Geology topics

Chad A. Toussant

Publications and source records attributed to Chad A. Toussant.

3 recordsLinked to original sources

USGS2026

Evaluation of best management practices at an edge-of-field site in the Eagle Creek watershed, Ohio, 2012–20

In 2010, the U.S. Geological Survey worked in partnership with the Great Lakes Restoration Initiative and the Natural Resources Conservation Service to identify farm fields in priority watersheds—watersheds critically important to Great Lake health. Intensive best management practices were implemented in five States to test the efficacy of best management practices, also referred to as agricultural conservation practices, to reduce sediment and nutrient runoff on agricultural fields. These fields were chosen as representatives of the priority watersheds because their farming practices and geographical conditions were common among farms in those watersheds. A farm site located near Findlay, Ohio, in the Eagle Creek watershed used two conservation practices, cover crop (Natural Resources Conservation Service practice standard 340) and variable rate technology (VRT; Natural Resources Conservation Service practice standard 590), which represent common practices in the Maumee priority watershed. This study monitored surface runoff and subsurface tile runoff at the Eagle Creek watershed site. The effects of cover crop and VRT nutrient application on sediment and nutrient runoff were assessed from October 2012 to September 2020. Cover crops were applied in fall of 2016, 2017, and 2018, coinciding with VRT applications. The following parameters were analyzed as part of the study: runoff discharge; peak discharge; and concentrations and loads of total phosphorus, particulate phosphorus, dissolved reactive phosphorus, and suspended sediment. High peak runoff events disproportionally affected nutrient concentrations and loads in runoff. A threshold of the 85th percentile of the peak discharge was chosen to assess the effect of cover crop and VRT nutrient application on nutrient mitigation at each gage. Runoff events below the 85th percentile were considered small, and runoff events over the 85th percentile were considered large. Concentrations from collected water-quality samples were used for the analysis; estimated concentrations were excluded from the statistical evaluation. All surface runoff parameters during small runoff events, except surface runoff volume, were significantly lower in the period with cover crops and VRT implementation. Contrarily, subsurface runoff parameters during small events were not statistically different between the periods with and without cover crops and VRT implementation. Surface and subsurface parameters during large events were also not statistically different between the periods with and without cover crops and VRT implementation. These results indicate cover crops and VRT may improve water quality during small runoff events, but additional best management practices that mitigate large runoff events may lead to greater water-quality improvement given the contribution of large events to overall losses.

Ohio↗

USGS2026

Assessing the influence of conservation implementation on water quality during surface runoff events at edge-of-field monitoring sites located in the Laurentian Great Lakes basin

The Laurentian Great Lakes are a vital freshwater resource in the United States, and nonpoint source (NPS) nutrient pollution, specifically phosphorus (P) and nitrogen (N), from agricultural land use continues to negatively impact water quality throughout the Great Lakes basin. One focus of the Great Lakes Restoration Initiative (GLRI), a mechanism to coordinate conservation efforts in the Great Lakes that began in 2010, is reducing NPS nutrient pollution through the implementation of conservation practices in priority watersheds (Genesee River, Fox River, Maumee River, and Saginaw River). As part of GLRI efforts, the objective of the study presented here was to evaluate the effects of conservation implementation, specifically increasing vegetative cover on fields and in primary flowpaths through perennial or cover crop planting and grassed waterways, on surface-runoff water quality at 12 agricultural fields (six paired and six unpaired) located in priority watersheds. We determined the percentage difference in mean event response variables between the periods before and after conservation implementation at individual sites, describing patterns across sites to synthesize lessons learned from these GLRI evaluations. Generally, we found that mean event flow-weighted concentration (FWC) and yield (kilograms per hectare) decreased for suspended sediment (SS) and nitrate (NO 3 – -N) across many sites. Mean event FWC and yield for total P (TP) showed mixed results across sites, while mean event FWC and yield for orthophosphate generally increased across sites. These results indicate that perennial or cover crop planting and grassed waterways effectively reduce SS and NO 3 – -N losses in surface runoff from agricultural fields, but mitigating TP and dissolved P losses remains a challenge.

Laurentian Great Lakes basin↗

USGS2021

Nutrient and suspended-sediment concentrations in the Maumee River and tributaries during 2019 rain-induced fallow conditions

Above average precipitation from October 2018 through July 2019 in the Maumee River (R.) Basin resulted in 29% of cropland left fallow, providing a glimpse of potential effects from decreased nutrient application. Ongoing monitoring at 15 water-quality sites on the Maumee R. upstream from Defiance enabled comparison with 2017, which was hydrologically similar to 2019 in precipitation and streamflow. In 2019, nitrate (as nitrogen; NO 3 -N) for March-July was significantly less than previous years (2015–2018), but the response for phosphorus (P) was more complicated. Relative to 2017, total P (TP) was lower at 7 of 15 sites, but higher at 7, reflecting higher suspended sediment (SS). Dissolved P (DP) was generally lower, but less different than NO 3 ; DP was higher at 3 sites. DP-P:NO 3 -N was generally higher in 2019, DP-P:TP was lower, and there was less TP relative to SS. Overall, less P was in the system in 2019. However smaller streams showed a large range of difference between 2019 and 2017 for all constituents, indicating variability in land management and physiography. In contrast, all constituents were lower in 2019 in larger (>5000 km 2 ) streams, including the Maumee R. near Defiance, where the difference in NO 3 (−37%) exceeded that for TP (−16%), DP (−10%), and SS (−20%). Differences in these relations among N, P, and SS indicate that P was available from legacy sources that are more difficult to distinguish during typical agricultural production years and that some material from 2019 was stored in the system upstream from the largest sites.

Indiana, Ohio↗