For the first time in nearly 30 years, the city is considering a request to the state Department of Natural Resources to change the level of Lake Mendota, dropping it by up to a foot. Larry Nelson, the city's chief engineer, said he proposed the change because of the growing threat of flooding and damage done by high water to wetlands such as Cherokee Marsh. Because of the dam on the Yahara River at Tenney Park, built in the late 1800s to power a grist mill and maintained in the intervening years even after the mill burned, Lake Mendota is now about five feet higher than its historic level.

The subject of lake levels is contentious and one of those classic Madison issues that never seems to go away. It is historically rife with dispute, going all the way back to the mid-1800s when Leonard Farwell dammed the Yahara River for his grist mill and, subsequently, angry farmers with flooded fields sued the city. In the intervening years, the rising waters of the lake have submerged a history that includes once-popular beaches, a cave in which Black Hawk was rumored to have hidden, and an island on which perched a famous vacation home designed by Frank Lloyd Wright.

This most recent proposal will probably fit in nicely with that history because it is also likely to stir up controversy. Nelson said opposition is probably going to come from recreational boaters as well as homeowners with piers that might be affected.

"We know full well what the issues are going to be,'' Nelson said.

So, apparently, does the DNR, which is in charge of setting lake levels throughout the state. Susan Josheff, with the DNR's Division of Water, agreed the issue of lake levels is sensitive.

"This is something that will affect thousands of people,'' Josheff said. She added that in considering a formal request from the city to lower the lake level, the agency would have to hold extensive public hearings as well as conduct an environmental impact assessment that would consider the impacts on fish and wildlife habitat, public safety, navigation and lakeshore property.

The DNR knows well how contentious dealings with lakeshore property owners can be, partly because of the furor over the agency's proposal to heighten regulation statewide of pier sizes and prohibit especially large piers. That debate became so heated that the State Legislature eventually intervened.

But Madison Mayor Dave Cieslewicz said the touchy nature of the issue should not preclude a public discussion about lake levels and their impact on everything from flooding to water quality.

Cieslewicz suggested that the role of lake levels be made a part of upcoming meetings about cleaning up the Yahara lakes. Those meetings, still being organized, are part of a new and broad effort to address lake issues known as Yahara Clean. The project is being spearheaded by a coalition that includes Madison, Dane County, the DNR, and the state Department of Agriculture, Trade and Consumer Protection.

"I think we ought to have a good, robust public discussion on lake levels,'' Cieslewicz said. "We should not be afraid of the question. We shouldn't run from the question.''

Doug Bach, president of the Yahara Lakes Association and a homeowner on Lake Monona, said the many and varied people who are affected by lake levels, from boaters to anglers to homeowners, will make any discussion lively, to say the least.

"It's a big issue,'' Bach said. "It's a complicated issue. It's potentially a very explosive issue.''

Nancy Mistele, a board member with the Yahara Lakes Association and a lakefront property owner on Mendota, said the proposal will definitely raise the ire of homeowners who much of the summer have to deal with lake levels that seem too low rather than too high.

"If they drop the level by a foot, I'll have difficulty using my boat lift,'' Mistele said. "And I'd have to extend my pier by another two sections.''

But Nelson said the increasing potential for severe flood damage to homes along the shores of Lakes Mendota and Monona should be incentive enough for lake property owners to favor a drop in the lake's level.

"We have to have more storage volume,'' Nelson said.

The worst floods on the Madison lakes have come in recent years. The DNR has set the flood level of Lake Mendota at 852 feet above sea level and the lake has neared or surpassed that level numerous times over the past 10 years. Last August, for example, heavy rainfall caused the lake to rise to 851.80 feet above sea level. The city of Madison was forced to erect sandbag barriers against the rising waters at several locations around the lake and the city of Middleton sandbagged homes on the lake north of James Marshall Park.

That near-disaster prompted Nelson to seek the lower lake level, according to a memorandum he wrote to his staff at the time.

"We believe that this current situation would have been less of a concern,'' he wrote, "had we been able to maintain a lake elevation one-foot lower than the maximum summer elevation established for both Lakes Monona and Mendota.''

The highest level for Mendota on record came during the waterlogged year of 2000 when on June 7, gauges pegged the flooded lake at 852.74 above sea level. Normal summer time levels for the lake are about 850 feet above sea level.

But during June of 2000, lake levels nearly three feet above normal caused more than $10 million in damage to homes and property. In Middleton alone, damage was estimated at $1.6 million including about $650,000 to private property. About 50 basements were flooded and many private shorelines suffered severe erosion.

In Maple Bluff, the village marina was inundated. Village parking lots were flooded. Carp and other fish swam through a culvert beneath a beach-side road to flooded tennis courts and a golf course, where enterprising children proceeded to fish for them.

Those same floodwaters — and the gradually increasing level of Lake Mendota through the years — have also destroyed area marshlands, important for flood storage and for wildlife and fish spawning. The change in Cherokee Marsh has been dramatic, according to Russ Hefty, who directs conservation efforts for the Madison Parks Division. Hefty said what in the early 1900s used to be a marsh complete with rare sedges and aquatic plants has become more like a lake.

One of Hefty's stranger jobs is to chase and corral pieces of floating bog that high waters and waves break off from the shrinking shoreline along Cherokee Marsh. One of those pieces sailed across Lake Mendota a few years ago and lodged against the Memorial Union Terrace. It was large enough that students were stepping onto it and hiking around, appreciating the ducks and other birds that were still nesting on the piece of runaway bog.

Now, Hefty has undertaken an ambitious project to restore Cherokee Marsh, planting and nursing new growths of aquatic plants to build up sections of marsh that have been lost over the years to high waters. A lower water level will help bring the marsh back, he said, restoring an important part of the lake ecosystem that provides not only protection against flooding but also important habitat for fish and wildlife.

Erosion of shorelines elsewhere around the lake, will continue and worsen if lake levels aren't lowered to offset the increasing amounts of water sluicing into the lake from suburban developments, Nelson said.

Increased development north of Lake Mendota is especially adding to the problem, Nelson said. Such development increases areas of pavement and rooftops and decreases places where rainwaters can soak into the ground. More stormwater runs into the lakes, reducing the capability of the lakes, especially Mendota, to store rising floodwaters.

It's similar to a bathtub, Nelson said. If a bathtub is full, you have to let water out before you can add more. Otherwise, you end up with a flooded floor. In the case of the Madison lakes, Nelson said, Mendota has always been used as storage for floodwaters to avoid problems downstream, in Lakes Monona and Waubesa. The level of Mendota is controlled with the dam at Tenney Park.

But Mistele, who owns a lake home on the north shore of Lake Mendota, wondered whether there would be a negative impact downstream if Mendota's level is dropped by a foot. "What is that going to do down the chain?'' she asked.

Bach, with the Yahara Lakes Association, said the city's efforts might better be put into controlling the sprawling development that is sending heavier volumes of stormwater into Lake Mendota.

"That's a big change after 30 years,'' Bach said of the proposal to lower the lake's level by a foot. "What else should we have been doing over that 30 years to manage stormwater? This exposes the lack of other stormwater management practices, practices they've failed to implement.''

Nelson, however, said making more room in Mendota will improve the city's ability to control flooding on Lake Monona because more floodwaters can be stored in the bigger lake if it is maintained at a lower summer level. And keeping the lake a foot lower, he added, doesn't mean that all of that excess water is released at once to course down the Yahara. Water is released gradually, he added, to keep Mendota's level constant and downstream lakes can easily absorb the excess over time.

"In order to control the lakes,'' Nelson said, "you have to control Mendota.''