Client Envirosure ASSESSMENT OF THE GROOT RIVER, MEIRINGSPOORT FOLLOWING DIESEL CONTAMINATION FINAL REPORT Prepared by Justine Ewart-Smith November 2017 Freshwater Consulting cc Unit F6, Prime Park Mocke Road Diep River, 7800 Email: [email protected] Phone: 082 3738380 Meirings River Monitoring: Baseline Assessment TABLE OF CONTENTS 1 INTRODUCTION ...................................................................................................................... 1 1.1 Background ....................................................................................................................................... 1 1.2 Terms of Reference ........................................................................................................................... 2 1.3 Limitations ......................................................................................................................................... 2 1.4 Use of this Report.............................................................................................................................. 3 2 CLEAN-UP OPERATIONS UNDERTAKEN TO DATE ...................................................................... 3 3 DESCRIPTION OF THE AFFECTED RIVER ECOSYSTEM ................................................................. 4 3.1 The Groot River Catchment .............................................................................................................. 4 3.2 A description of the Meirings River within the study area ............................................................... 4 3.3 The Conservation Importance of the Meirings River ........................................................................ 5 4 ASSESSMENT APPROACH AND METHODOLOGY ....................................................................... 8 4.1 Sampling dates .................................................................................................................................. 8 4.2 Sampling sites.................................................................................................................................... 8 4.3 Water quality Assessment .............................................................................................................. 12 4.3.1 Sample collection ............................................................................................................................ 12 4.3.2 Laboratory methods of analysis ...................................................................................................... 12 4.4 SASS5 Bioassessment ...................................................................................................................... 13 5 RESULTS .............................................................................................................................. 14 5.1 Water Quality .................................................................................................................................. 14 5.2 Macroinvertebrate fauna ................................................................................................................ 18 5.3 Fish communities ............................................................................................................................ 24 6 DISCUSSION .......................................................................................................................... 25 7 CONCLUSIONS AND RECOMMENDATIONS ............................................................................. 26 8 REFERENCES ......................................................................................................................... 27 i Meirings River Monitoring: Baseline Assessment 1 INTRODUCTION 1.1 Background On the 15th August 2017, 41 000 litres of diesel was accidentally spilled from an overturned tanker into a roadside stormwater drain which discharges runoff directly in the Groot River as it flows through the Meiringspoort Pass. The bulk of the diesel flowed down the drain and discharged into the sandy river bank, entering the Groot River immediately downstream of the bridge crossing the river. Efforts to contain the spillage through the deployment of emergency measures were implemented immediately through the placement of lime as an absorbent within the stormwater drain, building of sand berms and the construction of retention ponds within the river bank, as well as placement of absorbent booms about 600 m downstream from the point of entry into the Groot River (HilLand Environmental 2017). Nevertheless, the Spill Tech emergency clean up team, who arrived the same day, reported that the effect of the diesel spill could be seen as far downstream as 1 km, immediately upstream of the Derde Tol bridge crossing the Groot River. The emergency team therefore took immediate action to contain the fuel and prevent any further spread downstream. Envirosure Underwriting Managers (Pty) Ltd who insure the Kelrn Vervoer vehicle responsible for the spillage, contacted Freshwater Consulting cc and requested an initial assessment of the extent of ecological damage caused by the spillage and to make provisional recommendations for clean-up operations and the need for rehabilitation and monitoring. During the site visit on the 18th August 2017, Freshwater Consulting cc confirmed that refined diesel contamination was restricted to the active channel of the river and was visible as a floating film across the wetted perimeter for approximately 1 km downstream of the point of entry. Where diesel had made contact with either sediments or vegetation along the wetted margins of the channel, residues of diesel were evident and would likely leach into the sediments and remain within the system well beyond the period when diesel is visible. Also, significant numbers of the threatened redfin minnow (Pseudobarbus spp.) were struggling for oxygen and many were dying at the time of the site visit. Besides recommendations to ensure ecologically sensitive clean-up operations, it was strongly recommended that a fish rescue operation be implemented with immediate effect and that the system be monitored from an ecological perspective to evaluate the extent and rate of recovery following clean-up. In response to a directive issued by the Breede Gouritz Catchment Management Agency (BGCMA) Envirosure Underwriting Managers (Pty) commissioned Riaan van der Walt of Advanced Environmental Corporation Pty (Ltd) to undertake a fish rescue operation. Freshwater Consulting cc was commissioned to compile a Rehabilitation and Monitoring Plan for the Meirings River. 1 Meirings River Monitoring: Baseline Assessment 1.2 Terms of Reference Accordingly, the Freshwater Consulting Group was commissioned to: 1. Undertake a baseline assessment of the Groot River to understand its condition and integrity prior to the spill and to establish a baseline for evaluating the potential impacts of surfactants, if necessary, on the biota associated with clean-up operations. 2. Undertake a site visit to guide the removal of sediments and vegetation (if necessary) 3. Establish the extent and need for rehabilitation through collaboration with the clean-up team to understand the proposed Action Plan and the timeframe for implementation of the Action Plan. 4. Following on from the baseline assessment, compile a monitoring plan for fish and macroinvertebrates. 5. Monitor key biological (fish and invertebrates), physical (habitat) and chemical indicators for a minimum period of one year at key sites within the catchment. Monitoring will be undertaken every 3 months and the need for longer term monitoring will need to be addressed after this period. 6. Compile a report that specifically details the proposed Monitoring and Rehabilitation Plan. This report will include information on how the channel margins will be revegetated. 7. Compile quarterly reports that provide details of the recovery of the aquatic ecosystem based on data collected in the field with recommendations for ongoing monitoring or the need to adapt the monitoring approach. This report specifically addresses point 1 above. It constitutes the Baseline Assessment of the Meirings River which provides a basis for evaluation of the ecological state of the system for monitoring recovery over time. Following the approval of these Terms of Reference, it was decided that clean-up operations would include the use of surfactants in addition to the initial efforts that were based purely on mechanical removal of the contaminant (see section 2 for details). In addition to the Baseline Assessment, water samples were collected for assessment of the potential effects of surfactants on water chemistry following application of the surfactant, Biosolve®. These data are included in this report. 1.3 Limitations The assessment of ecosystem health for any river is dependent on an understanding of the reference state or condition of the system, prior to any anthropogenic impacts. There is no primary data set that provides an indication of the reference condition of the Groot/Meirings River. Interpretation of the biophysical data in this study is therefore limited to comparison with control sites upstream and downstream of the impacted reaches. Also, there is no reliable flow data for the Groot/Meirings River. Water quality and biological integrity is somewhat dependant on flow characteristics of river ecosystems and therefore interpretation of the data is further limited by a lack of reliable flow data for this catchment. 2 Meirings River Monitoring: