JACKSONVILLE — Clayton Gillette paused from his trail building to explain the difference between native blackberries and the invasive Himalayan variety to a visitor in the newest feature of Forest Park: a walkable wetlands area.

“We’ll keep the natural ones and pull the Himalayans,” said Gillette. Plantings of native species and removal of invasive ones are designed to turn a two-acre area between the park’s entrance parking lot and the former Jacksonville Reservoir earth dam structure into an accessible space where Jackson Creek meanders for 400 feet.

Notching the dam to create a new stream outlet and replacing a failing concrete spillway last summer provided the opportunity to create the new feature below the former dam.

A new trail runs through the wetland area and leads to a pond. Notching was required because the dam could have failed under severe flood conditions.

Volunteers Gillette, Gary Sprague, T.J. Murphy and Tony Hess were finishing a loop trail recently off the main pathway through the lower area. They also created spots for three benches in the cool area beneath a canopy of large trees surrounding the creek.

“This was a solid blackberry patch,” said Hess. “This is a great entrance trail. It’s easy for people.”

The new trail runs between the existing Norling and Rail trails east and west of the creek and the reservoir pond, which remains behind the notched dam. That area features willows and tall cottonwoods and is a sanctuary for many bird species.

Hand-lettered signs on temporary stakes identify various species. Volunteers have planted many native flora in the area, including mock orange, red twig, dogwood, currant, elderberry, spiraea and salal supplied by the city.

A trail with switchbacks now leads to the top of the dam and the pond. Plans call for building a bird-watching shelter on the east side of the pond near the overflow, said Gillette.

“This is one of those places where we don’t have to do anything,” said Gillette, who grew up in Jacksonville and spent many days around the pond.

The pond level has dropped to the point where water no longer comes down the outlet into Jackson Creek this year, but the creek continues to flow from springs in the area and an estimated million gallons of water in sand and gravel that have filled the old reservoir.

Trevor Cluff led efforts to create the main trail as his Eagle Scout project, pulling blackberries and spreading gravel on the trail.

Gillette, a retired Griffin Creek Elementary School outdoor education teacher, set up service learning projects for two groups of 15 middle-school students from Ruch Community School. They built a gravel loop trail that goes by three ponds. The Ruch students worked for about two hours, then Gillette spent time educating them on the plants and geology of the area.

Earth removed from the notch last year was hydro-seeded to prevent erosion, and pines were planted on the surface. Blackberries that covered the dam face were sprayed with herbicide this spring and will be pulled in fall when 50 more pines will be planted to stabilize the structure.

Forest Park is located a mile west of Jacksonville on Reservoir Road. The 1,100-acre park was once part of the city’s watershed. The city stopped getting water from the reservoir in the 1950s. Hess estimates from 10,000 to 15,000 people visit the park each year, as more than 8,000 copies of a trail map have been taken from the information kiosk over 16 months.

— Tony Boom is an Ashland freelance writer. Reach him at tboomwriter@gmail.com.