6. Noosa River DMP Ver0 (Combined)

Noosa River
Existing dredge operations have been in place since 2006 were designed around the erosion hotspots
of the time. These initial sites are no longed no longer problem sites due to the mobility of sand bars
and the river channel, however other sites along the river have become problematic.

The new dredge permits for the Noosa River foreshore are intended to allow Council flexibility to adapt
the annual dredge program to target areas that are currently eroding, and therefore allow council to
protect existing assets and maintain the foreshore as needed. There is no intention of this to increase
dredge volumes overall in this area, but to apply the nourishment volume in the most effective areas as
needed at the time of the campaign.

1.2 Existing Environment
The potential sources of contamination within the Noosa River are dominated by stormwater runoff from
urban and parkland areas, and discharges from recreational vessels, as the catchment is largely a
variety of coastal and hinterland townships. Major pollutant sources such as river side industries and
runoff from agricultural land are not present in the lower Noosa River, however there is some
agriculture present at far upstream reaches near Lake Cootharaba.

Noosa Spit
The lower Noosa River and river entrance are highly modified and dynamic environments influenced by
the prevailing fluvial and coastal processes, previous dredging and stabilisation works.

The area from which sand is to be sourced sits at the mouth of the Noosa River estuary, and consists of
mobile sand shoals adjacent to the trained river entrance. Historical images (refer to Figure 1.1), shows
the dynamic nature of the river mouth. Geotechnical surveys undertaken to support previous dredge
campaigns (Coffey Geotechnics, 2011) indicate that sediments are clean sands with a low proportion of
fine materials or ASS. Alluvial sediments are underlain by residual soils (consisting of sands, clayey
sands and clays) at a depth of approximately 15m below the bed level. Based on this previous
geotechnical data, Coffey concluded that ‘dredging of the material from the Noosa River can be
expected to have relatively quick settlement times’.

Because of the shifting nature of the sands and tidal currents, seagrass and other marine vegetation is
not present.




A10342 | 002                                        3                                   01 December 2021