Days after the stark images of homes collapsing into the raging waters of an unleashed Lake Delton first flashed across television screens, questions remain.

How could a seemingly solid piece of land give way in such dramatic fashion? And could it happen elsewhere? Are there ponds and lakes in other Wisconsin communities that could burst through their shorelines during floods?

Are we even looking for such potentially dangerous locations?

A breach similar to the one at Lake Delton is possible at Park Lake in Pardeeville.

But engineers and other experts say the catastrophic loss of Lake Delton can be blamed on a number of freakish circumstances that are unlikely to be duplicated anywhere else. Even so, dam safety experts and others who deal with the state's bridges and roads say shoreline inspections of dammed reservoirs are rare except in the case of the state's very largest dams.

Russ Rasmussen, who heads the DNR's Bureau of Watershed Management, said state law does not require such inspections for smaller dams and added it is unlikely there is enough time or personnel to inspect nearby shorelines.

"A dam like that at Lake Delton, we probably would not,'' Rasmussen said.

Chain of events

By early in the week, heavy and prolonged rainfall had already set in motion a series of events that would result in Lake Delton draining like a bathtub, according to Tuncer Edil, a professor in the UW-Madison's Department of Civil and Environmental Engineering who closely followed the happenings at Lake Delton.

Edil said the disaster had its foundation in the rainfall that saturated the ground, comparing the event to what happens when steep coastlines and bluffs slide down during heavy rainstorms.

The already unstable and sandy soil was another factor as was the location of the piece of land — between the flooded lake, which created high pressures on one side, and the rushing river 700 feet away and several feet lower than the lake.

The rainwater that soaked the sand caused every cubic-foot of the soil to weigh much more than normal, Edil said. At the same time, water from storms and the surging lake was moving over and through the sand, creating pores and channels that reduced the soil's ability to stay in place.

Finally, Edil said, the increasing force of gravity due to the heaviness of the waterlogged soil and the decreasing resistance of the water-weakened sand to those forces combined to send the narrow section of shoreline down the Wisconsin River.

Hundreds of dams

All of these things — the high lake on one side and a lower body of water on the other, the heavy rainfall, the sandy soil, and the flooding — would have to be combined elsewhere to create a similar disaster, Edil said.

But anyone driving through Wisconsin will come across hundreds of dammed reservoirs similar to Lake Delton.

At Yellowstone Lake State Park in Lafayette County, a dam and 1,800 foot-long dike hold back water from the Yellowstone River to create the 455-acre lake, which was filled in 1954.

Greg Pitz, who has worked at the park at various times from 1976 to 1983 and has been its manager since 1995, said the dam, which was retooled in the late 1990s, and dike were inspected last year and were found to be in good shape. He has never had concerns about the integrity of the dike, located on the lake's eastern shore and which serves as a popular area for shore anglers chasing crappies.

"In 1986 we had three 100-year floods," Pitz said. "It came up pretty high but we never had a concern about the dike being breached."

James McCaulley, director of the Land Conservation Department in Iowa County, said there are four man-made lakes in his county that cover more than 650 acres.

The biggest is 240-acre Blackhawk Lake, about 15 miles northwest of Dodgeville. Two dams were built for the lake, which was filled in 1969.

But in 1993, a no-wake requirement was approved for the lake, which helped ease shoreline erosion and wear and tear on the dams that are inspected yearly.

"It's the constant wave action created by the motorboats that we were concerned about," McCaulley said. "That could eventually become an issue of safety."

High-hazard dams

The state Department of Natural Resources is charged by state law with inspecting dams at least once every 10 years. And though the agency fell behind on that task, Rasmussen said dam inspections have been made a priority in the last year and added that the agency has caught up on inspection of all high-hazard dams — the failure of which would cause property damage and threaten safety.

But Rasmussen added that those inspections are largely of the dams themselves, not the nearby shoreline or road embankments. He said dam safety officials with the agency will probably be discussing the extent of such inspections.

"That's something we'll have to assess,'' said Rasmussen. "Nobody was really expecting this to happen. All our attention is focused on the dams.''

Nor does the Department of Transportation take a look at road embankments near dams and reservoirs with an eye toward such failures.

State Department of Transportation official Beth Cannestra said her agency doesn't have a formal process for inspecting embankments, noting they are so numerous on roads all over the state that it would make routine checks difficult.

Cannestra, who oversees bridge and large culvert inspections for the agency, said state, county or local workers traveling the roads will report embankments that are losing earth or stressed during floods when they see them.

But inspections during dry times probably wouldn't help much to determine which embankments might fail in the future, she said.

"I don't quite honestly know what you would be looking for,'' Cannestra said.

Digital models used

Ken Potter, a civil and environmental engineering professor at UW-Madison, specializes in hydrologic risk and storm-water modeling. He said the technology exists to analyze shorelines using digital models.

Such modeling, he said, would alert local officials to potential problem spots and possibly reinforce those weak areas that would be subject to failure during floods.

"It seems fairly obvious you'd want to know where the water is going to go,'' Potter said.

And such knowledge is only going to become more important, Potter said. Whether it can be attributed to climate change, Potter said, we have entered upon a time when storms are going to be more intense and dangerous.

"I've personally concluded we're seeing something that is going to continue in the future,'' Potter said.

Contact Ron Seely at rseely@madison.com or 608-252-6131. Contact Barry Adams at badams@madison.com or 608-252-6148.