1/18/2015 1 What it will take to improve the ecology and water quality of Lake Kegonsa Richard Lathrop Jan. 17, 2015 Photo: R. Lathrop, Sept. 1985 1 pound of phosphorus (P) can produce 500 pounds of algae! (Source: Vallentyne, 1974) Photo: Bryce Richter,UW-Madison Lake Kegonsa, June 2012 Photo: Dane Co. LWR Dept. Blue-green algal blooms have been a problem in the Yahara lakes since the early 1900s Blue-green algae, which typically “bloom” during the summer and early fall in nutrient-rich waters, create serious water quality problems: • Blooms can pile up as noxious scums on downwind shorelines • Blooms consume oxygen causing fish kills • Blue-green algae are generally inedible and not part of a lake’s food chain supporting desirable fish • Blue-green algae can produce toxins of concern to humans & wildlife • Seizures & respiratory problems can result from neuro-toxins • Liver & kidney lesions can result from hepato-toxins Lake Kegonsa, June 2012 Photo: Dane Co. LWR Dept. The Capital Times, Sept. 6-7, 2003 First recorded death in U.S. due to blue-green algal toxins! Madison, Wisconsin – July 2002 [The local teenager] … [ … …] Yahara lakes & watershed Map: Dane Co. LWR Dept. Mendota Kegonsa
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PowerPoint Presentation - Kegonsakegonsa.org/myhtml/pics.pdfMap: Dane Co. LWR Dept. Mendota Mendota Drainage Basin Land Use Total Area = 553 km2 59.7% 22.9% 12.0% 5.4% Agriculture
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1/18/2015
1
What it will take to improve the ecology
and water quality of Lake Kegonsa
Richard Lathrop
Jan. 17, 2015
Photo: R. Lathrop, Sept. 1985
1 pound of phosphorus (P) can
produce 500 pounds of algae! (Source: Vallentyne, 1974)
Photo: Bryce Richter,UW-Madison
Lake Kegonsa, June 2012
Photo: Dane Co. LWR Dept.
Blue-green algal blooms have been a problem in the
Yahara lakes since the early 1900s
Blue-green algae, which typically “bloom” during the
summer and early fall in nutrient-rich waters, create
serious water quality problems:
• Blooms can pile up as noxious scums on downwind shorelines
• Blooms consume oxygen causing fish kills
• Blue-green algae are generally inedible and not part of a lake’s
food chain supporting desirable fish
• Blue-green algae can produce toxins of concern to humans &
wildlife • Seizures & respiratory problems can result from neuro-toxins
• Liver & kidney lesions can result from hepato-toxins
Lake Kegonsa, June 2012
Photo: Dane Co. LWR Dept.
The Capital Times, Sept. 6-7, 2003
First recorded death in U.S. due to blue-green algal toxins! Madison, Wisconsin – July 2002
[The local teenager] …
[ …
…]
Yahara lakes &
watershed
Map: Dane Co. LWR Dept.
Mendota
Kegonsa
1/18/2015
2
Lake Mendota
Lake Area = 39.6 km2
Max depth = 25.3 m
Mean depth = 12.7 m
Flushing rate (ave.) = 0.23 yr -1 (23% of lake’s volume flushed per year)
Map: Dane Co. LWR Dept.
Mendota
Mendota Drainage Basin Land Use Total Area = 553 km2
59.7% 22.9%
12.0%
5.4%
Agriculture
Urban
Forest & Grasslands
Wetlands & Open Water(excludes lake area)
Lake Monona
Area = 13.7 km2
Max depth = 22.6 m
Mean depth = 8.3 m
Flushing rate (ave.) = 1.3 yr -1 (130% of lake’s volume flushed per year)
Map: Dane Co. LWR Dept.
Monona
8.1%
62.6%
23.8%
5.6%
Agriculture
Urban
Forest & Grasslands
Wetlands & Open Water(excludes lake area)
Monona Drainage Basin Land Use Total Area = 119 km2
Lake Waubesa
Area = 8.5 km2
Max depth = 11.3 m
Mean depth = 4.7 m
Flushing rate (ave.) = 4.3 yr -1 (430% of lake’s volume flushed per year)
Map: Dane Co. LWR Dept.
Waubesa
24.6%
38.8%
23.1%
13.5% Agriculture
Urban
Forest & Grasslands
Wetlands & Open Water(excludes lake area)
Waubesa Drainage Basin Land Use Total Area = 124 km2
Lake Kegonsa
Area = 13.0 km2
Max depth = 9.8 m
Mean depth = 5.1 m
Flushing rate (ave.) = 3.0 yr -1 (300% of lake’s volume flushed per year)
Map: Dane Co. LWR Dept.
Kegonsa
54.6%
18.6%
16.9%
9.8%
Agriculture
Urban
Forest & Grasslands
Wetlands & Open Water(excludes lake area)
Kegonsa Drainage Basin Land Use Total Area = 155 km2
Burke sewage treatment plant in 1920’s
Early pollution to the Yahara lakes was from Madison’s