PORTLAND — They came with canals, tidal barriers and a multi-tiered park.

But it was city-based Aceto Landscape Architects that went away May 3 with the prize for the best design idea in the Bayside Adapts Design Challenge, created by the city Sustainability Office.

The contest sought concepts to protect Bayside from projected increases in the water level due to climate change and to better control stormwater flow. On May 3, all were on public view in the Rines Auditorium at the Portland Public Library.

Aceto’s “Back to the Mill” concept would mitigate rising sea levels and stormwater overflow by “unshackling natural systems,” according to the presentation. First, Mill Cove, which once sat near the Forest Avenue exit off Interstate 295, would be unearthed as the highway is rerouted, converted into a parkway and elevated on a berm.

Aceto planners suggested the neighborhood arterial streets go underground by the end of the century as smaller streets course through mixed-use development that encourages alternative forms of transportation.

The contest was judged by city Director of Planning and Urban Development Jeff Levine, Boston Harbor Now Vice President of Policy and Planning Julie Wormser, National League of Cities Center for City Solutions Senior Associate Shafaq Choudry, and Addy Reiman of the Portland Society for Architecture.

Designs were also submitted by mbla + Canal 5 Studio, Alyssa Phanitdasack, Bild Architecture and a joint submission by Soren Deniord Design Studio and Kaplan Thompson Architects.

“It was an excellent cross-section of the design community,” Sustainability Coordinator Troy Moon said.

The contest was funded by the National League of Cities, which, with the Wells Fargo Foundation, provided a $10,000grant to study how Bayside could adapt and be protected from flooding.

“What stands out is the many different ways of dealing with water as a challenge,” National League of Cities Program Director Cooper Martin said. “Preparedness does not have to be one thing.”

There is also a Bayside Adapts working group that began meeting in December. It includes representatives from the Bayside and East Bayside neighborhood groups, Portland Society of Architecture, Portland Trails, the Portland Housing Authority and local business and property owners.

The National League of Cities includes Portland and nine other cities in a pilot program formed to study resiliency. Martin said from his observations, Portland most closely resembles Providence, Rhode Island; Annapolis, Maryland; and West Palm Beach, Florida, for the challenges faced.

In Providence, Martin said the rivers flowing through the city are mostly guarded by sea walls. Protecting one neighborhood where there is no seawall is a study goal.

Annapolis, which sits near the mouth of the Severn River as it empties into the Chesapeake Bay, is similar to Portland for its size and population, and West Palm Beach is similar because there are problems with inland stormwater flows, Martin said.

The concepts presented may have been conversation starters, but two planned efforts to control rising water levels are on hold.

As part of the $85 million mixed-use development on Somerset Street known as “Midtown,” the street will be elevated above projected flood levels. The city will pay two-thirds of $4 million cost, and is already paying interest on a U.S. Department of Housing & Urban Development loan for the work.

A plan to divert stormwater flowing to the Portland Water District treatment plant near East End Beach that was anticipated to cost $21.5 million in 2013 was put off last year by City Manager Jon Jennings when engineers from Wright Pierce estimated it would cost $35 million.

Department of Public Works Director Chris Branch said the city will now look to replace flood gates to control rising water levels. 

David Harry can be reached at 781-3661 ext. 110 or [email protected]. Follow him on Twitter: @DavidHarry8.

A sketch from Aceto Landscape Architects’ winning design for protecting Bayside from rising water levels shows how Mill Cove could be unearthed as Interstate 295 is reduced to a parkway in Portland.