Resource Condition Summary
The Suttor Basin is intermediate in size (~18,153 sq. km.) and
covers around 13% of the BWQIP region. Common to most of the BQWIP
basins, land use is dominated by grazing on native or modified
pastures. Approximately 6% of the land area is used for dryland
cropping of cereals, while less than 1% is set aside for
conservation and minimal use1. The condition of riparian
habitat throughout the basin has declined in condition over the
last 30 years, principally due to clearing along headwater streams
and floodplains, and is mostly assessed as poor (C)2.
Little is known about the ecology and condition of aquatic habitats
in the Suttor Basin, but numerous persistently and highly turbid
water bodies are reported to be widespread3.
Hillslope erosion is identified by models as the major source of
sediment and particulate nutrients affecting water quality within
the Suttor Basin, while gully erosion is also identified as a
significant contributor4. The overall rate of soil erosion is
predicted to be comparatively low and below the BWQIP region
average, but with some major differences between subcatchments. The
Sellheim River and Lower Suttor River subcatchments are predicted
to have the highest rates of soil erosion within the basin, while
the Lower and Upper Suttor River subcatchments are predicted to
contribute most sediment to the end-of-basin load. Field surveys of
grazing land identifies most of land area to be in poor (C) or fair
(B) condition5,6. However, analyses of ground cover from
satellite imagery7,8 identify extensive areas of high
density 'D' condition land, and highly vulnerable and marginal 'D'
condition land, particularly in the Logan Creek, Diamond Creek and
Upper Suttor River subcatchments.
Water quality in the Suttor Basin is predicted by models to have
moderately elevated suspended sediment concentrations and loads at
end-of-basin during wet season event flows4. However, modelled and
monitored sediment concentrations and loads display little
consistency9,10. The lack of significant flow events in
the Suttor Basin during the monitoring period resulted in less
confidence in the sediment and nutrient data from the Basin. In
light of the particular risk posed by very fine suspended sediment
from the Suttor Basin, which is more likely to reach to coast and
travel further in the marine environment, and the reported extent
of degraded land, further water quality monitoring of this basin
would be useful in order to resolve apparent discrepancies between
monitoring, modelling and land condition analyses.
Draft Water Quality Targets
The following water quality Resource Condition Target was
developed based on Best Management Practice Guidelines for Water
Quality Improvement, extensive modelling of a range of management
scenarios, preparation of a discussion paper12 and then,
finally, a series of workshops. These preparatory activities were
undertaken in collaboration with landholders (graziers and cane
farmers), industry representatives, Government, the scientific
community and NQ Dry Tropics staff.
- By 2058, attain a minimum 40% reduction in mean annual sediment
load from the Suttor River Basin (measured at Mt. Coolum) from
current (2008) - i.e. a reduction from approximately 175 kt/yr in
2008 to 105 kt/yr by 2058).
Footnotes: see References
