Geology topics

Amy Story

Publications and source records attributed to Amy Story.

3 recordsLinked to original sources

USGS2026

Groundwater nutrient contributions to surface water in the upper Maumee River basin

Harmful algal blooms triggered by nutrient loading have negatively affected Lake Erie water quality for decades, but the role groundwater plays in transporting nutrients to tributary streams is unclear. Here, we apply a multi-scale approach to investigate groundwater nitrogen (N) and phosphorus (P) dynamics at the field scale, along a groundwater flow path, and at the Maumee River basin scale. Unsaturated zone monitoring indicates that macropore flow is the primary mechanism for N and P leaching with nitrate and orthophosphate (OP) concentrations from macropore samplers more than double those from soil-matrix samplers. Shallow (< 4.5 m) groundwater nitrate concentrations indicate the timing of saturated-zone nitrate fluxes is crop dependent with more nitrate mobilized during the maize growing season whereas concentrations below soybeans can remain elevated (> 3 mg/L) through winter months. A three-end-member hydrograph analysis for the upper Maumee River basin indicates that tile drains transport most subsurface N and P with greater than 15,000 kg per day of nitrate transported between January and May. Orthophosphate concentrations in tile drainage at an edge-of-field site correlate well with concentrations in a nearby tributary of the Maumee River. While runoff is the dominant source of OP loading, tile drainage and groundwater discharge contributed an estimated 36% of OP load during a 2018–2022 analysis period with most subsurface loading occurring between January and March. These findings highlight how best management practices (such as cover crops and tile drainage control structures) can be used to help limit leaching and tile effluent during the nongrowing season.

Indiana↗

USGS2026

Evaluation of a eutrophication Beneficial Use Impairment in the Grand Calumet River Area of Concern in northwest Indiana, 2021–22

Eutrophication has been regularly documented in the Grand Calumet River and Indiana Harbor Canal in northwest Indiana. The area has undergone various remediation efforts since the development of a Remedial Action Plan for the area in response to a 1987 amendment to the Great Lakes Water Quality Agreement of 1978 between the United States and Canada and the designation of the Grand Calumet River Area of Concern by the U.S. Environmental Protection Agency. To address concerns of eutrophication and its effects, the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency and the Indiana Department of Environmental Management, collected data from the Grand Calumet River and Indiana Harbor Canal in 2021 and 2022 to document the effects of remediation and combined sewer overflow releases on water quality. This study used continuous monitors to collect real time data for dissolved oxygen, water temperature, chlorophyll fluorescence, specific conductance, and pH. Discrete sample analysis included biological oxygen demand, chemical oxygen demand, nutrients, nitrogen and oxygen isotopes in nitrate, nitrogen isotopes in ammonia, hydrogen and oxygen isotopes in water, and identification of algal communities (cyanobacteria and eukaryotic algae) by metabarcoding. Eutrophic conditions were found throughout the area. Isotopic results indicated the source of nitrate in samples was either from soil organic nitrogen or combined sewer overflows. Combined sewer overflows were shown to have considerable effects on the sites, and remediation status did not have a great effect. Algal community results identified several taxa capable of becoming nuisance species, including Microcystaceae (cyanobacteria) and Chrysophyceae, Cryptophyceae, and Bacillariophyceae (all eukaryotic algae). When sites with irregular flow patterns were excluded from datasets, minimum dissolved oxygen concentrations were often higher downstream from remediated sites than from unremediated sites. This study shows the potential for further and more targeted exploration into the unusual conditions found throughout the Grand Calumet River and Indiana Harbor Canal area.

Indiana↗

USGS2025

Road salt collection and redistribution at an urban rain garden on sandy soil, Gary, Indiana

Rain gardens installed as green infrastructure to divert storm runoff from entering combined sewers also collect dissolved constituents and particulates. An urban rain garden in northwestern Indiana, USA, was continuously monitored from November 2019 to May 2021 to evaluate the fate of dissolved constituents entering the rain garden in runoff. Physical and chemical properties of soils in the rain garden were also monitored, along with underlying groundwater. Linear regression models relating specific conductance to chloride concentration indicated that the 0.0371-ha (3998 square feet) rain garden collected approximately 1490 kg (3285 pounds) of road salt from the surrounding 0.2228 ha (24,500 square feet) of impervious surfaces. Soils and groundwater were seasonally affected by road salt application but carryover from year to year was not indicated. Rain garden soil permeability (5.20 × 10 −5 to 9.72 × 10 −5 m/s) remained unchanged during the study period and soil organic carbon generally increased under native vegetation. The results suggest that a rain garden built on sandy soil can divert substantial quantities of runoff and dissolved constituents from combined sewers; however, chloride is transported to sub-infrastructure groundwater that eventually discharges to adjacent waterways with concentrations lower than those observed in runoff.

Indiana↗