JAFFREY — The look and feel of downtown Jaffrey may be altered for a period of time between now and the first part of 2011, while water levels at the Main Street dam impoundment are lowered to allow for repair of the dam’s control gate operators.

The dam is part of a network that controls water flow on the Contoocook River, and repairs are being made for flood control purposes.

“Subject to weather and other conditions, the Main Street impoundment may be dewatered into mid-2011,” reads a notice regarding the dam issued by the Jaffrey Department of Public Works on Tuesday. “The Department is sensitive to the character and aesthetic benefits this dam brings to the downtown and will strive to minimize the time of drawdown to the greatest extent possible.”

Tuesday morning, DPW workers opened one control gate at the dam to allow the water to begin draining out of the impoundment, so that engineers planning to bid on the repair work could measure the gate openings.

“This action was necessary to allow bidders and fabricators for the gate replacement to take accurate measurements of the existing control gates to provide accurate and fair costs to replace the gates,” the notice reads. “Once a contract is approved, fabrication, construction and installation of the replacement gate(s) will occur over approximately a 12 to 20 week timeframe.”

The existing black operators that control the dam gates will be maintained as part of the repair plan, but will not longer serve a functional purpose, according to the notice. The operators are being kept to maintain the aesthetics of the dam, which is located in the center of downtown.

The work is being done at the behest of the state Dam Bureau, which has issued letters of deficiency for the dam. According to the 2008 town report, the state issued a letter on Oct. 3, 2007, identifying 18 deficiencies that affect the operation of the dam.

Another letter issued on April 5 of this year orders the town to make repairs to the gates by Aug. 31, 2011.

“The gate guides seem to have separated, and need to be reconstructed; the gates are leaking significantly, which is slowly eroding the concrete around these guides,” reads the recent letter issued by state Dam Safety and Inspection Section Administrator Steve N. Doyon.

On Tuesday at the dam, DPW Director Randall Heglin, said the opening of the bids would take place on Sept. 16.

The cost of the repair work is to be funded by the town’s Main Street Tax Increment Financing District.

The estimated cost of the work is not specified in the plan, and Heglin did not return a message Tuesday afternoon seeking comment.