of Tarkio, Clarinda and Shenandoah. Planning work began in February 2003.

The NRCS is working through a planning process that identifies and evaluates alternative approaches to meet local sponsors’ objectives. Those objectives include flood protection, grade stabilization in stream channels, upland gully control, water based recreation, water supply and water quality improvement.

The Watershed Protection and Flood Prevention Act of 1954 (PL-566) gives the USDA-Natural Resources Conservation Service the authority to conduct watershed studies. Congress has limited financial assistance under PL-566 to watershed projects of 250,000 acres or less. Congress has also stipulated that no structure with more than 12,500 acre-feet of floodwater detention capacity or more than 25,000 acre-feet of total capacity be included in a watershed project plan that would be funded with PL-566 funds. In southern Iowa, these limits typically correlate to a reservoir surface area of about 1,000 acres, depending on the pool area topography and the height of the dam.

The NRCS study team is examining several future works of improvement for the West Tarkio plan that may not qualify for funding through the PL-566 program. For example, some alternative scenarios might assume that some or all of the anticipated community and rural water needs might be met through measures (such as wells or a very large reservoir) that are not eligible for assistance through PL-566. These alternative scenarios will be evaluated on the basis of the expected costs and benefits associated with remaining sponsor objectives under each scenario.

According to Leroy Brown, NRCS State Conservationist, “The NRCS study team conducting the inventory and analysis of the watershed is not approaching its work with any particular end in mind. It is using a disciplined process to identify and evaluate a number of alternatives to meet the objectives of the watershed sponsors. The costs and benefits associated with each alternative will be assessed using standard federal water resource procedures and rules.”

NRCS is presenting preliminary findings to the West Tarkio Watershed Planning Committee (WTWPC) during its regular monthly meetings, as various study sections are ready for review. The WTWPC represents the sponsors and landowners within the watershed. It is anticipated NRCS will present a complete recommended plan to the sponsors about July 1, 2004.

After undergoing a technical review and public comment, it is expected the final plan and environmental impact study will be completed April 1, 2005.

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To interview a NRCS expert on this subject, please contact Dave Beck at 515-323-2232.
 

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