LAKES CARGELLIGO AND BREWSTER ALGAL WARNING SYSTEM AND STORAGE OPERATING PROTOCOL

Transcription

1 LAKES CARGELLIGO AND BREWSTER ALGAL WARNING SYSTEM AND STORAGE OPERATING PROTOCOL The Lower Lachlan Lakes Algal Warning System and Storage Operating Protocol is made up of a flexible algal sampling regime to allow appropriate monitoring and operational responses according to the levels of blue-green algae in the storages. The protocol also outlines responsibilities associated with sampling, reporting and river operations. The Protocol is to apply at all times when water is stored in either of the Lakes. The aim of the protocol is to manage blue-green algal concentrations in the Lower Lachlan River by maintaining concentrations below 0.4 mm 3 /L of total blue-green algal biovolume at Willandra Weir. The threshold of 0.4 mm 3 /L of total blue-green algal biovolume relates to the upper limit of the Green Level Surveillance mode for recreational waters. Details of the interim guidelines for Cyanobacteria in NSW are included in Appendix 1. To achieve this aim, water releases from Lakes Cargelligo and Brewster may be shandied by increasing flows at Lake Cargelligo Weir and/or Lake Brewster Weir via the conduit. This non-prescriptive protocol allows State Water the flexibility to manage the river to obtain the stated outcomes while minimising environmental damage and health risks. The responsibilities of sampling, reporting and operations are outlined in Table 1. Under current agreements between DWE and State Water, the RACC secretariat (DWE) has the responsibility of informing State Water and other relevant agencies of algal presence and issuing alerts as appropriate. State Water has the responsibility of routine sample collection and ensuring river management is appropriate in relation to algal presence. Table 2 outlines an appropriate sampling regime for assessing blue-green algal levels in the Lower Lachlan. Table 1 RACC Secretariat and State Water Responsibilities RACC Secretariat RACC Secretariat to inform SW of blue-green algal presence at the protocol reporting sites (Table 2). If average blue-green presence exceeds 0.4 mm 3 /L of total BGA biovolume in the Lakes or Lower Lachlan RACC Secretariat implements Central West Regional Algal Contingency Plan. RACC Secretariat will inform DWE, SW, other agencies and the public via media releases. RACC Secretariat will provide RACC members of algal presence on a regular basis using a summary sheet. If blue-green presence exceeds 4 mm 3 /L biovolume of all potentially toxic species combined; 10 mm 3 /L biovolume of total bluegreen algal species, or if blue-green algal scums are consistently present in Lower Lachlan for 2 successive weeks and control measures are not reducing the presence the emergency components of the Central West State Water SW is to actively manage water delivery from different sources to maintain blue-green algal levels at Willandra Weir at below 0.4 mm 3 /L of total blue-green algal biovolume. If average blue-green presence exceeds 0.4 mm 3 /L of total BGA biovolume in either Lake, SW are to provide formal notification of river operations to the RACC secretariat on a weekly basis or when changes are made. This includes amount, duration and source of releases. If blue-green presence exceeds 0.4 mm 3 /L at Willandra Weir then SW staff are to visually inspect lake outlets before releases. During releases lake staff will visually inspect releases twice weekly at each Lake. If either or both Lakes are the source of algal seeding of the river, Lake releases are to be reduced to restore the blue green presence in the river to <0.4 mm 3 /L total BGA biovolume.

2 Regional Blue Green Algal Contingency Plan will be implemented.

3 Table 2 Sample locations and frequencies Sample Locations Sample Frequencies Triggers Site No. Site Name May-Nov Dec-April Av. >0.04 mm 3 /L total blue green algal biovolume in lakes and outlets Lake Cargelligo Weir fortnightly Weekly Lake TWS fortnightly Weekly Weekly Lake fortnightly Weekly Weekly Tullibigeal Pump Lake Creek fortnightly Weekly Weekly Lake Brewster Weir fortnightly Weekly Weekly Lake Brewster fortnightly Weekly Weekly Bensons Drop* Willandra Weir fortnightly Weekly Hillston Weir fortnightly Weekly Booligal Weir fortnightly Weekly Willandra Roto Road As required * when Lake Brewster is in use Figure 1 provides a guide to managing blue-green algal presence at Willandra Weir based on total biovolume. The graph shows recommended % releases from Lower Lachlan River via the Lake Brewster conduit for blue-green algal biovolumes at Willandra Weir. It is recommended that any increases or decreases in Lake Brewster conduit releases should be maintained for a period of time (eg. 2 weeks) to allow for river management changes to control BGA biovolume in the Lower Lachlan and biovolume variability. Fortnightly changes in Brewster Weir conduit releases should not be >20% per step and should be implemented over a number of days. This will help minimise rapid river fluctuations that may cause bank slumping. 12 Willandara BGA Biovolumes (mm 3 /L) Toxic Total 0 0% 20% 40% 60% 80% 100% % River Releases Figure 1 Recommended % releases from Lake Brewster Weir conduit in response to potentially toxic blue-green algal biovolumes, and to total blue-green algal biovolumes at Willandra Weir

4 Forecasting of blooms and commencement of shandy releases. At this time it is not possible to accurately predict the on-set of algal blooms at the relative alert levels so as to give sufficient prior warning to commence shandy releases from Wyangala Dam. Nevertheless, past experience is that algal blooms in the Lakes commence with the warmer summer months of December and January, and can persist for many months. Therefore preparatory measures for shandy releases should be put in place at least by 1 December each year. A flow chart has been designed to assist in managing blue-green algal levels in the Lower Lachlan (Fig. 2). The flow chart and its attachments indicate triggers and appropriate responses to increasing algal concentrations in both the lakes and river. The objective is to maintain blue-green algal levels in the lower Lachlan River at <0.4 mm 3 /L.

5 Is BGA level >0.4 mm 3 /L total BGA Lisa biovolume Thurtell at Lake Page Brewster 521/05/2009 or Lake Cargelligo? No Continue monitoring (see Table 2) Deleted: 28/08/2007 Yes RACC Secretariat implements Central West Regional Algal Contingency Plan. Continue monitoring Are BGA levels >0.4 mm 3 /L total BGA biovolume at Willandra Weir? SW formally notify Secretariat of river operations on a weekly basis or when changes are made. Yes No Visual inspections of lakes by SW staff before and during lake releases SW to commence/increase releases from Lake Brewster Weir Conduit (See Fig. 1). SW to commence additional releases from Wyangala to make up losses at Lake Brewster Weir. Continue monitoring (see Table 2) Continue monitoring Are average lake biovolumes >4 mm 3 /L of all potentially toxic species combined; >10 mm 3 /L for total blue-green algal taxa, or are visible blue-green algal scums consistently present? Yes No Continue conduit releases (Fig. 1) and BGA monitoring. Lake releases are not to be made unless dilutions can be achieved at Willandra Weir to reduce biovolume to <0.4 mm 3 /L of all blue-green algal species combined. Biovolumes remain above >0.4 mm 3 /L of all species combined at Willandra Weir. If biovolumes at Willandra Weir stay above 0.4 mm 3 /L of all blue-green algal species combined and can t be controlled, the RACC, SW and RMC will discuss management options. RACC Secretariat to convene meeting. Yes No Continue monitoring and appropriate dilution responses (Fig. 1). Figure 2 Lower Lakes decision support chart

6 APPENDIX 1 Recreational Guidelines The new recreational guidelines are based on a colour alert scale with green alert being low concentrations but requiring monitoring, amber level being a heightened level of alert, with increased sampling and surveillance, and red alert being a state of action where waters are unsuitable for recreation. See tables below for information on levels associated with these levels. Table A1 Interpretation of cyanobacterial alert levels for recreational water Green level Surveillance mode > 500 to < 5000 cells/ml M. aeruginosa or biovolume equivalent of > 0.04 to < 0.4 mm 3 /L for the combined total of all cyanobacteria Amber level Alert mode 5000 to < cells/ml M. aeruginosa or biovolume equivalent of 0.4 to < 4 mm 3 /L for the combined total of all cyanobacteria Red level Action mode Level 1 guideline: 10 µg/l total microcystins or cells/ml toxic M. aeruginosa or biovolume equivalent of 4 mm 3 /L for the combined total of all cyanobacteria where a known toxin producer is dominant in the total biovolume OR a Level 2 guideline: The total biovolume of all cyanobacterial material exceeds 10 mm 3 /L or cyanobacterial scums are consistently present b. a This applies where high cell densities or scums of nontoxic cyanobacteria are present, ie where the cyanobacterial population has been tested and shown not to contain known toxins (microcystin, nodularin, cylindrospermopsin or saxitoxins). b This refers to the situation where scums occur at the recreation site each day, when conditions are calm, par ticularly in the morning. Note that it is not likely that scums are always present and visible when there is a high population, as the cells may mix down with wind and turbulence and then reform later when conditions become stable.

7 Table 2 Monitoring programs associated with cyanobacterial alert levels Cyanobacterial alert level Surveillance mode (Green level) Alert mode (Amber level) Action mode (Red level) Monitoring requirement Routine sampling to measure cyanobacterial levels. Investigations into the causes of the elevated levels and increased sampling to enable the risks to recreational users to be more accurately assessed. Local authority and health authorities to warn the public that the water body is considered to be unsuitable for primary contact recreation. Alert Level Surveillance mode (Green level) Alert mode (Amber level) Action mode (red level) Example of Monitoring Regular monitoring: weekly sampling and cell counts b at representative locations in the water body where known toxigenic species are present (ie Microcystis aeruginosa, Anabaena circinalis, Cylindrospermopsis raciborskii Aphanizomenon ovalisporum, Anabaena bergii, Nodularia spumigena); or for tnightly for other types including regular visual inspection of water surface for scums Notify agencies as appropriate. Increase sampling frequency to twice weekly c at representative locations in the water body where toxigenic species (above) are dominant within the aler t level definition (ie total biovolume d ) to establish population growth and spatial variability in the water body. Monitor weekly or for tnightly where other types are dominant. Make regular visual inspections of water surface for scums Decide on requirement for toxicity assessment or toxin monitoring Continue monitoring as for aler t mode. Immediately notify health authorities for advice on health risk. Make toxicity assessment or toxin measurement of water if this has not already been done. Health authorities warn of risk to public health (ie the authorities make a health risk assessment considering toxin monitoring data, sample type and variability a The cell numbers that define the aler t levels apply to samples of the recommended type (ie composite 50 cm hosepipes) that are taken at representative locations in the water body (ie the likely or designated recreational areas). b The actual numbers for a cell count in the > cells/ml range can vary greatly from the measured value.there is a likely minimum precision of ±50% for counting colonial cyanobacteria such as Microcystis aeruginosa at such low cell densities. For counting filamentous cyanobacteria such as Anabaena circinalis, the precision is likely to be much better at these cell densities (~±20%). c The recommendation to increase sampling frequency to twice weekly depends on the sensitivity and usage of the area.. For example, twice weekly sampling may be justified where there is a pressing need to issue advice for ongoing use if the site is being used heavily by recreational users, or a special event is coming up. In most circumstances, weekly sampling provides adequate information to assess the rate of change of algal populations, and to judge the population growth rate and spatial variability and therefore the hazard. d Biovolume equivalents given are calculated using the equivalent cell numbers of M. aeruginosa. Biovolume based on a single cell of M. aeruginosa having a volume of 87 µm 3, eg 5000 cells/ml 87 µm 3 = 4, µm 3 /ml = mm 3 /ml 1000 = mm 3 /L.This is rounded to 0.4 mm 3 /L Deleted: 28/08/07 DRAFT Lower Lachlan Lakes Storage Operating Protocol 21/05/09 Page 7 of 7