Little St. Germain Lake: Phosphorus loading, winter anoxia, and stage regulation Active
Little St. Germain Lake, Wis., consists of four main basins separated by narrows. This study monitored lake water quality, identified phosphorus sources, determined spatial and temporal distribution of oxygen, evaluated the effectiveness of winter aeration systems, and modeled groundwater/lake-water interactions.
PROBLEM
Little St. Germain Lake consists of four main basins (East Bay, Upper East Bay, South Bay, and West Bay) separated by narrows. Muskellunge Creek, the lake’s only inlet stream, enters East Bay. A dam at the lake’s outlet is used to regulate lake stage and flow from South Bay. Hence, the net flow of water is from East Bay to South Bay. Summer water quality ranges from good to very good in the West Bay, fair to good in the South Bay, and poor to very poor in the East Bay, based on monitoring from 1992–1994. Dissolved oxygen was absent at the South Bay monitoring site in late winter each year from 1992–1994. The areal extent and cause of the oxygen problem was identified in studies from 1994–2000. The Lake District is considering various measures to improve lake water quality. These include aeration of Upper East and South Bays in winter and possible treatment of Muskellunge Creek water before it enters the lake.
OBJECTIVES
The primary objectives of this project are to:
- Continue the water-quality trend monitoring at sites in the four main basins of the lake
- Continue monitoring to determine water and phosphorus loading to the lake from Muskellunge Creek
- Identify sources of phosphorus to Muskellunge Creek
- Determine spatial and temporal distribution of oxygen in winter before and after installation of aeration systems
- Model ground-water/lake-water interaction and estimate loading of phosphorus to the lake from ground water
- Synthesize all data, new and old, to evaluate the effectiveness of aeration systems and refine lake water and phosphorus budgets
- Examine the potential effects of releasing water from the lake at different times of the year.
APPROACH
The lake’s water and phosphorus budgets will be defined to better resolution than in previous studies by quantifying ground-water inflow and outflow through modeling aided by data from piezometers installed around the lake’s perimeter. Determination of inflow to the lake from Muskellunge Creek will be improved by the operation of a continuous stage monitor. Measurements of flow and phosphorus concentration will be made at three locations along Muskellunge Creek to identify general source areas for phosphorus. Phosphorus loading from ground water will be based on data from sampled near-lake piezometers and inflow estimates generated by the ground-water model (GFLOW). Lake-water quality trend monitoring will continue at the four main basins of the lake. Measurements will be made to determine the spatial and temporal distribution of oxygen in winter before and after installation of aeration systems. All new and old data will be synthesized to evaluate the effectiveness of the aerations systems and to refine lake water and phosphorus budgets.
Below are publications associated with this project.
Evaluation of the effects of changes in the timing of water-level drawdowns on the export of phosphorus from Little St. Germain Lake, Wisconsin
Interannual and long-term changes in the trophic state of a multibasin lake: Effects of morphology, climate, winter aeration, and beaver activity
Water quality, hydrology, and phosphorus loading to Little St. Germain Lake, Wisconsin, with special emphasis on the effects of winter aeration and ground-water inputs
Hydrology, water quality, and phosphorus loading of Little St. Germain Lake, Vilas County, Wisconsin
Below are partners associated with this project.
- Overview
Little St. Germain Lake, Wis., consists of four main basins separated by narrows. This study monitored lake water quality, identified phosphorus sources, determined spatial and temporal distribution of oxygen, evaluated the effectiveness of winter aeration systems, and modeled groundwater/lake-water interactions.
PROBLEM
Little St. Germain Lake consists of four main basins (East Bay, Upper East Bay, South Bay, and West Bay) separated by narrows. Muskellunge Creek, the lake’s only inlet stream, enters East Bay. A dam at the lake’s outlet is used to regulate lake stage and flow from South Bay. Hence, the net flow of water is from East Bay to South Bay. Summer water quality ranges from good to very good in the West Bay, fair to good in the South Bay, and poor to very poor in the East Bay, based on monitoring from 1992–1994. Dissolved oxygen was absent at the South Bay monitoring site in late winter each year from 1992–1994. The areal extent and cause of the oxygen problem was identified in studies from 1994–2000. The Lake District is considering various measures to improve lake water quality. These include aeration of Upper East and South Bays in winter and possible treatment of Muskellunge Creek water before it enters the lake.
OBJECTIVES
The primary objectives of this project are to:- Continue the water-quality trend monitoring at sites in the four main basins of the lake
- Continue monitoring to determine water and phosphorus loading to the lake from Muskellunge Creek
- Identify sources of phosphorus to Muskellunge Creek
- Determine spatial and temporal distribution of oxygen in winter before and after installation of aeration systems
- Model ground-water/lake-water interaction and estimate loading of phosphorus to the lake from ground water
- Synthesize all data, new and old, to evaluate the effectiveness of aeration systems and refine lake water and phosphorus budgets
- Examine the potential effects of releasing water from the lake at different times of the year.
APPROACH
The lake’s water and phosphorus budgets will be defined to better resolution than in previous studies by quantifying ground-water inflow and outflow through modeling aided by data from piezometers installed around the lake’s perimeter. Determination of inflow to the lake from Muskellunge Creek will be improved by the operation of a continuous stage monitor. Measurements of flow and phosphorus concentration will be made at three locations along Muskellunge Creek to identify general source areas for phosphorus. Phosphorus loading from ground water will be based on data from sampled near-lake piezometers and inflow estimates generated by the ground-water model (GFLOW). Lake-water quality trend monitoring will continue at the four main basins of the lake. Measurements will be made to determine the spatial and temporal distribution of oxygen in winter before and after installation of aeration systems. All new and old data will be synthesized to evaluate the effectiveness of the aerations systems and to refine lake water and phosphorus budgets. - Publications
Below are publications associated with this project.
Evaluation of the effects of changes in the timing of water-level drawdowns on the export of phosphorus from Little St. Germain Lake, Wisconsin
Little St. Germain Lake is a 978-acre, multibasin lake in Vilas County, Wisconsin. In the interest of improving its water quality, the Little St. Germain Lake Protection and Rehabilitation District initiated a cooperative study with the U.S. Geological Survey to describe the current phosphorus input into and export from Little St. Germain Lake and evaluate how water releases at different times ofAuthorsEric D. Dantoin, Dale M. RobertsonInterannual and long-term changes in the trophic state of a multibasin lake: Effects of morphology, climate, winter aeration, and beaver activity
Little St. Germain Lake (LSG), a relatively pristine multibasin lake in Wisconsin, USA, was examined to determine how morphologic (internal), climatic (external), anthropogenic (winter aeration), and natural (beaver activity) factors affect the trophic state (phosphorus, P; chlorophyll, CHL; and Secchi depth, SD) of each of its basins. Basins intercepting the main flow and external P sources had hAuthorsDale M. Robertson, William Rose, Paul C. ReneauWater quality, hydrology, and phosphorus loading to Little St. Germain Lake, Wisconsin, with special emphasis on the effects of winter aeration and ground-water inputs
Little St. Germain Lake is a 978-acre, multibasin lake in Vilas County, Wisconsin. In the interest of protecting and improving the water quality of the lake, the Little St. Germain Lake District initiated several cooperative studies with the U.S. Geological Survey between 1991 and 2004 to (1) document the water quality and the extent of winter anoxia in the lake, (2) evaluate the success of aeratoAuthorsDale M. Robertson, William J. Rose, David A. SaadHydrology, water quality, and phosphorus loading of Little St. Germain Lake, Vilas County, Wisconsin
Little St. Germain Lake, which is in Vilas County. Wisconsin, just northeast of St. Germain (fig. 1), is one of 21 impoundments operated by Wisconsin Valley Improvement Company (WVIC) to provide storage for power and recreational use. The level of the lake, which was originally dammed in 1882, has been maintained by the WVIC at about 5 feet above its natural level since 1929, and it is annually drAuthorsDale M. Robertson, William J. Rose - Partners
Below are partners associated with this project.