No one has actually seen the Bowersock Dam for more than 30 years now.
Sure, thousands of motorists a day can get a peek at the structure as they drive across the twin Kansas River bridges near Massachusetts Street. They can see the constant white fury of foam, and notice how the dam divides the river into peace and chaos. They can see the "flash boards," the jagged pieces of lumber atop the dam that look like a broken-down 19th century ballpark fence.
But what isn't seen is the muscle. The face of the dam that obviously lies below the water and is responsible for keeping the Kaw contained. Not even the divers who are hired by the city to periodically inspect it and do maintenance have really seen it well.
"They mainly are just going by feel," said Philip Ciesielski, the assistant director of the city's Utilities Department, which is responsible for maintaining the dam. "It is too muddy and murky to really see."
The last time anyone had a good look at the dam was when the Kansas River bridges were being built - and the water levels were low - in the late 1970s.
City leaders, though, sure would like to get a good look at it now. That's because a new report by a city-hired engineering firm says there is reason to be concerned about the dam's future.
"Based upon the visual observations made alone it is not possible to determine if the dam is in immediate danger of failing, as significant structural concerns exist," engineers with Black & Veatch Engineering wrote.
This much is known about the Bowersock Dam: it is one of the older pieces of infrastructure in the city. It was built in 1874 by an entrepreneurial engineer named Orlando Darling. The major undertaking came as a result of the city largely running out of easily accessible wood to burn for steam power. And attempts to locate coal beneath the Lawrence landscape were unsuccessful.
But at City Hall there's a very here-and-now reason that leaders care about Bowersock. The dam is an absolute linchpin in the city's water system.
Without the dam, the city's Kaw Water Treatment Plant - just upstream of the dam - would have a very difficult time capturing enough water to treat to meet the city's needs. The dam raises the river's water elevation by about 10 to 15 feet, Ciesielski said. Without the dam, the stretch of river near the water plant would look much like the river does downstream of the dam - a hodgepodge of rock islands and sandbars.
In short, the city's drinking water system relies heavily on 1870s technology.
The technology is still working for the city, but it may require large amounts of new funding in the future to keep it working. That was the general conclusion from the recent Black & Veatch report.
The report broke down the needed repairs into short-term and long-term categories. The short-term work - which really needs to be done this winter when water levels are lower - amounts to at least $320,000.
That's within the city's means. Ciesielski said the city's utility department has budgeted $1.1 million for dam maintenance in 2007. The budget also includes $1.4 million for a significant maintenance project in 2013. Both projects would be paid for through existing water rates.
But engineers aren't certain that the short-term fixes will do much to fix the dam's problems. If not, then the long-term costs become expensive and outside of what the city has budgeted.
The engineers estimate long-term costs could range from $7.5 million to about $18 million, depending on how much work is needed. Before that work is done, the engineers recommend that the city study building a new dam, which has a rough cost estimate of $20 million to $25 million.
Ciesielski said the city is taking that recommendation to heart.
"Our next step after this maintenance project is to determine whether there is another maintenance cycle left in the dam or whether there needs to be a replacement of the dam."
Ciesielski said that decision ideally should come before 2013 when the next major maintenance project is budgeted to occur.
Ciesielski said city engineers will be watching the dam closely following the repairs for evidence that the short-term fixes are working.
Even the watching won't be easy. Basically, the city will be looking for small signs - like whirlpools in the water - to determine whether water is flowing through the dam instead of being routed through the spillways and designated outlets.
Everything about the dam is complicated by the fact that it was built so long ago and very little is understood about how it was built.
"What we know is that it is just a mass of materials held in place by its own weight," Ciesielski said. "But there aren't a lot of drawings to go by."
Engineers do know that inside the dam, cage-like structures hold boulders, rubble and other heavy objects that were available in 1870s Lawrence. The cages largely were built with wire mesh and timbers.
That's right, a portion of the dam is built out of wood.
That's part of the concern with the dam. Wood, Ciesielski explained, is a decent enough material as long as it always remains dry or always remains wet. When it starts alternating back and forth between the two conditions, it becomes a problem.
In some places on the dam, that is what is happening. The engineers noted that some timbers that were exposed in 2004 have now "eroded completely." The problem is complicated because water is leaking through the dam. In the past, crews have put bags of grout along the face of the dam to stop the leaking, but engineers have said that isn't a permanent fix.
The report expresses concerns that if the timbers begin to give way, it would "compromise the integrity of the structure."
On the river
Sarah Hill-Nelson spends more time than most thinking about the Bowersock Dam. Her great-great-grandfather - J.D. Bowersock - was the entrepreneur credited with making repairs and improvements to the dam in the late 1870s. The town was so pleased with his work and the power the dam provided to a growing hub of industry that citizens labeled him "Master of the Kaw."
Hill-Nelson spends many of her workdays right alongside the Bowersock Dam, in the same spot J.D. Bowersock ruled. She's an owner/operator of the Bowersock Power Co., the small red brick building behind City Hall. It contains turn-of-the-century hydroelectric turbines that crank out electricity that is sold to Westar Energy and is marketed to consumers wanting to buy "green energy."
Hill-Nelson is glad that city leaders are poised to take a serious look at the dam's future. She thinks the city - with help from her crews - has done a good job of keeping the dam in working order. She doesn't think the dam - which isn't a flood-control dam - is in any real danger of immediately giving way. But she doesn't want it to get to that point either.
"Without the dam, Lawrence would be in trouble," Hill-Nelson said. "If something were to happen to the dam, it could be really, really costly after the fact."
She has mixed emotions about the talk of abandoning the historical dam and building a new one. If the city got serious about that idea, Hill-Nelson said her company likely would get serious about exploring the feasibility of building an additional hydroelectric power plant on the north side of the river.
But Hill-Nelson said she does enjoy marveling at her family's work, of how teams of oxen hauled large boulders from Jefferson County to build the dam.
"I think a lot about how it was such a huge endeavor," Hill-Nelson said. "And it marked a time when the community was thinking so big. They were building the dam because Lawrence had aspirations to be the dominant industrial center of the plains.
"For me, it is endlessly fascinating."