City commissioners are willing to spend at least $1 million to make emergency repairs to the aging Bowersock Dam, but they were told Tuesday the 135-year-old dam could easily need $8 million or more worth of work.

The $1 million is already in the city’s budget, but commissioners did not come up with a plan for how to pay for millions of additional dollars worth of work.

They did agree, though, that they’re going to have to start figuring.

“Quite honestly, we don’t have a choice but to fix the dam,” Commissioner Sue Hack said. “It has to be as economical as possible, but we don’t have the choice as a community to do nothing.”

Commissioners were told by engineers that if the dam were to fail, the two adjacent Kansas River bridges that lead to downtown also would be seriously compromised.

“Removal of the dam is really not an option,” said Clay Adams, district engineer for the Kansas Department of Transportation.

The loss of the dam also would cause the water level of the Kansas River to drop enough that it would be difficult for the nearby Kaw Water Treatment Plant to operate. The city has emergency plans to allow the plant to continue operating in the event of a failure, but does not have a good long-term solution for how to keep the plant running.

“This is an issue that could change the face of Lawrence if we don’t do what we need to do to take care of the dam,” Mayor Mike Dever said.

Commissioners tentatively agreed that the first step is to build a coffer dam — a temporary dam just upstream of the dam — later this year to allow engineers to get their first look in about three decades at the face of the structure. At that time they also want to do about $700,000 worth of work to plug holes in the dam.

Commissioners are hoping they can do all the work for the $1.1 million that currently is built into the city’s utility budget. City staff members expressed concern over that idea. They estimated a coffer dam alone would cost $500,000 to $1 million to construct.

But Stephen Hill, whose family owns the adjacent Bowersock Mills & Power Co., said the coffer dam likely could be built for $350,000. He said that is an estimate he has received from the company who has built coffer dams at other locations on the Kansas River.

Hill’s company also technically owns the dam, but a 1977 contract calls for the city to pay for maintenance costs associated with the dam. That deal was struck when the city was purchasing land from Hill’s family for the current City Hall.

Hill told commissioners that his company — which uses the dam to generate electricity — had no ability to pay for the dam’s maintenance.

In January, the Federal Energy Regulatory Commission ordered the flashboards be lowered because regulators were concerned about the structural integrity of the dam. FERC’s concerns came after a city engineering report in 2006 found that it could not be determined “if the dam is in immediate danger of failing, as significant structural concerns exist.”

The city in the past has used money from water rates to pay for dam maintenance. Staff members also said using property tax funds would be an option, as well as looking at ways to tap into federal stimulus money.

City staff members on Tuesday agreed to further research the cost of constructing a coffer dam, and to report back to commissioners in the next several weeks.

In other news, commissioners unanimously:

• agreed to allow several streets near The Oread hotel project at 12th and Indiana streets to remain closed until at least Dec. 31 to accommodate construction of the hotel.

• directed staff to issue a building permit for G-Force Athletics to begin work at 725 N. Second Street.

— Visit city reporter Chad Lawhorn’s Town Talk blog.