On April 25, three much-needed athletic fields will open at Magnuson Park as part of a long-term project that is also creating wetlands at Sand Point.

Three emerald-green, all-weather ballfields will open at Seattle’s Magnuson Park on April 25, and two others will be ready in about a year — marking a significant transformation in the long-debated property at Sand Point.

Four of the five new fields will have lights, much to the delight of players and coaches who have complained for years about a lack of sports venues in the area.

“It’s huge anytime you can get a lit synthetic field that allows you to play most of the year,” said Bill Farmer, board member of Friends of Athletic Fields and an Ultimate Frisbee player.

“There is so much demand for field space that we have to play in Shoreline a lot and sometime go to Tukwila or SeaTac.”

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The ballfields did not come easily.

While neighbors have lamented the prospect of night glare from the lights, along with more noise and increased traffic, environmentalists have worried about the interplay of construction, sports and ecology.

In response, Seattle’s Parks and Recreation Department and a team of landscape architects have engineered and built 30 acres of wetlands and passive areas as mitigation for the athletic fields.

Deep marshes, ponds and vegetation have been built next to existing stands of red alder and black cottonwood and span property where a tarmac and buildings once served U.S. Navy aircraft.

The goal has been to restore habitat, improve drainage, treat stormwater and undo damage to the soil caused by concrete runways that existed at the 360-acre property when the Navy used the land.

Guy Michaelsen, a landscape architect with The Berger Partnership, said the ballfields will act as sponges, absorbing rainwater before slowly releasing it into the wetlands downstream.

There, “leaky” berms consisting of rocks and permeable fabric have been built to control and treat the runoff.

And just above the ponds that eventually connect to Lake Washington through underground pipe is a series of shallow pools, one flowing into the next. The pools resemble paddies and provide habitat for amphibians and migrating shorebirds.

Ship Canal

The Sand Point peninsula once consisted of wooded hills, wetlands and a 15-acre lake.

That changed in 1916 as Lake Washington was lowered to make way for the Ship Canal. And when the Navy moved in during the mid-1920s, the site was flattened and graded for a base and airstrip.

Debate over how best to use the property has been waging since the Navy began phasing out the base in 1970 and turning the property over to the city for what is now Magnuson Park.

At one point, the city planned to install 11 fields at Magnuson, nearly all of them lighted, which would have created Seattle’s largest recreational-sports complex.

The city’s master plan now allows for a total of up to nine fields. Whether the other four ultimately are built will depend on funding and whether environmental and neighborhood concerns can be resolved.

Lynn Ferguson is a longtime neighbor of the park and a volunteer with the Magnuson Environmental Stewardship Alliance (MESA), a volunteer group dedicated to preserving and rehabilitating habitat within the park.

She praises the new wetlands and the diligence of the city’s project manager, Andy Sheffer, but says the wetlands only address a fraction of the needed habitat protection and enhancement.

She has other concerns, too, including the potential effects on wildlife of the recycled rubber pellets that are embedded in the fields’ turf to enhance cushioning.

“Endangered chinook salmon swim the shores, chorus frogs are croaking, swallows are due back soon,” Ferguson said.

Wildlife habitat, she said, “is a treasure that needs to be valued by the powers that be in our ‘green’ city.’ “

Ultimate Frisbee

The three fields opening next month will accommodate soccer, rugby, lacrosse and Ultimate Frisbee and will have lighting.

All three are large enough to accommodate two simultaneous matches of Ultimate Frisbee, a popular game in Seattle.

The first league that played at Magnuson in 1984 had five teams and about 50 players. Now, the local association, DiscNW, manages year-round leagues that include more than 3,500 players.

Sheffer, the city’s project manager, has overseen construction of the entire development — from the fields to the new wetlands that surround them.

The work has entailed removing and restoring acres of pavement and ridding the property of tons of concrete foundations and debris left by the Navy.

It also involved listening and working with sports groups, park neighbors and environmental stewards.

“It is very inspiring to see how many acres” MESA has restored in the park “and equally rewarding to watch my daughters play sports here,” Sheffer said.

He also said the differing points of view in the end have made for a better park.

“Generally, the desires of user groups have the common denominator of wanting to enhance the health of our city — it is just a matter of stepping back and looking at the big picture.”

Richard Seven: 206-464-2241 or rseven@seattletimes.com