Jonathan Barry: Six ways to address Yahara lakes flooding

September 25, 2018

It’s past time to act on flooding of the Yahara lakes. It’s not as though we lack information —policymakers have long known the problem and how it may be addressed.

Madison historian Dave Mollenhoff, in a recent column, correctly called for lowering the level of Lake Mendota to better retain major rainstorms.

UW limnologist Richard Lathrop, who has studied the Yahara chain of lakes for decades, is spot on with his call last weekend for moving excess water out of the downstream lakes more rapidly by aggressively clearing weeds and improving flow with channel improvements from lakes Monona through Waubesa and to Kegonsa.

But these steps alone will not be enough.

UW-Madison professor Ken Potter’s research put the challenge in perspective: In 1930, a 6-inch rain increased Lake Mendota 6 inches. But by 1995, a 6-inch rain increased Mendota 10 inches. And in 2018, that 6-inch rain would increase the lake even more, he says.

Had the recent big rain occurred directly over the Lake Mendota watershed (instead of over Black Earth Creek and the Sugar River, draining into the Wisconsin and Rock rivers) the rise in Lake Mendota would have topped the Tenney Park dam.

That could have breached the dam and allowed perhaps five or six or more feet of Lake Mendota to flow unrestricted down the Yahara River. Imagine the catastrophic flooding in the Isthmus and into Lake Monona and beyond.

It is this reality that must be immediately addressed.

Back in the 1980s, as Dane County executive, I ran into a buzz saw of opposition when I requested that Public Works lower Lake Mendota to the summer minimums in the spring. Pier owners and big boaters howled at the inconvenience, and policymakers wilted.

Since then we have added some 200,000 people to the watershed with many more impervious surfaces of roofs and roads and parking lots.

Since then, agricultural practices have changed dramatically with the decline of the livestock and dairy base that kept much of the land in grasses. Row cropping now dominates the lands above the Yahara River. We’ve gotten much more non-farm ownership of land, often rented, where good land and water stewardship slides.

Water runoff is fast and furious and carries more nutrients. Agricultural practices must change to better hold water.

Here is what is needed immediately at the city, county and state levels:

Lower Lake Mendota. The channels in the upper Yahara will need dredging to mollify boat owners, but the lake level ranges should come down now, even though lake property owners will be adversely impacted.Dane County must do a far better job in keeping the lower Yahara River as open as possible. Weed cutters were not fully deployed until the crisis hit.Tighten development standards for water runoff and retention at the city and county levels. Real estate and developers will see increased costs, and housing might be impacted. But authorities and builders must think outside the box with new and different development configurations.Consider more public land acquisition and conservation easements for protecting environmentally sensitive lands, while also doing our best to restore former wetlands. A useful example is the Milwaukee Sewerage District buying former wetlands and plugging drain tiles to increase water retention. This will be expensive. But contrast this with the staggering costs of the Tenney dam being breached. And consider that we may otherwise be looking at many Isthmus properties being mapped into a flood plain at a huge loss in valuation.The state should relax its hammer-lock on local development review and approvals and allow for appropriate local standards that meet community goals. I’m not suggesting that development be halted. But it must accommodate population growth while meeting water-quality and volume goals.Agricultural practices that lead to increased runoff need to evolve. The state must stop kowtowing to big farm groups when the evidence for changed policy is irrefutable.

Agricultural landowners are favored with use-value property tax benefits, which is good public policy. But farmland owners also should be required to preserve the health of the lands and waters in exchange for these tax preferences. It isn’t too much to ask that we farmers preserve the productivity of the land and cease, to the degree possible, sending the soil, nutrients and water rushing downstream to become somebody else’s problem.

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