Institute of Water Research

Project Background

This project addressed inadequate habitat for fish and degraded water quality in Michigan’s Maple River Watershed (MRW), two of the major resource concerns that align with both the USDA-NRCS National and Great Lakes Critical Conservation Area priorities. Fish habitat in the Maple River Watershed has been impacted by groundwater pumping, tile drainage and sediment. Water quality has also been degraded by phosphorus runoff, causing issues such as excessive algal growth and affecting habitat for aquatic wildlife.

In 2009, Michigan began tracking high-capacity water withdrawals through the Water Withdrawal Assessment Tool (WWAT). It required all high-capacity withdrawals (>70 gallons/minute) to run the online WWAT to estimate a withdrawal’s impact on stream baseflow and subsequent fish populations. The WWAT combines several models and technologies from the U.S. Geological Survey, Michigan Department of Environmental Quality, Michigan Department of Natural Resources, and the Michigan State University Institute of Water Research (IWR) to estimate stream flows, fish response curves, and groundwater depletions from withdrawals that are screened through the WWAT. Results from the tool are categorized into zones A through D. Results in zones A and B are unlikely to negatively affect nearby streams, whereas results in zones C and D are likely to negatively impact nearby streams and characteristic fish populations. These cases require a site-specific review from the State before the withdrawal may proceed. There were 75 withdrawals that were evaluated as zone C or D in the MRW, and 173 high-capacity withdrawals were registered in the watershed since 2010. This puts significant stress on the water resources in the area by reducing baseflow, increasing temperature, and leaving many streams on the edge of degraded fish habitat. In select sub-watersheds within the MRW such as the Styx- Pine River sub-watershed, all proposed withdrawal screening results are in zone D. This particular sub-watershed has one of the highest numbers of site-specific reviews in the state. Expanding irrigation and tile drained fields will continue to put additional stress on fish habitat in the MRW. Tile drained fields short-circuit the conversion of precipitation to groundwater replenishment and baseflow to streams, making them flashier and more turbid. They also do not allow enough time for subsurface water to cool, making drain discharge warmer than natural subsurface baseflow. Warmer water holds less dissolved oxygen, affecting water quality for fish.

Fish habitat and water quality are also severely impacted by sediment throughout the MRW. Sediment was identified as the highest priority pollutant in the Upper Maple Watershed Management Plan (WMP), threatening the achievement of the warmwater fishery and other indigenous aquatic life/wildlife designated uses. Cropland was listed in the WMP as the primary source of sediment, with specific causes including tillage practices and lack of buffers. A tillage survey conducted for the WMP found that the percentage of surveyed fields with 0-10% residue ranged from 20.6% to 65.2% depending on the sub-watershed. The WMP also indicated that there are 365.5 miles of unbuffered channels in the MRW and that nearly 28,500 tons of sediment loading to streams occurs annually across the Upper Maple. Nutrients were identified as the second highest priority pollutant in the WMP, with cropland and livestock as the primary sources. Row-crop agriculture is the dominant land use and 94 animal agriculture facilities exist in the watershed. The WMP called for nutrient management and vegetative filtering practices to mitigate this resource concern.

To address the concerns outlined above, targeted agricultural practices were implemented to reduce sediment and nutrients entering the water bodies within the MRW. Project partners, including conservation technicians, worked with farmers to identify eligible practices and enroll them into the RCPP. The metrics used to assess project success included: type of BMP installed, number of acres enrolled (certified and planned), sediment reduction, nutrient reductions, and groundwater recharge.

Accomplishments and Outcomes

A total of 15,240 acres of BMPs were contracted to producers through the Maple RCPP. Out of these 15,240 acres, 9,145.8 acres had been certified as of 9/10/2023, and 6,094.2 additional acres of conservation practices were installed in 2024-2025. The certified conservation practices enrolled were conservation cover, cover crops, drainage water management, grassed waterways, mulching, nutrient management, residue and tillage management (reduced till), and structures for water control.

Through the application of these BMPs on the 9,145.8 certified acres, the Maple River RCPP accomplished:

• 394.7 tons/year of sediment reduction
• 1,824 tons/year of erosion reduction
• 34,720.82 gallons/acre/year of groundwater recharge (totaling 317,549,675.56 gallons of groundwater recharge)
• 573.94 lbs of Phosphorus load reduction