Annual Compliance Report 2023: Snowy Hydro Limited Cloud Seeding Program

The EPA has reviewed Snowy Hydro Limited’s annual compliance report for the 2023 cloud seeding season and has found that:

the compliance report was submitted to the relevant Ministers and the EPA by the due date
Snowy Hydro Limited has complied with all of its obligations as detailed in the Act
Snowy Hydro Limited complied with all its obligations in the Environment Management Plan.

Snowy Hydro Limited has been conducting a winter cloud seeding trial in the NSW Snowy Mountains area since 2004. On 31 May 2013 amendments to the Snowy Mountains Cloud Seeding Act 2004 (the Act) came into effect enabling Snowy Hydro Limited to conduct permanent cloud seeding operations within an expanded area of the Snowy Mountains, in accordance with an Environmental Management Plan approved by relevant Ministers. The Act defines the relevant Ministers as the Minister for the Environment and the Minister for Planning and Environment, who approved the Environmental Management Plan on 28 June 2018. In accordance with the Act, the Environmental Management Plan must be reviewed at least once every 5 years. The EPA coordinated the 5-yearly review in 2023 in consultation with relevant stakeholders. The revised Environmental Management Plan was approved by the relevant ministers in July 2023

The Act also authorises aerial application of existing and alternative cloud seeding chemicals and prescribed a review and oversight role for the NSW Environment Protection Authority (EPA).

Snowy Hydro Limited is required to provide a report to the EPA detailing its compliance with the Environmental Management Plan and the results of any research and monitoring into the impact of cloud seeding operations on the environment by 31 March each year. The EPA is required to review this report and convey its findings, along with any recommendations, to the Board of the Environment Protection Authority and the relevant Ministers.

About cloud seeding

Cloud seeding is a process used to improve the capacity of orographic clouds (clouds formed as moist air rises over mountains) to yield precipitation as snow. To achieve this, chemical particles are introduced, or seeded, into these clouds. Snowy Hydro Limited (SHL) uses silver iodide as the seeding particle in the Snowy Mountains. Silver iodide has physical properties very similar to natural ice crystals. In addition, silver iodide is practically insoluble in water, tends not to dissociate to its component ions of silver and iodine, and does not become biologically available in the environment. Instead, it remains as a solid in soils and sediments.

During cloud seeding operations, the seeded silver iodide particles combine with naturally occurring supercooled water droplets in the clouds to form ice crystals. These crystals then grow until they become too heavy to stay within the cloud and fall as snow.

To seed the clouds, ground based generators are arranged along the western side of the Snowy Mountain range. The generators are able to disperse minute quantities of the seeding agent into winter storm clouds as they pass across the range. Cloud seeding operations only target cloud systems travelling from west to east and when temperatures guarantee that precipitation will fall as snow above 1400 metres.

Snowy Hydro Limited has been conducting a winter cloud seeding trial in the NSW Snowy Mountains since 2004. Independent evaluation of the trial indicates that snowfall can be increased by an annual average of 14% through cloud seeding. Environmental monitoring has to date not detected any significant adverse environmental impacts. The 2023 cloud seeding operations comprised 36 hours and 16 minutes of cloud seeding between 25 June 2023 and 9 September 2023. Approximately 13.8 kilograms of silver iodide were dispersed during these operations, covering a target area about 2110 square kilometres.

Under the Snowy Mountains Cloud Seeding Act 2004 (the Act), cloud seeding operations may only occur in accordance with an Environmental Management Plan that has been jointly approved by the relevant Ministers. The current Environmental Management Plan was approved by the relevant Ministers in July 2023 following the five yearly review as required under the Act.

The Act requires that Snowy Hydro Limited provide an annual report to the NSW Environment Protection Authority (EPA) and the relevant Ministers by 31 March, detailing its compliance with the Environmental Management Plan and the results of any research and monitoring into the impact of cloud seeding operations on the environment. The EPA is required to review this report and convey its findings, along with any recommendations, to the Board of the EPA and the relevant Ministers.

Review and findings
Compliance with the act
Compliance with EMP

The EPA has undertaken its review of Snowy Hydro Limited’s Annual Compliance Report (the report), in accordance with the Act and the approved Environmental Management Plan. In carrying out its review of the report, the EPA consulted with the Department of Climate Change, Energy, the Environment and Water (DCCEEW). The EPA also consulted with the National Parks and Wildlife Service (NPWS) in respect to cloud seeding operations that took place within Kosciuszko National Park.

Findings

The review of the 2023 Annual Compliance report found that:

Snowy Hydro Limited has complied with all of its obligations as outlined in the Act. Snowy Hydro Limited complied with all its obligations within the Environmental Management Plan.
There were no accidents or breakdowns to report that resulted in spillage of cloud seeding agents or fuel, or failure of controls specified in the Environmental Management Plan.
Monitoring was carried out in accordance with the Environmental Management Plan.
Analysis of the monitoring data did not detect any evidence of significant adverse environmental impacts associated with cloud seeding activities.
Cloud seeding is not having a measurable effect on the concentrations of silver in various parts of the environment.
There were no new operations involving land-based methods of discharge of seeding or tracing agent within any area of land managed under the National Parks and Wildlife Act 1974.
Minor modifications were made to equipment at three existing cloud seeding weather station sites to install new meteorological instrumentation following the 5-yearly review of the EMP.

Discussion

During 2023 cloud seeding operations, Snowy Hydro Limited dispersed approximately 13.8 kilograms of the approved seeding agent, silver iodide, into suitable storm systems. Weather conditions suitable for seeding in the Snowy Mountains during the 2023 period resulted in 36 hours and 16 minutes of cloud seeding events, and a decrease of 20 hours and 44 minutes on the previous year. Consequently, this resulted in a decrease of silver iodine being used, with 5.3 kilograms less than in the previous year.

During the 2023 cloud seeding season, there were no new operations involving land-based methods of discharge of seeding or tracing agent within any area of land. SHL advised that with the exception of a fuel leak, no accidents or breakdowns resulting in spillage of cloud seeding agents occurred.

The Environmental Management Plan includes an adaptive environmental monitoring program where the future program is informed by the results of the previous environmental monitoring. Based on the analysis of samples collected from 2004 to 2019, the Environmental Management Plan’s prescribed five-year interval between environmental monitoring programs was found to be appropriate.

Given this, during the 2023 season, all matrices were sampled as required by the Environmental Management Plan. The Annual Compliance Report indicated that most 2023 samples were similar to those from previous years.

Four of the samples taken as part of the 2023 sampling program exceeded the GTV of 1 mg/kg. Snowy Hydro have committed to resampling these locations as part of the 2024 cloud seeding season to determine the potential cause of higher silver concentrations as these sites. It is suspected that the cause of these exceedances is in response to the 2019/2020 bushfires as these samples were taken in fire affected locations.

However, silver concentrations have increased from previous years but remain several orders of magnitude below relevant guideline values. Analysis of silver concentrations from samples collected through the environmental monitoring program prior to the commencement of cloud seeding in 2004 through to 2023 showed no evidence that cloud seeding has contributed to increased levels of silver in any area or in any environmental matrix monitored.

Macroinvertebrate sampling took place during the 2023 cloud seeding season in accordance with the EMP. Analyses of data collected following the 2018 and 2023 season has shown no evidence of any difference over time in the impairment of the macroinvertebrate assemblages.

Internal audits of cloud seeding sites were undertaken by Snowy Hydro personnel with NPWS, although no site visits were undertaken by NPWS in the 2023 reporting period. NPWS requested that SHL continue its site inspection and auditing process and requested reports of any significant issues or change

Snowy Hydro Limited reported that there was no new infrastructure established or decommissioned during the reporting period, however minor modifications were made to existing infrastructure to install new meteorological instrumentation. No accidents or breakdowns were reported that resulted in spillage of cloud seeding agents or fuel, or failure of any of the controls specified in the Environmental Management Plan.

No current or emerging issues were formally raised by stakeholders for the 2023 cloud seeding season, mechanisms within the Environmental Management Plan allow relevant agencies of the Minister for the Environment to request consideration by Snowy Hydro Limited of emerging environmental issues between each five-yearly review.

Conclusions and recommendations

After reviewing the Snowy Hydro Limited 2023 Annual Compliance Report and Snowy Hydro Limited on-ground operations, the EPA concludes that:

Snowy Hydro Limited has complied with all obligations as detailed in the Act.
Snowy Hydro Limited has complied with all obligations as detailed in the Environmental Management Plan for cloud seeding operations approved by the relevant Ministers in July 2023.
Snowy Hydro Limited has complied with all obligations as detailed in the Protection of the Environment Operations Act 1997.
Analysis of sampling across all matrices carried out during the 2023 cloud seeding season showed silver concentrations remain several orders of magnitude below relevant guideline values.

It is recommended that:

Monitoring should be continued as per the schedule of the EMP, and data compared over time to identify trends.
Future reviews are also undertaken in consultation with input from partner agencies of the NPWS and DCCEEW.
Snowy Hydro Limited continues to pursue research opportunities on the cloud seeding operations in the Snowy Mountains.
The outcomes of this review are communicated to the relevant Ministers.

Obligations under the Snowy Mountains Cloud Seeding Act 2004	Compliance status (report reference)
The area to be primarily targeted for the increased precipitation is land within the Snowy water catchment.	(1.4) Addressed
Operations may be carried out only if there is an approved Environmental Management Plan.	(1.1) Addressed
Operations must be carried out in accordance with the approved Environmental Management Plan (whether being carried out within or outside the Snowy water catchment).	(1) Addressed All operations carried out within the catchment.
The seeding agent used must be an approved seeding agent and used in accordance with the conditions (if any) of its approval as a seeding agent.	(2.2) Addressed
The tracing agent used must be an approved tracing agent and used in accordance with the conditions (if any) of its approval as a tracing agent.	(2.2) Addressed Tracing agent not used.
The seeding agent and tracing agent must be discharged by the use of an approved method.	(2.2) Approved Land-based aerosol generators.
The discharge must be carried out in accordance with the conditions (if any) of its approval as a method of discharge.	(2) Addressed
The discharge of the seeding agent is to be carried out at a time when increased precipitation in the Snowy water catchment is likely to fall as snow at an elevation above 1400 metres from the mean sea level.	(3.1) Addressed
Snowy Hydro Limited must consult with the NPWS before carrying out any new operations involving a land- based method of discharge of seeding or tracing agent within any area of land reserved under the National Parks and Wildlife Act 1974 (that is, operations in an area that has not been the subject of previous consultation with the NPWS).	(2.3) Addressed No new operations carried out.
Snowy Hydro Limited must consult with the NPWS before installing, or carrying out major modifications to, any facilities required to carry out cloud seeding operations within any area of land reserved under the National Parks and Wildlife Act 1974.	(2.3) Addressed No major modifications or new installations carried out.
Installation of new facilities for cloud seeding operations must not be carried out within any wilderness area (within the meaning of the National Parks and Wildlife Act 1974).	(2.3) Addressed No new facilities installed.
A seeding agent is not to be discharged from land-based aerosol generators in any wilderness area (within the meaning of the National Parks and Wildlife Act 1974).	(1.4) Addressed All land-based generators located in approved areas by NPWS.
An application for approval of the use of a thing as a seeding agent in cloud seeding operations must be accompanied by details of the health risk assessment carried out in relation to the proposed use of the seeding agent (including the process used to carry out the assessment and the results of the assessment).	(N/A)
An application for approval of the use of a thing as a tracing agent in cloud seeding operations must be accompanied by details of the health risk assessment carried out in relation to the proposed use of the tracing agent (including the process used to carry out the assessment and the results of the assessment).	(N/A)
An application for approval of an Environmental Management Plan must be accompanied by an independent scientific assessment of any proposed cloud seeding operations that differ from the operations currently authorised. Any such scientific assessment must comply with any requirements imposed by the relevant Ministers and notified to Snowy Hydro Limited.	(N/A)
Snowy Hydro Limited must, by 31 March in each year or such later date as agreed by the relevant Ministers, provide a report on its cloud seeding operations during the period of 12 months ending on 31 December in the previous year to the relevant Ministers and to the EPA. Without limiting the generality of subsection (1), the report must contain the following information: details of compliance with the approved Environmental Management Plan details of research concerning, and monitoring of, the impact of tracing agents and seeding agents on the environment (including the findings of any such research or monitoring).	(4) Addressed Report on cloud seeding operations received by EPA 28 Mar

Obligations under the Environmental Management Plan	Compliance status (report reference
Cloud seeding will not commence if the freezing level over the catchment is greater than 1600 metres, and will be suspended or terminated if the freezing level rises above 1600 metres during cloud seeding campaigns.	(3.1) Addressed There were no instances where the freezing level rose above 1600 m, therefore additional controls were not triggered.
Additional controls will be implemented when the freezing level is between 1550 metres and 1600 metres above sea level, including: video monitoring at locations over the target area at approximately 1400 metre elevation to assist in determining that precipitation is not falling as rain when required, undertaking telephone polling to external parties and/or Snowy Hydro Limited personnel within the target area to confirm that precipitation is not falling as rain at approximately 1400 metre elevation.	(3.1)Addressed There were no instances where the freezing level was between 1150 -1600 m.
Snowy Hydro Limited will consult with the NPWS prior to undertaking major vegetation management and site access beyond maintenance of the existing tracks and site footprints.	(2.3) N/A
The Annual Compliance Report will include: sample locations, data results, evaluation and adaptive management recommendations for the environmental monitoring program details (including results and evaluation) of any emerging environmental issues results from meteorological monitoring that can demonstrate Snowy Hydro Limited’s compliance with the requirement to ensure that increased precipitation falls as snow in areas at an elevation above 1400 metres above sea level results from analyses of downwind precipitation the event time and duration over which cloud seeding occurred any accidents or break downs resulting in spillage of cloud seeding agents, fuel, or failure of controls specified in this Environmental Management Plan the quantity of cloud seeding agents that were released per seeding event per generator	(a – 4.1-4.3) Addressed (b – 4.4) Addressed: No emerging environmental issues (c – 3.1) Addressed: Table 3.1. (d – 3.2) Addressed: Figure 3.1 (e – 2.1) Addressed: Table 2.1 (f – 2.3) Addressed: No accidents or breakdowns (g – 2.2) Addressed: Table 2.2
In addition to the Annual Compliance Report, Snowy Hydro Limited will also prepare a Cloud Seeding Operations Annual Report which is to be made publicly available on the Snowy Hydro Limited website within a reasonable timeframe after any recommendations from the Board of the EPA and the relevant Ministers. The Cloud Seeding Operations Annual Report will include, but not be limited to: summary statistics of the Environmental Monitoring Program details of compliance with approved Environmental Management Plan summary statistics on the overall duration over which cloud seeding occurred and the total amount of cloud seeding agents that were released over the season.	(1.2) N/A
Disputes between NSW government agencies and Snowy Hydro Limited with regards to cloud seeding operations will be resolved in accordance with the following escalation process: use of established paths of communication between Snowy Hydro Limited and the agency (officer to officer) communication between Snowy Hydro Limited Executive Officer and agency Department Director communication between the Chief Executives of Snowy Hydro Limited and the agency.	(2.4) Addressed No disputes between NSW Government agencies and Snowy Hydro Limited.
Snowy Hydro Limited will continue to consult with other relevant land managers with respect to vegetation management and site access. Snowy Hydro Limited will also consult with relevant land managers in situations where major visual modifications are made to infrastructure or if new sites are installed and/or existing sites are removed. No new infrastructure will be established without the prior endorsement by the relevant land manager.	(2.3) Addressed No new infrastructure established, no major visual modifications made to existing infrastructure, and no infrastructure decommissioned.
DCCEEW, the EPA and other identified stakeholders will be advised as soon as practicable following the commencement of, and on the conclusion of cloud seeding campaigns.	(2.1) Addressed DCCEEW and EPA and other identified stakeholders were advised by email.
Existing sites authorised under the Act will be defined by Snowy Hydro Limited (coordinates and identified on a map), and provided to DCCEEW and the EPA prior to commencement of first annual winter operations. Thereafter, prior to the installation of any new authorised sites, updated coordinates and maps are to be provided to DCCEEW and the EPA.	(1.4) Addressed A map of existing sites and details of their coordinates were provided to the EPA and DCCEEW in June 2013. There were no changes to infrastructure in 2023.
Implement all Management Controls (Table 1), being those included for each of the following activities: installation and modification of generators operation and maintenance of generators (including release of cloud seeding agents and increased precipitation) storage and preparation of cloud seeding agents and other chemicals installation and modification of weather stations installation and modification of communications equipment operation and maintenance of weather stations and communications infrastructure operation and maintenance of snow sampling sites Environmental Monitoring Program removal of infrastructure and rehabilitation of sites.	(2.3) Addressed Infrastructure, including cloud seeding agents and fuel, are managed in accordance with these requirements.
Meteorological monitoring
Undertake monitoring of downwind precipitation - mean wintertime daily precipitation anomalies will be updated each year and included in the Annual Compliance Report following cloud seeding operations to continue to monitor downwind precipitation.	(3.2) Addressed Figure 3.1
Snow sampling profile sites and preferred access routes will be defined by Snowy Hydro Limited (coordinates and identified on a map) and provided to DCCEEW and EPA prior to commencement of first annual winter snow sampling operations. Updated coordinates and maps are to be provided to DCCEEW and EPA if sites change.	(1.4) Addressed No snow profile sampling took place in 2023.
Environmental chemistry monitoring
Environmental sampling to be undertaken as per Table 3 in the Environmental Management Plan.	(4.1.2) Addressed Table 4.1.
Specific quality controls applied to the collection and handling of all samples collected for the cloud seeding program include: the use of a new clean plastic vial/bag for each sample the use of a new pair of clean disposable gloves at each site and procedures to minimise contact with the inside of vials/bags to minimise the potential for sample contamination all sampling equipment is washed with ultra-pure water or water from the sampling location prior to use the use of a data management system including the barcoding of each sample to ensure every sample is individually trackable from collection, return to base, dispatch to the laboratory and the return of results.	(4.1.3) Addressed Samples are collected and processed in accordance with internal work instructions and quality assurance and quality control procedures.
Samples sent for laboratory analyses will be analysed for total silver concentration with an appropriate level of quality assurance and quality control (QA/QC).	(4.1.3) Addressed
For those samples that are analysed chemically, the data is to be analysed	(4.1.5) Addressed
statistically and interpreted on the basis of three statistical tools.	Due to extremely low values observed in 2023 and previous surveys, no statistical analysis were undertaken for this matrix.
Implementation of steps in decision tools and environmental suspension criteria.	(4.1.1, 4.1.5) Addressed
Macroinvertebrates monitoring
Sampling will be undertaken on a five- year sampling interval, with the first round of sampling to be undertaken following the first year of cloud seeding operations. In the event that additional river sediment sampling is required as a result of the triggers outlined in the Environmental Management Plan, macroinvertebrates sampling will also be undertaken at the affected locations.	(4.2) Addressed Macroinvertebrate sampling was required in 2023.
If macroinvertebrate sampling sites are changed and/or added outside of the Environmental Management Plan Review process, updates to the Environmental Management Plan will be provided to EPA/DCCEEW prior to sampling being undertaken.	(4.2) Addressed No changes made during the 2023 sampling.
The macroinvertebrate sampling program implemented by Snowy Hydro Limited (and endorsed by DCCEEW) uses the NSW Australian River Assessment System (AUSRIVAS) protocol.	(4.2) Addressed Macroinvertebrate sampling was conducted using the AUSRIVAS protocol during the 2023 season.
Additional monitoring
Relevant agencies of the Minister for the Environment may request consideration by Snowy Hydro Limited of emerging environmental issues between reviews of this Environmental Management Plan. In order for issues to be considered by Snowy Hydro Limited, the agency will provide a clear outline of the issue to Snowy Hydro Limited based on direct evidence or established scientific theory. The agency and Snowy Hydro Limited will then agree on an appropriate research/monitoring/consultation/reporting regime.	(4.4) N/A No emerging environmental issues were raised with, or identified by, Snowy Hydro Limited during this reporting period.

Updated 06 December 2024