Medford’s Conservation Commission has approved plans to clear 12.8 acres of unwanted plants at the Mystic River Reservation, the state-owned nature preserve located between the Mystic River and Mystic Valley Parkway.

According to the commission’s April 6 meeting agenda, the Massachusetts Department of Conservation and Recreation (DCR) intends to start an Invasive Species Management Program to target phragmites, known as the common reed, at the site.

“They look kind of like wheat,” said Alicia Hunt, Medford’s energy and environment director. “They grow really fast. They take over, and they crowd out all the native plants.”

The DCR’s project required city approval because of the site’s proximity to waterways.

Starting in the fall, the DCR will treat the reeds with an EPA-approved herbicide called glyphosate, Hunt said.

“These plants are pretty hard to get rid of,” she said. “Physically cutting them back isn’t good enough.”

It will take several years before the reeds are removed in full, Hunt said.

Currently, the plants cover nearly 13 acres of the land, much of which could be used for recreation.

“That park is a lot bigger than people even realize it is because the [reeds] have taken over a huge portion of it,” Hunt said. “We want people to love and enjoy the river, and people don’t even realize the river is there. They can’t even see it because of these things.”

Once complete, the project will allow visitors clearer access to the river.

“It will definitely be more open space, more grass, more native plants in general,” Hunt said. “Area that people could walk through, get closer to the edge of the river.”

The project also includes improvements at the adjacent Macdonald State Park, including upgrades to pedestrian and bike pathways that run through the park, connecting the I-93/Mystic Valley Parkway intersection to Station Landing.

The improvements should make it easier for pedestrians or bikers to access the MBTA’s Wellington station, Hunt said.

“It should really open things up for them, particularly for that end of the park by Station Landing,” she said. “That area is one that will particularly get opened up.”

Park upgrades might also include a new playground, in addition to landscape improvements, Hunt said.