The city of Madison, Wisconsin, in the Upper Midwest of the United States is a rapidly growing medium-sized city of 255,000 people. Arguably, its most unique asset is an isthmus ranging in width from a kilometer to a little more than a mile wide (1.8 km) that separates Lake Mendota from Lake Monona. On this isthmus is the State Capitol building, the downtown area and just to the west is the University of Wisconsin campus with 44,000 students enrolled. However, recent events seem to make Madison WI a microcosm of Earth changes all over the world and what will likely happen in the future.
The first time I ever saw the Isthmus from an airplane, I was shocked at how tiny the strip of land looked compared to the lakes that surround it. Lake Monona is about two to three miles wide and Lake Mendota is six to seven miles wide. If someone drew a straight line from the northern shore of Lake Mendota to the southern shore of Lake Monona, northwest to southeast, bisecting the southwest-to-northeast running Isthmus at a 90 degree angle, at least nine-tenths of that line would be in one of the two lakes.
It’s strange because a person standing on the Isthmus would be scarcely aware that they were, in fact, on such a narrow strip of land. The Isthmus has a number of hills, and one of the only places one might see both lakes would be from the top of the Capitol. .
Nevertheless, from the airplane flying over the northern shores of Lake Mendota, it seemed like the lakes could easily engulf the Isthmus. Unfortunately, that view might be closer to reality than one might think.
Flood of August 20, 2018
On August 20, 2018, heavy rains devastated the west side of Madison and the nearby towns of Middleton, Cross Plains, Black Earth, and Mazomanie. An unthinkable 11.63 inches of rain fell on Middleton and 15.33 inches on Cross Plains. The Isthmus and the east side of Madison were spared the worst—“only” 3.92 inches of rain fell at Dane County Regional Airport.
The rising lakes
However, since then, Madison residents have been getting a crash course in hydrology. All that water has had to go somewhere. As it turns out, about a third of Dane County is within the Yahara River Basin, meaning that within the basin, water flows into the Yahara River. The river starts in northern Dane County and connects four major lakes—Lakes Mendota, Monona, Waubesa, and Kegonsa—and then flows into the Rock River just a few miles south of the Dane/Rock county line. (The Rock River, in turn, flows into the Mississippi River at Rock Island, Illinois.)
As such, Lake Mendota began to rise several inches over the course of several days after the August 20 rains. By August 23, the lake had risen five inches. Where the Yahara River flows south from Lake Mendota, the Tenney Locks regulate the flow of water into the Yahara River and to the lakes below it. As it rose, officials had to increase the amount of water being released water through the locks in order to protect the lock and dam from failing. This caused the Yahara River to overflow its banks in several spots along the Isthmus—however a failed dam would have caused far worse damage.
But the Yahara River isn’t the only source of water flowing among and between the lakes. Groundwater under the surface of the Isthmus interacts with the waters from both lakes. There are also human-made storm sewers that divert water from the streets into the lake.
The first place where flooding on the Isthmus became noticeable was Tenney Park itself. Tenney Park has a ring-shaped lagoon that was built out of marshland in 1900. While the lagoon is not linked by a surface waterway to Lake Mendota, groundwater interacts between the lagoon and the lake. The Tenney Park Lagoon flooded onto East Johnson Street–a main thoroughfare of the Isthmus that is 2-3 blocks south of the lake. About a half mile stretch of East Johnson continues to be closed as we speak.
With the floodwaters flowing into the Yahara River Basin, the storm sewers began to back up. As a result, giant puddles began to form in the middle of the Isthmus near East Washington Avenue, a six lane road that bisects the Isthmus lengthwise. As such, one lane on each side of East Washington was closed, as well as several streets that cross East Washington.
For nearly three weeks, the Isthmus has stood on a precipice. Heavy rains on the Isthmus could disrupt the delicate balance being kept and cause flash flooding. The city has released maps of areas that are at high risk for flooding, based on their proximity to the river, one of the lakes, or the storm sewers. The city taped notices to doors in areas considered to be at high risk of flooding. Some homes have sandbags, others don’t, but the lake front properties near Tenney Park have endured damage, as well as some properties abutting the river.
Rain was predicted for August 23, then August 28, and September 1 through 3. Some severe storms barreled through southwest and south central Wisconsin, causing flooding in large parts of western and central Wisconsin, but the severe weather passed to the west and north of Dane County. The area has dodged several bullets.
To be quite honest, these are strange times on the Isthmus. On most parts of the Isthmus, life looks normal. But then one sees floodwaters appearing at unlikely places on the Isthmus that are nowhere near a body of water, such as East Washington Avenue and the intersection of East Mifflin Street and North Livingston Street. Other places like East Main Street have been flooded by the river. The Yahara River bike path is under water.
The Isthmus weekly paper reported that Lake Mendota has, over the years, been kept artificially high for the benefit of boaters, and many people are now questioning whether this should be permitted to continue. But there are other contributing factors to the flood risk Madison faces. To understand those factors, it’s important to understand the history of the lakes.
History of the Yahara River Basin
What we now know as the Yahara river has existed in various forms for millions of years. At one point it carved a 500 foot deep valley through the area sandstone. The last glaciation period had what is now downtown Madison under 800 feet of ice, but the ice tapered and ended wherethe Driftless Area now begins in places like Cross Plains, Verona, and Evansville—all about 15-20 miles from downtown Madison.
When the glaciers retreated, meltwater retraced the path of the Yahara River. A large chunk of ice and stone about 17,000 years ago broke loose and dammed the Yahara south of Stoughton, and created a single giant lake that engulfed the four lakes area. The ice in the dam eventually melted, and the current contours of the lake developed about 8,000 to 10,000 years ago.
Human beings started being drawn to the area almost 12,000 years ago. One of the first permanent human settlements in Wisconsin was built between the Village of McFarland and Lake Kegonsa. It was a place for nomadic groups of people to meet and interact. Between 800 BCE and 1100 CE, Native Americans built over 1,200 mounds near the shores of the four lakes lakes and the river. These mounds were cone-shaped, linear shaped, and the shape of various animals, including one of the largest bird-shaped mounds with a wingspan of over 600 feet. The concentration of mounds was the highest in the Midwest and the most diverse.
But after the Blackhawk War in the 1830s, Native Americans—particularly the Ho-Chunk Nation—were forced out, though many members of the tribe returned back to Wisconsin. Early settlers in the Madison area were amazed by the mounds but nevertheless dug up and dismantled them.
Madison’s lakes were a big selling point for the city, which became the territory’s capital in 1846. The center of the city on the Isthmus was originally built mostly on swampland, meaning that it had to be drained and filled in as much as possible. The Dividing Ridge, a ridge just west of Lake Monona along part of what is now Park Street, had a spectacular view of the lakes (and many remarkable mounds), but the entire ridge was quarried and dismantled to fill in swamp land and backyard gardens. The winding Yahara River was straightened as it passed through the Isthmus. Left alone, much of the Isthmus would not have been suitable for settlement.
European settlement and the decline of the lakes
It could be argued that the health of the lakes has not been the same since then. Lake Monona had a severe problem with sewage starting in the late 1800s, and smelled horrible. The sandy bottom viewable from the surface had disappeared. Massive growths of aquatic weeds and often toxic blue-green algae (which are actually cyanobacteria) caused the sandy bottom of the formerly clear lake to disappear from view. Boaters had to wash black slime off their boats after use. It wasn’t until the 1950s that the sewage was pumped into Lake Waubesa, and then later to Badfish Creek, which feeds into the Yahara River below Lake Kegonsa. Finally, the federal Clean Water Act of the 1970s forced significant improvements to water treatment. However the growth of agricultural runoff has affected the four lakes, including now Lake Mendota, which still appeared to be clear as late as the 1970s. Initial efforts to develop incentives to minimize agriculture runoff have been marginal in their success, and the problem of algae and aquatic weeds continues unsolved to this day.
Near the capitol, there has been an unprecedented number of high rise buildings constructed, especially since 2013. These high-rises range in height from ten to sixteen stories high, though their height is limited by the height of the capitol dome on top of the highest hill in the Isthmus. Madison’s population growth requires approximately one thousand new units of housing to be built in the city every year and the influx of high tech workers into this boom town has developers gearing themselves more towards upper income tenants. In addition to displacing a lot of water and doubling runoff, these developments are also displacing middle and low income people who have contributed to the unique culture of Madison over the decades. In much of the west Isthmus, groundwater is just eighteen feet below the surface. This means that a lot of buildings are being built into the water table. This water is displaced and has to go somewhere.
The level of Lake Mendota has been rising since 1916 . The Wisconsin State Journal reported that since 1970, the volume of the Yahara River has been 30% greater than the previous four decades, and average annual precipitation has increased by 13%. Precipitation is the biggest factor—southern Wisconsin has been getting wetter. Several days of heavy rains in 2008 caused Lake Delton–an artificial reservoir and a popular tourist area, to overflow its banks–wash out several homes and a highway, and then empty itself into the Wisconsin River, leaving a giant field of mud in its wake. Repeated floods of the Kickapoo River in southwestern Wisconsin caused the entire village of Gays Mills, WI to start relocating to higher ground in 2008, and parts of the old village have been flooded again in 2016, 2017 and 2018, with the 2018 rains setting anew record. Other villages of southwestern Wisconsin have been similarly affected, including Soldiers Grove.
For all the difficulties caused by the settlement of Madison, Madison has also developed a rich, unique culture that has a chance of thriving even as the rest of civilization seems to atrophy. Why I believe this to be the case will be the subject of future blog posts, but I will offer a few examples now. The University of Wisconsin is a powerful research center. One result of this is that Lake Mendota is arguably the most studied lake in the world. People tend to be more ecologically aware, bikes are more likely to be a source of transportation here than elsewhere, and vital neighborhoods provide a sense of community not seen in many other urban areas in the Western world. Madison is not, by any means, perfect, but it has many social assets that can be used to address the issues the region faces.
Are these assets enough to reverse the problems caused by human mismanagement of the region? The history of lake pollution and the increased water runoff due to real estate development exacerbates the trend of lakes rising due to southern Wisconsin becoming wetter. This trend is accelerating due to hyper-development, rapid population growth, and climate change, the latter of which is causing heavier rains than usual to fall on southern Wisconsin. There will need to be major changes to how Madison addresses its water. But will there be enough resources to make these changes possible?
I believe that Madison has the chance to thrive in the face of these rapid changes. But any improvements made to the Yahara lakes, if any, will at best be temporary, as technology and current organization of human societies have mostly just exacerbated the problem. I suspect that due to the effects of peak oil and greater scarcity of resources will ultimately, keep Madisonians from reversing the rise of the lakes. It is possible that by the end of the century, the Isthmus that runs between east and west Madison and many developments close to the lakes will be underwater, a monument to human shortsightedness in its pleasure-seeking ways and hubris. Many such monuments in various forms will dot the world, markers to the changes that are occurring, and a reminder that we human beings need to humble ourselves before we can truly progress.