Tammy Zimmerman
I currently serve as Chief, New Cumberland Hydrologic Studies, Pennsylvania Water Science Center. In 2023, I also served as Acting Chesapeake Bay Associate Coordinator.
Recent projects address bacteriological issues in Lake Erie on and near the beaches at Presque Isle, as part of the Great Lakes Restoration Initiative, and pesticide issues in vulnerable aquifers in cooperation with the Pennsylvania Department of Agriculture.
Science and Products
Pennsylvania and the Chesapeake Bay Watershed
USGS provides monitoring, analysis, modeling and research on streams and water quality to better understand the fate and transport of nutrients and sediment to the Susquehanna and other rivers, and their tributaries, and eventually to the Chesapeake Bay. Additional research focuses on emerging contaminants and other stressors that effect human and aquatic life in the watershed and estuary.
Pesticides in Pennsylvania Groundwaters
USGS annually samples domestic groundwater wells to characterize pesticides, nutrients, and radon in agricultural areas, in cooperation with the Pennsylvania Department of Agriculture. Beginning in 2021, samples for major ions, trace elements, bacteria, and isotopes will also be collected. A subset of wells will be sampled for per- and polyfluoroalkyl substances (PFAS), emerging industrial...
Sediment and Stream Health - Pennsylvania
Sediment in streams, from land surface erosion in watersheds, is an important factor in determining the quality of Pennsylvania's surface waters and of downstream water bodies such as the Delaware Estuary and Chesapeake Bay. The USGS has a long-standing tradition of measuring suspended-sediment concentrations and estimating loads. Recent technological advances allow real-time estimates of...
Tracking Status and Trends in Seven Key Indicators of River and Stream Condition in the Chesapeake Bay Watershed
Identifying and tracking the status of, and trends in, stream health within the Chesapeake Bay watershed is essential to understanding the past, present, and future trajectory of the watershed’s resources and ecological condition. A team of USGS ecosystem scientists is meeting this need with an initiative to track the status of, and trends in, key indicators of the health of non-tidal freshwater...
Susquehanna River and Basin
In Pennsylvania, the USGS's water-resources roots date back to the late 1800's, with the initiation of streamflow gaging on the Susquehanna and Delaware Rivers and assessments of groundwater resources near Philadelphia. The USGS Pennsylvania Water Science Center continues to provide scientific information about the water resources of the Susquehanna River Basin, in cooperation with regional and...
Harmful Algal Blooms in Pennsylvania
The U.S. Geological Survey is collaborating with State and local partners to develop models that provide real-time estimates of Escherichia coli (E. coli) (for pathogens) and (or) microcystin (for freshwater cyanotoxins) levels at Great Lakes beaches and drinking-water intakes.
Freshwater Flow into Chesapeake Bay
Explore resources here describing estimates of freshwater flow entering Chesapeake Bay. The health of the Chesapeake Bay is greatly affected by freshwater flow from rivers draining its watershed. The amount of freshwater flow (also called streamflow) will: • Change salinity levels in the Bay, which affect oysters, crabs, and finfish. • Influence the amounts of nutrients, sediment, and contaminants...
Predictive Modeling of Bacteria Concentrations at Presque Isle State Park, Erie, Pennsylvania
Approximately 7 miles of Lake Erie shoreline lies within Presque Isle State Park in Erie, Pa. Monitored public bathing beaches at Presque Isle make up less than 1 mile. Concentrations of Escherichia coli (E. coli) at monitored beaches in Presque Isle State Park occasionally exceed the single-sample bathing-water standard of 235 colonies per 100 milliliters resulting in potentially unsafe swimming...
Bacteriological quality of groundwater used for household supply
In fractured bedrock aquifers used for domestic supply conditions can exist where contaminants such as bacteria are not filtered out by the soil. Once in the fracture system, little additional filtration takes place. The results of a synotic sampling of domestic wells in the Lower Susquehanna River basin, Pennsylvania and Maryland, showed that bacteria concentrations were higher in areas with high...
Science and Products
Pennsylvania and the Chesapeake Bay Watershed
USGS provides monitoring, analysis, modeling and research on streams and water quality to better understand the fate and transport of nutrients and sediment to the Susquehanna and other rivers, and their tributaries, and eventually to the Chesapeake Bay. Additional research focuses on emerging contaminants and other stressors that effect human and aquatic life in the watershed and estuary.
Pesticides in Pennsylvania Groundwaters
USGS annually samples domestic groundwater wells to characterize pesticides, nutrients, and radon in agricultural areas, in cooperation with the Pennsylvania Department of Agriculture. Beginning in 2021, samples for major ions, trace elements, bacteria, and isotopes will also be collected. A subset of wells will be sampled for per- and polyfluoroalkyl substances (PFAS), emerging industrial...
Sediment and Stream Health - Pennsylvania
Sediment in streams, from land surface erosion in watersheds, is an important factor in determining the quality of Pennsylvania's surface waters and of downstream water bodies such as the Delaware Estuary and Chesapeake Bay. The USGS has a long-standing tradition of measuring suspended-sediment concentrations and estimating loads. Recent technological advances allow real-time estimates of...
Tracking Status and Trends in Seven Key Indicators of River and Stream Condition in the Chesapeake Bay Watershed
Identifying and tracking the status of, and trends in, stream health within the Chesapeake Bay watershed is essential to understanding the past, present, and future trajectory of the watershed’s resources and ecological condition. A team of USGS ecosystem scientists is meeting this need with an initiative to track the status of, and trends in, key indicators of the health of non-tidal freshwater...
Susquehanna River and Basin
In Pennsylvania, the USGS's water-resources roots date back to the late 1800's, with the initiation of streamflow gaging on the Susquehanna and Delaware Rivers and assessments of groundwater resources near Philadelphia. The USGS Pennsylvania Water Science Center continues to provide scientific information about the water resources of the Susquehanna River Basin, in cooperation with regional and...
Harmful Algal Blooms in Pennsylvania
The U.S. Geological Survey is collaborating with State and local partners to develop models that provide real-time estimates of Escherichia coli (E. coli) (for pathogens) and (or) microcystin (for freshwater cyanotoxins) levels at Great Lakes beaches and drinking-water intakes.
Freshwater Flow into Chesapeake Bay
Explore resources here describing estimates of freshwater flow entering Chesapeake Bay. The health of the Chesapeake Bay is greatly affected by freshwater flow from rivers draining its watershed. The amount of freshwater flow (also called streamflow) will: • Change salinity levels in the Bay, which affect oysters, crabs, and finfish. • Influence the amounts of nutrients, sediment, and contaminants...
Predictive Modeling of Bacteria Concentrations at Presque Isle State Park, Erie, Pennsylvania
Approximately 7 miles of Lake Erie shoreline lies within Presque Isle State Park in Erie, Pa. Monitored public bathing beaches at Presque Isle make up less than 1 mile. Concentrations of Escherichia coli (E. coli) at monitored beaches in Presque Isle State Park occasionally exceed the single-sample bathing-water standard of 235 colonies per 100 milliliters resulting in potentially unsafe swimming...
Bacteriological quality of groundwater used for household supply
In fractured bedrock aquifers used for domestic supply conditions can exist where contaminants such as bacteria are not filtered out by the soil. Once in the fracture system, little additional filtration takes place. The results of a synotic sampling of domestic wells in the Lower Susquehanna River basin, Pennsylvania and Maryland, showed that bacteria concentrations were higher in areas with high...