Tim Cowdery has been a groundwater geologist in Minneapolis, MN since 1991. Tim's research interests include glacial geology, groundwater/surface-water interactions, quantification of groundwater flows, groundwater instrumentation, and numerical modelling.
Tim Cowdery currently serves as Leader for the Hydrogeology Team of the National Hydrologic Geospatial Fabric project. He also serves as a groundwater and database specialist for the Upper-Midwest Water-Science Center in Minnesota.
Tim has extensive experience in collecting groundwater data, including both instrumentation, telemetry, and correction automation. His interests also include graphical presentation of scientific ideas and graphical design.
In 1992, Tim became the groundwater specialist for the Red River of the North National Water-Quality Assessment, conducting groundwater-quality research at many spatial scales in that basin. He has designed and executed to several groundwater modeling studies at local and regional scales throughout Minnesota. He has developed systems for automated groundwater data collection, telemetry, and processing and has used these data to estimate the spatial and temporal variability of groundwater recharge.
During 2002–2018, Tim managed the USGS' Glacial Ridge Hydrologic Assessment, a groundwater/surface water interaction study that documents changes in the hydrology of a large area in northwestern Minnesota that underwent extensive wetland and prairie restorations. This project documented changes in hydrologic flows and quality resulting from the restorations. He continues to manage several other projects involving groundwater modeling, water-quality sampling, groundwater recharge, and continuous groundwater-level measurement.
During 2016–2020, Tim led a team constructing groundwater-flow models of the St. Louis River Basin as a whole and the area of historic iron-mining in detail. These models will provide boundary flows for future inset groundwater-flow models in the area and quantified the effects of historic iron mining on baseflows in the St. Louis River.
Professional Experience
Tim has spent his hydrogeology professional career at the USGS in Minnesota as a project chief, groundwater specialist and team leader. He started as a student in 1991 and a permanent employee in 1992.
Groundwater Characterization Team leader, 2019–2020.
Glacial Ridge Hydrologic Assessment project chief, 2002–2018.
Minnesota Water-Science Center Groundwater Specialist for Data, 2013–2017.
Red River of the North National Water-Quality Assessment groundwater specialist, 1992–1997.
Education and Certifications
Master of Science degree in hydrogeology from the University of Minnesota in 1997.
Bachelor of Arts degree in geology from Carleton College in 1983. Minor in East-Asian Studies.
Affiliations and Memberships*
Sigma Xi, the Scientific Honor Society, 1983-present
Geological Society of America,1993-present
Minnesota Groundwater Association, 1995-present
Abstracts and Presentations
Cowdery, T.K., 2021, Hydrologic Change in the St. Louis River Basin from Mining in Northeastern Minnesota: Abstracts, 64th Annual Conference on Great Lakes Research, International Association of Great Lakes Research, Virtual meeting, https://iaglr.org/conference/downloads/2021_abstracts.pdf Accessed 15 December 2021.
Science and Products
Groundwater monitoring and research
Assessing Hydrologic Changes in the St. Louis River Basin from Past Land Uses
Continuous Groundwater Monitoring Network - Minnesota
A Soil-Water-Balance model and precipitation data used for HEC/HMS modelling at the Glacial Ridge National Wildlife Refuge area, northwestern Minnesota, 2002-15.
Long-term hydrologic sustainability of calcareous fens along the Glacial Lake Agassiz beach ridges, northwestern Minnesota, USA
The hydrologic benefits of wetland and prairie restoration in western Minnesota—Lessons learned at the Glacial Ridge National Wildlife Refuge, 2002–15
Simulation of the regional groundwater-flow system in the St. Louis River basin, Minnesota
Mercury in wetlands at the Glacial Ridge National Wildlife Refuge, northwestern Minnesota, 2007-9
Redox Conditions in Selected Principal Aquifers of the United States
Hydrology Prior to Wetland and Prairie Restoration in and around the Glacial Ridge National Wildlife Refuge, Northwestern Minnesota, 2002-5
Hydrogeology and ground-water/surface water interactions in the Des Moines River valley, southwestern Minnesota, 1997-2001
Regional ground-water-flow models of surficial sand and gravel aquifers along the Mississippi River between Brainerd and St. Cloud, central Minnesota
Comparison of two methods for delineating land use near monitoring wells used for assessing quality of shallow ground water
Transport and fate of nitrate in a glacial outwash aquifer in relation to ground water age, land use practices, and redox processes
Using chemical, hydrologic, and age dating analysis to delineate redox processes and flow paths in the riparian zone of a glacial outwash aquifer‐stream system
Ground-water quality in the Red River of the North Basin, Minnesota and North Dakota, 1991-95
Science and Products
- Science
Groundwater monitoring and research
Groundwater is an important water resource. The USGS collects information on the quality and quantity of groundwater and conducts advanced modeling of groundwater flow and groundwater/surface-water systems. The USGS also evaluates the effects of water-use, land-use, and climate change on groundwater, surface-water, and the ecosystems that rely on them.Assessing Hydrologic Changes in the St. Louis River Basin from Past Land Uses
Resource managers can use assessments of past and future land use to make science-based decisions. This project characterizes how changes in land use can change groundwater and surface-water flows in the St. Louis River Basin, MN. The USGS is constructing a set of groundwater models to simulate groundwater/surface-water interactions and evaluate how water flows have changed.Continuous Groundwater Monitoring Network - Minnesota
This project monitors groundwater level, groundwater temperature and precipitation at hourly intervals at a long-term network of sites throughout Minnesota. These data are collected from surficial and buried aquifers and can be used to estimate groundwater recharge and assist water-availability assessments. Data are corrected to manual measurements at least twice per year and are available through... - Data
A Soil-Water-Balance model and precipitation data used for HEC/HMS modelling at the Glacial Ridge National Wildlife Refuge area, northwestern Minnesota, 2002-15.
A soil-water balance model (SWB) was developed to estimate evapotranspiration in six ditch basins of the Glacial Ridge National Wildlife Refuge area, northwestern Minnesota, during 2002-2015. The model was used to estimate evapotranspiration in water balances in six ditch basins as part of the associated report, U.S. Geological Survey Scientific Investigations Report 2019-5041 (http://dx.doi.org/1 - Publications
Filter Total Items: 19
Long-term hydrologic sustainability of calcareous fens along the Glacial Lake Agassiz beach ridges, northwestern Minnesota, USA
Calcareous fens are peat-accumulating wetlands fed by calcium-rich groundwater that support several threatened species of plants that thrive in these geochemical conditions. This investigation characterized the hydrology of two calcareous fens in the Glacial Lake Agassiz beach ridge complex in northwestern Minnesota, USA. Sandy surficial beach ridge aquifers and underlying buried glacial aquifersThe hydrologic benefits of wetland and prairie restoration in western Minnesota—Lessons learned at the Glacial Ridge National Wildlife Refuge, 2002–15
Conversion of agricultural lands to wetlands and native prairie is widely viewed as beneficial because it can restore natural ecological and hydrologic functions. Some of these functions, such as reduced peak flows and improved water quality, are often attributed to restoration; however, such benefits have not been quantified at a small scale. To inform future restoration efforts, especially in noSimulation of the regional groundwater-flow system in the St. Louis River basin, Minnesota
The St. Louis River Basin (SLRB) covers 3,600 square miles in northeastern Minnesota, with headwaters in the Mesabi Range and extensive wetlands and lakes throughout the basin. To better understand the regional groundwater system in the SLRB, a two-dimensional, steady-state groundwater-flow model of the SLRB was developed by the U.S. Geological Survey, in cooperation with the Minnesota Ojibwe BandMercury in wetlands at the Glacial Ridge National Wildlife Refuge, northwestern Minnesota, 2007-9
The Glacial Ridge National Wildlife Refuge was established in 2004 on land in northwestern Minnesota that had previously undergone extensive wetland and prairie restorations. About 7,000 acres of drained wetlands were restored to their original hydrologic function and aquatic ecosystem. During 2007–9, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service and the Red LaRedox Conditions in Selected Principal Aquifers of the United States
Reduction/oxidation (redox) processes affect the quality of groundwater in all aquifer systems. Redox processes can alternately mobilize or immobilize potentially toxic metals associated with naturally occurring aquifer materials, contribute to the degradation or preservation of anthropogenic contami-nants, and generate undesirable byproducts, such as dissolved manganese (Mn2+), ferrous iron (Fe2+Hydrology Prior to Wetland and Prairie Restoration in and around the Glacial Ridge National Wildlife Refuge, Northwestern Minnesota, 2002-5
The Nature Conservancy (TNC) owned and managed 24,795 acres of mixed wetland, native prairie, farmland and woods east of Crookston, in northwestern Minnesota. The original wetlands and prairies that once occupied this land are being restored by TNC in cooperation with many partners and are becoming part of the Glacial Ridge National Wildlife Refuge. Results of this study indicate that these restorHydrogeology and ground-water/surface water interactions in the Des Moines River valley, southwestern Minnesota, 1997-2001
Increased water demand in and around Windom led the U.S. Geological Survey, in cooperation with the Minnesota Department of Natural Resources, local water suppliers, and Cottonwood County, to study the hydrology of aquifers in the Des Moines River Valley near Windom. The study area is the watershed of a 30-kilometer (19-mile) reach of the Des Moines River upstream from Windom. Based on stratigraphRegional ground-water-flow models of surficial sand and gravel aquifers along the Mississippi River between Brainerd and St. Cloud, central Minnesota
This report documents regional ground-waterflow models constructed by the U.S. Geological Survey in cooperation with the Minnesota Department of Health (MDH) to satisfy the requirements of their Source Water Protection Plan (SWPP). Steady-state single-layer ground-water-flow models were constructed with the computer program MODFLOW to simulate flow in surficial sand and gravel aquifers along the MComparison of two methods for delineating land use near monitoring wells used for assessing quality of shallow ground water
Two methods were compared for delineating land use near shallow monitoring wells. These wells were used to assess the effects of agricultural cropland on the quality of recently recharged ground water in two sand and gravel aquifers located near land surface. The two methods for delineating land use near wells were (1) the sector method, which used potentiometric-surface maps to estimate average fTransport and fate of nitrate in a glacial outwash aquifer in relation to ground water age, land use practices, and redox processes
A combination of ground water modeling, chemical and dissolved gas analyses, and chlorofluorocarbon age dating of water was used to determine the relation between changes in agricultural practices, and NO−3 concentrations in ground water of a glacial outwash aquifer in west-central Minnesota. The results revealed a redox zonation throughout the saturated zone with oxygen reduction occurring near tUsing chemical, hydrologic, and age dating analysis to delineate redox processes and flow paths in the riparian zone of a glacial outwash aquifer‐stream system
A combination of chemical and dissolved gas analyses, chlorofluorocarbon age dating, and hydrologic measurements were used to determine the degree to which biogeochemical processes in a riparian wetland were responsible for removing NO3−from groundwaters discharging to the Otter Tail River in west central Minnesota. An analysis of river chemistry and flow data revealed that NO3− concentrations inGround-water quality in the Red River of the North Basin, Minnesota and North Dakota, 1991-95
Surveys of water quality in surficial, buried glacial, and Cretaceous aquifers in the Red River of the North Basin during 1991-95 showed that some major-ion, nutrient, pesticide, and radioactive-element concentrations differed by physiographic area and differed among these aquifer types. Waters in surficial aquifers in the Drift Prairie (west) and Lake Plain (central) physiographic areas were simi
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government