.. .. .... ~;~ter data services Report Prepared for: South Australia Envii ronment Protection Authority South Australia Adelaide Coastal Water Study : S1t ormwater Data Audit Report 2015 Water Data Services Pt¥ Ltd www .waterdata.com.au. 1 Erudf11a Ave Edwa rdstown SA 5039 P 08 837'4 3522 F OS- 8374 3566 Date: Tuesday 20th June 2017 Delivery: Electronic Copy (via email) Principal Environment Protection Officer (Water Quality) Environment Protection Authority SA Level 9, 250 Victoria Square, ADELAIDE, 5000 Via email: Report: Adelaide Coastal Waters Study : Stormwater Data Audit Report 2015 Client Contact: Principal Environment Protection Officer (Water Quality) Environment Protection Authority SA Level 9, 250 Victoria Square, ADELAIDE, SA, 5000 Via email: Contractor: Prepared and submitted by: Operations Manager Water Data Services Pty Ltd 1 Erudina Ave Edwardstown SA 5039 Telephone 08 8374 3522 Facsimile 08 8374 3566 E-mail ~~ter data services Environment Protection Authority SA Executive Summary In 2005 a data audit was undertaken to investigate data availability for current and historical monitoring programs in the Adelaide Coastal Waters Study (ACWS) area. The audit was focussed on stormwater quality and quantity and identified data gaps in the monitoring programs. This report in 2015 is an audit of the data collected in the period 2005 to 2014 to determine if previous monitoring gaps have been filled and identify current and future gaps in the monitoring programs. The report also summarises changes and improvements to data sets report in the 2005 audit. Flows observed during this period were influenced by drought conditions. The several years of below average rainfall resulted in prolonged periods of below average flow. Environmental flow regimes were designed and introduced to the major rivers to maintain river health and ecosystems. These environmental flow releases occurred in the Gawler (South Para), Torrens and Onkaparinga Rivers and were facilitated by water released from the reservoirs. A consequence of this was that the water released had a proportion of River Murray water which has substantially different water quality characteristics to the natural stormwater runoff in the lower catchments. Water quality improvement and water security infrastructure was installed across the ACWS catchments as part of the Australian Government's Water for the Future initiative which included wetlands and MAR schemes. The primary objective of these initiatives is to improve water security but they may also have some direct and indirect benefits to water quality. Major transport infrastructure projects were constructed in the ACWS catchments including the Southern Expressway duplication, Northern Expressway, Port River Expressway and bridge, South Road Superway and the extension of the Seaford railway line. The availability of flow and water quality data has improved substantially since the previous audit and a strong shift towards data sharing between the many different agencies operating monitoring programs in the ACWS has meant that added value can be extracted from capital expenditure on monitoring infrastructure. The majority of the monitoring projects utilise hydrometric monitoring stations with flow proportional composite sampling instrumentation to facilitate the data collection. Natural Resources - Adelaide and Mount Lofty Ranges (AMLR) operate the largest water quality monitoring network in the ACWS area and have a designated website available to the public to view the data. The architecture of this website has i ~ -~ter data services Environment Protection Authority SA been made available to local council and SA Water monitoring programs to become a data hub for the region. Auditing of the monitoring programs and data identified that many of the previous data gaps from 2005 have been filled. This fits with the set up of the AMLR designed Outfall Flow network. New monitoring stations have been commissioned near the stormwater discharge points for most of the major creeks and rivers. Remaining gaps in the ACWS stormwater catchments include the Southern coastal catchments, the Patawalonga Coastal stormwater drainage systems (Holdfast drains) and the Buckland Park Lake (Gawler River Discharge). Rainfall runoff models were developed for the un-gauged catchments with the objective to provide a mean annual discharge from the AWCS catchments into the gulf. Combining the modelled flow with the data from the gauging stations determined that the mean annual flow from 2005 to 2014 was 92GL/yr. Water quality monitoring was not performed at all sites for the reporting period, therefore a reduced period of 2009-2014 was used as the data set. Combining the flow proportional composite sample water quality results with the corresponding flow data determines the mean annual water quality pollutant loads. The results observed were 149T/year Total Nitrogen, 14.2T/year Total Phosphorus and 4140T/year Suspended Solids. Over 50% of each of the total pollutant loads is discharged from the Torrens, Gawler and Onkaparinga Rivers. The following recommendations have been provided to continue to meet and better inform the objectives of the ACWS: Verification monitoring for the stormwater drain system flow models Flow monitoring of the Buckland Park Lake Flow and WQ monitoring of the southern creek catchments Maximise use of instrumentation technology including flow and water quality alerts Real time monitoring for turbidity, customised web pages and reports Investigate a catchment targeted pesticide sampling program Incorporate wetland and MAR scheme monitoring programs into reports and database for the ACWS catchments Maintain the current regime of historical monitoring stations to observe changing trends in the catchments. ii ~~ter data services Environment Protection Authority SA Table of Contents Executive Summary ..................................................................................................................... i 1 Introduction ........................................................................................................................ 1 2 Climate Summary ................................................................................................................ 3 3 Stormwater Sources ............................................................................................................ 4 3.1 Stormwater Source Classification ............................................................................................. 4 3.2 Influences on stormwater flow and quality 2005-2014 .............................................................. 9 3.3 ACWS Catchment Summaries ................................................................................................. 12 3.3.1 Gawler River ................................................................................................................................................ 12 3.3.2 Thompson Creek and Smith Creek .............................................................................................................. 15 3.3.3 Helps Road Drain and Adams Creek ............................................................................................................ 17 3.3.4 Little Para River ........................................................................................................................................... 18 3.3.5 Dry Creek .................................................................................................................................................... 20 3.3.6 Port Adelaide and Barker Inlet .................................................................................................................... 22 3.3.7 Torrens River ............................................................................................................................................... 25 3.3.8 Patawalonga Basin ...................................................................................................................................... 28 3.3.9 Field River ................................................................................................................................................... 31 3.3.10 Christie Creek.......................................................................................................................................... 33 3.3.11 Onkaparinga River .................................................................................................................................. 35 3.3.12 Pedler Creek ........................................................................................................................................... 38 3.3.13 Silver Sands Catchment (Washpool Lagoon) .......................................................................................... 40 4 Availability of Flow Data.................................................................................................... 42 4.1 Data compatibility across the ACWS area ............................................................................... 49 4.2 Flow Data Gaps ..................................................................................................................... 49 5 Flow Data Summary .......................................................................................................... 50 5.1 Estimating Flows in Un-gauged Catchments ............................................................................ 50 5.1.1 Estimating Losses in Buckland Park