The Cape York Marine Advisory Group (CYMAG) and South Cape York Catchments (SCYC) monitored ambient water quality in the Annan & Endeavour Rivers between July 2002 and May 2009, and the Jeannie River between 2007 and 2009. The Annan & Endeavour Rivers are located near Cooktown in southeast Cape York Peninsula between latitude 15º 11’ to the north and 15º 53’ to the south, and longitude 145º 00’ to 145 º 21’. The Jeannie River is an undeveloped catchment located 50 km north of Cooktown at 14° 39’ and 144° 55’.
Prior to 2002, there had been little monitoring of water quality in the Annan, Endeavour or Jeannie Rivers and no known monitoring of estuary waters. The aim of the CYMAG monitoring program was to document baseline water quality in these rivers during the wet and dry seasons and to assess for potential anthropogenic impacts, including effluent outfall in the Endeavour River from a new sewerage treatment plant (STP) and the Bluestone tin mine in the Annan River catchment.
Monitoring was conducted monthly at six Endeavour River estuary sites and five Annan River freshwater and estuary locations. Four Jeannie River estuary sites and one freshwater site were monitored quarterly. Monitoring included: temperature, conductivity, salinity, dissolved oxygen, and pH (2002 – 2009), and nutrients and chlorophyll-a (2005- 2008). Water and sediment grab samples were analysed annually for metals, pesticides, herbicides and hydrocarbons, and 30-day passive samplers for herbicides and PAHs were deployed in the Endeavour River during the 2008/2009 wet season. Additional monitoring has occurred at some sites since 2009.
Key Outcomes from this program
1. For the first time a set of water quality guidelines have been developed that are specifically attuned to the conditions in a south-eastern Cape York estuary
2. Dramatically different water quality conditions were documented in the wet and dry season, particularly during floods, and this must be considered when setting guidelines and assessing anthropogenic impacts.
3. Recognition that impacts from dry season disturbances generally do not show up until the following wet season (as was the case with the Bluestone Tin Mine on the Annan River). This has major implications for monitoring land-use impacts on rivers.
4. We believe that this study represents an example of how an independent community driven water quality monitoring program can and should be run.
5. At the time of the program’s inception there were a number of community concerns regarding water quality threats in this region and the program was established as an independent community driven program to evaluate these perceived threats using best practice scientific methods. As a result of the rigour applied to the program we were able to establish that:
a. The perceived threat to water quality from the Cooktown STP established in 2006 has not been substantiated. Monitoring of nutrients, chlorophyll-a and bacteria showed no evidence (as of 2009) of impacts from effluent outfall.
b. Concerns regarding potential impacts on the Annan River from the Bluestone Tin Mine were found to be justified, with significant increases in turbidity and metals recorded. Thanks largely to community pressure, the mine was required to alter operations to reduce the impact on water quality.
6. It is argued that these two examples alone demonstrate the benefit to the community of an independent water quality monitoring program.
7. The dataset developed as part of this program will now form an invaluable baseline against which future threats to water quality in the region can be evaluated, and from which additional freshwater guidelines can be developed.
8. The available data from the relatively pristine Jeannie River estuary demonstrate the need for understanding site specific geomorphic and hydrodynamic characteristics in the interpretation of water quality data. At face value some of the data could be interpreted as indicating poor WQ, requiring remediation – when in fact it is likely that they are the natural conditions for that system.