Clarence Valley Council
Estuarine beaches: Iluka Bay, Wooli Estuary North, Wooli Estuary South. Lagoons: Kolora Lake. Riverine swimming sites: Maclean Jetty, Lawrence, Ulmarra Jetty, Corcoran Park, Grafton Sailing Club, South Mariner, Prince Street (Grafton). For details see (08472Clarence.pdf, 337 KB)
Local government area description
Clarence Valley Council extends from the temperate New England Plateau to the rugged Gibraltar Ranges, through rural lands and river plains to 80 kilometres of coastline. The council area covers 11 000 square kilometres and has a total population of approximately 49 000.
Clarence Valley Council is the largest local government area in the northern rivers region, covering 51% of the land area. The region has significant agricultural areas as well as extensive areas of National Parks and State Forests.
The Clarence River is the area’s most significant natural feature, stretching over 400 kilometres from the Queensland border to Yamba (Clarence Valley Council 2004).
Program outline
Eleven swimming locations were monitored in the Clarence Valley council area during summer 2007–2008. The sites were a coastal lagoon, three estuarine swimming locations (one at the mouth of the Clarence River and two in the lower reaches of the Wooli Wooli River) and seven locations in the Clarence River itself.
Lawrence and South Grafton Mariner were added to the program in 2006–2007 summer season. The remaining nine locations were also monitored during the 2004–2005, 2005–2006 and 2006–2007 summer seasons and the results were reported in the State of the Beaches report for those years (DEC 2006a and 2006b, DECC 2007).
Monitoring in this region was also undertaken during the 2003–2004 summer swimming season and the 2002–2003 summer swimming season. The results were reported in the BPPP State of the Beaches reports for these years (DEC 2004b and 2004c).
Enterococci samples were collected between November 2007 and March 2008 to assess compliance with NHMRC (1990) swimming water quality guidelines. It should be noted that the five samples necessary to calculate compliance were not collected in all months. Where only four samples were collected, the closest sample in time from an adjacent month was ’borrowed’ in order to provide the five data points required. Where only three samples were collected, guideline compliance could not be determined.
Rainfall
Rainfall data presented in the timeseries plots were obtained from the Bureau of Meteorology’s gauges at Grafton Olympic Pool, Yamba and Wooli. Rainfall for each site is from the closest rain gauge.
Clarence River
Guideline compliance
Eight locations were monitored in the Clarence River: an estuarine swimming site (Iluka Bay) and seven riverine swimming sites (Maclean Jetty, Lawrence, Prince Street, Grafton Sailing Club, South Mariner, Corcoran Park and Ulmarra Jetty).
Iluka Bay complied in all four months sampled in the 2007–2008 summer swimming season in which sufficient samples were collected (Figure 4). Insufficient data were collected in January to calculate compliance for that month. Compliance at this site has varied substantially between years. The lowest level of compliance was recorded in summer 2004–2005 when the site complied in only one of four months (DEC 2006). The highest level of compliance was recorded in the 2003–2004 and 2006–2007 summer seasons when the site passed the NHMRC (1990) swimming guidelines all six months (DEC 2004c, DECC 2007).
Maclean Jetty, located farther upstream on the Clarence River near the town of Maclean, complied with the NHMRC (1990) swimming guidelines in three of the five months sampled during the 2007–2008 summer season. Compliance was higher during the previous summer season when the site complied all six months. The 2007–2008 summer season results are more similar to the results from the 2004–2005 summer season, when the site failed in two of the four months (2006a). For details see (08472Clarence.pdf, 337 KB)
Figure 4: Summary of compliance with NHMRC (1990) microbiological guidelines for swimming at Clarence Valley Council swimming sites during the 2007–2008 summer swimming season
Lawrence is located upstream of Maclean at the town of Lawrence. The site passed the NHMRC (1990) swimming guidelines in all five months of the 2007–2008 summer season (Figure 4). This result is similar to the previous summer season when the site passed all six months (DECC 2007).
Ulmarra Jetty is located upstream of Lawrence at the town of Ulmarra. The site complied in only two of the four months sampled in the 2007–2008 summer swimming season (Figure 4). Insufficient data were collected in January to calculate compliance for that month. Although the 2007–2008 summer swimming season compliance is less than the previous season it is still an improvement on the results from the 2005–2006 summer season when the site failed in all four months of monitoring (DEC 2006).
Compliance levels at Prince Street, Grafton Sailing Club, South Mariner and Corcoran Park, all located in the town of Grafton, were varied (Figure 4). South Mariner passed the NHMRC (1990) swimming guidelines in three of the five months, Corcoran Park passed in two of the five months, Prince Street passed the guidelines in only one of the five months and Grafton Sailing Club failed all five months sampled in the 2007–2008 summer swimming season. Although compliance at these sites is lower than that for the previous summer season, the results from Prince Street and Corcoran Park are an improvement on results from the 2005–2006 summer season when both sites failed the swimming guidelines in all four months in which compliance was assessed.
Clarence Valley Council has erected warning signs at sites with low compliance and has undertaken further monitoring to investigate the pollution source at these locations.
Response to rainfall
During the 2007–2008 summer swimming season, slightly elevated enterococci levels were recorded at Maclean Jetty and Iluka Bay. Previous monitoring conducted at these swimming locations has indicated that water quality at these two sites may be unsuitable for swimming for up to two days following heavy rainfall (DEC 2004b).
Slightly elevated enterococci levels were also recorded at Prince Street, South Mariner and Corcoran Park in response to heavy rainfall.
Elevated enterococci levels were measured at Grafton Sailing Club throughout the monitoring period in both dry and wet weather conditions.
Wooli Wooli River Estuary
Guideline compliance
Two locations were monitored in the Wooli Wooli River estuary. The southern site was suitable for swimming in all five months of the 2007–2008 summer swimming season. The northern site was suitable for swimming in four of the five months, failing to comply with guidelines in February due to elevated levels of enterococci (Figure 4). For details see (08472Clarence.pdf, 337 KB)
Response to rainfall
Levels of enterococci in Wooli Wooli River estuary generally remained below the geometric mean guideline throughout the monitoring period. Slightly elevated results were recorded on a number of occasions, generally following rainfall.
Kolora Lake
Guideline compliance
Kolora Lake, located between the town of Yamba and the Clarence River, complied with the swimming water quality guidelines in three of the five months of the 2007–2008 summer swimming season (Figure 4). For details see (08472Clarence.pdf, 337 KB)
Response to rainfall
Elevated enterococci levels were measured on several occasions during summer 2007–2008, generally in response to rainfall.
Sampling conducted at the site during wet weather events in May and June 2003 indicated that water quality in the Lake may be unsuitable for swimming for up to two days following heavy rainfall (DEC 2004b).
Page last updated: 26 February 2011
