Corona del Mar drivers beware: A major water pipeline improvement project along area roads could create some traffic snarls starting this spring and into summer.

"It's big, it's going to be a pain — no question about it," Newport Beach City Councilwoman Nancy Gardner said Tuesday.

She warned residents about the likely back-ups to come in a monthly newsletter.

But, Gardner explained, the installation of new pipelines to move water from Big Canyon Reservoir to the Corona del Mar area is a kind of necessary evil.

"We've got really aging infrastructure in parts of the city — like Corona del Mar," she said.

The project aims to improve water-supply pressure in the area, increase firefighting supply flows, and create pipeline redundancy to improve service reliability, a staff report said.

Construction is expected to start in April and be completed by summer of 2014. The council voted unanimously to move the project forward at its meeting late last month.

New transmission mains will be installed along several streets branching from MacArthur Boulevard between East Coast Highway and San Miguel Drive, including segments of San Miguel and segments of Carnation, Dahlia and Fifth avenues.

A pressure regulator will also be moved to a spot near East Coast Highway and Dahlia.

The city allotted about $5.1 million for the project, including a $4.4 million contract with firm T.E. Roberts Inc., and other construction-related costs, according to the report.

Though the council had voted earlier in the Jan. 22 meeting to opt out of state prevailing-wage requirements unless specifically noted otherwise, the pipeline project had already been put out for bids with those requirements, staff said.

The city's 1998 Water Master Plan anticipated the need for a new pipeline because of the city's growing density and because of wear and tear on existing infrastructure.

Deputy Public Works Director and city engineer Pat Thomas said at the meeting that pipes ranging from 16 to 30 inches in diameter will be installed several feet into the ground alongside busy thoroughfares — so delays are inevitable.

But mitigation measures are part of the city's plans, he said.

That means work will be concentrated on less heavily traveled areas during the summer, Gardner said.

And in the meantime, she wrote in her newsletter, "summer traffic will be improved in another part of town."

A much-needed left-turn signal at Marguerite Parkway and East Pacific Coast Highway is expected to be in place by April.

jill.cowan@latimes.com

Twitter: @jillcowan