The Mercer Island Sewer Lake Line project end is near. Maybe.

Oct. 14 is the last day for lakeside construction, as allowed by the Washington Department of Fish and Wildlife. If the project overshoots the deadline, it will again resume on June 22, 2011, said Project Manager Anne Tonella-Howe.

“The hiccups — if we encounter any — would be the new sewer lateral connections,” she said of line offshoots that connect with Island homes. About 100 North-end residences are affected by the project.

Barring any delays, the project is expected to be finished on time, meaning the in-water work will be done by Oct. 14 and all land work will be done by Oct. 31, she said.

“All signs indicate yes,” she said of completing the project by the deadline. “We are keeping our fingers crossed.”

It’s unlikely that the department would grant any further extensions for this project, she said at a recent Utility Board meeting.

The department has already granted eight weeks of extensions to the city of Mercer Island over the course of the project. The extra time included two weeks before the official start date, and two weeks after the Oct. 1 cutoff, both in 2009 and this year, she said.

In exchange for the extended work window, Mercer Island agreed to make environmental improvements to the area, including the shoreline habitat improvements and the addition of spawning gravel over the old lake line, new lake line and all other disturbed areas.

Some sections of the old lake line — constructed of asbestos cement material in the mid-1950s — were removed and disposed of by the Mason Construction team.

Stellar J, the contractor hired for the pump station construction, began its work in January 2009. The pump is currently in a 30-day commissioning phase, which is expected to be complete by the end of the month.

The project required the input of state and federal agencies, including the Washington Department of Fish and Wildlife, Department of Ecology, Army Corps of Engineers, U.S. Fish and Wildlife Service and Washington State Department of Transportation.

The Sewer Lake Line project is the largest single capital improvement project since the city was incorporated, said City Manager Rich Conrad. The City Council approved a lake line project budget totaling $24.2 million.

Although the final cost is still to be determined, the pump station is expected to run $4.3 million and the lake line work is estimated at $14.8 million. Those figures don’t include inspections, city employee hours, divers and a variety of other costs associated with the project, Tonella-Howe said.

Funding for the project was drawn from a $7 million Public Works Trust Fund loan, a $477,000 federal STAG grant, $7.1 million in cash savings and transfers from the CIP and general fund, bonds and utility rate increases.

“Ultimately, the rate payers have to pay those loans off,” Conrad said.

Assuming that the work is done by the end of October, the completion will bring an end to a nearly decade-long project that began in 2002 when the city commissioned Economic and Engineering Services, Inc. to study the feasibility of the project.