Rocky Branch Load Monitoring TWA 2017-2019

Purpose

Western District staff have partnered with UWRF to collect suspended sediment and total phosphorus load information from Rocky Run Creek in Pierce County. Rocky Run Creek is a tributary to the Kinnickinnic River which is part of the Lake St. Croix TMDL and is a 319 eligible watershed. As part of the TMDL implementation Plan, a farmer lead council has prioritized the Rocky Run Watershed for NPS BMP implementation. WD has agreed to collect pre-implementation TP and sediment load data to establish a baseline for the project. Two years of load monitoring has been completed but an additional year is needed to more fully develop the flow rating curve and address annual variability. If practices are implemented to reduce TP and sediment, followup load monitoring can be completed to determine if water quality improved. HUC 12 070300051105.

Objective

This project will help estimate the annual TP and sediment load from Rocky Run Creek to the Kinnickinnic River. Follow up load monitoring will be completed after significant BMP implementation is completed

Outcome

WD has installed a water level sensor and collected streamflow measurements to establish and stage discharge relationship. Due to the small watershed size and steeper topography, storm events occur quickly (rapid rises and falls in discharge) making it difficult to capture event flows to develop a rating curve and obtaining TP samples from events. Two major events have occurred the past two years and the water level sensor was either scoured or dislodged and deposited downstream. Discharge measurements have been collected on smaller events but additional measurements on larger events are needed to more fully develop the rating curve. Also, another year might help characterize the chemistry of event flows. Biweekly sampling for TP and suspended solids will be completed by UWRFs.

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Targeted Watershed Approach
Evaluation (TP SSC, Stressor, Bioassess)
West_TWA_6_2017
2017
Complete
 
Activities & Recommendations
Monitor to Evaluate Projects