Gosford City Council Historical Water Quality Review & Analysis

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RESULTS OF WATER QUALITY DATA ANALYSIS 3-21 Table 3.29 Chlorophyll-a results (µg/L) 1996 – 1998 (Laxton, 1999) Location Median (50%ile) Mean Maximum Wamberal Lagoon 3.8 5.1 21.4 Terrigal Lagoon 4.6 5.2 13.6 Avoca Lagoon 4.2 5.0 19.6 Cockrone Lagoon 6.2 14.3 193.5 Narara Creek 3.9 5.0 29.0 Erina Creek 4.1 5.4 20.0 Kincumber Creek 8.5 12.1 65.9 Cockle Broadwater 2.3 2.5 5.2 Koolewong 2.7 2.7 5.7 Woy Woy 1.9 2.4 6.1 Booker Bay 2.5 3.0 8.9 Once again Cockrone Lagoon showed a period of excessive algal growth, as indicated by the very high chlorophyll-a recording (193.5 µg/L on 1 July 1997). A closer examination of this event has revealed that the high levels were recorded the day before the entrance broke out. Thus, the algae bloom was not the result of an entrance breakout as was the case in February 2002 (as described in Section 3.3.3.1 above). Overall, Cockrone Lagoon had relatively high levels of chlorophyll-a. Likewise, Kincumber Creek also had high levels of chlorophyll-a, although the amount of chlorophyll-a in all of the coastal lagoons and the tributary creeks was higher than what would be expected under more natural conditions. Typical chlorophyll-a concentrations in the broader, more flushed, sections of Brisbane Water, were generally lower than the lagoons and tributary sites. 3.3.4 Metals Very little water quality data regarding soluble metals is available. The only information in the database is from 1974, when concentrations of some basic metals (Calcium, Copper, Lead, Mercury, Zinc) were measured at a number of locations in the four coastal lagoons by R.A. Creelman, as noted in the Gosford Coastal Lagoons Estuary Processes Study (Webb McKeown & Associates, 1995). The results of the monitoring generally indicated low metal concentrations (mostly below the detection limits for the analysis). D:\R.N0754.002.01.DOC 7/11/03 16:11
FUTURE DIRECTIONS FOR WATER QUALITY / ENVIRONMENTAL HEALTH MONITORING 4-1 4 FUTURE DIRECTIONS FOR WATER QUALITY / ENVIRONMENTAL HEALTH MONITORING 4.1 Discussion of Previous Monitoring Programs Water quality has been collected within Gosford City Council’s waterways since 1974. The most recent monitoring program was carried out by Dominic Cheng of Ecoscience Technology, and concluded in June 2002 (following nearly 3 years of data collection at 10 sites within Brisbane Water and the coastal lagoons). In total, water quality data has been collected from over 200 different sites within the Gosford waterways, with over 60 different parameters monitored. Generally, it can be said that water quality monitoring in the past has not been carried out in a consistent or integrated manner. New programs have generally targeted new sites and sometimes new parameters. Programs have also been carried out for specific purposes, such as the water quality monitoring of the tributary creeks (AWT, 2001) and the periodic algae monitoring (Ecoscience Technology, 2000, 2002). The result of the generally uncoordinated and inconsistent monitoring programs of the past is the fact that the data provides little opportunity for interpretation of long-term trends and spatial distribution patterns. At best the data provides a ‘snap shot’ of conditions at a particular place and time. This conclusion is supported by Umwelt and SMEC (2002) as part of the Brisbane Water Data Compilation Study. 4.2 The Notion of ‘Environmental Health’ The term ‘environmental health’, or sometimes more specifically ‘ecosystem health’, has been used for at least the last 10 years. The idea of quantifying the health of the environment has great appeal to managers, as it can provide an indication of how a system is improving, or degrading. Quantification of environmental health can help prioritise works for rehabilitation, and can provide a measure of the effectiveness of the works, once implemented. While the notion of environmental health is attractive to managers, it proves to be problematic for scientists. Coates at al (2002) points out the difficulties in defining ecosystem health given the large variability that natural ecosystems experience (as highlighted by the data presented in this document). He also highlights the difficulties in selecting an appropriate range of biotic and abiotic indicators to represent the ecosystem. It is generally agreed that an ecosystem measure based on single indicators is unreliable and possibly unrepresentative. 4.2.1 Coastal CRC EHMP The most comprehensive environmental health assessment currently underway is likely to be that by the CRC for Coastal Zone, Estuary and Waterway Management (Coastal CRC) in South – East Queensland. The CRC’s Ecosystem Health Monitoring Program (EHMP) monitors estuarine waterways to determine if: • Key environmental processes operate to maintain stable ecosystems D:\R.N0754.002.01.DOC 7/11/03 16:11
Page 1 and 2: Gosford City Council Historical Wat
Page 3 and 4: CONTENTS I CONTENTS Contents List o
Page 5 and 6: LIST OF FIGURES III 4.4 Outcomes fr
Page 7 and 8: LIST OF TABLES V Table 3.23 Water Q
Page 9 and 10: INTRODUCTION 1-2 locations in Brisb
Page 11 and 12: INTRODUCTION 1-4 aquatic ecosystems
Page 13 and 14: INTRODUCTION 1-6 Default trigger va
Page 15 and 16: GWQ: A DATA MANAGEMENT AND ASSESSME
Page 23 and 24: RESULTS OF WATER QUALITY DATA ANALY
Page 41: RESULTS OF WATER QUALITY DATA ANALY
Page 45 and 46: FUTURE DIRECTIONS FOR WATER QUALITY
Page 67 and 68: MHL DATASONDE RESULTS: AVOCA LAGOON
Page 69: MHL DATASONDE RESULTS: KOOLEWONG C-

Gosford City Council Historical Water Quality Review & Analysis

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