6. Noosa River DMP Ver0 (Combined)

Executive Summary
The lack of riparian vegetation coupled with high levels of boat wash is creating erosion issues
along some reaches of the Noosa River foreshore. To rectify this issue, replenishment is
proposed at two sites at Munna Park, Munna Crescent and Gympie Terrace, Noosaville. An
additional extraction location is proposed at Hilton Esplanade, Noosaville that will expand an
existing approved area.

This report has been prepared to identify if any marine plants are likely to be impacted by the
proposed works. Marine plants include mangroves, seagrass, samphires, saltcouch and
saltmarsh plants, algae and other tidal plants growing adjacent to the tidal zone, landward and
seaward. They provide important habitat for fish and are protected against deliberate damage
or destruction under the Fisheries Act 1994.

Seagrass surveys were undertaken by wading the shallow areas of the extraction and
nourishment sites and using an underwater drone in the deeper areas. No seagrass was
recorded.

Marine plants growing in the intertidal and foreshore areas were recorded along the Gympie
Terrace and Hilton Esplanade foreshores and included mangroves (Avicennia and Rhizophora
species) and Casuarina glauca. No marine plants were recorded at Munna Park.

While most of the marine plants along the foreshore could be avoided, one mangrove requires
management of replenishment spoil to minimise impacts. Two options have been suggested:

      1. Replenishment material be place at a depth so that the pneumatophores are not
         completely covered (i.e. leave at least 2 cm of the pneumatophores exposed); or
      2. Place replenishment material on either side of the tree protection zone of this specimen
         and allow natural processes to move the sediment.

If neither of these options are adopted, damage or destruction of this specimen will occur, and
its loss may require offsetting. An offset delivery agreement will be required to be entered into
between the proponent and the Department of Agriculture, Fisheries and Forestry.

Soft sediment at all locations had evidence of bioturbation to a depth of approximately 2.5 m.
At the proposed extraction site along Hilton Esplanade, the soft sediment was replaced by a
rocky substrate approximately 20-25 m from the shore. Extraction and nourishment activities
will result in a temporary loss of benthic fauna, although is expected to recolonise rapidly.

Other impacts associated with the project include an increase in turbidity and noise while the
extraction/nourishment activities are in operation.

Recommendations made in this report include:

     •     No extraction or replenishment activities should be undertaken during the closed
           seasons for important fin fish species likely to occur in the Noosa River (specifically, July
           to August); and
     •     Ensuring extraction contractors have protocols in place for dealing with contaminant
           spills.




Noosa River                                                                                     Page iii
Marine Plant Impact Assessment
Project Number: BC-20067