Standing on a scrubby slope overlooking the Evergreen Brickworks, investment banker David Townley rustles a pair of landscape diagrams as he picks his way down a snow-dusted trail from Chorley Park to the Mud Creek ravine.

Mr. Townley, president of the South Rosedale Residents' Association (SRRA), points to a stand of protected butternut elms and a crumbling wooden staircase.

"This is where the new path is proposed to go," he says, tracing the route with his finger. "What you see here is a very naturalized situation."

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The city's plans to alter this hillside have led to a fierce debate over the future of an exclusive park little known outside Rosedale, pitting some locals against cycling and accessibility advocates. Signs calling on the city to "Stop the Chorley Switchback" have sprouted on lawns across the neighbourhood.

At issue is a $1-million proposal to replace the trails with a 535-metre zig-zagging path buttressed by stone retaining walls. The city's plan introduced last year, called for meandering asphalt paths with railings, which keep people from wearing down the ravine slope and also provide far easier access to seniors, cyclists, and those with mobility problems. But some Rosedale residents felt the city's scheme was "excessive" and "over-engineered" and suggested that the accessibility measures would too fully alter the landscape.

The showdown sets an important precedent for other Toronto ravines, many of which are threatened by over-use. As Robert Wright, a professor of landscape architecture at the University of Toronto, says, "The Don Valley is in an ecological crisis. It is a failing ecosystem."

Chorley Park was once the site of the sprawling official residence of Ontario's lieutenant governor-general, a grand chateau-style house which later became a hospital and was demolished in 1959.

At one end, it slopes down to a ravine connected to the Don Valley; it was here that conflict came to a head last spring after the city removed 138 small-diameter trees and shrubs from the slope in preparation for summer construction. But after a volley of complaints from the SRRA and an ad hoc Friends of Chorley Park network, the city last summer halted the project and set up a working group, with representatives from several residents' associations, the Brickworks, and cycling and disability advocacy organizations. They have been meeting under the supervision of an external facilitator since the summer to hammer out a solution.

Rosedale residents, however, ponied up several thousand dollars – Mr. Townley declined to give a precise figure – to hire their own landscape architect. Their proposal called for a shorter and steeper pathway with grass swales instead of railings, fewer switchbacks and a smaller footprint than the initial plan.

Two public meetings will be held in coming weeks to solicit feedback on a new, as-yet-approved plan developed by city landscape architects. It bears some resemblance to the Rosedale residents' proposal, but is longer and wider.

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Kristyn Wong-Tam, the area councillor, said she's "optimistic" the players can come to a consensus. Mr. Townley agrees. But in an interview, Ms. Wong-Tam added the city fully intends to settle on a final plan very

shortly. "It is going to happen soon," she said. "I don't want to miss another construction season."

The overgrown trails and rotting staircases between Chorley Park and the ravine have been on the city's radar for a decade. Then, when council in 2012 approved a plan to build more off-road cycling routes, parks officials identified that slope as a potential "quick win," says Ms. Wong-Tam. The new path would connect Rosedale to the Beltline Trail.

While some Rosedale activists, such as Mr. Townley and Kathleen Hanly, a lawyer who heads the Friends group, say they were caught off-guard by the removal of the trees, Ms. Wong-Tam stresses the city had already held meetings and advertised the project with north Rosedale residents.

Ms. Hanly says her group doesn't care for features such as railings. "I think there's a real dislike of being channelled into these fenced areas." But Ms. Wong-Tam insists the city can use natural materials, plantings and "beautiful" design to ensure that the structure blends to the landscape. "Having a ramp without rails," she adds, "would be potentially dangerous."

As for the accessibility provisions, when municipalities upgrade infrastructure they must comply with building code regulations and provincial accessibility laws, which specify paving surfaces, grades and rest stops. With this and other such projects, the design must also pass muster with a panel of individuals with physical disabilities. A slope of 8 to 10 per cent, as in the Friends' proposal, is considered too difficult for those with mobility problems.

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Ms. Wong-Tam casts the issue in terms of human rights. "When we design spaces for residents, we're not only designing for able-bodies residents or residents who just live in the catchment area."

Others agree: "The notion of accessibility should trump everything," says Blaine Pearson, who speaks for Love the Ravines, an advocacy network that is pushing to have Ontario's Greenbelt extend to include Toronto's ravines.

The Friends group and the SRRA initially balked at the use of asphalt paving on the slope, although Mr. Townley concedes they've moved on that point. But they remain unenthusiastic about including a paved path through Chorley Park, leading from the street to the top of the proposed trail. Ms. Wong-Tam says that will be built within a year or two once the city determines natural use patterns.

While Rosedale residents insist they aren't trying to block access to Chorley Park, some participants at public meetings have expressed concerns that a new switch-back trail leading to a side entrance to the Brickworks will increase traffic, and spur conflicts between cyclists and pedestrians negotiating the path.

Mr. Townley suggests that there are alternatives. Disabled users, he says, can access Rosedale's ravines either by Wheel-Trans to the Brickworks parking lot or via Milkman's Lane, an unpaved and somewhat eroded trail a bit further west. (It has also been recently fitted out with railings to keep users off the slopes.)

Ms. Hanly also raises the spectre of thrill-seeking skateboarders gravitating towards a paved switchback, citing a website that touts its potential. She says long-boarders have been spotted using a similar path recently built in the Brickworks.

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But Evergreen spokesperson Anthony Westenberg says he's only seen a few skateboarders there. While the city would have to address reckless usage it if escalated, he adds that this particular issue isn't at the top of his list of concerns.

With a decision looming, Ms. Wong-Tam is taking the long view on a political headache that has meandered across the northern flank of her ward for a year. "When you're building for the next 50 or 60 years, [you] better get it right."