Portions of the trails bordering Lake Calhoun and Lake Harriet are expected to be under construction this summer and fall, bringing improvements for bicyclists and pedestrians who account for the vast majority of visits to Minneapolis' Chain of Lakes.

Three sites were selected for upgrades: northeast Calhoun, southeast Harriet and a portion of trail along West Lake Street.

Before construction can begin, the Minneapolis Park Board and Metropolitan Council — as well as members of the public — have to sign off on a Minneapolis Park and Recreation master plan for the project.

The master planning process turned out to be more complicated than expected, and it's caused some delays, said planner Deb Bartels. Seven meetings turned into 12, and a process that was supposed to be over in December 2015 stretched to May 2016.

"It's a very complex area, with the amount of use and the history and where those lakes are ecologically and the watershed," she said. "We couldn't just lightly touch on those subjects and ignore them. They had to be discussed in depth, and that's what took so long."

Still, Bartels said, the project will be done before its main funding source — a nearly $3 million grant from the Met Council's Parks and Trails Fund — sunsets in June 2018.

If all goes according to plan, a 45-day public comment period will open Jan. 18 and a public hearing will be held April 5. Construction is expected to begin in May.

Emma Nelson