Project Detail

Sediment Budget and Sediment Source Apportionment Study for Apple Creek

Purpose

Apple Creek (drainage area of 54 mi2) is part of the Total Maximum Daily Load (TMDL) and watershed management plan for total phosphorus (TP) and total suspended solids (TSS) in the Lower Fox River Basin. Apple Creek has 24 miles of stream length on the Wisconsin state impaired waters list for TP and TSS. The confluence of Apple Creek with the Fox River is about 8 miles upstream of the Green Bay/Fox River AOC. The AOC has proposed BUI targets for eutrophication and undesirable algae based on achieving the load reductions identified in the TMDL for 7 subbasins, including Apple Creek.Based on SWAT modeling results, Apple Creek produces an estimated 35,100 lbs/yr of TP and 6,400 tons/yr of TSS (Cadmus, 2012). The TMDL goal is to reduce the TP loading by 79 percent and the TSS load by 56 percent from agricultural sources. One of the first steps in the sediment TMDL process along with identifying targets is to identify the major sources of sediment. A stream corridor-based sediment budget and source apportionment study was started in nearby Plum Creek in 2016 to quantify the proportion of the TP and TSS loading originating from in-stream sources of bank and channel erosion compared to soil erosion. Gullying associated with headward extension of stream networks will be quantified as a possible TP and TSS source. The Apple Creek watershed has clayey soils, similar to Plum Creek (fig. 1) but Apple Creek has less relief and more urban land than Plum Creek (fig. 2).

Objective

This study conducted by the US Geological Survey (USGS) will take two years to complete; the first year we will write a QAPP, compile existing data, verify the geomorphic setting of the watershed, and collect sediment source and target samples. The second year is needed for laboratory analyses, data workup, and publishing results. This proposal for Apple Creek describes a similar combined sediment budget/fingerprinting approach that will help identify the proportion of annual loading of TP and TSS originating from stream corridor sources in Apple Creek. The glacial geology and landforms on the west side of the Fox River are considerably different than those on the east side. The results from the Apple Creek study will be compared to expected field contributions based on RUSLE2 calculations and SWAT estimated TP and TSS loadings. The results will be contrasted with apportionment results from Plum Creek. The source assessment results can be used in all subsequent steps of the TMDL process, including monitoring and targeted implementation of the plan.

Project Type

Great Lakes Restoration Initiative

Project Sub Type

Toxics and Areas of Concern

Project ID

GL00E02288_GBF1701_AppleCreek

Year Started

2017

Status

Active

Reports and Documents

2019 Q2 Progress Report