Cooperator: Price County
Project Chief: William J. Rose
Location: Ashland and Price Counties
Project Number: 9KB34
Period of Project: October 2002–December 2006
Problem
Butternut Lake area residents and authorities would like to improve the lake’s water quality, which they feel was degraded by past activities in the watershed. Prior to the 1960s, untreated municipal and cheese factory waste and losses from agricultural fields and inadequate failing septic systems were the main sources of nutrients to the lake. Since the 1960s, implementation and enforcement of a zoning ordinance regulating these systems has likely eliminated or significantly reduced these sources of nutrients. Agricultural activity in the watershed, particularly dairy farming, has declined considerably in the last 30 years. In the early 1980s, conditions in the lake appeared to be improving (written commun., Wisconsin Department of Natural Resources, 1982); however, the lake is still quite eutrophic, having occasional algal blooms and excessive weed growth. Recycling of accumulated phosphorus from bottom sediments, rather than loading from external sources, is now believed to be the major cause of current poor water quality.
Lake-area residents and lake users would like to implement management or restoration steps to return the lake to a more natural, pre-settlement state. Before management decisions are made, a good understanding of the lake’s hydrology, nutrient loading by specific source, and internal recycling of nutrients is needed. In addition, the lake’s likely response to incremental increases or decreases in phosphorus loading needs to be determined.
Objective
The objectives are to: (1) Define hydrology and water budget of the lake, (2) determine the phosphorus loads from various sources and develop a phosphorus budget for the lake, (3) evaluate current lake water quality (trophic state) in relation to longer-term trends and in relation to current nutrient loading from external sources, and (4) evaluate the effects of increases or decreases in phosphorus loading on the trophic status of the lake using the BATHTUB model.
Approach
Stream data will be collected from November 2002 through October 2004. Lake water-quality monitoring will begin in March 2003 and continue through September 2004. Instrumentation needed for the water and phosphorus budget determination will be installed in October 2002. Data collection for water and phosphorus budget determination will be for two years, November 2002 through October 2004. Water and phosphorus budgets will be compiled using the measured major inputs and outputs and estimated minor inputs and outputs. Lake water quality will be evaluated using data collected for this study in addition to available historical data. The BATHTUB model will be calibrated using the detailed data collected during this study and then the model will be used to simulate lake water-quality response to incremental increases and decreases in phosphorus loading.
Progress (July 2003–June 2004)
Operation of the data-collection network on the lake, streams, precipitation, and ground water continued. First-year data were published in the annual data reports, “Water Resources Data—Wisconsin” and “Water-Quality Data and Lake-Stage Data for Wisconsin Lakes.” Preliminary water and phosphorus budgets for the first year of data collection were constructed.
Plans (July 2004–June 2005)
Continue operation of the data collection network through October 31, 2004 and publish second-year data in the annual data reports. Complete interpretation of data and begin preparing the final report for the study.
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