TMDL Implementation Research Projects
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This page presents information and research conducted in coordination with MDE and other entities that may inform TMDL implementation.
MDE's Watershed Protection, Restoration, and Planning Program (WPRPP), in conjunction with the Interstate Commission on the Potomac River Basin (ICPRB), has compiled a comprehensive database of historic municipal seprate storm sewer system (MS4) permit required monitoring information, including chemical, biological, habitat, and geomorphic data for targeted sub-watersheds. MDE, ICPRB, and the Center for Watershed Protection (CWP) have conducted pilot trend analyses of historic chemical monitoring data for three targeted sub-watersheds, which had the longest periods or record, fewest data quality issues, and ideal monitoring designs to relate any changes in ambient water quality to watershed restoration. The comprehensive database and report summarizing the pilot trend analyses of the chemical data are available for download below. MDE IWPP intends to conduct further pilot analyses of the biological and habitat data. MDE WPRPP is currently working with ICPRB to populate the database with the geomorphic monitoring data. The version of the database below only contains the chemical, biological, and habita data. Once the geomorphic data is added to the database, an updated version will be posed. Once MDE and ICPRB conclude the analysis of the biological and habitat data, those final reports will be posted as well.
EPA’s Watershed Management Optimization Support Tool (WMOST v3) is an application designed to facilitate cost-effective integrated water resource management at the scale of 12- to 10-digit Hydrologic Units (HUC12 – HUC10). A case study application of WMOST was carried out by EPA and MDE to evaluate the effectiveness of WMOST for informing management options for the heavily urbanized watershed of Cabin John Creek in Maryland, a tributary to the Potomac River, for the 10-year period 2014 - 2025.
WMOST provides optimizations in implementation strategies to meet constraints imposed by total nitrogen and total phosphorus load reduction targets associated with the Chesapeake Bay TMDL or the TSS loading reduction targets of the local non-tidal sediment TMDL with the least-cost solution. The Cabin John Creek WMOST implementation outcomes and evaluation of the software for management uses are provided in this report.
The report and other related documents/data are available at:
WMOST general software documentation link:
This study was conducted by the University of Maryland Center for Environmental Science (UMCES) on behalf of MDE and completed in 2019. Looking at the Back River estuary and the upgrade of the Back River Wastewater Treatment Plant to ENR in 2017, the data which spans the time period from mid-1980s to 2018, shows the trend in the water column and sediment over time as loads in nitrogen, phosphorus and sediment were reduced. The study indicates that well-mixed estuaries recover rapidly in response to nutrient remediation. For full details of the study, click the link below.
Back River Sediment Flux Measurements to Assess Impacts of Large Reductions in Point Source Nutrient Loading, UMCES 2019 The University of Maryland Center for Environmental Science (UMCES) Chesapeake Biological Laboratory has developed a report to quantify both the ecosystem response of the Patapsco River estuary to long-term Waste Water Treatment Plant (WWTP) load reductions and the effects of recent WWTP load reductions on the Back River estuary water quality.
In this report, UMCES combined analysis of historical data, numerical modeling, and diagnostic mass balance computations to comprehensively assess estuarine water quality changes in response to WWTP load reductions. UMCES also evaluated the potential for failed sewage treatment operations during part of 2021 and 2022 in the Patapsco and Back River WWTPs to impact water quality, including the reversal of water quality improvements in the Back River.
The study indicates that investments in improved wastewater treatment technologies and the associated load declines to the Patapsco River has resulted in relatively rapid and substantial reductions in water-column nutrient concentrations and chlorophyll-a concentrations. However, several metrics of hypoxia have persisted or even increased over the record at a sentinel station, suggesting that factors beyond nutrient loading and local phytoplankton growth are important. For full details of the study, click the link below.
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Contact Information
Please direct questions or comments concerning this project to Maryland's TMDL Program at (410) 537-3884.
