RCRCA is in the process of putting together a new phosphorous calculator that is more applicable and accurate for determining BMP

RCRCA is in the process of putting together a new phosphorous calculator that is more applicable and accurate for determining a BMP's impact on phosphorous runoff into the Redwood and Cottonwood Rivers.

Project Vision and Scope

History:

The Cottonwood River Restoration Project and the Redwood River Clean Water Project are managed by the Redwood-Cottonwood Rivers Control Area Joint Powers Organization. Both projects have approved Watershed Implementation Plans prioritizing different reaches of the watersheds based on their disproportionate share of pollutant loadings. Pollutant loadings are a result of current contiguous water quality monitoring programs extending over a period of thirteen years. Total Maximum Daily Loading (TMDL) impairments are being assessed based on these water chemistry results, the Plans and priority areas have been adjusted to reflect those impairments in order to re-focus best management practice implementation. The need for accurate pollutant reduction estimation tools, based on current research, is an urgent priority. We need to have the ability to accurately credit implementation projects and correlate those reductions to water quality trends in order to delist current and future impairments.

The ensuing debate in Minnesota on what reduction credits can be attributed to open tile intake replacements with rock inlets and slotted risers has been the catalyst for this comparison project. Making the jump from treatment efficiencies and life expectancies of alternative tile intakes (ATIs) to the phosphorus indices has been a logical step with the Lower Minnesota River (DO) TMDL and the focus on phosphorus reductions. Using the indices and actual project site soil samples collected using University of Minnesota protocols, we can quantify the phosphorus delivery in pounds per acre per year.

Vision:

It is our intention to utilize the indices as a platform for pre-site evaluation and post practice pollutant reduction estimation based on commonly installed structural/non-structural best management practices. With this comparison using watershed specific parameters, we have created a preliminary phosphorus delivery calculator. We have already begun using the treatment efficiencies of various ATI replacements to figure net reductions of total phosphorus. We intend to expand this to other historical best management practices implemented in the Cottonwood and Redwood River Watersheds. After refinement of our methods using peer-review feedback, we will distill our efforts to create a calculator that can be both predictive and reactive. New project requests will have a preliminary assessment done to determine net pollution reduction return on investment. This will serve as a project ranking. This assessment will also serve as the reported pollutant reduction on successfully funded projects. This information is needed for grant reporting purposes and entry into the E-link database. As new research refinements emerge, we will update the calculator to reflect those refinements.

James Doering, Executive Director, Redwood - Cottonwood Rivers Control Area

P-Index Information	P-Index Maps, Figures & Graphs	P-Index Prototype Software Users Guide	P-Index Sample Problems
P-Index Prototype Calculator Excel Format (Read Only Copy)

Redwood-Cottonwood Rivers Control Area (RCRCA)
1241 East Bridge Street
Redwood Falls, MN 56283
Phone: 507-637-2142, ext. 4
Fax: 507-637-2134
E-mail: rcrca2day@yahoo. com