The South West Aboriginal Land and Sea Council says a heritage management plan will be created to protect sites around the proposed Lloyd Street Bridge in Perth’s eastern suburbs.

Traditional Owners and other critics of the proposed bridge design in Midland have warned the traffic-busting project is a threat to Aboriginal heritage and ecological values.

But a SWALSC spokesperson said the agreement with Main Roads to create the heritage management plan would deliver employment and procurement opportunities for Aboriginal people.

“We trust that survey participants will be shown this management plan and given the opportunity to endorse it before any work begins, to ensure that those commitments will be honoured,” they said.

“We are assured that the uninterrupted span over the main Helena River channel remains in place and the river will not be impacted during construction.”

Nyoongar Elder Greg Ugle said out of at least eight recommendations put forward by Traditional Owners consulted on the bridge design, only one was incorporated.

“A number of our Traditional Owners were not happy because our recommendations, including to build a span bridge with a 30-metre buffer on each side was not even looked at, it was deemed too expensive,” he said.

Traditional Owner Murray Jones said the design, rather than the bridge itself, posed a problem.

“We are not opposed to a bridge in itself, it is the design of the bridge that is going to affect the flora and fauna in the area,” he said.

“The impact will be quite devastating in that area.”

The SWALSC spokesperson said Whadjuk Traditional Owners who participated in the survey had taken a pragmatic approach to find the least impactful design.

“They worked constructively with Main Roads on a design that wouldn’t obstruct the flow of the river or its movement across the floodplain,” the spokesperson said.

“They also negotiated to ensure that the adjacent rock shelter not be impacted by the construction.

“The consensus view was that, given the accommodations made to ensure that impact to this important Aboriginal heritage site is minimal, this design was acceptable.”

The spokesperson said there had been community confusion about whether the concept design matched the one Traditional Owners were shown in the original surveys.

“We have spoken with Main Roads who have assured us the design has not substantially changed from the one shown during the survey, other than to marginally increase the span length across the main river channel, and to add retaining walls in places to reduce the overall project footprint,” they said.

Five City of Swan councillors, which is collaborating with Main Roads and the State Government on the project, have unsuccessfully attempted pursue a new design to reduce the impact to the area.