Armidale Regional Council Mayor Sam Coupland, Northern Tablelands MP Adam Marshall and New England MP Barnaby Joyce chatted with visitors and chewed on snags after unveiling a $3.9 million upgrade of the historic site.

"This project came in under budget, which allowed us to expand the playground," Mayor Coupland said.

"Credit must go to Council staff and the contractors of this project for doing such a great job."

The upgrade took nearly a year to complete and was co-funded by the federal and NSW government's Bushfire Local Economic Recovery Fund.

Armidale contractor JNC Group Indigenous Contractors secured the contract for the upgrade.

It included a children's playground, picnic and barbecue facilities, new amenities block and upgraded jetty.

To celebrate the reserve's official opening, Council organised a free beach party for residents and visitors.

At least 200 people attended the opening which featured a lolly hunt, free ice cream and a free barbecue lunch.

Mr Marshall congratulated Council for the turnaround from an "eyesore to a tourist drawcard".

"Dumaresq reserve now has one of the region's best recreational playgrounds and will open the area up to an additional 30,000 visitors per year," he said.

Mr Joyce said the upgraded reserve added to Armidale's social infrastructure.

"If you want to attract people to Armidale then you need to invest in educational and social infrastructure and this fits the bill," Mr Joyce said.

"This will draw families here and hence, business. A big plus for the area."

Built in the final years of the 1800s, Dumaresq Dam was Armidale's water supply until Malpas Dam was built in 1968.

In 2020 and after more than five years of delays, work began on buttressing the dam's ageing wall, which eventually cost ratepayers $10 million.

Once the wall was made safe work could begin on turning the area into a regional jewel.

A camp site area/unpowered motorhome parking area was constructed, along with new amenities block, picnic shelters and barbecue facilities.

Bitumen was laid on internal roads and parking areas, parking upgraded to include long bay parking near the upgraded boat ramp, there was landscaping and new pathways and additional boardwalks.

Safety rails and signage around the jetty have been installed and ecological interpretive signs on flora and fauna have also been placed along the walking trail.

The new playground was built, featuring natural materials, plants, rocks and other elements found in nature.

At the official opening, families, councillors, politicians and visitors enjoyed the party, with free music and entertainment.

Many brought picnic rugs on which to sit, enjoy the day and soak up the autumn sunshine.