Articles and Reports

 

"Madison Lakes and Nearby Waters" Report

A special daylong event, "Madison's Lakes and Nearby Waters," took place Friday, November 11, 2005 at Monona Terrace in downtown Madison, as part of the North American Lake Management Society's 25th Annual International Symposium. Expert presentations addressed the latest research and developments about Dane County lakes, streams, and groundwater. They also emphasized important future challenges that will require an integrated approach with strong citizen support and involvement to effectively manage, protect and restore our local waters. Many of the presentation slides from the event are available online (Google Drive).

The winter 2005 issue of NALMS' quarterly LakeLine magazine summarizes the session presentations and serves as a springboard for future actions coordinated by the state and local managers in parthership with interested citizens. To obtain a copy of this issue, contact lakes@countyofdane.com or call 608-224-3617.

Many thanks for the generous contributions from the following sponsors that helped make the event possible: Wisconsin Department of Natural Resources, the Burish Group of UBS Financial Services Inc., Madison Gas and Electric Foundation, Yahara Lakes Association, and the Dane County Lakes and Watershed Commission.

 

Water Quality Implications From Three Decades of Phosphorus Loads and Trophic Dynamics in the Yahara Chain of Lakes

Partial abstract: Trophic responses to phosphorus (P) loads spanning 29–33 years were assessed for the eutrophic Yahara chain of lakes: Mendota, Monona, Waubesa, and Kegonsa. During extended drought periods with low P loads, summer (Jul–Aug) total phosphorus (TP) concentrations declined substantially in all 4 lake. In years when P loads were high due to major runoff events, summer TP in the lakes was high (especially in shallower Waubesa and Kegonsa); in some summers dissolved inorganic P was elevated, indicating algae growth was not P limited. Summer TP returned to normal levels following both low and high load years, signifying the lakes were responsive to P load changes. The proportion of P input loads passed via a lake’s
outlet to the next lake downstream increased as flushing rates increased. Because Monona, Waubesa, and Kegonsa received 60, 83, and 76% of their surface water P load from the respective upstream lake’s outlet, reducing P loads in Mendota’s large watershed was predicted to produce significant water quality benefits downstream. Modeling indicated a significant grazing effect of Daphnia on summer TP and Secchi transparency readings for Mendota and Monona. Finally, using drought loads as targets, our study established P loading reductions needed to improve water quality in all
4 Yahara lakes.

This paper is available upon request to lakes@countyofdane.com.