Storm water runoff sullies lakes and Arboretum
The heavy rains and flooding that hit Madison in early June have left their mark on city lakes and the University of Wisconsin-Madison Arboretum.
In the Arboretum, numerous trails and fire lanes need repair and a non-native plant species is thriving on storm-driven nutrients. On the lakes, massive blooms of dangerous blue-green algae have closed city beaches and are making it hard to enjoy lake life.
"I doubt that many Madison-area residents are aware of just how bad the lakes are getting in Madison right now," said Jeffrey Strobel, a Madison resident who described Lake Monona as "downright putrid."
"Recently, the Olin beach was listed as open, though it was a weed and algae mess when I kayaked by. The lake was so disgusting that I gave up and went home."
As the state Department of Natural Resources recently put it in a surprisingly colorful news release, the "stinky, odorous pond scum on many area waterways in southern Wisconsin is a direct result of unprecedented flooding last month."
When combined with hot weather and bright sunlight, the nitrogen and phosphorus carried by floodwaters to area lakes and streams produced the ideal conditions for the growth of blue-green algae. Classified as Cyanobacteria, blue-greens are buoyant and tend to float on the surface, where they form scum layers or floating mats. They are commonly known as pond scum.
Kirsti Sorsa, environmental technical services supervisor for the Madison-Dane County Public Health Department, said the algae situation is much worse than in past years.
"The blooms are more massive," she said, noting she had already received or heard of four reports of illness. "In a normal year, we may get one or none in the whole summer."
Susan Graham, a DNR water resources management specialist based in Fitchburg, said a huge blue-green algae bloom is forming on Lake Mendota and her office is receiving many complaints about a "massive, very stinky algae bloom on Lake Wisconsin."
The algae are not always toxic, Sorsa said, and samples are viewed with a microscope to find out if they are potentially dangerous. Chemical tests are also done.
"After microscopic observation, we make a decision if we need to close a beach or just tell people to watch out," she added. The decision is based on the abundance of blue-greens that could be toxic.
The Public Health Department monitors public beaches daily for bacteria and blue-green algae and posts closings at www.cityofmadison.com/beaches.
Blue-green algae can contain skin toxins, liver toxins or neurotoxins, Sorsa said, warning that the algae can be fatal to animals. Pets and children, who are more vulnerable than adults, should be kept out of contaminated waters.
For humans, exposure can cause rashes, eye and throat irritation, hives, runny noses and respiratory problems including coughs or asthma-type reactions. Swallowing water with an algal bloom may cause vomiting, diarrhea, nausea, headaches, throat irritation, muscle and joint pain, convulsions or even death in extremely rare cases.
"I don't want to turn people away from beaches, but they need to be careful," Sorsa said. Both Sorsa and Graham warned that it's best to stay out of a water body that has a bloom.
Eating fish from algae-infested waters is not a problem, however, said Sorsa.
"Just practice good hygiene. Wash the fish and your hands well," she advised. The internal organs of the fish, however, should not be eaten, Graham said.
The odor that makes the lakes so unappealing comes after the algae starts to decompose. Unfortunately, it's very hard to remove. Chemical treatments are not always effective and can sometimes make the problem worse, said Graham. Besides, they're not allowed on Madison's public beaches.
And manual removal is not much of an option either, Sorsa added.
"It would be difficult to rake an algal bloom because it breaks more easily than weeds and would be harder to get," she said.
THE intense long-lasting rain that pounded Madison in early June also damaged trails, roads and plants in the UW-Madison's Arboretum -- a 1,260-acre collection of restored prairies, forests and wetlands, flowering trees and shrubs in the heart of urban Madison.
Storm water channels and detention ponds were overwhelmed and suffered serious erosion and gouging, allowing sediments and nutrients to flow to wetlands and Lake Wingra, said Steve Glass, Arboretum land care manager.
Sections of dozens of footpaths and fire lanes were washed out entirely and others were so deeply eroded that they are still blocked off to foot or vehicle traffic. A concrete tunnel under the Beltline that links the Aldo Leopold Pines to the Grady Tract near Seminole Highway was also blocked temporarily. Arboretum Drive, the main road in the Arboretum, was washed out by Marshland Creek and remained closed for 48 hours. The road's shoulder also was eroded in other areas, requiring repair.
"Two culverts carrying overflow from a detention pond in Curtis Prairie were compromised," said Arboretum ecologist Brad Herrick. "The earth on top of the culverts was washed away."
The deluge magnified the storm water damage that has occurred in the Arboretum in recent years and underscored the need to implement a storm water management plan that was completed in 2006, say Arboretum officials.
A proposal in the plan to build a new detention pond next to Manitou Way at Nakoma Road, where there is a storm water outlet, will be discussed at a public meeting Thursday, July 31, at 7 p.m. at Westminster Presbyterian Church, 4100 Nakoma Road. The pond would be designed to collect sediment and debris before it reaches Lake Wingra.
A public meeting about the entire five- to seven-year wastewater management plan -- which would cost millions of dollars and is expected to be paid for by the various government and university entities that helped develop it -- will be held at the Arboretum Visitor Center in September, though no date has been set.
"The waters coming down from the Beltline and the Arbor Hills and Todd Drive developments all come together and ultimately drain to Lake Wingra," said David S. Liebl, a faculty associate at the University of Wisconsin who led the team that developed the storm water management plan. "There are two detention ponds upstream, but when they are full, the water comes right through, and it washed out Arboretum Drive.
"When we get high flows, we get quite a bit of water flowing through there. All the sediment and soil that is eroded by that storm goes through the wetlands and into the lake."
Liebl said it is hard to know whether this overflow is causing the growth of blue-green algae, but, he added "the conditions are ripe for a bloom."
The Public Health Department tests Vilas Beach on Lake Wingra but has found no blue-green algae there.
Development around the Arboretum has contributed to its flooding problems, say Arboretum officials.
Greene Prairie, on the southern edge of the Arboretum, receives storm water runoff from the Harlan Hills development (which was unsuccessfully opposed by Arboretum management before it was built), and from Dunn's marsh and neighborhoods upstream in Fitchburg and Madison, Liebl said.
"When that happens, much of the prairie submerges," he said. One result has been an infestation of reed canary grass, an aggressive invasive species not native to Wisconsin.
"The seeds are carried by storm water and it thrives in areas that are inundated because of the nutrients and sediment," he said.
Soaked soil and high winds also caused many trees to fall in the Arboretum, though director Kevin McSweeney doesn't see that as much of a problem.
"Generally our policy is that if it is not a danger to the public, we leave it to do its own thing. If it blocks a trail, we will cut the portion that is on the trail off. And if limbs are hanging in the canopy high up in the tree branches and that poses a danger, we will take those down. Otherwise, we treat trees falling as a natural process to regenerate soil."
Liebl said that the heavy rains would have had no impact on the Arboretum at all if it hadn't received millions of gallons of storm water runoff from polluted urban areas. Overall, he said, "the Arboretum is very resilient."
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The weeds and algae on Lake Monona are "downright putrid," says Madison resident Jeffrey Strobel.
