A community-assisted water quality monitoring project was established in late 2002 by the Australian Centre for Tropical Freshwater Research (ACTFR), James Cook University for Burdekin Dry Tropics NRM. Its aim is to investigate suspended sediment (SS) and nutrient concentrations in waterways throughout the Burdekin Dry Tropics region.

The catchment's large size (over 130, 000 square km), steep upper catchments and dry tropical environment exacerbated by widespread grazing , all combine to form a system that is highly efficient in transporting freshwater runoff and associated SS and nutrients off the landscape into downstream environments, including wetlands and the Great Barrier Reef lagoon.

The water quality monitoring project targets wet season rainfall flow events which comprise approximately 80% of the annual discharge from the Burdekin River . Due to the irregular nature of event sampling, it has been necessary to develop a network of landholder volunteers to assist with sampling, especially where sampling sites were easily accessible from homesteads on pastorally leased land and sometimes inaccessible from other parts of the catchment.  Since monitoring commenced the number of volunteers and sites have grown considerably.  The last wet season (2006/2007) saw 30 volunteers monitoring 54 sites.

During flow events community volunteers collect grab samples from subcatchment waterways to capture changes in SS and nutrient concentrations over the flow hydrograph. This project has successfully collected samples from the major subcatchments in the Burdekin region (Belyando, Suttor, Bowen, Upper Burdekin and Cape catchments) over the 2002/03, 2003/04, 2004/05 and 2005/06 and 2006/07wet seasons. 

Volunteers sampling.  Photo: Z. Bainbridge.

In 2006/07 results, consistent with the 3 previous monitored wet seasons, showed the Bowen River sub-catchment to have the highest total suspended solids (TSS) concentration compared with all other monitored sub-catchments. The Upper Burdekin River sub-catchment  also showed high  TSS concentrations, with the highest Particulate Nitrogen and Particulate  Phosphorous  loads.  This is due to the very high volumes of flow discharged by this sub-catchment.

Coastal catchments with intensive land uses (such as sugar cane farming and horticulture), all showed disproportionately high nitrate, nitrite and phosphate  event mean concentrations, with the highest levels recorded at the Barratta Creek sites. 

These data provide a baseline from which to examine trends in sediment and nutrient delivery over time and will help to validate modelling of sediment transport. All of these data will feed into the development of the Burdekin’s Water Quality Improvement Plan.