They had hoped to get the bridge inspected by a structural engineer this month, Voss said, but that's now looking unlikely.
The engineer will decide whether the bridge needs to be repaired or replaced.
It is Forest & Bird policy not to do any new work while New Zealand is in the red light setting for Covid-19.
The Rangitīkei branch of Forest & Bird maintains six reserves in its district, all on land bequeathed and owned by national office, totalling 100ha.
They are poorly signposted, Voss said, so most people don't know they exist. One has a toilet, and more amenities are planned.
The active branch has a small budget for maintenance and lots of voluntary hours are given at monthly working bees.
"We are very fortunate to have a core group of people very keen to get out and about and preserve and maintain what we have had in reserves," Voss said.