Hydrology, Water Quality, and Response of Minocqua and Kawaguesaga Lakes to Phosphorus Loading
Project Number: 9KB41
Project Chief: Dale Robertson and Herbert Garn
Project Topics: Water quality
Cooperators: Minocqua/Kawaguesaga Lake Protection Assoc., Town of Minocqua
Period of Project: October 2005–September 2009
Minocqua Lake, Wisconsin. The effects of increasing development in the watershed and possible resulting increased stormwater runoff and nutrient loading are a concern to residents, the Town, and other entities.
The Lake Association is concerned about the lakes’ water quality, occasional algal blooms, excessive weed growth and the effects of additional development. The lakes are heavily used over the summer and are a popular recreation/tourist area. Like many northern lakes undergoing urbanization, Minocqua is having a building boom with a population that has grown by 39 percent since 1990. The sensitivity of the lake’s water quality to changes in nutrient loading associated with additional development within the lake’s watershed is unknown. The trophic state of Minocqua and Kawaguesaga Lakes is mesotrophic-eutrophic, and quantified information on actual phosphorus loading sources and rates are not available to accurately evaluate the potential changes in lake condition under increased or decreased loading. The effects of increasing development in the watershed and possible resulting increased stormwater runoff and nutrient loading are a concern to residents, the Town, and other entities. In order to establish realistic water-quality goals for the Lakes, accurate nutrient loading estimates are needed to enable water-quality models to be calibrated and used to simulate future response of the lake. With a calibrated model, the lake’s response to incremental increases or decreases in phosphorus loading can be evaluated and used to refine the lake-management plan.
This study will quantify the actual phosphorus and sediment loads entering and leaving Minocqua/Kawaguesaga Lake from the watershed, and will determine how incoming loads affect lake water quality. The objectives of the project are to:
- quantify the flows, phosphorus and sediment loads entering and leaving the Lakes;
- determine measured water and phosphorus budgets for Minocqua and Kawaguesaga Lakes, thereby providing a better understanding of the problems and sources of nutrients for developing future lake management actions;
- evaluate and relate the measured water and contaminant loads to observed and modeled water-quality responses within the Lakes using lake models such as BATHTUB or WiLMS; and
- model the response of the Lakes to future phosphorus-loading scenarios and to specific management actions aimed at reducing phosphorus loads to the Lake.
A better understanding of the hydrologic and phosphorus inputs and potential response of the lake to various management scenarios will enhance the management of Minocqua and Kawaguesaga Lakes.
An old lakeside cabin at Minocqua Lake, Wisconsin. The Lakes Studies team will model the response of the lakes to future phosphorus-loading scenarios and to specific management actions aimed at reducing phosphorus loads to the lake.
The study will consist of gage installation and two years of data collection followed by data analysis and report preparation. Water quality will be sampled six times per year in both Lakes and water levels will be recorded. To estimate the nutrient loading at the Tomahawk and Link Creek inlets and the outlet, daily streamflow will be measured continuously and water samples will be collected manually. Phosphorus load data at the stream sites will be used to estimate unit-area loads for unmonitored portions of the basin. Piezometers will be installed around the shore of the lakes to measure ground-water levels and phosphorus concentration to develop a ground-water model and evaluate inputs. These measured data, along with other estimates, will be used to develop complete hydrologic and phosphorus budgets for the lake. Concurrent water and phosphorus budgets for the lake and in-lake water-quality data will be used to calibrate a lake water-quality model used to estimate the response of the lake to various phosphorus-loading scenarios. The calibrated model will be used to simulate the likely response of Minocqua and Kawaguesaga Lakes to phosphorus loading changes from the watershed.
Publications and Reports
Published all streamflow, load, and concentration data in the WY 2006 Wisconsin annual data report, which is now available as Site Data Sheets on the web-based Annual Data Reports and also on CD.
Lake water-quality data were published in the USGS Open-File Report 2007-1173, “Water-quality and lake-stage data for Wisconsin lakes, Water Year 2006.”
Final Report on the Project: “Hydrology, Water Quality, and Response to Changes in Phosphorus Loading of Minocqua and Kawaguesaga Lakes, Oneida County, Wisconsin, With Special Emphasis on Effects of Urbanization.”
Minocqua/Kawaguesaga Lakes Protection Association