Draining the northwestern quarter of the Maroochy Catchment, the North Maroochy River rises in the steep, forested slopes of the Blackall Ranges, and confluences with the South Maroochy River near the town of Yandina to form the Maroochy Estuary.
The landform of the upper subcatchment is mostly steep hills formed of volcanics, intrusives and metamaorphic geology. The drainage lines in this area tend to be steeply angled and incised, ephemeral low order streams flowing swiftly over rocky beds. Midway down the subcatchment is an area of low rolling hills on Laterised Rhyolite.
As the river channel increases in size, small, discontinuous valley flats develop into a continuous, almost level floodplain on unconsolidated freshwater sediments of gravel, sand, silt and clay. This is confined to a narrow corridor by the low steep hills that bound the subcatchment.
Remnant vegetation covers approximately one third of the subcatchment area, about two thirds of which is on freehold land.
The upper subcatchment supports tall open forests of Blackbutt (Eucalyptus pilularis) and Grey Gum (Eucalyptus punctata). Other tree species found on these crests and upper slopes are Tallowwood (Eucalyptus microcorys) and Turpentine (Syncarpia glomulifera). The riparian areas support open forests of Forest Red Gum (Eucalyptus tereticornis), open forests of Melaleuca sp and fringing closed forests of rainforest species. The areas of Laterised Rhyolite support tall open forests of Grey Gum and Tallowwood on the crests and upper slopes, closed forest of Flooded Gum (Eucalyptus grandis) in the drainage lines and on the lower slopes.
North Maroochy River near the confluence with the South Maroochy River. River bank vegetation can be seen on the left side.
As the North Maroochy subcatchment is sparsely populated in comparison to the remainder of the area, the main land uses within the subcatchment are native vegetation, grazing and sugar cane. These three land uses collectively account for 83% of the catchment area. Native vegetation is predominant in the upper western reaches of the subcatchment, in the Brown, York and Carol Creek Catchments, where the slope is too steep for other land uses. Grazing, the next most dominant land use in terms of area, utilizes nearly one third of the subcatchment. The majority of the grazing is conducted in the north of the subcatchment on the floodplain and in the less steep foothills of the Blackall Ranges. Fully two thirds of the remnant native vegetation is outside the reserves system, being located on freehold land. Sugar cane, which occupies 15% of the subcatchment area, is grown exclusively on the floodplain surrounding the river channel in the lower subcatchment.
Browns Ck
North Maroochy River upper catchment. Land use in this area is grazing, primarily dairy and beef cattle. Note the lack of vegetation in the low lying areas.
The State of the Rivers report gives most of the streams in the North Maroochy subcatchment a poor rating, due mostly to very poor riparian vegetation, and unstable bed and bars. Most of the riparian zone vegetation is dominated by Camphor Laurel (Cinnamomum camphora), and is quite narrow due to extensive clearing for agricultural pursuits. Exceptions to this are Browns, York and Carol creeks, which are in much better condition as York and Carol Creeks run their entire length in State Forest, which also forms one bank of Browns creek for about half its length along its middle reaches. The other bank is covered by relatively undisturbed native vegetation on freehold land. However, there is still instability in the bed and banks of Browns creek due to the clearing of its upper reaches for grazing. The lower reaches of Browns Creek are similarly cleared.