HARTENBOS ESTUARY MANAGEMENT
PLAN
2016-2021: First Generation EMP
MAY 2016
HARTENBOS ESTUARY MANAGEMENT PLAN
2016-2021: First Generation EMP compiled by
Anchor Environmental (VERA MASSIE, KENNETH HUTCHINGS AND
BARRY CLARK)
2018-2023: Second Generation EMP compiled by Mossel Bay Municipality
January 2018
TABLE OF CONTENTS
1 INTRODUCTION ...... 1
1.1 BACKGROUND...... 1 1.2 PURPOSE AND SCOPE OF THE HARTENBOS ESTUARY MANAGEMENT PLAN ...... 1
2 SITUATION ASSESSMENT ...... 4
2.1.1 INTRODUCTION ...... 4 2.1.2 GEOGRAPHIC AND SOCIO-ECONOMIC CONTEXT ...... 4 2.1.3 ECOLOGICAL CHARACTERISTICS AND FUNCTIONING...... 5 2.1.4 ECOSYSTEM SERVICES ...... 9 2.1.5 LEGISLATION AND MANAGEMENT ISSUES ...... 10 2.2 UITVOERENDE OPSOMMING ...... 15 2.2.1 INLEIDING ...... 15 2.2.2 GEOGRAFIESE EN SOSIO-EKONOMIESE KONTEKS ...... 15 2.2.3 EKOLOGIESE EIENSKAPPE EN FUNKSIONERING ...... 15 2.2.4 EKOSISTEEM DIENSTE ...... 15 2.2.5 WETGEWING EN BESTUUR KWESSIES ...... 15
3 VISION ...... 15
4 ESTUARY MANAGEMENT OBJECTIVES ...... 15
4.1 IMPROVE ESTUARY HEALTH ...... 15 4.2 MAXIMISE ECONOMIC BENEFITS ...... 15 4.3 RESTORE AESTHETIC VALUE ...... 15 4.4 INCREASE AWARENESS ...... 16 4.5 HARMONIOUS AND EFFECTIVE GOVERNANCE...... 16
5 STRATEGIES TO MEET MANAGEMENT OBJECTIVES ...... 17
6 KEY MANAGEMENT OBJECTIVES AND MANAGEMENT ACTION PLANS ...... 19
6.1 KEY MANAGEMENT OBJECTIVES 1: IMPROVE ESTUARY HEALTH ...... 19 6.2 KEY MANAGEMENT OBJECTIVES 2: IMPROVE WATER QUALITY ...... 24 6.3 KEY MANAGEMENT OBJECTIVES 3: EFFECTIVE MOUTH MANAGEMENT ...... 28 6.4 KEY MANAGEMENT OBJECTIVES 4: IMPROVE RECREATIONAL VALUE ...... 33 6.5 KEY MANAGEMENT OBJECTIVES 5: IMPROVE AESTHETIC VALUE ...... 36 6.6 KEY MANAGEMENT OBJECTIVES 6: INCREASE AWARENESS AND APPRECIATION FOR THE HARTENBOS ESTUARY ...... 36 6.7 KEY MANAGEMENT OBJECTIVES 7: RESEARCH AND MONITORING ...... 39 6.8 HARMONIOUS AND EFFECTIVE GOVERNANCE...... 39 6.9 SUMMARY OF MANAGEMENT ACTIONS AND TIMING ...... 45
7 APPENDICES ...... 48
7.1 APPENDIX 1: PROPOSED HARTENBOS ESTUARY ZONATION PLAN ...... 48 7.1.1 INTRODUCTION ...... 48 7.1.2 GEOGRAPHICAL EXTENT OF THE ESTUARY ...... 49 7.1.3 COASTAL PROTECTION ZONE, COASTAL MANAGEMENT LINES AND FLOOD LINES ...... 51 7.1.4 PROPOSED MANAGEMENT ZONES FOR THE HARTENBOS ESTUARY ...... 52 7.2 APPENDIX 2: PROPOSED ESTUARY MOUTH MANAGEMENT PROTOCOL FOR THE HARTENBOS ESTUARY, MOSSEL BAY MUNICIPALITY ...... 55 7.2.1 PROBLEM STATEMENT ...... 55 7.2.2 OVERALL OBJECTIVE OF THE LOCAL MOUTH MANAGEMENT PROGRAMME ...... 57
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7.2.3 DESCRIPTION OF THE ESTUARY ...... 58 7.2.4 MOTIVATION FOR ARTIFICIAL BREACHING ...... 60 7.2.5 BREACHING PROCEDURE ...... 76 7.2.6 KEY MONITORING INFORMATION ...... 82 7.2.7 ADAPTIVE MANAGEMENT THROUGH POST BREACHING REPORTING AND CONSULTATION SESSIONS . 84 7.2.8 REFERENCES ...... 85 7.3 APPENDIX 3: ECOLOGICAL SPECIFICATIONS AND THRESHOLDS OF POTENTIAL CONCERN (TPC) FOR MONITORING PARAMETERS LISTED IN APPENDIX 4 ...... 86 7.4 APPENDIX 4: RECOMMENDED MONITORING PROTOCOL FOR THE HARTENBOS ESTUARY ...... 89 7.5 APPENDIX 5: NATIONAL RESPONSE PROTOCOL FOR FISH KILLS ...... 96 7.6 APPENDIX 6: LISTED ACTIVITIES FOR WHICH AN EIA IS REQUIRED FOR ESTUARIES IN THE WESTERN CAPE ACCORDING TO THE NATIONAL ENVIRONMENTAL MANAGEMENT ACT (NEMA) ...... 99
8 REFERENCES ...... 105
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LIST OF ABBREVIATIONS
AEC Anchor Environmental Consultants (Pty) Ltd. C.A.P.E. Cape Action Plan for People and the Environment CPZ Coastal Protection Zone CSIR Council for Industrial and Scientific Research DAFF Department of Agriculture Forestry and Fisheries DEA Department of Environmental Affairs DEA:O&C Department of Environmental Affairs: Oceans and Coasts DWS Department of Water and Sanitation DEADP Department of Environmental Affairs & Development Planning DPWs Department of Public Works ECR Ecological Reserve Category EDM Eden District Municipality EIA Environmental Impact Assessment EFZ Estuarine Functional Zone EMP Estuary Management Plan EAF Estuary Advisory Forum IDP Integrated Development Plan KRA Key Result Area MAPs Management Action Plans MAR Mean annual runoff MSL Mean sea level MEC Member of Provincial Executive Council Mm3 Million cubic metres MBM Mossel Bay Municipality NEMA National Environmental Management Act (Act 107 of 1998) ICMA National Environmental Management: Integrated Coastal Management Act (Act No 24 of 2008) NEMP National Estuary Management Protocol NWA National Water Act, 1998 (Act 36 of 1998) PES Present Ecological Status REC Recommended Ecological Category WWTW Waste Water Treatment Works
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GLOSSARY
Term Description Abiotic Non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems Biotic Associated with or derived from living organisms Estuarine resident fish species Estuarine fish species, which breed in estuaries Estuarine-dependent Euryhaline marine species which usually breed at sea with the juveniles showing varying degrees of dependence on southern African estuaries Euryhaline The ability to adapt to a wide range of salinities Eutrophication Eutrophication is a process whereby water bodies, such as lakes, estuaries, or slow-moving streams receive excess nutrients that stimulate excessive plant growth (algae and nuisance plants & weeds). This enhanced plant growth, often an algal bloom, reduces dissolved oxygen in the water when dead plant material decomposes and can cause other organisms to die Mean annual runoff The mean of the the total quantity of water that is discharged ("runs off") from a drainage basin per year within a specified time period Mean sea level An average level for the surface of one or more of Earth's oceans from which heights such as elevations may be measured
iv Draft Hartenbos Estuary Management Plan Introduction
1 INTRODUCTION 1.1 Background The Hartenbos Estuary is one of South Africa’s approximately 289 functional estuaries and is one of 21 estuaries within the warm temperate biogeographic region to be classified as a temporarily open/closed (Turpie et al., 2012, Van Niekerk and Turpie, 2012). The Hartenbos is a small estuary with a relatively large floodplain and covers in total approximately 268 ha. The Hartenbos Estuary ranks 74th of all South African estuaries in terms of its overall conservation importance and can be considered as moderately important for estuarine biodiversity on a national scale. The Hartenbos Estuary is an important recreational area along the Cape south coast. The estuary faces pressures from reduced freshwater inflow due to the upstream Hartebeeskuil Dam and drought, reduced tidal exchange due to increasing rates of sedimentation at estuary mouth since the construction of the Hartebeeskuil dam, increasing coastal development and tourism activities and deteriorating water quality. This document is the second generation of the Draft Management Plan for the Hartenbos Estuary (from here on referred to as Hartenbos EMP) and was compiled in accordance with the National Estuarine Management Protocol (Regulations in terms of the National Environmental Management Integrated Coastal Management Act No. 24 of 2008) (ICMA).
1.2 Purpose and scope of the Hartenbos Estuary Management Plan Drawing on the Situation Assessment prepared for the Hartenbos Estuary (Mossel Bay Municipality 2015), inputs from key stakeholders and other supporting documents prepared for the C.A.P.E. Estuaries Programme (e.g. Turpie & Clark 2007 – Cape Estuaries Classification, Prioritisation, Protection and Rehabilitation report), the Hartenbos EMP sets out the Vision and Management Objectives for the Hartenbos Estuary. It also identifies Strategies needed to meet these objectives, and indicates the main actions required in the next five years in order to achieve the overall vision. The Hartenbos EMP focuses on strategic priorities and should be seen as a flexible document that can be altered as required to achieve the overall vision and objectives for the estuary. While planning for some emergencies, e.g. floods, is part of this plan, it remains possible that unforeseen disasters could disrupt the prioritisation set out here.
1.2.1 Institutional Arrangements
A set of Key Management Objectives (KMO) have been identified for the estuary for the next five years. A KMO is a priority area of action for the estuary and addresses one or more of the strategies required to meet the objectives. Each strategy will be implemented through a set of actions and will result in a number of deliverables. A plan of implementation is provided for each KMO. The implementation of the EMP strategies by the Responsible Management Authority for the estuary (the Mossel Bay Municipality) and its strategic partners (Cape Nature, DEA Oceans and Coasts, Eden District Municipality, Western Cape Provincial Government, Department of Water and Sanitation), will be monitored by the Hartenbos Estuary Advisory Forum (hereafter referred to as Hartenbos EAF) comprising representatives of all key stakeholders groups on the estuary, using indicators within a set time-frame.
1 Draft Hartenbos Estuary Management Plan Introduction
The institutional arrangements outlined above must however be considered together with disclaimer below:
Readers of this EMP must note that delegation of local authorities as the Responsible Management Authority (RMA) was done as per the National Estuarine Management Protocol (NEMP). Circular DEA&DP 011/2017 confirms that the NEMP is flawed and that the Department of Environmental Affairs will be considering amendments to the NEMP. The aforementioned Circular also confirms that Department of Environmental Affairs and Development Planning (DEA&DP) intends to undertake a rapid appraisal of all coastal Municipalities in the Western Cape. The purpose of this appraisal is to determine the appetite and capacity of the Municipalities to take up all, or elements of, the functions of RMAs as described in the NEMP. The interim institutional arrangements outlined in Circular DEA&DP 011/2017 states that until the review of NEMP and the appraisal of coastal municipality’s has been completed, DEA&DP, together with CapeNature, will continue to take the lead in ensuring coordinated planning, implementation and management of estuaries in the Western Cape. Mossel Bay Municipality’s acceptance of the delegation as Responsible Management Authority will this be subject to the completion of the DEA’s review of NEMP and if DEA&DP’s appraisal of coastal municipalities confirms that Mossel Bay Municipality is suitably capacitated to perform the RMA function.
It is important to recognize that this document is designed to focus management attention at a strategic level and does not provide detailed guidance on the day-to-day management actions required for management of the estuary. Annual Business or Action Plans will have to be developed by the MBM and in consultation with the Hartenbos EAF. These should be guided by this EMP and should be directed towards priority activities that support the strategic objectives identified in this EMP. Progress towards achieving the objectives set out in this EMP should be reviewed on an annual basis by the Hartenbos EAF and focal efforts of the participating agencies adjusted to ensure targets are met within specified time frames. The Hartenbos EMP should be reviewed every five years in order to reflect goals that have been achieved and to accommodate changing priorities.
The 2017 review of the Hartenbos Estuary Management plan is being conducted by Mossel Bay Municipality and the Hartenbos Estuary Advisory Forum. The amendments made to the Hartenbos EMP is informed by the experiences in 2016, 2017 and the information received from the Hartenbos Estuary Advisory Forum. The first generation EMP was compiled in 2016 and 2017 represented the first year in which the EMP was applied. The lessons learnt are extremely valuable and thus it forms a major informant of the review of the first generation EMP. More specifically the review and amendment of EMP is being informed by:
2 Draft Hartenbos Estuary Management Plan Introduction
1. The artificial breaching’s that have occurred between the period November 2016 – October 2017 and the information contained in the breaching and audit reports. The breaching reports were compiled as per the requirements of the first generation mouth management plan and have therefore yielded very useful information. They were compiled by Mossel Bay Municipality and Hilland Environmental. 2. The daily DO, Salinity, Temp and pH sampling that was conducted December 2016-January 2017 and December 2017 – January 2018. The sampling was done by Ocean’s Research an independent research organisation. 3. The section 30A Directives issued to Mossel Bay Municipality in November 2016, December 2016, February 2017, June 2017, August 2017 and October 2017. The section 30A directives were issued by the Region Three DEA&DP Land Use Management office. 4. The 200 mm contour surveys of the estuary mouth conducted July 2017- September 2017. The surveys were conducted by LNJ Surveyors. 5. The opinion expressed by DAFF that the system would benefit from being open during the peak fish recruitment period and that the removal of anoxic sediments would improve the health of the estuary. 6. The historical information provided by the Hartenbos Advisory Forum. 7. The MMP agreement which authorises Mossel Bay Municipality to artificially breach the Hartenbos Estuary. The MMP agreement was issued by the Region Three DEA&DP Land use Management office. 8. The water level data prior to and after the release of 150 000 cubic meters of water from the Hartebeeskuil dam during November 2016. The water level data showed that none of the water released reached the lower reaches of the estuary. Water level data provided by DWS. 9. The water level data for the periods preceding and after the artificial breaching noted in point 1. Water level data provided by DWS. 10. The groundtruthing of the state of the water course upstream of the lower reaches of the estuary, which indicate that the assertion that there is currently a mean annual runoff of 2.8 Mm is not correct. 11. The survey of Alien Invasive Plant species in the Estuary Functional Zone. Survey conducted by Credo Environmental. 12. The detailed study of the Estuary done by Bickerton (1981).
3 Draft Hartenbos Estuary Management Plan Situation Assessment Summary
2 SITUATION ASSESSMENT 2.1.1 Introduction Recognising the importance of the Hartenbos Estuary and estuaries in South Africa more generally, the Mossel Bay Local Municipality (MBM) commissioned Anchor Environmental Consultants (Pty) Ltd. (AEC) to prepare the first generation Estuarine Management Plan (EMP) for the Hartenbos Estuary. The following summary provides background material and the context for the development of this second generation Estuary Management Plan.
2.1.2 Geographic and socio-economic context The Hartenbos catchment lies within the MBM (part of the Eden District Municipality) in the Western Cape Province and forms part of the Breede-Gouritz Catchment Management Area. The Hartenbos River originates in the foothills of the Outeniqua Mountains and its tributaries drain a relatively small area of approximately 205 km2 in south-easterly direction. The Hartenbos River has a total length of approximately 34 km from the source to the mouth and drains into the Indian Ocean 7.5 km east of Mossel Bay. The Umvoto Africa 2010 study Sea Level Rise and Flood Risk Assessment commissioned by DEA&DP, divided the coastline of Mossel Bay into different coastal management units based on its risk profile. The section of the coast where the Hartenbos estuary drains into the sea is identified as the Hartenbos Coastal management unit which stretches from Bayview to the southern bank of the Klein Brak estuary. In terms of the sea level rise and flood risk assessment done, the Hartenbos Coastal Management Unit has a relatively high risk score. Umvoto Africa (2010c:5) qualifies the findings of the risk assessment by stating the following:
The severity of sea level rise induced erosion/inundation and extreme events can be affected by various factors, including mean wave height, the amount of sea level rise, tidal range, geomorphology, coastal slope and rates of accretion/erosion (Thieler and Hammar- Klose, 1999). The mean wave height, rate of sea level rise and tidal range is generally the same along the Eden DM coastline, and the rates of accretion/erosion are unknown, therefore geomorphology and coastal slope were the two variables used to assess the severity of both hazards.
Tidal exchange is amongst the criteria used to assess risk. Citing Bicketon (1982 in Umvoto Africa 2010) the afore-mentioned study suggests that the tidal range of the Hartenbos Estuary is approximately 2, 5 km. Mossel Bay Municipality together with DEA&DP then commissioned RHDHV to do a Sediment Supply Study. The purpose of this study was to provide information on accretion and erosion rates so that a more accurate risk assessment of Coastal Management Units could be conducted. The sediment supply study indicated that the sand berm forming across the Hartenbos river mouth was inhibiting tidal exchange. The study suggested that the accretion occurring at river mouths along the coast of Mossel Bay, which is occurring despite the fact that the beaches adjacent to them are eroding, may be related to the fact that the MAR of rivers have been so badly affected by compoundments and extraction. The importance of noting this will become evident in later sections as the trimming of the sand berm at the Hartenbos River mouth is one of the management actions proposed in the second
4 Draft Hartenbos Estuary Management Plan Situation Assessment Summary generation EMP. The fact that the Hartenbos Coastal Management Unit has a high level of risk may be used to suggest that any trimming of the sand berm may be un-wise. Yet the sedimentation study shows that accretion is the net process at the Hartenbos Rivermouth. In addition there is no indication that this will change particularly as the removal of the Hartebeeskuil dam is not feasible. Surveys conducted indicate that berm the berm height raises 400 mm per month under closed mouth conditions. In addition surveys were also conducted at low laying properties within the estuary functional zones. This represents an opportunity to manage the risk associated with any efforts to manage berm heights.
The catchment falls within the Fynbos Biome, but most of the area is transformed and under agriculture (pasture, wheat and vegetables) or forestry. The catchment has also been invaded by invasive alien acacias, including Acacia cyclops (rooikrans), especially in the lower reaches of the estuary. The transformation of the catchment has had an impact on the state of the water course. Historical aerial photographs suggest that the sand mining that has occurred North West of the estuary functional zone may have altered the alignment of the channel. Furthermore, historical aerial photographs suggest that the north western extent of the estuary functional zone has become overgrown with reeds. This is confirmed by the 2016 survey of Alien Invasive Plant species conducted by Credo Environmental. The mean annual temperature of the Hartenbos catchment is 17°C and is located within a region of bimodal rainfall, where precipitation peaks in spring and autumn. The average annual rainfall is 446 mm and is contrasted by 1400 mm mean annual evaporation with a mean annual runoff (MAR) for the whole catchment of approximately 5.7 million m3. The Western Cape is currently in the midst of one of the worst droughts in recorded history. The change in weather patterns observed in the last few years is consistent with the predicted effects of climate change for the Eden District area. Prolonged drier periods will untimely greatly reduce mean average runoff with mean annual evaporation rates increasing.
The geographic trend in economic activity along the catchment is predominately agriculturally based in the middle and upper reaches and tourism related industry near the mouth. One of the larger tourism developments is the Afrikaanse Taal en Kultuur Vereniging (Hartenbos ATKV) Holiday Resort, located at the estuary mouth, which includes permanent holiday cottages, caravan sites and recreational amenities. Urban areas in the catchment are almost exclusively in the surroundings of the estuary, while the lower reaches of the estuary and remaining catchment are dominated by agricultural land. The average annual growth rate of the MBM population based on the years from 2001-2011 is 2.24% and pressures on the Hartenbos River system and estuary are likely to increase over time.
2.1.3 Ecological characteristics and functioning The channel and mouth dynamics of the Hartenbos Estuary have been strongly influenced by anthropogenic developments in the catchment and have been sporadically managed since the Hartebeeskuil Dam was built. Bickerton’s (1981) assessment shows that the construction of the Hartebeeskuil dam has had the most significant effect on the channel and mouth dynamics. Bickerton (1981:31) suggests that:
5 Draft Hartenbos Estuary Management Plan Situation Assessment Summary
‘The primary effect of the Hartebeeskuil Dam on the estuary has been the closure of the mouth for extended periods’
Bickerton (1981:16) also asserts that:
‘Since dam construction the estuary has usually been stagnant with high salinities and dense mats of algae, due to eutrophication’’
In the 1970s and 1980s artificial breaching was motivated primarily by the desire of holiday makers to access holiday facilities on the northern bank. Information received from the Hartenbos EAF suggests that the mouth was also frequently artificially breached in response to concerns about water quality and excessive algae growth. In addition artificial breaching of the estuary mouth done by the local authority occurred in response to the risk of flooding. This is confirmed in the Bickerton (1981) study. Information received from the Hartenbos EAF suggests that the mouth was breached in the past to prevent water level in the estuary raising to levels where it covers storm water outlets. The estuary is also dug open illegally by bait harvesters to reduce water levels and allow easy access to the burrowing sand prawns. While Bickerton’s (1981) study confirmed that artificial breaching did occur historically, it also cautioned against ill-timed breaches. Illegal opening of the mouth in January 2015 is thought to have contributed to a large fish kill, as the dramatically reduced water levels resulted in higher water temperatures and decreased dissolved oxygen concentrations. The mouth dynamics are also heavily influenced by coastal processes. Bickerton (1981) provides a detailed description of sediment dynamics as of 1981.
Sediment Dynamics of Hartenbos Estuary as on 12 November 1981 (Source Bickerton 1981)
6 Draft Hartenbos Estuary Management Plan Situation Assessment Summary
Legend to the figure above (Source: Bickerton 1981)
The 2010 Umvoto Africa Sea Level Rise and Risk Assessment report commissioned by DEA&DP, confirms that sea level rise and its concomitant influence on erosion and accretion rates is having an influence on the Hartenbos coastline. The 2015 Sedimentation Supply Study commissioned by Mossel Bay Municipality suggests that certain sections of the Mossel Bay coastline are experiencing varying levels of erosion or accretion rates, which are having an influence on the tidal ranges of estuaries. Recent surveys conducted at the Hartenbos Estuary Mouth suggest that the accretion rate of the sand berm across the mouth is approximately 400 mm per month under closed mouth conditions. The historic breaching described earlier ceased when legislation was introduced which made breaching illegal. It is currently illegal to breach the river mouth without an environmental authorisation or a legally recognised breaching protocol and associated management plan in terms of Government Notice 983 (Activity 19) of the EIA Regulations 2014. Note that since the compilation of the first generation EMP, Mossel Bay Municipality has obtained environmental authorisation (via an MMP agreement) to artificially breach the estuary.
The first generation EMP suggested that the estuary currently receives some 64% of its natural MAR due to the Hartebeeskuil Dam and water abstractions downstream of the dam. Controlled
7 Draft Hartenbos Estuary Management Plan Situation Assessment Summary water release records show that releases from the dam have increased since 1988, peaking in 1998 and 2009. Overall, most water is released for irrigation purposes, followed by downstream river ecology and the least is released for the maintenance of ecological functioning of the Hartenbos Estuary. The release of water from the Hartebeeskuil dam was envisioned as a mitigation measure in response to the Department of Water Affairs decision to authorise the discharge of treated effluent into the estuary, which was already prone to eutrophication. Water use for irrigation purposes is seasonal and is most frequently released from the Hartebeeskuil Dam in low flow months at higher average volumes compared to the remainder of the year. Ecological releases are much more constant all year around, but are on average of a much lower volume than releases for irrigation. Water is seldom released for the estuary, but when releases are made these are usually during the hot summer months, where very large volumes are released in the hope that those will reach the estuary. During November 2016, DWS authorised the release of 150 000 cubic meters of water from the Hartebeeskuil dam, prior to a planned artificial breach to be conducted as per a Section 30A Directive issued by DEA&DP. Water level data from DWS shows that none of this water reached the estuary. In is therefore important that it is noted in this the second generation EMP, that there may in fact be no natural MAR at all. The cumulative effects of the anthropogenic impacts in the upper catchment and the drought may have led to this. A review of aerial photographs shows that there are up to 8 instream irrigation dams between the north western extent of the estuary functional zone and the Hartebeeskuil dam. In addition the Hartebeeskuil dam is currently virtually empty.
The Regional Waste Water Treatment Works (from hereinafter referred to as the Hartenbos WWTW) became operational in 1986 and has been discharging treated effluent into the upper reaches of the estuary (Figure 3.4). Bickerton (1981) study advised against the authorisation of the discharge, as the estuary had been so negatively affected by the construction of the Hartebeeskuil dam. Nevertheless the WWTW was approved. The WWTW has since then been upgraded to more than double the original treatment capacity from 7.8 to 18 mega litres per day (Swartz et al., 2000). Full capacity has not been reached to date but approximately 6-10 mega litres of treated effluent is released into the estuary per day. This means that the WWTW is discharging 3.45 Mm3 of freshwater to the estuary. Consequently, the water contained in the estuary below the WWTW currently exceeds the MAR that was provided by the flow regime prior to the construction of the Hartebeeskuil Dam by almost 2 Mm3 per year. In the midst of the current drought, water levels in the Hartebeeskuil dam has dropped significantly. It is currently just over 6%. It is thus probable that the current flow regime is derived only from the WWTW discharge. It is also important to note that the WWTW will be undergoing significant upgrades during the next few funding cycles. In addition interventions are being implemented to ensure that the discharges to WWTW is more effectively monitored. Also Mossel Bay Municipality is in process of assessing the opportunities for diverting treated effluent away from the estuary. The possibilities in this regard include: treating up to 5 ML of treated effluent to drinking water or process water standard via our Reverse Osmosis Plant, diverting treated effluent for agricultural use and/or for use at composting facilities. These options are currently being explored. If implemented thus will reduce the discharge of treated effluent to the river by up to 50%.
8 Draft Hartenbos Estuary Management Plan Situation Assessment Summary
Macroalgal blooms have been reported in the Hartenbos Estuary during closed mouth conditions and form thick algal mats in the estuary. Bickerton’s (1981) study suggests that this began happening after the construction of the Hartebeeskuil dam and that it was occurring prior to the construction of the WWTW. During the night photosynthesis ceases but these algal continue to respire lowering dissolved oxygen concentrations, whilst the decay of these algal mats further reduces available oxygen in the water. There are three main types of vegetation associated with the Hartenbos Estuary: terrestrial vegetation including invasive plants that have encroached into the riparian zone, intertidal and supratidal salt marsh, and macroalgae. The distribution and extent of these vegetation types is determined by water levels in the system and salinity. Bickerton (1982) study suggests that the tidal range of the estuary used to be 2.5 km. This may indeed have been true, but all the subsequent anthropogenic impacts on the catchment, as well as the accretion at the sand bar across mouth since then has undoubtedly changed the tidal range. This is evident by the invasion of the lower reaches of the estuary by vegetation e.g. reeds which would not have been present had the tidal range remained 2,5 km.
Benthic invertebrates of the Hartenbos Estuary are dominated by the sandprawn Callichirus kraussi and the bivalve Loripes clausus. Diversity and abundance is considered to be low relative to other temporarily open/closed estuaries in the region. The invasive tube worm Ficopomatus enigmatica has also been reported in the estuary in the 1980s, however, the present day extent and abundance of this aggressive species is unknown. A total of 17 fish species have been recorded from the Hartenbos Estuary to date, which is considered to be low compared to other temporarily open/closed estuaries in the region. During a survey conducted in October/November 1997 a total of nine species were recorded of which three taxa were estuarine resident species (Category Ia) and six species were Euryhaline marine species that breed at sea, with juveniles showing varying degrees of dependence on estuaries. The presence of both estuarine-resident and estuarine-dependent species in the Hartenbos Estuary indicate that fishes typical of estuarine habitats are supported by this system. The absence of any more recent data on both fish and benthic invertebrates is unfortunate. This data would greatly assist management efforts.
A total of 59 water-associated bird species of nine taxonomic orders, excluding rare vagrant species, have been recorded at the Hartenbos Estuary to date. The most species-rich taxonomic group is the Charadriiformes, which include the waders, gulls and terns. The relative contribution of taxa to the bird numbers on the estuary differs moderately in summer and winter, due to the presence of migratory birds in summer. There are no important populations of red data species on the estuary, although wader numbers, especially resident wader numbers have slowly but steadily increased since 2005. Birds of prey and kingfishers have decreased in abundance, while waterfowl abundance has increased over time.
2.1.4 Ecosystem services Estuaries provide a range of services that have economic or welfare value. In the case of the Hartenbos Estuary, the most important of these are the recreational and tourism values of the estuary as well as the provision of a nursery area for marine fish. Recreational anglers on the Hartenbos Estuary are mainly shore anglers. Bait collection (prawn pumping) occurs regularly
9 Draft Hartenbos Estuary Management Plan Situation Assessment Summary on the northern and southern banks of the estuary mouth. The Hartenbos EAF asserts that Water-contact recreational activities were common in the past and included canoeing or pedal boating, while motorised boat use is minimal. The Hartenbos Estuary, particularly the mouth area, was always extensively used for bathing as it provided a safe swimming environment for kids. Dog walking is a common activity near the mouth. This information is corroborated by observations during the 2016 and 2017 peak holiday period. There may be additional services, such as carbon sequestration, but these are not likely to be of major value. Hartenbos has been a popular holiday and retirement destination for decades. The estuary forms part of the beginning of the Garden Route and is also in close proximity to towns such as George and Mossel Bay, and within easy reach of Cape Town and Port Elizabeth. The main ecosystem services provided by the Hartenbos Estuary i.e. contact and non-contact recreational use, tourism and as a nursery for fish is all connected to the tidal range of the estuary. As described in earlier sections, the reduction in tidal range, has been problematic. It follows then that the restoration of tidal influence would be necessary if the system is to be rehabilitated.
2.1.5 Legislation and management issues The Hartenbos Estuary is a highly disturbed system, which has been manipulated for at least four decades. The system is currently managed in a state which is quite different from its natural condition, as has been necessitated by the low-lying developments around the estuary. There are a number of factors that threaten the future health of the system and hence its biodiversity and capacity to deliver ecosystem services. The main threats to the system or areas of potential conflict are as follows:
1. Water quantity and quality
a. Reduction in freshwater inflows due to water storage in the catchment (Hartebeeskuil Dam and other instream dams) and insufficient controlled releases to maintain the flood regime of the system; b. Increased and continuous input of treated freshwater from the WWTW into the upper reaches of the estuary; c. Nutrient enrichment resulting from effluent discharges by the WWTW; d. Loss of important habitat area such as salt marsh through eutrophication and stagnation; e. Reduced tidal exchange which means that there is not the regular change in water level and salinity required to ensure a healthy estuarine functional zone.
2. Land-use and associated disturbance
a. potential for increased residential/resort development around the estuary leading to change in sense of place and existence value, increased human disturbance of biota, and damage or loss of estuarine habitat. Mossel Bay Municipality is currently in the process of compiling a Hartenbos Precinct Plan. This plan will limit land uses within the estuary functional zone and catchment to those which will not negatively impact on the environment.
10 Draft Hartenbos Estuary Management Plan Situation Assessment Summary
3. Ineffective management of estuary mouth
a. Prolonged closed mouth conditions, particularly during the peak fish recruitment periods, negatively affect the health of the system. The good health of the Hartenbos Estuary is directly related to prolonged periods of either tidal exchange or open mouth conditions.
The fact that estuaries contain freshwater, terrestrial and marine components, and are heavily influenced by activities in a much broader catchment and adjacent marine area, means that they are affected by a large number of policies and laws. The National Departments of Water and Sanitation (DWS), Cape Nature and Environmental Affairs (DEA) are the primary agencies responsible for estuary management in South Africa with a small amount of responsibility (fisheries) attributable to the Department of Agriculture Forestry and Fisheries (DAFF). Environmental management in most instances is devolved to provincial level, aside from water resources and fisheries which remain a national competency. At a municipal level, by-laws are passed which cannot conflict with provincial and national laws. Water quality and quantity are mainly controlled under the National Water Act (Act No. 36 of 1998) (NWA). This makes provision for an Environmental Reserve which stipulates the quantity and quality of water flow required to protect the natural functioning of each water resource, including estuaries.
The extent to which an estuary’s functioning is catered for is determined by the designated future management “class” (where classes A – F describe state of health), called the Ecological Reserve Category (ERC). In future this will be determined using a recently-developed, holistic classification process. In the interim, however, the amount of freshwater allocated to estuaries is determined through a “Reserve Determination” study. The preliminary reserve determination process was recently completed for the Hartenbos Estuary (and other systems in the Breede-Gouritz Water Management Area). The estuarine health index score was determined to be 51, giving it a Present Ecological Status (PES) of Category D. The RDM study also concluded that the Hartenbos Estuary should be managed as a Recommended Ecological Category (REC) of C (moderately modified) i.e. management should achieve an improvement in ecological status of the estuary. The RDM recommended REC of C suggests that the Hartenbos estuary must be actively managed. It follows then that the main management interventions e.g. mouth management cannot only be re-active. This is a principal which is central to the second generation Hartenbos EMP. The first generation EMP proved an important step in ensuring that its Present Ecological Status does not drop lower than a D. The consensus amongst the Hartenbos EAF is that this has occurred through the efforts during 2017. However, now the emphases has to be on achieving the Recommended Ecological Category.
The Integrated Coastal Management Act, 2008 (ICMA) requires that a management plan be developed for each estuary in the country. The National Estuary Management Protocol (NEMP) has been published in the in terms of ICMA and provides guidance for the management of estuaries through the development of individual estuarine management plans (such as this one). The NEMP also outlines a national vision for estuarine management in
11 Draft Hartenbos Estuary Management Plan Situation Assessment Summary
South Africa, lays out strategic objectives for effective integrated management of estuaries in this country, and prescribes standards for the management of estuaries.
The National Biodiversity Assessment (NBA) conducted in 2011 (Van Niekerk and Turpie 2012) did not recommend the establishment of a protected area in the Hartenbos Estuary but did identify focus areas for the rehabilitation of the estuary, including alien plant clearance, increasing freshwater inflow, improving water quality, fixing of inappropriate bank stabilisation and possibly the removal of the Hartebeeskuil Dam. Interestingly, mouth management and management of siltation of the estuary were not recommended for the Hartenbos Estuary. The Hartenbos Estuary Advisory Forum suggests that this was an oversight. The historic information provided by the Hartenbos EAF suggests that the breaching of the estuary was an important part of managing the estuary since the construction of the Hartebeeskuil dam. This is ratified by the information contained in Bickerton (1981). The Bickerton (1981) study makes explicit the degree to which the system was disturbed by the construction of the Hartebeeskuil dam and the various other obstructions. The study also suggested that should the construction of the WWTW be authorised, as it was, the estuary would need to be actively managed, by means of water releases, to prevent prolonged closed mouth periods. In considering the proposed construction of the WWTW and the proposed discharge of treated effluent into the Hartenbos Estuary Bickerton (1981) writes:
‘The release of sewage effluent into a normally closed estuary already affected by eutrophication is not to be recommended. However the Directorate of Water Affairs of the Department of Environmental Affairs may be able to maintain the estuary in an ecologically viable condition by controlled release of water from the Hartebeeskuil dam”
Bickerton’s (1981: 31 & 32) assertion that the estuary needs to be managed via ecological releases from the dam is explained as follows:
‘The primary effect of the Hartebeeskuil Dam on the estuary has been the closure of the mouth for extended periods. This has been due to reduction of the hydraulic force which used to open the mouth and maintain it that way during spring and autumn. In essence, the dynamic balance between flow tending to open it. Has been tipped towards the latter, resulting in consolidation of the sandbar. Further, the natural scouring force necessary to keep the rover channel free of silt, has been reduced except during times of heavy floods’
‘A secondary effect of the Hartebeeskuil Dam has been the establishment of the hypersaline and eutrophic conditions in the estuary. This has been to evaporative water loss exceeding riverine replenishment when the estuary has been closed, particularly during the summer months’
As stated in earlier sections the Hartebeeskuil dam is not able to provide the water needed to negate the effects described above. The purpose of the ecological release was to prevent prolonged closed mouth conditions. The only other alternative is artificial breaching. Our
12 Draft Hartenbos Estuary Management Plan Situation Assessment Summary experiences in 2016 and 2017 have conclusively shown that artificial breaching contributes positively to the health of the system. In the NBA (2011: 46) it is suggested that:
‘Perched estuaries tend to have more restricted mouths with limited tidal range due to their elevation relative to sea level (Figure 5.7). An additional feature is that small perched estuaries tend to drain between 30 – 70 % of their water under open mouth conditions, i.e. they have more water column habitat when closed than open. These types of estuaries also tend to be more productive (and better nurseries) during the closed phase’
This is typically part of the reasoning used to motivate that estuaries should not be breached. However the Hartenbos Estuary has a tidal range which is not as limited as most perched estuaries. The estuary mouth is situated on a large flat sand bar, which was typically between 1- 2m above mean sea level. Tide charts suggest that tidal range in Mossel Bay may be between 1, 5 and 1m, meaning that the Hartenbos would historically be tidal. Bickerton (1981) asserts that surveys suggest that there is approximately 0.5 m fluctuation in water level due to tidal influence. The last detailed assessment of the bathymetry of the Hartenbos estuary was conducted in 1981. The surveys conducted is explained in the following extract from Bickerton (1981:8):
‘A deep water channel of 1 to 2m depth, depending on conditions of the tide, ran along the south western bank from the Riveira Hotel down to the parking area on the south-western sandspit. From there the channel turned sharply across the estuary towards its north-eastern bank, and then broke out to sea in an S-shaped bend, where the water depths decreased to approximately 1m. All the other areas of the lower estuary are dominated by relatively shallow areas and sand shoals of less than 0,5 m water depth. From the railway bridge upstream to the southern drift (Grid Ref 0704) depths varied from 1,3 to 1.2 m on high spring tide (ECRU survey)
The lowest water level recorded following the artificial breaches conducted in 2016 and 2017 was 0.849 m. Even though the estuary does tend to drain between 30 and 70% of its water during open mouth conditions, water levels do not drop to below that which is to be expected given the Bathymetry and tidal range information described in Bickerton (1981). Lastly is the issue of whether closed or open mouth conditions are better conditions for fish. In relation to fish Bickerton’s (1981:29 & 31) study asserts the following:
‘Fish were abundant in the estuary during the ECRU survey. This may be attributed to the fact that there was good tidal exchange at the time and that the mouth had been virtually open for the most of 1981’
‘With the mouth open the whole estuary becomes tidal, water circulation is good and recruitment of marine organisms occurs (as seen during the ECRU survey). When the estuary is tidal, it is aesthetically pleasing and attractive to holiday makers, thereby becoming an asset’
13 Draft Hartenbos Estuary Management Plan Situation Assessment Summary
14 Draft Hartenbos Estuary Management Plan Estuary Management Vision & Objectives
3 VISION A vision is a high level statement which defines the strategic intent of a management intervention. The following vision was developed for the Hartenbos Estuary using stakeholder input collected after a stakeholder meeting held in June 2015.
“The Hartenbos Estuary is a highly disturbed system and must be managed as such. Well managed breaching of the estuary must form an essential component of the management of this highly disturbed estuary. In a system where the flow regime is dominated by a discharge from a WWTW, regular breaching is essential. It facilitates tidal exchange and promotes good water quality that supports a healthy and functioning ecosystem. This contributes towards economic growth and
facilitates improved recreational use for the benefit of present and future generations.”
4 ESTUARY MANAGEMENT OBJECTIVES Key management objectives for the Hartenbos Estuary were identified subsequent to the stakeholder workshop held in Hartenbos, in June 2015 and were reconfirmed at a meeting held in Hartenbos on 2 February 2016. These objectives are displayed in the form of a circular diagram in Figure 1 as none are considered as being of greater importance than any other.
4.1 Improve estuary health Use of freshwater resources and land in the Hartenbos River catchment must be effectively managed so as to improve the quality and quantity of freshwater reaching the estuary. Water quality within the estuary must also be managed by restoring MAR and tidal exchange, reducing discharges from WWTW and reducing pollution.
4.2 Maximise economic benefits Increasing the recreational value of the estuary will directly benefit local and regional economic growth. The estuary must also be managed to maximize the value of ecosystem goods and services delivered in the long term, ensuring an equitable balance among local, regional and national benefits.
4.3 Restore aesthetic value The aesthetic value of the estuary needs to be restored through improving water quality and quantity in the system. This will reduce water stagnation, excessive algae proliferation as well as odours associated with biological decay. Furthermore, removal of alien vegetation and rehabilitation of degraded riparian areas will play an important role in enhancing the aesthetic value of the estuary.
15 Draft Hartenbos Estuary Management Plan Estuary Management Vision & Objectives
4.4 Increase awareness Residents and visitors need to be made aware of the importance and economic value of the estuary, be knowledgeable regarding regulations applicable to the system, and understand the rationale for management measures and interventions.
4.5 Harmonious and effective governance Institutional roles and responsibilities pertaining to the management of the estuary must be clearly defined, and coordination between responsible institutions improved and maintained.
Figure 1 Management Objectives for the Hartenbos Estuary.
16 Draft Hartenbos Estuary Management Plan Strategies
5 STRATEGIES TO MEET MANAGEMENT OBJECTIVES Strategies required for meeting the management objectives are summarized in Figure 2. Each management objective requires a number of strategies. Note that some of the management objectives form part of the strategy for other management objectives. Estuary health can be improved through a multitude of strategies. Water quality must be improved by reducing and/or treating waste water inputs to the estuary, increasing tidal exchange, effective catchment management and improved agricultural practices. Estuary mouth management, securing adequate freshwater supplies to the estuary as well as rehabilitation and alien plant clearing within the Estuarine Functional Zone (EFZ) (defined as below the 5 m contour) will be essential to complement efforts to reduce pollution. A clear zonation plan is required for the system to prevent further encroachment of development onto the estuary and to ensure successful implementation of short-term and long-term rehabilitation goals. Implementing rules and regulations through compliance monitoring will be essential in achieving this objective. Monitoring and research into estuary health and human utilisation of the estuary should be undertaken to ensure adequate information is available to track changes in the health of the system and to inform best management of the system in future.
Economic objectives as well as the management of current and future development will be subject to coastal management lines and guidelines that improve and safeguard both development and the estuary. These guidelines will need to be integrated into regional and local development plans. Ecotourism growth will require improving visitor facilities that draw people to the area and will also depend on future developments being sensitive to, or even supporting rehabilitation efforts within the estuary and its catchment. Generally improving ecosystem function, especially the value of water quality improvement that natural estuary functioning can provide, should be prioritised for improving the recreational value of estuaries. However it must be recognised that the natural flow regime of the Hartenbos system has been modified to the extent that natural mouth functioning is not possible and that management is required to mitigate flood risk and water quality deterioration. The estuary mouth should therefore be managed to improve the recreational value and ecological functioning of the estuary, especially during peak visitor periods. Given the unique situation at the Hartenbos estuary and the extent to which it has been modified, mouth management cannot be constrained by restrictive policy which by default does not view artificial breaching as a management tool. The zonation plan will assist in the management of recreational uses and ensure that those will not be in conflict with rehabilitation efforts. The accessibility to the estuary for recreational users needs be improved (i.e. formalised) through the implementation of facilities (e.g. boardwalks) and amenities.
To achieve harmonious and effective governance, an Estuary Advisory Forum (EAF) comprising representatives from various stakeholder groups (e.g. the Hartenbos Conservancy, the Bird Club, farming associations in the catchment, etc.) and government agencies (local, provincial and national departments) responsible for various aspects of management of the estuary must be established for the Hartenbos Estuary. The EAF must oversee the implementation of the Estuary Management Plan (EMP) and ensure that local communities and stakeholders have input into and are informed about the management of the estuary.
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Figure 2 Strategies to meet management objectives for the Hartenbos Estuary.
Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs
6 KEY RESULT AREAS AND MANAGEMENT ACTION PLANS Key result areas (KRA) are management objectives and strategies (Refer to Figure 2) that were chosen to become focus areas for action. A management action plan was compiled for each KRA, which details at least one KRA strategy that should be implemented by means of various actions and assessed using quantitative and measurable targets, limits or thresholds (Table 1- Table 8). The following KRAs were identified for the Hartenbos Estuary:
1. Improve estuary health 2. Improve water quality 3. Effective mouth management 4. Improve recreational value 5. Improve aesthetic value 6. Increase awareness and appreciation of the Hartenbos Estuary 7. Research and monitoring 8. Harmonious and effective governance
6.1 Key Result Area 1: Improve estuary health A desktop reserve determination study was conducted for the Hartenbos Estuary in 2015 under the auspices of the Resource Directed Measures (RDM) Directorate of the Department of Water and Sanitation (DWS 2015). As part of the reserve determination study, estuary health was assessed in terms of the degree to which the current state resembles the natural condition. Considering hydrology, hydrodynamics and mouth condition, water quality, physical habitat alteration and the ability of the habitat to support fauna and flora, the estuary was assigned a Present Ecological Status (PES) of Category D. Furthermore, the Hartenbos Estuary was considered to be “important” (score = 66/100) when considering its size, habitat performance, zonal type rarity and biodiversity importance (Turpie and Clark 2007). The Hartenbos Estuary did not form part of the core set of priority estuaries in need of protection to achieve biodiversity targets in the National Estuary Biodiversity Plan for the National Biodiversity Assessment (Turpie et al. 2012). Having been identified as an “important” system, it was recommended that the estuary should be managed in a Category C (Recommended Ecological Category) (DWS 2015) (Please refer to Ecological Specifications and Thresholds of Potential Concern in Appendix 3).
Anthropogenic pressures on the system are manifold and those that contribute most to a current negative trajectory of change were identified as (1) reduced base flow to the estuary from the catchment and the inability of the Hartebeeskuil dam to do the ecological releases required, (2) poor water quality, (3) improper mouth management, as well as (4) poor condition of riparian areas and wetlands (DWS 2015). Accretion of sediment
at the mouth of estuary which severely limits tidal exchange is also a major driver of the negative trajectory of change in the system. Bickerton (1981) suggests that closed mouth conditions become more prevalent after the construction of the Hartebeeskuil dam.
19 Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs
Freshwater flows reaching the Hartenbos Estuary have been strongly influenced by anthropogenic developments in the catchment, of which the most significant were the construction of the Hartebeeskuil Dam and the Hartenbos Regional Waste Water Treatment Works (WWTW). The Hartebeeskuil Dam was constructed in 1970 and is situated 12 km upstream of the estuary, impounding a large proportion of the MAR from the catchment. Consequently, the estuary currently receives only 64% of its natural MAR and overall variability in the flow regime shows little resemblance to the natural condition, where the frequency and magnitude of floods has decreased significantly. The Bickerton (1981) study makes explicit the effects of the Hartebeeskuil dam. The construction of the dam meant that the system no longer functioned as a natural system. Bickerton (1981) identifies a number of other impoundments or obstructions in his study. As far as is known these have never been properly investigated, although many of the obstructions listed by Bickerton (1981) may have subsequently addressed. Nevertheless Bickerton’s (1981) list is included below:
1. Two road causeways which cross the two main causeways of the Hartenbos River approximately 2,5 km upstream of the mouth. The one is a low laying concrete structure. 2. The old national road single span bridge built prior to 1940 which crosses the Hartenbos approximately 2 km upstream of the mouth. 3. The new national road bridge constructed in 1973 which crosses the Hartenbos approximately 1.6 km from the mouth of the estuary. 4. A cause way, which supports the old water pipeline, located approximately 1.2 km from the estuary mouth. Note that this may have since been removed. 5. The railway bridge constructed in 1956 located approximately 800 m from the mouth. 6. The remains of the old railway bridge immediately downstream of the railway bridge. The old bridge was removed in 1950’s, but the remains of the pylons were never removed.
The Hartenbos Regional Waste Water Treatment Works (WWTW) became operational in 1986 and since then has been discharging effluent into the upper reaches of the estuary. The WWTW has since been upgraded to more than double the original treatment capacity from 7.8 to 18 mega litres per day (Swartz et al. 2000). Full capacity has not been reached to date but approximately 10 mega litres of treated effluent is released into the estuary per day. This means that the WWTW is discharging an estimated 3.45 Mm3 of freshwater to the estuary. Consequently, the estuary below the WWTW currently receives approximately 2 Mm3 of water per year in excess of the MAR that was provided by the flow regime prior to the construction of the Hartebeeskuil Dam. Although the WWTW has more than replaced the MAR impounded by the Hartebeeskuil Dam, the water is of poor quality and has been contributing significantly to the deterioration of estuary health (Lemley et al. 2015). It is important to note that the discharges that are occurring is licensed by the Department of Water Affairs and that the water quality parameters for the discharge are determined by this licence. In issuing this licence the Department of Water Affairs accepted that the estuary would be completely transformed, that it no longer will be a natural estuary and that it would require active management to mitigate the effects of both the Hartebeeskuil dam and the WWTW.
20 Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs
Alien invasive plant species are prevalent in the Hartenbos Estuarine Functional Zone, as well as in the catchment as a whole. Alien invasive plants are known to have greater water requirements compared to indigenous vegetation and rehabilitation of invaded areas throughout the catchment could assist in increasing water availability in the estuary. Clearing efforts are currently not focused on the Hartenbos River catchment as the Hartebeeskuil Dam does not contribute towards the supply of potable water to the Mossel Bay municipal area. Systematic alien clearing within the EFZ could contribute towards reducing erosion of the banks and improving health of riparian vegetation and improve wetland areas situated within the flood plain.
Historically, artificial manipulation of the Hartenbos Estuary mouth has been used as a means to pro-actively mitigate impacts of anthropogenically induced changes to the natural flow regime of the Hartenbos system and its effects on the ecological functioning and recreational utility of the estuary. Following the promulgation of the EIA regulations this practice ceased. Since then artificial breaching have occurred in reaction to risk of flooding or illegally in response to fish kills or deteriorating water quality. Information from the Hartenbos Estuary Advisory Forum suggests that this has had a negative impact on the estuary. Bickerton’s (1981) study shows that prolonged closed mouth conditions are bad. Bickerton (1981) asserts that the health of the Hartenbos Estuary is directly related to restoring flow regimes, ensuring tidal exchange and avoiding prolonged closed mouth conditions. Bickerton (1981) suggest that all aspects of estuary health e.g. physical-chemical conditions and fish and invertebrates all benefit from tidal influence. The experiences of 2017, where the Hartenbos Estuary was breached a number of times re-enforces this assertion. Bickerton’s (1981) study shows that eutrophic conditions, reduced dissolved oxygen and hyper salinity are all associated with closed mouth conditions. The physical-chemical data gathered during the daily DO, pH, Salinity, Temperature and electrical conductivity, conducted in 2016 and 2017, show that under closed mouth conditions there is a deterioration of estuary health.
The priority of the first generation EMP was to reverse the negative trajectory of change of the Hartenbos Estuary health and therefore two of the above mentioned key pressures, namely improving water quality and effective mouth management (addressing point (2) and (3)), were identified as separate KRAs (Section 6.2 and 6.3). The Management Action Plan (MAP) for improving estuary health in the first generation EMP thus only includes detailed actions concerning adequate freshwater supplies for the estuary and eradication of alien invasive species (addressing point (1) and (4)). The priority for this second generation EMP is to restore Hartenbos Estuary Health and to emphasise that active, and not reactive management, is required to achieve the goal of the Recommended Ecological Category of C. The Management Action Plan for improving estuary health in the second generation EMP thus makes reference to the need to manage the mouth of estuary, as described in greater detail in later sections.
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Table 1 Management Action Plan to improve Hartenbos Estuary health.
Strategies Actions Deliverables/Indicators Timing Implementation Indicative budget 1. Improve or re-establish i. DWS/BGCMA to conduct a water A database of all license holders detailing 2017-2019 DWS, BGCMA, N/A flow regimes in audit of the Hartenbos abstraction volumes is available Hartenbos Estuary catchment to establish the Illegal water abstractions have been location and number of, and located and abstraction volumes have volumes abstracted by – been determined
a. water use license holders An estimate of the total water volume ii. illegal water abstractions that is abstracted from the Hartenbos catchment per annum has been calculated. iii. DWS/BGCMA to ensure Compliance monitoring records are 2017- DWS, BGCMA N/A compliance with water use available licenses iv. Negotiate highest environmental Environmental release records are 2017 EMF, DWS, BGCMA, MBM To be release volume for the estuary available determined with DWS/BGCMA. The largest proportion of the allocation should be released from 1 December – 31 February. v. Develop operating rules for the Operating rules for the Hartebeeskuil 2017 EMF, DWS, BGCMA, MBM To be Hartebeeskuil Dam in Dam are in place. determined accordance with the allocated environmental release volume. 2. Investigate obstruction in vi. Assessment of impacts of Assessment of obstructions. Apply for estuary obstructions in flow regime and environmental authorisation for removal. identify who is responsible 3. Addressing areas where vii. Obtain environmental Obtain environmental authorisation for 2018 EMF, DWS, BGCMA, MBM To be reeds and associated authorisation for the removal of the removal of reeds and sediment in key determined sedimentation is reeds and sediment in key areas areas impeding flow 4. Eradication/management i. Assess extent of alien invasive A plan of action for the clearing of alien 2016 EMF, MBM, DEA, SANBI To be of alien invasive species species in the EFZ. invasive plants that prioritises certain determined
from the estuary and ii. Prioritise areas for the clearing of species and areas within the 2017 catchment alien invasive plants in the EFZ. rehabilitation focus area (Appendix 1). iii. Organise funds to clear alien Records from alien clearing programmes 2017 invasive plants in the EFZ (ha cleared of alien vegetation). iv. Clearance of alien invasive 2017-2021 vegetation from the Hartenbos EFZ and catchment. Improve tidal exchange v. Implement the second generation Obtain approval for the second 2018 MBM, Hartenbos EAF EMP and mouth management plan generation Mouth Management Plan
Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs
6.2 Key Result Area 2: Improve water quality The water quality characteristics of the Hartenbos Estuary are influenced by a number of factors the most important of which are runoff and mouth state. As long as the mouth of the estuary is open or runoff is sufficient to maintain adequate flushing in the system, water quality is generally good and poses no risk to human health or the health of the fauna or flora of the estuary. Following periods of prolonged closure water quality characteristics can change rapidly and begin to pose a threat to either human or ecosystem health. For example, prolonged exposure to either very low (hyposaline <5 PSU) or very high (hypersaline, >40 PSU) conditions can cause mass mortality of marine (mostly the former) and estuarine organisms (mostly the latter), while even short term exposure to low levels of dissolved oxygen (< 4 mg/l) can cause mass mortalities of all types of aquatic organisms. Large-scale fish kills have become a common phenomenon in estuaries impacted by anthropogenic activities and the Hartenbos Estuary is no exception. The most recent fish kills in the Hartenbos Estuary occurred in January 2015, in March 2016 and October 2016. Understanding the causes of fish kills will be fundamental in order to implement preventative measures to reduce their frequency and magnitude in the long-term. The need for a standardised national protocol to deal with such incidences was recognised and a national protocol has been proposed by Grant et al. 2014 (Refer to Appendix 5).
High nutrient levels (nitrates, ammonia, phosphates) in the estuary can lead to proliferation of macroalgae or blooms of microalgae in the estuary (phytoplankton or benthic microalgae) which are unsightly, can smother natural vegetation (e.g. saltmarsh), clog gills of fish, inhibit feeding by fish and birds, and frequently leads to occurrence of low oxygen events. Bickerton’s (1981) study showed that the system was prone to eutrophication prior to the construction of the WWTW and that it was directly related to closed mouth conditions. Under closed mouth conditions Nitrate and Phosphate levels in the estuary are elevated. This was true even prior to the construction of the WWTW. It follows then that after the construction of the WWTW which discharges nutrient rich effluent into the estuary, the existing historical trend towards eutrophication under closed mouth conditions would be exacerbated. This is indeed what is happening. High levels of indicator bacteria (E. coli, faecal coliforms and/or Enterococci) are indicative of the possible presence of pathogens or disease causing organisms in the estuary that can pose a risk to the health of recreational users. Bickerton’s (1981) study suggested that closed mouth conditions increase the risk in terms of public safety.
Although the WWTW has more than replaced the MAR impounded by the Hartebeeskuil Dam (refer to section 6.1), the water is of poor quality and has been contributing significantly to the deterioration of estuary health (Lemley et al. 2015). This is true in the context that the river as not been actively managed as was required when the Department of Water Affairs authorised first the construction of the Hartebeeskuil dam and the WWTW. Cognisance must be taken that the licence conditions of the WWTW does not require that all nitrates and phosphates be removed. Agricultural return flows containing fertilisers, stormwater outlets, malfunctioning septic tanks, as well as cattle and ostrich farming along the river banks are other sources of pollutants that influence water quality in the estuary. While the WWTW provides the bulk of nitrogen and phosphate to the estuary, it has been shown that contrary to popular belief,
24 Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs bacterial contamination mostly originates from sources upstream of the WWTW. In addition, the septic tanks on the southern bank of the estuary has always been considered a possible source of bacteriological pollution. Recent investigations have shown that illegal dumping and septic tanks along the northern bank of the estuary may also be a contributing source. A recent storm water monitoring project have also shown that storm water is a potential point source.
Water quality in the Hartenbos Estuary has been monitored by the Mossel Bay Municipality and the Department of Water and Sanitation (DWS) at various stations in the Hartenbos Estuary since 1982 (Appendix 4). Early detection of low oxygen events, eutrophication risks or bacterial contamination and their appropriate management actions (short to long-term interventions) rely on continued monitoring that is aligned with existing water quality sampling locations and methods of the Mossel Bay Municipality and the DWS. KRA 7 – Research and monitoring – presents a more detailed action plan for the implementation of such a monitoring programme, while the recommended monitoring programme in Appendix 4 provides more details regarding temporal and spatial scales for different water quality variables.
The MAP for improving water quality in the first generation EMP includes detailed actions concerning the management of pollutant sources, pollutant reduction and ensuring compliance with legislation related to water quality and waste disposal. However this does not address the fact that the water quality in the estuary is not only related to the pollution sources identified. Bickerton (1981) asserts that water quality in the Hartenbos estuary after the construction of the Hartebeeskuil dam, is directly related to the change in mouth conditions and reduced tidal influence. The point being that even if all the pollution sources were to be addressed, the goal of achieving good water quality would still require, management of the mouth. Bickerton (1981) suggests that ideally this must be done via ecological releases from the Hartebeeskuil dam, however as explained earlier this is simply not feasible given that the dam cannot be removed, cannot do a release of sufficient size and with the drought there simply is not water. The only other means available is artificially breaching. The Management Action Plan for improving water quality in the second generation EMP thus makes reference to the need to manage the mouth of estuary, as described in greater detail in later sections.
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Table 2 Management Action Plan to improve water quality of the Hartenbos Estuary.
Strategies Actions Deliverables/Indicators Timing Implementation Indicative budget 1. Identify pollution i. DWS/BGCMA to conduct a water audit Water audit has been completed 2017 EMF, DWS, BGCMA, N/A sources to identify unlicensed discharges and and a licence database is available establish the location and number of Unlicensed discharges have been water use license holders and the licensed amount of effluent that is discharged in the Hartenbos Catchment (as a minimum below the Hartebeeskuil Dam) 2. Reduce pollutants into i. WWTW to improve effluent quality in Improved water quality in the 2016- EMF, DWS, BGCMA, MBM R230 000 the Hartenbos Estuary terms of inorganic nutrient estuary as evidenced by water p.a. concentrations quality monitoring data • Thoroughly investigate the E. coli and Enterococci counts possibility of installing floating comply with the ranges for good or wetlands or conventional wetlands excellent water quality in terms of ii. Investigate how contingency plans for the receiving water quality the malfunctioning of the WWTW can guidelines for recreational use (RSA be updated to reduce the risk of poorly DEA 2012) or untreated sewage entering the Thresholds of potential concern for Hartenbos Estuary the Recommended Ecological Category C have been exceeded iii. Lobby farmers to reduce application of inorganic fertilizer and to reduce runoff Ecological Specifications for a from livestock holding areas in the Recommended Ecological Category Hartenbos catchment C are met iv. Ensure that malfunctioning conservancy tanks are replaced/upgraded v. Improved treatment and diversion of waste water outside of the Hartenbos catchment 3. Improve compliance i. Improved compliance by water users Compliance monitoring records are 2016- EMF, DWS, BGCMA, MBM N/A regarding discharge limits (volume and available pollutants) contained in water use licenses.
1. Improve tidal exchange ii. Implement the second generation EMP Obtain approval for the second 2018 and mouth management plan generation Mouth Management Plan 2018 MBM, Hartenbos EAF
Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs
6.3 Key Result Area 3: Effective mouth management The first generation EMP suggested that channel and mouth dynamics of the Hartenbos Estuary have been strongly influenced by anthropogenic developments in the catchment, of which the most significant developments were the construction of the Hartebeeskuil Dam 12 km upstream of the estuary in 1970 as well as the construction of the WWTW in the upper reaches of the estuary in 1980s. Bickerton (1981:9) identifies 3 typical mouth conditions that can be drawn from historic aerial and terrestrial photographs. These are described in the table below:
1) After a flood, the channel along the north-eastern bank is widened and straightened into a well-developed funnel shaped tidal inlet. This situation existed in 1963, during the ECRU survey in November 1981 and also probably throughout most of 1981 after the floods earlier that years. During such conditions the tidal inlet is close to the north-eastern bank, causing heavy erosion just below the railway line.
2) Narrow channel meandering from the deep water area at the south-western side of the lagoon towards the north-eastern bank to sea via a sand delta at the foreshore. The south-western sandspit is fully developed, pushing the channel towards the north-eastern bank (without causing erosion). The lagoon is apparently not tidal and channel is merely an overflow of lagoon water. These conditions existed in 1957 and also during a visit to the Hartenbos ERCU personnel at the beginning of December 1981.
3) Mouth closed with a large sandbank on the north-eastern side and deep water on the south-western side. There is a solid beach bar across the entire mouth area. This closed-mouth conditions existed when aerial and terrestrial photographs were taken in January 1940, December 1968, June 1969 and April and December 1977. It has been the typical situation in the Hartenbos since the construction of the Hartebeeskuil dam in 1970.
Most of the runoff in the catchment is impounded by the Hartebeeskuil Dam, which was commissioned in 1970. Since then the estimated Mean Annual Runoff (MAR) has been reduced from 4.6 Mm3 to 2.8 Mm3 (64%) and the frequency and magnitude of smaller flood events have been considerably reduced. At the same time, the regional waste water treatment plant (WWTW) currently discharges approximately 10 mega litres of treated effluent into the estuary per day. This amounts to 3.45 Mm3 of freshwater (treated sewage) that enters the estuary in addition to 2.8 Mm3 provided by the current flow regime per year (MAR). Consequently, the water contained in the estuary below the WWTW currently exceeds the MAR that was provided by the flow regime prior to the construction of the Hartebeeskuil Dam by almost 2 Mm3 per year. Surveys of the state of the water course suggests that the current flow regime is much less that the 2.8 Mm3 estimated in the first generation EMP. It may even be zero. This is based on observations by the forum that there is no flow entering the estuary from the section of the water course west of the estuary functional zone boundary. See photographs of catchment in appendix 3 (add photograph of the area upstream of Die Ark)
28 Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs
Although the WWTW has more than replaced the MAR impounded by the Hartebeeskuil Dam, the water is of poor quality and has been contributing significantly to the deterioration of estuary health (Lemley et al. 2015). It is important to note that the discharge to the estuary from the WWTW is licenced by the Department of Water Affairs and Sanitation. The quality of the treated effluent discharged is determined by the parameters in the Water Use Licence. By issuing the Water Use Licence DWS has in effect authorised the total transformation of the system from a significantly disturbed system to a completely transformed system. The risk of occasional malfunctioning of the WWTW and associated releases of incompletely treated sewage constitutes a serious threat to the human health and the estuarine ecosystem. Agricultural return flows containing fertilisers, stormwater outlets, malfunctioning septic tanks, as well as cattle and ostrich farming along the river banks are other suspected sources of pollutants that influence water quality in the estuary.
Bickerton’s (1981) study indicated that should the Department of Water Affairs give authorisation for the discharge of treated effluent into the estuary, they would need to actively manage the system via releases from the Hartebeeskuil dam so that prolonged closed mouth periods are avoided. Historical accounts suggest that the system was managed via artificial breaching. Historically artificial breaching has been used in an attempt to reactively mitigate water quality deterioration and its impacts on the ecological functioning of the estuary and recreational utility. Historical information obtained from the Hartenbos Advisory Forum suggests that the artificial breaching of the estuary occurred regularly. In the past the estuary was breached when water level approached the 1,6 m mark, when there were signs of eminent algae blooms, when the stagnant water in the estuary released offensive odours and when there where un-seasonally large swarms of midges. Importantly, artificial breaches where also done prior to the peak holiday seasons. In the past the MBM occasionally breached the estuary artificially in response to alleviate flood risk. This account of the history of artificial breaching in the estuary is largely supported by Bickerton’s (1981) study. Reports provided by the Hartenbos EAF suggest that there was a marked worsening of water quality since early 2000s. This co-incided with the promulgation of environmental legislation which made artificial breaching of the estuary illegal. Large-scale fish kills have become a common phenomenon in the Hartenbos Estuary in recent history. The most recent of which occurred in January 2015, March 2016, and October 2016.
In summary, there is a need to clearly define future mouth management options and protocols for the Hartenbos Estuary to ensure that eutrophic conditions and fish kills can be prevented. Two types of breaching can be distinguished, namely planned breaching undertaken for the management of the estuary and emergency breaching. Planned breaches in spring and summer are a common management method to maintain seasonal estuary-sea connectivity in impacted temporarily open/closed systems (e.g. Groot Brak Estuary). Planned breaches can facilitate fish and invertebrate recruitment and improve flushing of the estuary. Unfortunately, the Hartebeeskuil dam cannot release large quantities of water in a short period of time, which would be required if environmental releases were to simulate major flood events. The outlet pipe is small and the experiences in November 2016 showed that water released from the dam does not reach the estuary. Planned breaches that rely on a water release is therefore not a
29 Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs suitable management method for the Hartenbos Estuary. However, the fact that there is a constant discharge of treated effluent into the estuary provides an opportunity to simulate a water release from a dam. Surveys conducted of low lying properties and infrastructure show that water level in estuary can be allowed to safely reach 1.8 m. The results of the artificial breaching’s done in 2017 show that a breach done when water levels are near 1.8 m can produce good scouring. Water level data shows that under closed mouth conditions water level in estuary can get to 1.8 m in 2 to 3 months. This allows an opportunity for a planned breach. The experiences during 2017 have also indicated that another possibility exists for planned breach. Under this scenario, breaches at low water levels are seen to present an opportunity to trim the height of the berm. If timed correctly i.e. prior to spring tide, it provides an opportunity to allow tidal exchange to occur over a much larger area. The beneficial impacts of tidal exchange is well documented. This combination was successfully demonstrated by the August 2017 (a high water level breach) and the October 2017 (berm trimming at low water levels) breaches. The success of this combination is evident from the fact that the estuary mouth remained open during the fish recruitment period, while tidal exchange occurred throughout most of December 2017. Throughout this period a well-developed funnel tidal inlet was maintained, as per the first typical mouth dynamic condition identified by Bickerton (1981). The erosion associated with this scenario was mitigated by the sand that was moved and deposited along the northern bank of the estuary and by making sure that the channel was excavated just north of the south western sandspit. Consequently water quality in the estuary was better than previous years. Residents also reported less midges. While this conception of planned breaches may be deemed un-conventional, as stated earlier the Hartenbos System is highly disturbed, so un-conventional interventions are required. It is suggested that if sufficient thought is placed into planned breaches, the need for emergency breaches would be less. However the second generation will not propose that a provision for emergency breaches is not needed. Instead it seeks to add and refine the emergency scenarios described in the First generation EMP.
The first generation EMP suggested that emergency breaching to alleviate flood risk caused by small to medium floods (note that artificial breaching to prevent damage by major floods is ineffective) was not required. Mossel Bay Municipality and the Hartenbos EAF is of the opinion that provision must be made of emergency breaches in response to the threat of possible flooding. The sample of water level data used for the compilation of the first generation EMP suggested that the natural breaching level of the estuary is approximately 2.1 metres above mean sea level. Based on the information available it was suggested that this is not causing flood damage to existing infrastructure situated within the estuarine functional zone. However, the experiences in 2017 showed that water levels of 2.1 m is not safe. Surveys of the berm have shown that under closed mouth conditions the height of berm can rise 400 mm in a month. The highest berm height recorded in 2017 was 2.4 m, so there is no guarantee that the estuary will breach ‘naturally’ when water level gets to 2.1 m. It is important to note that the outflow from the WWTW is constant, meaning that under closed mouth conditions the water level is always rising. A survey of low laying properties along the Hartenbos Estuary show that properties will be inundated if water levels in the estuary exceed 2.21 msl. Municipal storm water infrastructure will also be inundated at 2.17 msl. The sump of the municipal pump station located on the southern bank of the river is inundated at 2.17 msl, meaning that river water
30 Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs enters the municipal sewer system. There is thus significant risk of flooding if the mouth of estuary is closed for a prolonged period. This position is affirmed by the fact that DEA&DP issues Section 30A Directives allowing Mossel Bay Municipality to breach the Hartenbos Estuary when water levels were so high. A protocol for emergency breaching to prevent flood damage caused by small and medium floods is therefore required.
The first generation EMP suggests that Emergency breaching should also be allowed to mitigate environmental impacts (1) as a result of malfunctioning of the WWTW and associated releases of insufficiently treated sewage. The emergency mouth management protocol for the Hartenbos Estuary compiled for the first generation EMP was prepared in accordance with the DRAFT key principles and guidelines which are currently being developed as part of the Estuary Management Framework and Implementation Strategy project initiated by the Department of Environmental Affairs and Development Planning (Note that the structure of the mouth management plan may have to be amended once the guidelines have been finalised).and is included as an Annex to this EMP (Appendix 2: Proposed Estuary Mouth Management Protocol for the Hartenbos Estuary).
While the emergency breach constitutes a short-term relief and is a reactive mitigation measure in the case of extreme conditions. Mossel Bay Municipality and the Hartenbos EAF agrees that long term efforts should be undertaken to improving water quality by addressing problems at the source. Bickerton’s (1981) study shows that this will need either the removal of the Hartebeeskuil dam or an effective means to do ecological releases, the removal of obstructions in the river, the removal of all septic tanks and ideally the ending of discharges from WWTW. This however will require extensive capital investment and is simply not feasible in the short or medium term. Long term weather projections for the area suggests that MAR will not be restored via an increase in annual rainfall. The First Generation EMP suggests that an emergency breach is required to mitigate environmental impacts is limited to scenarios where a disaster has already occurred i.e. a malfunction at the WWTW etc. More specifically this refers to a mechanical malfunction i.e. like the scenario in November 2016 when there was a breakdown of one of the bio-reactors. In cases like these the break down cannot really be anticipated while the effect on the quality on treated effluent is significant and immediate. Certainly then an emergency breach will be required after the insufficiently treated sewerage has been discharged to the estuary. The first generation EMP and MMP does however not specify what is meant by improperly treated sewerage. The discharge of treated effluent to the estuary is authorised by a Water Use Licence issued by the Department of Water Affairs and Sanitation. The compliance record of the WWTW, as measured by the tests conducted on treated effluent by BGCMA and Eden District Health, show that raw sewerage or sewerage with high e-coli levels has never been discharged from the WWTW. The design of the plant prevents this from occurring. The non-compliant discharges documented in 2016 relate to instances where the levels of ammonia, phosphates and nitrates have exceeded the parameters set in the Water Use Licence. Mossel Bay Municipality and the Hartenbos EAF is of the opinion that the parameters set in the Water Use Licence should be used as the criteria to determine what is meant by insufficiently treated sewerage. An emergency breach in response
31 Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs to non-compliance with any of the water quality parameters specified in the Water Use Licence must be included as a scenario under which an emergency breach is allowed.
There are also instances where the quality of the incoming raw effluent indicates that problems may be expected i.e. if something is discharged to our sewer illegally etc. In addition to the testing of the quality of incoming raw effluent, daily operational tests are conducted at the WWTW. These results are a good indicator of whether insufficiently treated sewerage may be released into the estuary. Mossel Bay Municipality and the Hartenbos EAF is of the opinion that these results should also be used to determine when an emergency breach is required. It will allow a proactive response to anticipated problems at the WWTW. As stated earlier The WWTW discharges 6-10 ML of treated effluent into the estuary. It is only possible to divert up to 4 ML of effluent away from the estuary. There will thus always be a discharge of significant volume of treated effluent, if something goes wrong at the plant. If it is accepted that an emergency breach is a useful mitigation in response to the discharge of insufficiently treated sewerage, then it follows that an emergency breach conducted in lieu of an anticipated discharge of insufficiently treated sewerage should likewise be acceptable.
The first generation EMP confirms that the Hartenbos Estuary is an important recreational area. Improving the recreational value of the EMP is identified as a Key Result Area. The volume 2 of the South African Water Quality Guidelines for Coastal Marine Waters sets the recreational water quality parameters for marine waters. Parameters are set from a human health and safety perspective as well as from an aesthetical perspective. In terms of human health and safety, limit values for bacteriological i.e. e-coli and Enterococci and chemical parameters e.g. pH, inorganics, temperature etc. are set. Mossel Bay Municipality and the Hartenbos EAF insist that an emergency breach is warranted if any the parameters stipulated in the aforementioned guidelines are exceeded. Experiences during December 2016 showed that it is practically impossible to close the estuary as there are simply too many points of entry. The guidelines also stipulate that caution must be exercised when there are algae blooms as these may represent a risk to public health. This leads to the last scenario under which an emergency breach is warranted. The first generation EMP suggested that an emergency breach is allowed in response to a low oxygen event. As indicated earlier the outflow from the WWTW accounts for all the MAR in the system. This outflow is nutrient rich even when it is compliant with the parameters of the Water Use Licence. Eutrophication will thus always be an issue. An algae bloom typically precedes a low oxygen event. It thus makes sense that action taken in response to an algae bloom would be beneficial from both a human health and ecological perspective. Experiences have shown that a change in water level and salinity is effective in disrupting an algae bloom. DO readings taken during algae blooms in the Hartenbos indicate that the initial stages of an algae bloom is characterised by supersaturated conditions i.e. DO readings in excess of 10 mg/L. This is then followed by a steady decrease in DO readings until it goes below the 3-4 mg/l threshold. It is during this phase when fish kills are most likely. The DO sampling done over the last year has shown that artificial breaching has a positive impact on DO levels. Mossel Bay Municipality and the Hartenbos EAF assert that an emergency breach conducted during the early stages of an algae bloom is appropriate. In summary then the mouth management plan emanating from the second generation will make provision for:
32 Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs
Planned breaches and the trimming of the mouth berm height at regular intervals to prevent prolonged closed mouth conditions and to facilitate the recruitment of fish. Emergency breaches to: avert flooding; when WWTW is or will discharge insufficiently treated effluent into the estuary and in response to algae blooms.
The details will be described in the Mouth Management Plan
6.4 Key Result Area 4: Improve recreational value The Hartenbos Estuary forms part of an important recreational area along the Cape south coast. The town of Hartenbos is home to a well-established resident community and accommodates a very large holidaying community. The primary challenge facing the future management of the estuary is to provide a quality experience for residents as well as visitors to the estuary alike, while at the same time managing recreational activities in a manner that ensures that management efforts to improve the health and water quality of the estuary are not compromised. Currently, the recreational value of the Hartenbos Estuary is compromised due to poor water quality and frequently does not provide a safe environment for contact recreation. Improving water quality is a key aspect in enhancing recreational value of the estuary and is dealt with in detail in Section 6.2 (KRA 2). Bickerton (1981) suggests that tidal influence is critical for the Hartenbos Estuary to keep delivering recreational value. While Bickerton (1981:31) cautions against irresponsible artificial breaching, in the context of the mouth state obtained after a flood event he does suggest that:
‘With the mouth fully open, the whole estuary becomes tidal, water circulation is good and the recruitment of marine organisms occurs (as seen during the ECRU survey). When the estuary is tidal, it is aesthetically pleasing and attractive to holiday makers, thereby becoming an asset to the holiday resort’
It must be noted that Bickerton (1981) assertion is made in support of his argument that the future management of the Hartenbos estuary must include ecological releases from the dam. The argument developed here is that the need to increase tidal influence was central to the call for an ecological release from the dam. We know now that an ecological releases from the dam is simply not viable. This leaves artificial breaching and flood simulation as the only viable means to improve tidal influence. The second generation MAP for improving recreational value thus includes a reference to the need to actively manage the mouth of estuary.
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Table 3: Management Action Plan for effective mouth management of the Hartenbos Estuary.
Strategies Actions Deliverables/Indicators Timing Implementation Indicative budget 1. Implement and improve the Emergency i. Submit the Emergency Mouth Mouth Management Protocol 2016 EMF, MBM, EDM - Mouth Management Protocol for the Management Protocol for the accepted and approved Hartenbos Estuary [National Hartenbos Estuary for stakeholder Environmental Management Act 1998, review and sign-off National Environmental Management Act: Integrated Coastal Management ii. Conduct Emergency breaches Post breaching reports are compiled 2016- EMF, MBM, EDM, DWS, - Act 2008]. responsibly and transparently in timeously and the public has access DEADP, CapeNature, DEA accordance with the Emergency to these reports Mouth Management Protocol Registered stakeholders are notified and kept up to date leading up to, during and after a breaching event iii. Regular review of the Emergency Review report is available and the 2018- EMF, MBM, EDM, DWS - Mouth Management Protocol by Mouth Management Protocol has CapeNature, DEA, specialists been amended accordingly DEADP, consulting specialists 2. Prevent illegal breaching, defined as i. Develop a law enforcement Reduced occurrence of illegal 2016 EMF, MBM, EDM, - breaching done at incorrect times i.e. strategy to prevent illegal breaching DEADP, CapeNature not as specified in Mouth Management breaching Protocol ii. Create public awareness about the This aspect has been integrated into 2016- EMF, MBM Cost as ecological consequences of pamphlets, information boards etc. as per KRA 6 illegally breaching an estuary per KRA 6 - Enhance awareness and appreciation of the Hartenbos Estuary
Table 4 Management Action Plan for improving the recreational value of the Hartenbos Estuary
Strategies Actions Deliverables/Indicators Timing Implementation Indicative budget 1. Establish and manage i. Erect informative and educational signage at Visitors are sensitive to and aware of 2016- EMF, MBM Budget as visitor’s facilities. key access points that highlights the activities affecting health and functioning of per KRA 6. ecological importance and value of the the estuary, and management regulations Hartenbos Estuary. governing use of the estuary. ii. Develop appropriate nature friendly Visitor infrastructure and facilities have been 2017- R2.3 M infrastructure for visitors to the estuary erected. (ablutions, parking, bird hides, walking paths, nature trails, mountain bike trails) in collaboration with local communities and independent contractors that does not detract from sense of place of the area or impact on the environment. iii. Ensure that visitor facilities are maintained in Facilities receive good reviews. 2018- To be good condition at all times to maximise determined. visitor experiences.
Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs
6.5 Key Result Area 5: Improve aesthetic value The Hartenbos catchment is largely transformed where agricultural land dominates in the middle and lower reaches of the river. Urban built-up areas, mines (rock), the Regional Hartenbos WWTW, cultivated fields, generally disturbed areas (old fields) and urban green spaces have encroached onto the estuarine floodplain. South of the estuary mouth, urban development is dense in the coastal area and the town of Hartenbos is estimated to have grown by 20% since 2006 (AEC, 2015). A number of green spaces (parks and golf courses) are interspersed throughout the built-up areas. Although cultivated fields are concentrated north of the estuarine floodplain, some cultivated lands occur in the upper estuary directly adjacent and south of the main open water channel, as well adjacent to the N2 on the northern bank of the estuary. To preserve the aesthetic value of the estuary, further encroachment of development into the EFZ must be prevented and strategic and regular collection of solid waste (rubbish, debris and flotsam) in key areas of the estuary must occur. Rehabilitation of areas invaded by alien invasive plants will also help in improving the aesthetic value of the estuary and is covered in the Management Action Plan for the improvement of the Hartenbos Estuary health (KRA 1 in Table 1).
6.6 Key Result Area 6: Increase awareness and appreciation for the Hartenbos Estuary Effective management of the Hartenbos Estuary will be dependent on stakeholder buy-in (through adequate consultation and communication) and visitors’ appreciation of the management regulations. Education is also considered to be among the most important functions provided by estuaries. Estuaries are heavily utilised for recreational purposes and provide opportunities where the public are able to view species in their natural environments, and (preferably) to experience natural ecosystems. Provision of interpretive and educational material at these sites can greatly enhance this experience as it focuses attention of visitors on goods and services provided by the environment of which they may not have been aware, highlights keys aspects of the environment that are special or unique to the area, and can be used to highlight the impact of human activities on the environment. Furthermore, the better people understand the issues surrounding the rehabilitation of an ecosystem, the more they are likely to respect the management requirements and regulations. The various agencies responsible for the management of the Hartenbos Estuary will need to provide state of the art service in this field.
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Table 5 Management Action Plan for improving the aesthetic value of the Hartenbos Estuary.
Strategies Actions Deliverables/Indicators Timing Implementation Indicative budget 1. Prevent further encroachment by i. Finalise and adopt the zonation plan Final Zonation plan ratified and adopted 2017 EMF, DEA: O&C, R25 000 development into the estuarine for the Hartenbos Estuary including by all stakeholders. MBM, EDM functional zone of the Hartenbos the position of the coastal protection Estuary [National Environmental zone and coastal management line Management: Integrated Coastal and overlay zones. Management Act 2008, Municipal ii. Incorporate coastal management lines 2017- Systems Act 2000] Coastal management lines contained in into the IDP and SDF documents the Hartenbos EMP Zonation Plan and published by the Eden District and incorporated into Municipal IDP and SDF Mossel Bay Municipalities and the documents. Eden District Coastal Management Programme
2. Manage solid waste pollution in the i. Erect ‘Do not litter’ signs in popular The Hartenbos Estuary is cleaner. 2016- EMF, MBM R15 000 p.a. Hartenbos Estuarine Functional recreational spots.. Zone ii. Ensure that enough rubbish bins are available in popular recreational spots. iii. Conduct strategic and regular collection of rubbish in key areas within estuarine functional zone.
Table 6 Management Action Plan for increasing awareness and appreciation for the Hartenbos Estuary.
Strategies Actions Deliverables/Indicators Timing Implementation Indicative budget 1. Create effective mechanisms for i. Develop an effective communication Communication strategy 2016- HEMF, MBM, EDM R23 000 on-going communication with strategy. developed. stakeholders ii. Maintain stakeholder database. Stakeholder database developed and maintained. iii. Explore alternative communications Record of communications kept. mechanisms (workshops, signage, radio etc.).
2. Develop an effective education i. Establish a visitor centre at the estuary Visitors centre open to the public. 2017 EMF, MBM R290 000 and awareness programme for which will act as a focal point where the Hartenbos Estuary that visitors can go to learn more about the enhances visitor experiences estuary, the ecology of the system, and the need for rationale behind existing management interventions. ii. Source and/ or commission educational Posters, pamphlets, signage, 2017 and informative material including literature developed and signage, posters, pamphlets, and relevant distributed/displayed. literature that will be housed in appropriate localities that will enhance visitor experiences. iii. Encourage field excursions to the estuary Field excursions undertaken. 2017- by local schools, community groups, and other stakeholder groupings.
6.7 Key Result Area 7: Research and monitoring The first generation Hartenbos Estuary management plan was drafted based on current understanding of the functioning of the estuary. It is evident that ongoing research and monitoring is required to fill information gaps and to improve the management plan. The second generation EMP is informed by the experiences of 2016 and 2017, as well as the information provided by the Hartenbos EAF. Increasing use by visitors, surrounding development, changes in freshwater supply from the catchment, climate and sea-level change could also impact on the health and ecological functioning of the estuary, as well as its value at different spatial scales. This second generation EMP is attempting to ensure that the management of the estuary is informed by practical experience as well as theory.
Monitoring and research is essential in enabling the respective agencies responsible for management of the Hartenbos Estuary to adapt management plans, operational plans and activities to changing circumstances. Key focal areas for monitoring and research associated with the Hartenbos Estuary include water quantity and quality, mouth management, physical characteristics, and rehabilitation.
Recommended protocols for monitoring the health of the Hartenbos Estuary are included in Appendix 4. The “Ecological Specifications” and “Thresholds of Potential Concern” (TPCs) for the Hartenbos Estuary should guide the monitoring programme and are included as Appendix 5. In addition to monitoring the biotic and abiotic health of the Hartenbos Estuary, it is also strongly recommended that visitor numbers, profiles, behaviour and opinions are monitored on a regular basis to gauge management effectiveness and user responses to management. Monitoring protocols for these aspects are also included in Appendix 4.
6.8 Harmonious and effective governance Owing to their position on the boundary between freshwater, terrestrial and marine environments, management of estuaries requires cooperation from a large number of separate national, provincial and local government agencies, each acting under a different legislative mandate. As a minimum the following national government agencies are implicated in management of the Hartenbos Estuary: Department of Environmental Affairs (DEA)), Department of Water and Sanitation (DWS), Department of Public Works (DPW), and the Department of Agriculture, Forestry & Fisheries (DAFF). Provincial and local government agencies implicated in management of the estuary include the Department of Environmental Affairs & Development Planning (DEADP), Cape Nature, Eden District Municipality (EDM), and the Mossel Bay Local Municipality (MBM). Recognising that the difficulties of ensuring a sufficiently high level of integration and cooperation amongst all of these different agencies are likely to extend beyond the mandate and capacity of a single local authority or agency, an estuary advisory forum (Hartenbos EAF) will be established. The EAF will include representatives from all of the principal national, provincial and local government agencies as well as representatives of key stakeholder groups. The purpose of the Hartenbos EMF will be to provide a body for stakeholders with an interest in the future of the Hartenbos Estuary to exchange information and ideas, and to reach agreement on action for the effective management of the estuary. It is essential that all these agencies work co-operatively to ensure the vision and defined management
Klein Brak River Estuarine Management Plan 39
objectives can be realised. Individual agencies may also have to make provision for the funding required to fulfil their management obligations in the medium and long-term.
6.8.1 Institutional and Management Structures
Co-management and effective governance is the keystone for achieving the vision set by the stakeholders for the Hartenbos estuary, and therefore attainment of the overall objective of conserving the system’s ecological functioning and biodiversity. Without well-structured and efficient institutional and management arrangements, integrated environmental management of the estuary may be no more than a series of uncoordinated reactions to immediate problems. Ensuring effective governance is therefore probably the most important objective to be achieved. To this end, DEADP is in the process of developing the Western Cape Estuaries Framework and Implementation Strategy to assist with conformance with respect to establishing institutional and management structures for estuarine management within the province.
As per Chapter 5 of the ICM Act five main ‘institutions’ will be in effect regarding the management of activities in and around or relating to the Klein Brak River estuary. These are the Responsible Management Authority, the Mossel Bay Municipality (see disclaimers in earlier sections); the Hartenbos Estuary Advisory Forum (EAF), the municipal coastal committee, the provincial coastal committee, the National Coastal Committee; and the collection of stakeholders with vested interest in the estuary. These institutions will represent the vehicles through which the implementation of the EMP can be coordinated and monitored.
The Hartenbos EAF is pivotal to effective governance, provided it is administered proficiently and remains functional. It should champion the integration of the EMP into the Integrated Development Plans and Spatial Development Frameworks of the local, district municipalities. The provincial coastal committee must in turn champion the integration of the EMP into the Provincial Coastal management Programme, the Provincial Spatial Development Framework as well as the strategic planning and budget plans of DEA&DP, Cape Nature, regional / provincial office of DWS, BGCMA and regional / provincial office of DAFF. The National Coastal Committee should be the institution which ensures that the various parastatals and State Owned Entities which have a duty towards protecting estuaries affected by their infrastructure i.e. SANRAL and Transnet etc. ensure that the objectives of the EMP informs their business models. The provincial and national coastal committee should also serve as the main institution for securing funding from Provincial and National Treasury for estuarine management. Through this, on-going funding of the management of the estuary can be secured. In addition, co-operative governance is required for identifying, lobbying, and promulgation of additional by-laws or amendments to existing by-laws. The importance of the National and Provincial Coastal committees become evident when considering the responsibility of these committees as specified in the ICM Act:
6.8.2 The National Coastal Committees
The National Coastal Committee, led by DEA, must promote integrated coastal management in the Republic and effective co-operative governance by co-ordinating the effective implementation of this Act and of the National coastal management programme, and in particular must -
Klein Brak River Estuarine Management Plan 40
(a) promote integrated coastal management -
(i) within each sphere of government;
(ii) between different spheres of government; and
(iii) between organs of state and other parties concerned with coastal management;
(b) promote the integration of coastal management concerns and objectives into -
(i) those environmental implementation plans and environmental management plans
referred to in Chapter 3 of the National Environmental Management Act to which they are relevant;
(ii) national, provincial and municipal development policies, plans and strategies;
(iii) other plans, programmes and policies of organs of state whose activities may create
adverse effects on the coastal environment; and
(c) perform any function delegated to it.
6.8.3 The Provincial Coastal, led by DEA&DP Committee Provincial Coastal Committee must
(a) promote integrated coastal management in the province and the co-ordinated and effective implementation of this Act and the provincial coastal management programme;
(b) advise the MEC, the provincial lead agency and the National Coastal Committee on matters concerning coastal management in the province;
(c) advise the MEC on developing, finalising, reviewing and amending the provincial coastal management programme;
(d) promote a co-ordinated, inclusive and integrated approach to coastal management within the province by providing a forum for, and promoting, dialogue, co-operation and co-ordination between the key organs of state and other persons involved in coastal management in the province;
(e) promote the integration of coastal management concerns and objectives into the plans, programmes and policies of other organs of state whose activities may have caused or may cause adverse effects on the coastal environment; and
The NCC and PCC will need to ensure that funding is allocated by the relevant departments for building sufficient capacity to perform various actions within this EMP, as per the mandate and responsibilities of each department and state owned entity. The RMA will where possible ensure that funding is made available for activities it is directly responsible for. Funding will also be required to perform activities such as provision of interpretative and compliance signage, and information material, while funding may be solicited from the relevant national departments for
Klein Brak River Estuarine Management Plan 41
specific actions, for example, rehabilitation of degraded areas, and assistance with research and monitoring of biophysical indicators and human use.
In addition, the RMA may need to promulgate, and amend from time to time, municipal by-laws in order to provide the necessary legal support for the execution of their functions and ultimately give effect to the EMP management objectives, particularly in terms of compliance management. This will however be limited to those functions which are directly assigned to the RMA’s as per the Constitution.
Klein Brak River Estuarine Management Plan 42
Table 7 Management Action Plan for research and monitoring of the Hartenbos Estuary
Strategies Actions Deliverables/Indicators Timing Implementation Indicative budget 1. Promote scientific research. i. Identify information gaps and develop Research projects. 2016- EAF, DWS, EDM, - research programme(s) aimed at gathering/ Scientific reports, paper and DEA: O&C consolidating ecological data. publications. ii. Engage local research institutes and universities to collaborate on priority research projects. iii. Solicit research funding support.
2. Implement monitoring i. Implement a monitoring programme in Monitoring data and reports are R580 000 programme for biological, Appendix 4. available on a real time basis. p.a. physical and chemical a. Clearly define responsible agencies for Monitoring data and reports inform indicators of estuary health each monitoring component (i.e. short-term and long-term (Appendix 4) [National municipality, conservancies, service management interventions (e.g. Water Act 1998]. providers, CapeNature etc). dealing with fish kills, mouth b. Ensure that each monitoring management, alien clearing) component has a clearly defined methodology. ii. Assess results in terms of thresholds of potential concern (Appendix 3).
3. Monitor human use of the iii. Carry out monitoring programme as R116 000 estuary [National Water Act outlined in Appendix 4. 1998].
Table 8 Management Action Plan for harmonious and effective governance of the Hartenbos Estuary
Strategies Actions Deliverables/Indicators Timing Implementation Indicative budget 1. Constitute the Hartenbos Estuary i. Invite representative members of stakeholders A list of members of 2016 EAF, DEA: O&C, R12 000 p.a. Advisory Forum (EMF) [National and government to be members of the the forum and their DWS, DPW, DAFF, Environmental Management Hartenbos Estuary Management Forum (EMF) contact details DEADP, Integrated Coastal Management Act CapeNature, EDM, 2008] MBM
2. Define co-operative governance i. Estuary management Forum to obtain Signed letters of 2016 EAF, DEA: O&C, - arrangements for management of the agreement from participating agencies in respect commitment from all DWS, DPW, DAFF, Hartenbos Estuary [National of their roles and responsibilities agencies to be DEADP, Environmental Management: involved with the CapeNature, EDM, Integrated Coastal Management Act management of the MBM 2008; Protected Areas Act 2003] Hartenbos Estuary 3. Secure financing i. Individual government agencies to make Provision made for 2016- EAF, DEA: O&C, - provision for the necessary resources in the estuary management DWS, DPW, DAFF, short, medium and long-term expenditure in budgets and DEADP, frameworks to create and fill posts, and acquire expenditure CapeNature, EDM, necessary infrastructure and resources for frameworks MBM effective management of the Hartenbos Estuary ii. Develop a long-term financing plan 4. Develop adequate resources and i. Individual agencies to acquire access to Staff & resources 2017 EAF, DEA: O&C, - capacity necessary equipment (office equipment, water deployed for DWS, DPW, DAFF, quality meter, boat, vehicle) for effective management of DEADP, management of the Hartenbos Estuary Hartenbos Estuary CapeNature, EDM, MBM ii. Individual agencies to identify and address Training records training needs among staff involved in estuary management iii. Evaluate performance of staff, contractors and Performance 2018- volunteers evaluations 5. Ensure that all stakeholders are i. Create and administer a website for the Website is available 2017 EAF, MBM To be determined informed regarding management Hartenbos Estuary Forum (upload minutes, and up to date (website to be progress and challenges faced photos, data, monitoring reports. Possibly administered as include a blog to facilitate discussions) part of the MBM?)
Draft Hartenbos Estuary Management Plan Key Result Areas and MAPs
6.9 Summary of management actions and timing Table 9 provides a summary of the tasks to be carried out over the next 5 years for the implementation of the Hartenbos Estuary Management Plan. The Mossel Bay Municipality is the primary agency responsible for the management of the estuary (mandated in terms of the National Estuary Management Protocol published under the National Environmental Management: Integrated Costal Management Act of 2008)but will be assisted by the Hartenbos Estuary Management Forum and a range of other government agencies including the Department of Water and Sanitation (DWS), Department of Environmental Affairs - Branch Oceans and Coasts (DEA: O&C), Department of Agriculture, Forestry & Fisheries (DAFF), the Department of Environmental Affairs & Development Planning (DEADP), Cape Nature, and the Eden District Municipality (EDM).
Readers of this EMP must note that delegation of local authorities as the Responsible Management Authority was done as per the National Estuarine Management Protocol (NEMP). Circular DEA&DP 011/2017 confirms that the NEMP is flawed and that the DEA will be considering amendments to the NEMP. The aforementioned Circular also confirms that DEA&DP intends to undertake a rapid appraisal of all coastal Municipalities in the Western Cape. The purpose of this appraisal is to determine the appetite and capacity of the Municipalities to take up all, or elements of, the functions of RMAs as described in the NEMP. In terms of the interim institutional arrangements outlined in Circular DEA&DP 011/2017 i.e. until the review of NEMP and the appraisal of coastal municipality’s has been completed, DEA&DP, together with CapeNature, will continue to take the lead in ensuring coordinated planning, implementation and management of estuaries in the Western Cape. Mossel Bay Municipality’s acceptance of the delegation as Responsible Management Authority will this be subject to the completion of the DEA’s review of NEMP and DEA&DP’s appraisal of coastal municipalities.
45
Table 9 Summary of actions and timing of actions pertaining to each of the key result areas over the period January 2018 – June 2023
Key Result Area Action Agency responsible 2018 2019 2020 2021 2022 2023 Improve estuary health Assess water use (who, where and how much) in the catchment and DWS, & BGCMA publish operating rules for the Hartebeeskuil Dam. Assess extent of alien invasive species, prioritise areas and clear alien EAF, DWS, MBM invasive species. Improve water quality Identify pollution sources EAF, DWS, MBM, EDM Reduce inputs of nutrients and waste water to the Hartenbos Estuary EAF, DWS, MBM, EDM, and ensure compliance. DAFF Effective and efficient Finalise and implement the Draft Mouth Management Protocol for the EAF. Key Result Area Action Agency responsible 2018 2019 2020 2021 2022 2023 Harmonious and effective Constitute the Hartenbos Estuary Management Forum. EAF, DEA:O&C, DWS, DPW, governance DAFF, DEADP, CapeNature, Define co-operative governance arrangements for the management of EDM, MBM the estuary. Secure financing for effective management. Secure resources and capacity for effective management. Draft Hartenbos Estuary Management Plan Appendices: Zonation Plan 7 APPENDICES 7.1 Appendix 1: Proposed Hartenbos Estuary Zonation Plan 7.1.1 Introduction The Hartenbos is a small estuary and is of intermediate importance for estuarine biodiversity on a national scale, ranking 74th of all South African estuaries in terms of its overall conservation importance. Consequently the Hartenbos Estuary was not included on the list of estuaries that require partial or full protection in order to meet South Africa’s biodiversity targets for conservation of estuarine biodiversity (Van Niekerk and Turpie, 2012). Nevertheless, the Hartenbos Estuary is an important recreational area along the Cape south coast. The estuary faces pressure from reduced freshwater inflow due to the upstream Hartebeeskuil Dam, deteriorating water quality, reduced tidal influence, increasing tourism at the estuary mouth and generally increasing coastal development. Although the Provisional Present Ecological State of the Hartenbos Estuary falls within an Ecological Category of D, it is likely that the estuary is on a negative trajectory of change if the situation remains unmanaged. Increasing developmental pressures in the Hartenbos resulting from growing coastal populations due to influx from rural inland areas as well as the increasing popularity as a holiday destination could have negative impacts on water quality and available water quantity for the ecological reserve. This first generation Estuarine Management Plan recommended that rehabilitation should be achieved through invasive alien plant clearing, increasing freshwater inflow, improving water quality, fixing of inappropriate bank stabilization. The second generation review of the EMP proposes important additions to this list of rehabilitation focus areas. It is suggested that rehabilitation can also be achieved by: implementing measures so that prolonged periods of closed mouth conditions are avoided, implementing measures to increase the periods of tidal exchange; the removal of reeds and excess sediments near the western extent of the estuary functional zone; the dredging of the estuary to remove anoxic sediments. A zonation plan has been prepared for the Hartenbos Estuary in accordance with the Integrated Coastal Management Act (2008) taking consideration of discussions with and submissions received from stakeholders engaged in the development of the Hartenbos Estuary Situation Assessment Report (Mossel Bay Municipality 2015) and the Draft EMP. The zonation plan aims to represent the best possible means of satisfying conflicting requirements of the different user groups and stakeholders who wish to enjoy the benefits provided by the Hartenbos Estuary. Zonation will allow for partitioning of activities within the estuary thus permitting their co-existence without one activity precluding or conflicting with another. It will also reduce management costs as it will focus activities in particular geographic areas and hence eliminate the need to deploy all types of management staff across the whole estuary at all times. Requirements, for which the greatest scope for conflict exists, most likely include exploitative resource use, recreation and rehabilitation. 48 Draft Hartenbos Estuary Management Plan Appendices: Zonation Plan 7.1.2 Geographical extent of the estuary Estuarine Systems are defined differently under different legislative acts in South Africa. The National Water Act (Act No. 36 of 1998) defines an estuary as “a partially or fully enclosed body of water— a) which is open to the sea permanently or periodically; and b) within which the sea water can be diluted, to an extent that is measurable, with fresh water derived from land; This is very similar to the definition included in the National Environmental Management: Coastal Management Act (2008) and listing notices 1 (GN R. 983), 2 (GN R. 984) and 3 (GN R. 985) regulations applicable to the Free State, Limpopo, Mpumalanga Provinces, Northern Cape and North West Province, published under the National Environmental Management Act (NEMA), Environmental Impact Assessment (EIA) Regulations (2014), which define an estuary as a body of surface water- a) that is permanently or periodically open to the sea; b) in which a rise and fall of the water level as a result of the tides is measurable at spring tides when the body of surface water is open to the sea; or c) in respect of which the salinity is higher than fresh water as a result of the influence of the sea, and where there is a salinity gradient between the tidal reach and the mouth of the body of surface water This definition of what constitutes estuarine habitat is considerably larger in terms of listing Notice 3 (GN R 985) applicable to the Western Cape, Eastern Cape and KwaZulu Natal and is published under the National Environmental Management Act (NEMA), Environmental Impact Assessment (EIA) Regulations (2014), where the definition of an estuary includes the estuarine functional zone as defined in the National Biodiversity Assessment: Estuary Component (van Niekerk & Turpie 2012): “’estuary” means the estuarine functional zone as defined in the National Estuaries Layer, available from the South African National Biodiversity Institute’s BGIS website (http://bgis.sanbi.org)”. In defining the “estuarine functional zone” and hence in the preparation of the most recent edition of the “National Estuaries Layer”, van Niekerk & Turpie (2012) used the following definition of an estuary: ‘‘…a partially enclosed permanent water body, either continuously or periodically open to the sea on decadal time scales, extending as far as the upper limit of tidal action or salinity penetration. During floods an estuary can become a river mouth with no seawater entering the formerly estuarine area or when there is little or no fluvial input an estuary can be isolated from the sea by a sandbar and become a lagoon or lake which may become fresh or hypersaline”. 49 Draft Hartenbos Estuary Management Plan Appendices: Zonation Plan In each case, the estuary mouth was taken as the downstream boundary or, where the mouth was closed, the middle of the sand berm between the open water and the sea. The upstream boundary was determined as the limits of tidal variation or salinity penetration. Lateral boundaries of each estuary were defined to include all associated wetlands, intertidal mud and sand flats, beaches and foreshore environments that are affected by riverine or tidal flood events whichever penetrates furthest, and were mostly plotted as the 5 m topographical contour surrounding each estuary. For the purposes of this management plan, the geographical limits of the Hartenbos Estuary have been defined in accordance with the National Biodiversity Assessment: Estuary Component (van Niekerk & Turpie 2012) and is shown in Figure 3. Head of tidal influence Estuary mouth Figure 3 Geographical extent of the estuarine functional zone of the Hartenbos Estuary as defined in the National Biodiversity Assessment: Estuary Component (van Niekerk & Turpie 2012, South African National Biodiversity Institute http://bgis.sanbi.org). 50 Draft Hartenbos Estuary Management Plan Appendices: Zonation Plan 7.1.3 the riparian area and the 1:100 year flood line in accordance with guidelines published by the Coastal Protection Zone, Coastal Management Lines and flood lines The Provincial MEC in consultation with the Local Municipalities is required to define a coastal protection zone of at least 1 km from the coastal and estuarine high tide mark under the Integrated Coastal Management Act (2008 as amended in 2014) for all areas surrounding the Hartenbos Estuary zoned agricultural or undetermined use and that are not part of a lawfully- established township, urban area or other human settlement, and a corresponding zone of 100 m for all other land. The Integrated Coastal Management Act (2008) also provides for the establishment of a coastal management line, designed to protect the coastal protection zone. Any future development seawards of the coastal management lines is automatically be subject to an Environmental Impact Assessment (EIA) and would have to be compatible with the vision and objectives defined within this management plan. A methodology has been developed for defining coastal management lines in the Western Cape (WSP Africa Coastal Engineers 2010) and it is now up to the district and/or local municipality to implement these guidelines in their respective areas. DEA&DP is currently in the process of developing coastal management lines. The final draft coastal management lines have been completed and they have been subjected to a public participation process. The following lines have been determined: a) An accurate delineation of the high water mark; b) A line demarcating physical processes or hazards; c) One or more management lines, or coastal management lines, that can be used to manage development along the coast; and d) A line demarcating the Coastal Protection Zone (CPZ) as required by ICMA. DEA&DP must now move towards getting the CML adopted by the Minister. Establishment of coastal management lines around the Hartenbos Estuary will prevent development from encroaching too close to the estuary and hence will ensure an adequate buffer for the estuary. It is recommended that as a starting point for the coastal management line for the Hartenbos Estuary corresponds with the estuarine functional zone for this estuary as defined in the National Biodiversity Assessment: Estuary Component (van Niekerk & Turpie 2012) and depicted in Figure 3. The Hartenbos Estuary Advisory forum should be involved in determining the final coastal management line position (e.g. exclusion of already developed areas within the 5m contour). The coastal management line will serve to protect ecological functioning and integrity of the estuary, limit disturbance to estuarine flora and fauna, and will assist in successful rehabilitation of disturbed areas in the estuary and enhance its ecotourism appeal. In addition to these provisions, the NEMA EIA regulations also list a number of activities which, if undertaken within the estuarine precinct, require an EIA (see Appendix 5). The National Water Act (1998) also places some restrictions on development adjacent to water courses, which includes estuaries. This Act requires that authorisation (a water use licence) be obtained for any alterations to the bed, banks, course or characteristics of a water course (which 51 Draft Hartenbos Estuary Management Plan Appendices: Zonation Plan includes changes in land use, vegetation cover, topography, soil, etc.) or the adjacent riparian habitat (defined as any flooded area adjacent to the river channel) from the Department of Water and Sanitation (DWS). The riparian habitat is considered to include everything within the 1:100 year flood line of a water course. The 1:50 and 1:100 year flood lines have been delineated for the Hartenbos Estuary. 7.1.4 Proposed management zones for the Hartenbos Estuary The proposed management zones shown in Figure 4 are intended to satisfy conflicting requirements of the different user groups and stakeholders who wish to enjoy the benefits provided by the Hartenbos Estuary. Zonation will allow for partitioning of activities within the estuary thus permitting their co-existence without one activity precluding or conflicting with another. Details of the extent, intention and supported/not supported uses of the estuary are provided in (Table 10). The proposed zonation plan focuses rehabilitation efforts in ecologically important areas and restricts the area where bait can be collected. Bait collection is defined as prawn and/or blood worm pumping. Except for the limitations placed on bait collection, no restrictions pertaining to other recreational activities or harvesting of marine and estuarine living resource are recommended in the Hartenbos Estuary (note that cast netting for harders is not restricted in the estuary). Notwithstanding, legal requirements such as maximum speed of motorised vehicles, bag limits for harvesting, types of species and implements for harvesting etc. will still apply. Note: This section will be reviewed in conjunction with the Hartenbos Precinct Plan which is currently being compiled. The precinct plan attempts to describe which land uses would be most appropriate for land adjacent to and within the estuary functional zone. The idea is that these land uses would assist is rehabilitating the estuary. The Hartenbos Precinct plan is currently in draft form. It will be added to the EMP upon completion of the study. 52 Figure 4 Map of proposed spatial management zones for the Hartenbos Estuary. Table 10 Details, purpose, goals and management guidelines for recommended spatial planning categories for the Hartenbos Estuary. Spatial Management Description and Purpose Goals Management Guidelines Zones Location Rehabilitation Focus Riparian Buffer Strip To contribute towards a) Reduce sediment load No bait collection. Area (30 m inland from improving: surface run-off and No cultivation except where rehabilitation is underway. the bank), Riparian ecosystem health leaching of pollutants Vegetation and Salt into the estuary. No clearing of indigenous vegetation on public land except for facilities aesthetic value in line with MAP for improving recreational value (e.g. boardwalks, bird Marsh areas within b) Control of invasive alien hides, access points for fishing). Encourage private land owners to assist the Estuarine recreational value vegetation. Functional Zone. the rehabilitation process. economic value c) Flood attenuation and Invasive alien vegetation management programme in place. minimisation of flood damage. No fertilisers or pesticides to be used. d) Mitigate visual impact of No new edge-hardening of the Riparian Buffer. development. No new development or infrastructure below the 1:50 year floodline. e) Formalise access to the No septic tank, soakaway, solid or liquid waste disposal within 50 m of estuary. the river bank. No establishment of new informal paths, formalise selected existing paths. Erect signage and information boards to inform the public about rehabilitation efforts. Bait collection area Area designated for Restricting bait harvesting a) Promote easy Bait collection restricted to this zone. bait collection. to this area will allow compliance with MLRA Bait collection restricted to daylight hours using legal implements. rehabilitation of the regulations. remaining estuary. Bait collection subject to periodic review of MLRA regulations. No bait collection permitted during emergency mouth breaching events. Resort/Tourism Areas Existing tourism Enhance contribution a) Promote eco-tourism and Promote eco-tourism developments: guest houses, resorts, camping in nodes. towards economic growth associated visitor accordance with Municipal SDF. of the area. facilities. Ensure that these areas have formalised access to the estuary. Plant indigenous gardens. Maintain existing indigenous vegetation. Rehabilitate transformed areas where possible. Draft Hartenbos Estuary Management Plan Appendices: Mouth Management 7.2 Appendix 2: Proposed Estuary Mouth Management Protocol for the Hartenbos Estuary, Mossel Bay Municipality The Hartenbos Estuary is one of South Africa’s approximately 289 functional estuaries and is one of 21 estuaries within the warm temperate biogeographic region to be classified as a temporarily open/closed (Turpie et al., 2012; Van Niekerk and Turpie, 2012). The Hartenbos is a small estuary (open water approximately 40 ha) with a relatively large floodplain and covers in total approximately 268 ha. The Hartenbos Estuary is not particularly important for estuarine biodiversity on a national scale and ranks 74th of all South African estuaries in terms of its overall conservation importance. Nevertheless, the Hartenbos Estuary is an important recreational area along the Cape south coast, and is home to a well-established resident community as well as a much larger holidaying community. This document constitutes the second generation Estuary Mouth Management Protocol (MMP) for the Hartenbos Estuary. It is an amendment of the first generation MMP which was drafted in accordance with the DRAFT key principles and guidelines which are currently being developed as part of the Estuary Management Framework and Implementation Strategy project initiated by the Department of Environmental Affairs and Development Planning (Note that the structure of the mouth management plan may have to be amended once the guidelines have been finalised). 7.2.1 Problem Statement The channel and mouth dynamics of the Hartenbos Estuary have been strongly influenced by anthropogenic developments in the catchment and have been sporadically managed since the Hartebeeskuil Dam was built. Bickerton’s (1981) assessment shows that the construction of the Hartebeeskuil dam has had the most significant effect on the channel and mouth dynamics. Bickerton (1981:31) suggests that: ‘The primary effect of the Hartebeeskuil Dam on the estuary has been the closure of the mouth for extended periods’ Bickerton (1981:16) also asserts that: ‘Since dam construction the estuary has usually been stagnant with high salinities and dense mats of algae, due to eutrophication’’ In 1986 the WWTW was constructed and the discharge of treated effluent to the estuary was authorised by the Department of Water Affairs. The licence issued did not require the removal of all nutrients, so since 1986 between 6 and 10 ML of nutrient rich treated effluent has been discharged into an estuary which had already been significantly disturbed by the construction of the Hartebeeskuil dam. Since then the primary mitigation measure had been the release of water from the Hartebeeskuil dam, which for a number of reasons had not been sufficient to prevent prolonged period of closed mouth conditions. Historical and contemporary records shows that following periods of prolonged periods of closure water quality characteristics can change rapidly and begin to pose a threat to either human or ecosystem health. For example, prolonged exposure to either very low (hyposaline <5 PSU) or very high (hypersaline, >40 55 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management PSU) conditions can cause mass mortality of marine (mostly the former) and estuarine organisms (mostly the latter), while even short term exposure to low levels of dissolved oxygen (< 4 mg/l) can cause mass mortalities of all types of aquatic organisms. Large-scale fish kills have become a common phenomenon in estuaries impacted by anthropogenic activities and the Hartenbos Estuary is no exception. The most recent fish kills in the Hartenbos Estuary occurred in January 2015, in March 2016 and October 2016. Bickerton (1981:9) study shows that while closed mouth conditions did occur prior to the construction of the Hartebeeskuil dam, there were two other typical mouth conditions namely: 1) After a flood, the channel along the north-eastern bank is widened and straightened into a well-developed funnel shaped tidal inlet. This situation existed in 1963, during the ECRU survey in November 1981 and also probably throughout most of 1981 after the floods earlier that years. During such conditions the tidal inlet is close to the north-eastern bank, causing heavy erosion just below the railway line. 2) Narrow channel meandering from the deep water area at the south-western side of the lagoon towards the north-eastern bank to sea via a sand delta at the foreshore. The south-western sandspit is fully developed, pushing the channel towards the north-eastern bank (without causing erosion). The lagoon is apparently not tidal and channel is merely an overflow of lagoon water. These conditions existed in 1957 and also during a visit to the Hartenbos ERCU personnel at the beginning of December 1981. Historically, artificial manipulation of the Hartenbos Estuary mouth has been used as a means to pro-actively mitigate impacts of anthropogenically induced changes to the natural flow regime of the Hartenbos system and its effects on the ecological functioning and recreational utility of the estuary. Following the promulgation of the EIA regulations this practice ceased. In terms of the Environmental Impact Assessment Regulations promulgated in terms of the National Environmental Management Act (Act No. 107 of 1998), movement of more than 5m3 of material in an estuary is a listed activity unless it is undertaken in accordance with an agreed management plan: Listing Notice 1 R983 “The infilling or depositing of any material of more than 5 cubic metres into, or the dredging, excavation, removal or moving of soil, sand, shells, shell grit, pebbles or rock of more than 5 cubic metres from: (i) a watercourse; (ii) the sea; (iii) the seashore; (iv) the littoral active zone, an estuary or a distance of 100 metres inland of the highwater mark of the sea or an estuary, whichever distance is the greater but excluding where such infilling, depositing , dredging, excavation, removal or moving; (b) occurs behind the development setback line (b) is for maintenance purposes undertaken in accordance with a management plan; […]”. Since no environmental authorisation was in place the artificial breaching of the Hartenbos Estuary ceased. Information from the Hartenbos Estuary Advisory Forum suggests that this has had a negative impact on the estuary. Bickerton’s (1981) study shows that prolonged closed mouth conditions are bad. Bickerton (1981) asserts that the health of the Hartenbos Estuary is directly related to restoring flow regimes, ensuring tidal exchange and avoiding prolonged 56 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management closed mouth conditions. Bickerton (1981) suggest that all aspects of estuary health e.g. physical-chemical conditions and fish and invertebrates all benefit from tidal influence. The experiences of 2017, where the Hartenbos Estuary was breached a number of times re-enforces this assertion. Bickerton’s (1981) study shows that eutrophic conditions, reduced dissolved oxygen and hyper salinity are all associated with closed mouth conditions. The physical- chemical data gathered during the daily DO, pH, Salinity, Temperature and electrical conductivity, conducted in 2016 and 2017, show that under closed mouth conditions there is a deterioration of estuary health. The first generation mouth management plan was informed mainly by the first generation EMP Estuary Management Plan and a Desktop Reserve Determination study report (DWS 2015) which were recently prepared for the Hartenbos Estuary by Anchor Environmental Consultants (Pty) Ltd. and the CSIR respectively. These two documents have pulled together an extensive body of specialist and stakeholder knowledge regarding this estuary and address a range of management issues including management of the estuary mouth. The drafting of the Hartenbos EMP involved a total four meetings that were held between June 2015 and May 2016, which included a meeting with relevant authorities, two multi-stakeholder group meetings, and the Estuary Advisory Forum founding meeting. Comments pertaining to existing and new issues were received during this process and were in some cases discussed during extensive telephone conversations with individual stakeholders. The first generation Mouth Management Plan prosed that artificial breaching should only occur as an emergency measure in response to a spill from the WWTW or a low oxygen event. In other words artificial breaching would be re- active to an emergency event that has already occurred. This was sufficient to meet the problem statement of the first generation MMP which was to halt the negative trajectory of the health of the estuary. However experiences in 2016 and 2017 has shown that it is insufficient to restore estuary health. The problem statement for the second generation Mouth Management Plan is as follows: ‘Given that historic and contemporary information related to the health of the estuary confirms that prolonged closed mouth conditions are bad and that artificial breaching is the only means to prevent this, what configuration of breaching scenarios will actively serve to restore the Hartenbos estuary?’ 7.2.2 Overall objective of the local mouth management programme The first generation EMP was used to compile a mouth management protocol. Now that a second generation EMP has been produced, it must be used to amend the mouth management protocol. As stated in the EMP, the second generation EMP took into consideration the practical experiences gained during 2016 and 2017 while implementing the first generation Mouth Management Protocol. There is now much more information available, that was not previously available during the compilation of the first generation EMP. Generally two types of breaching can be distinguished, namely planned breaching undertaken for the management of the estuary and emergency breaching. Planned breaches in spring and summer are a common management method to maintain seasonal estuary-sea connectivity in impacted temporarily open/closed systems (e.g. Groot Brak Estuary). Planned breaches can facilitate fish and 57 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management invertebrate recruitment and improve flushing of the estuary. Emergency breaching can (1) reduce or avoid an ecological disaster or health and safety risk after the occurrence of major spills (note that persistent pollutants should not be flushed out to sea but should rather be removed from the estuary followed by rehabilitation efforts) and (2) alleviate flood risk caused by small to medium floods (note that artificial breaching to prevent damage by major floods is ineffective). The first generation Mouth Management Protocol only made provision for emergency breaches. The second generation Mouth Management Protocol makes provision for planned breaches and emergency breaches. Key objectives for the first generation mouth management plan for the Hartenbos Estuary evolved throughout the EMP drafting process, facilitated through research as well as stakeholder engagement at three meetings that were held between June 2015 and February 2016. Comments pertaining to mouth management of the Hartenbos were received during this process and were in some cases discussed during telephone conversations and email communications with individual stakeholders and experts in the field. The objectives for the first generation mouth management protocol of the Hartenbos Estuary was to: (1) Prevent large scale fish kills due to severely reduced availability of dissolved oxygen; and (2) Prevent a health hazard as a result of malfunctioning of the WWTW and associated releases of insufficiently treated sewage. The First Generation Mouth Management protocol thus made provision only for emergency breaches. The second generation mouth management protocol suggests that there should be two important additions to the objectives which inform any mouth management protocol for the Hartenbos Estuary. The proposed additional objectives are informed by the sources of information used in the compilation of the second generation EMF and they are: (3) Rehabilitation of estuary by facilitating greater tidal exchange and recruitment of estuary fish (4) Ensure water quality in the estuary remains compliant with the water quality guidelines for recreational use. (5) Alleviation of flood risk 7.2.3 Description of the estuary Estuary component Description Location The Hartenbos estuary is situated on the south coast approximately 7.5 km east of Mossel Bay and is one of 21 estuaries within the warm temperate biogeographic region classified as a temporarily open/closed system (Turpie et al., 2012; Van Niekerk and Turpie, 2012). The geographical boundaries for the estuary are defined as follows: Downstream boundary: Estuary mouth 34°7’0.66”S, 22°7’27.20”E Upstream boundary: 34°6’42.45”S, 22°5’3.95”E Lateral boundaries: 5 m contour above Mean Sea Level along each bank. 58 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management Head of tidal influence Estuary mouth Estuary Importance The Hartenbos is a small estuary with a relatively large floodplain and covers in total approximately 268 ha. The estuary was rated as ”Important” based on its Estuary Importance Score (EIS) of 66/100. The EIS takes size, the rarity of the estuary within its biogeographical zone, habitat, biodiversity and functional importance of the estuary into account. Conservation Status The Hartenbos Estuary does not have any statutory protection and does not form part of the core set of priority estuaries in need of protection to achieve biodiversity targets as detailed in the NBA 2011 (Van Niekerk and Turpie, 2012). Importance for fish A total of 17 species of fish have been recorded from the Hartenbos estuary to date, which recruitment is considered to be low compared to other temporarily open/closed estuaries in the region. During a survey conducted in October /November 1997 a total of nine species were recorded of which three taxa were estuarine resident species (Category Ia) and six species were euryhaline marine species that breed at sea, with juveniles showing varying degrees of dependence on estuaries. The prevalence of both estuarine-resident and estuarine-dependent species in the Hartenbos estuary indicate that fishes of very different life cycles are supported by this system. Importance for water The Hartenbos estuary is classified as a sandy estuary with little other intertidal habitat associated birds and is characterised by a large number of gulls and terns with relatively low wader numbers (Turpie and Clark, 2007). Prior to the building of the Hartebeeskuil Dam and the WWTW, brackish conditions in combination with predominantly closed mouth would have been particularly suitable for waterfowl (Type B estuary according to (Turpie and Clark, 2007)). To date, a total of 59 water-associated bird species of nine taxonomic orders have been recorded at the Hartenbos estuary (excluding rare vagrants). The most species-rich taxonomic group is the Charadriiformes, which include the waders, gulls and terns. The relative contribution of taxa to the bird numbers on the estuary differs moderately in summer and winter, due to the presence of migratory birds in summer. There are no important populations of red data species on the estuary, although wader numbers, especially resident wader numbers have slowly but steadily increased since 2005 (this trend is possibly related to an increase in open mouth state of the estuary). Estuary condition w.r.t. The estuary is negatively impacted by breaching flow reduction (impoundment by the Hartebeeskuil Dam, abstraction for irrigation, alien vegetation in the riparian zone along the river and in the estuarine functional zone); increased nutrient loading (WWTW, septic tanks, agricultural return flow and effluent and informal settlements); and Illegal breaching. The second generation EMP suggests that artificial breaching is not by default bad for the estuary, particularly one that is as highly disturbed as the Hartenbos Estuary. The Present Ecological Status of the Hartenbos Estuary was therefore determined to be a Category D (DWS 2015). However, having been identified as an “important” system, it was recommended that the estuary should be managed in a Category C (Recommended Ecological Category) (DWS 2015). 59 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management 7.2.4 Motivation for artificial breaching The first generation EMP suggested that channel and mouth dynamics of the Hartenbos Estuary have been strongly influenced by anthropogenic developments in the catchment, of which the most significant developments were the construction of the Hartebeeskuil Dam 12 km upstream of the estuary in 1970 as well as the construction of the WWTW in the upper reaches of the estuary in 1980s. Bickerton (1981:9) identifies 3 typical mouth conditions that can be drawn from historic aerial and terrestrial photographs. These are described in the table below: 1) After a flood, the channel along the north-eastern bank is widened and straightened into a well-developed funnel shaped tidal inlet. This situation existed in 1963, during the ECRU survey in November 1981 and also probably throughout most of 1981 after the floods earlier that years. During such conditions the tidal inlet is close to the north-eastern bank, causing heavy erosion just below the railway line. 2) Narrow channel meandering from the deep water area at the south-western side of the lagoon towards the north-eastern bank to sea via a sand delta at the foreshore. The south-western sandspit is fully developed, pushing the channel towards the north-eastern bank (without causing erosion). The lagoon is apparently not tidal and channel is merely an overflow of lagoon water. These conditions existed in 1957 and also during a visit to the Hartenbos ERCU personnel at the beginning of December 1981. 3) Mouth closed with a large sandbank on the north-eastern side and deep water on the south-western side. There is a solid beach bar across the entire mouth area. This closed-mouth conditions existed when aerial and terrestrial photographs were taken in January 1940, December 1968, June 1969 and April and December 1977. It has been the typical situation in the Hartenbos since the construction of the Hartebeeskuil dam in 1970. Most of the runoff in the catchment is impounded by the Hartebeeskuil Dam, which was commissioned in 1970. Since then the estimated Mean Annual Runoff (MAR) has been reduced from 4.6 Mm3 to 2.8 Mm3 (64%) and the frequency and magnitude of smaller flood events have been considerably reduced. At the same time, the regional waste water treatment plant (WWTW) currently discharges approximately 10 mega litres of treated effluent into the estuary per day. This amounts to 3.45 Mm3 of freshwater (treated sewage) that enters the estuary in addition to 2.8 Mm3 provided by the current flow regime per year (MAR). Consequently, the water contained in the estuary below the WWTW currently exceeds the MAR that was provided by the flow regime prior to the construction of the Hartebeeskuil Dam by almost 2 Mm3 per year. Surveys of the state of the water course suggests that the current flow regime is much less that the 2.8 Mm3 estimated in the first generation EMP. It may even be zero. This is based on observations by the forum that there is no flow entering the estuary 60 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management from the section of the water course west of the estuary functional zone boundary. See photographs of catchment in appendix 3 (add photograph of the area upstream of Die Ark) Although the WWTW has more than replaced the MAR impounded by the Hartebeeskuil Dam, the water is of poor quality and has been contributing significantly to the deterioration of estuary health (Lemley et al. 2015). It is important to note that the discharge to the estuary from the WWTW is licenced by the Department of Water Affairs and Sanitation. The quality of the treated effluent discharged is determined by the parameters in the Water Use Licence. By issuing the Water Use Licence DWS has in effect authorised the total transformation of the system from a significantly disturbed system to a completely transformed system. The risk of occasional malfunctioning of the WWTW and associated releases of incompletely treated sewage constitutes a serious threat to the human health and the estuarine ecosystem. Agricultural return flows containing fertilisers, stormwater outlets, malfunctioning septic tanks, as well as cattle and ostrich farming along the river banks are other suspected sources of pollutants that influence water quality in the estuary. Bickerton’s (1981) study indicated that should the Department of Water Affairs give authorisation for the discharge of treated effluent into the estuary, they would need to actively manage the system via releases from the Hartebeeskuil dam so that prolonged closed mouth periods are avoided. Historical accounts suggest that the system was managed via artificial breaching. Historically artificial breaching has been used in an attempt to reactively mitigate water quality deterioration and its impacts on the ecological functioning of the estuary and recreational utility. Historical information obtained from the Hartenbos Advisory Forum suggests that the artificial breaching of the estuary occurred regularly. In the past the estuary was breached when water level approached the 1,6 m mark, when there were signs of eminent algae blooms, when the stagnant water in the estuary released offensive odours and when there where un-seasonally large swarms of midges. Importantly, artificial breaches where also done prior to the peak holiday seasons. In the past the MBM occasionally breached the estuary artificially in response to alleviate flood risk. This account of the history of artificial breaching in the estuary is largely supported by Bickerton’s (1981) study. Reports provided by the Hartenbos EAF suggest that there was a marked worsening of water quality since early 2000s. This co-incided with the promulgation of environmental legislation which made artificial breaching of the estuary illegal. Large-scale fish kills have become a common phenomenon in the Hartenbos Estuary in recent history. The most recent of which occurred in January 2015, March 2016, and October 2016. In summary, there is a need to clearly define future mouth management options and protocols for the Hartenbos Estuary to ensure that eutrophic conditions and fish kills can be prevented. Two types of breaching can be distinguished, namely planned breaching undertaken for the management of the estuary and emergency breaching. Planned breaches in spring and summer are a common management method to maintain seasonal estuary-sea connectivity in impacted temporarily open/closed systems (e.g. Groot Brak Estuary). Planned breaches can facilitate fish and invertebrate recruitment and improve flushing of the estuary. Unfortunately, the Hartebeeskuil dam cannot release large quantities of water in a short period of time, which would be required if environmental releases were to simulate major flood events. The outlet 61 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management pipe is small and the experiences in November 2016 showed that water released from the dam does not reach the estuary. Planned breaches that rely on a water release is therefore not a suitable management method for the Hartenbos Estuary. However, the fact that there is a constant discharge of treated effluent into the estuary provides an opportunity to simulate a water release from a dam. Surveys conducted of low lying properties and infrastructure show that water level in estuary can be allowed to safely reach 1.8 m. The results of the artificial breaching’s done in 2017 show that a breach done when water levels are near 1.8 m can produce good scouring. Water level data shows that under closed mouth conditions water level in estuary can get to 1.8 m in 2 to 3 months. This allows an opportunity for a planned breach. The experiences during 2017 have also indicated that another possibility exists for planned breach. Under this scenario, breaches at low water levels are seen to present an opportunity to trim the height of the berm. If timed correctly i.e. prior to spring tide, it provides an opportunity to allow tidal exchange to occur over a much larger area. The beneficial impacts of tidal exchange is well documented. This combination was successfully demonstrated by the August 2017 (a high water level breach) and the October 2017 (berm trimming at low water levels) breaches. The success of this combination is evident from the fact that the estuary mouth remained open during the fish recruitment period, while tidal exchange occurred throughout most of December 2017. Throughout this period a well-developed funnel tidal inlet was maintained, as per the first typical mouth dynamic condition identified by Bickerton (1981). The erosion associated with this scenario was mitigated by the sand that was moved and deposited along the northern bank of the estuary and by making sure that the channel was excavated just north of the south western sandspit. Consequently water quality in the estuary was better than previous years. Residents also reported less midges. While this conception of planned breaches may be deemed un-conventional, as stated earlier the Hartenbos System is highly disturbed, so un-conventional interventions are required. It is suggested that if sufficient thought is placed into planned breaches, the need for emergency breaches would be less. However the second generation will not propose that a provision for emergency breaches is not needed. Instead it seeks to add and refine the emergency scenarios described in the First generation EMP. The first generation EMP suggested that emergency breaching to alleviate flood risk caused by small to medium floods (note that artificial breaching to prevent damage by major floods is ineffective) was not required. Mossel Bay Municipality and the Hartenbos EAF is of the opinion that provision must be made of emergency breaches in response to the threat of possible flooding. The sample of water level data used for the compilation of the first generation EMP suggested that the natural breaching level of the estuary is approximately 2.1 metres above mean sea level. Based on the information available it was suggested that this is not causing flood damage to existing infrastructure situated within the estuarine functional zone. However, the experiences in 2017 showed that water levels of 2.1 m is not safe. Surveys of the berm have shown that under closed mouth conditions the height of berm can rise 400 mm in a month. The highest berm height recorded in 2017 was 2.4 m, so there is no guarantee that the estuary will breach ‘naturally’ when water level gets to 2.1 m. It is important to note that the outflow from the WWTW is constant, meaning that under closed mouth conditions the water level is always rising. A survey of low laying properties along the Hartenbos Estuary show that properties will be inundated if water levels in the estuary exceed 2.21 msl. Municipal storm water 62 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management infrastructure will also be inundated at 2.17 msl. The sump of the municipal pump station located on the southern bank of the river is inundated at 2.17 msl, meaning that river water enters the municipal sewer system. There is thus significant risk of flooding if the mouth of estuary is closed for a prolonged period. This position is affirmed by the fact that DEA&DP issues Section 30A Directives allowing Mossel Bay Municipality to breach the Hartenbos Estuary when water levels were so high. A protocol for emergency breaching to prevent flood damage caused by small and medium floods is therefore required. The first generation EMP suggests that Emergency breaching should also be allowed to mitigate environmental impacts (1) as a result of malfunctioning of the WWTW and associated releases of insufficiently treated sewage. The emergency mouth management protocol for the Hartenbos Estuary compiled for the first generation EMP was prepared in accordance with the DRAFT key principles and guidelines which are currently being developed as part of the Estuary Management Framework and Implementation Strategy project initiated by the Department of Environmental Affairs and Development Planning (Note that the structure of the mouth management plan may have to be amended once the guidelines have been finalised).and is included as an Annex to this EMP (Appendix 2: Proposed Estuary Mouth Management Protocol for the Hartenbos Estuary). While the emergency breach constitutes a short-term relief and is a reactive mitigation measure in the case of extreme conditions. Mossel Bay Municipality and the Hartenbos EAF agrees that long term efforts should be undertaken to improving water quality by addressing problems at the source. Bickerton’s (1981) study shows that this will need either the removal of the Hartebeeskuil dam or an effective means to do ecological releases, the removal of obstructions in the river, the removal of all septic tanks and ideally the ending of discharges from WWTW. This however will require extensive capital investment and is simply not feasible in the short or medium term. Long term weather projections for the area suggests that MAR will not be restored via an increase in annual rainfall. The First Generation EMP suggests that an emergency breach is required to mitigate environmental impacts is limited to scenarios where a disaster has already occurred i.e. a malfunction at the WWTW etc. More specifically this refers to a mechanical malfunction i.e. like the scenario in November 2016 when there was a breakdown of one of the bio-reactors. In cases like these the break down cannot really be anticipated while the effect on the quality on treated effluent is significant and immediate. Certainly then an emergency breach will be required after the insufficiently treated sewerage has been discharged to the estuary. The first generation EMP and MMP does however not specify what is meant by improperly treated sewerage. The discharge of treated effluent to the estuary is authorised by a Water Use Licence issued by the Department of Water Affairs and Sanitation. The compliance record of the WWTW, as measured by the tests conducted on treated effluent by BGCMA and Eden District Health, show that raw sewerage or sewerage with high e-coli levels has never been discharged from the WWTW. The design of the plant prevents this from occurring. The non-compliant discharges documented in 2016 relate to instances where the levels of ammonia, phosphates and nitrates have exceeded the parameters set in the Water Use Licence. Mossel Bay Municipality and the Hartenbos EAF is of the opinion that the parameters set in the Water Use Licence should be used as the criteria to 63 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management determine what is meant by insufficiently treated sewerage. An emergency breach in response to non-compliance with any of the water quality parameters specified in the Water Use Licence must be included as a scenario under which an emergency breach is allowed. There are also instances where the quality of the incoming raw effluent indicates that problems may be expected i.e. if something is discharged to our sewer illegally etc. In addition to the testing of the quality of incoming raw effluent, daily operational tests are conducted at the WWTW. These results are a good indicator of whether insufficiently treated sewerage may be released into the estuary. Mossel Bay Municipality and the Hartenbos EAF is of the opinion that these results should also be used to determine when an emergency breach is required. It will allow a proactive response to anticipated problems at the WWTW. As stated earlier The WWTW discharges 6-10 ML of treated effluent into the estuary. It is only possible to divert up to 4 ML of effluent away from the estuary. There will thus always be a discharge of significant volume of treated effluent, if something goes wrong at the plant. If it is accepted that an emergency breach is a useful mitigation in response to the discharge of insufficiently treated sewerage, then it follows that an emergency breach conducted in lieu of an anticipated discharge of insufficiently treated sewerage should likewise be acceptable. The first generation EMP confirms that the Hartenbos Estuary is an important recreational area. Improving the recreational value of the EMP is identified as a Key Result Area. The volume 2 of the South African Water Quality Guidelines for Coastal Marine Waters sets the recreational water quality parameters for marine waters. Parameters are set from a human health and safety perspective as well as from an aesthetical perspective. In terms of human health and safety, limit values for bacteriological i.e. e-coli and Enterococci and chemical parameters e.g. pH, inorganics, temperature etc. are set. Mossel Bay Municipality and the Hartenbos EAF insist that an emergency breach is warranted if any the parameters stipulated in the aforementioned guidelines are exceeded. Experiences during December 2016 showed that it is practically impossible to close the estuary as there are simply too many points of entry. The guidelines also stipulate that caution must be exercised when there are algae blooms as these may represent a risk to public health. This leads to the last scenario under which an emergency breach is warranted. The first generation EMP suggested that an emergency breach is allowed in response to a low oxygen event. As indicated earlier the outflow from the WWTW accounts for all the MAR in the system. This outflow is nutrient rich even when it is compliant with the parameters of the Water Use Licence. Eutrophication will thus always be an issue. An algae bloom typically precedes a low oxygen event. It thus makes sense that action taken in response to an algae bloom would be beneficial from both a human health and ecological perspective. Experiences have shown that a change in water level and salinity is effective in disrupting an algae bloom. DO readings taken during algae blooms in the Hartenbos indicate that the initial stages of an algae bloom is characterised by supersaturated conditions i.e. DO readings in excess of 10 mg/L. This is then followed by a steady decrease in DO readings until it goes below the 3-4 mg/l threshold. It is during this phase when fish kills are most likely. The DO sampling done over the last year has shown that artificial breaching has a positive impact on DO levels. Mossel Bay Municipality and the Hartenbos EAF assert that an emergency breach conducted during the early stages of an algae bloom is appropriate. In summary then the mouth 64 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management management plan emanating from the second generation will make provision for planned and emergency breaches 1) Planned breaches Involve manipulating the mouth so that it is closed in the lead up to the end of October. Water levels will then be allowed to raise to 1.8 m. While closed the height of the berm will be trimmed. The mouth will then be breached a few days prior to the spring tide. The height of the berm will then be trimmed a few days before the next two spring tides. 2) Emergency breaches To be conducted when water levels in the estuary reach 1.8 m To be conducted when there is a marked spike in concentrations of ammonia, nitrates, phosphates or hydrocarbons in incoming raw effluent to Regional WWTW. To be conducted if the quality of the treated effluent discharged to the estuary is not compliant with the parameters of the water use licence. To be conducted when the physio-chemical or bacteriological parameters of water in the estuary do not comply with acceptable limits for recreational use. To be conducted when there are significant algae blooms To be conducted in response to low oxygen events. The proposed planned breaches is to give effect to the key management objectives related to improving estuary health, improving water quality and improving recreational value. Mossel Bay Municipality shares the view expressed by Bickerton’s (1981) that closed mouth conditions was and will always remain one of the typical states of the Hartenbos Mouth. However, there is no doubt that an open mouth at the correct time has a significant positive effect on the health of the estuary. This is indicated by the evidence collected during 2017. Bickerton (1981) assertion below sums up the intention of the planned breaches: ‘With the mouth fully open, the whole estuary becomes tidal, water circulation is good and recruitment of marine organism occurs (as seen during the ECRU survey). When the estuary is tidal, it is aesthetically pleasing and attractive to holiday makers, thereby becoming an asset to the holiday resort’ The breaches conducted in August 2017 and October 2017 is a good example of what is envisioned by the planned breach. The August breach was a high water level breach which produced a good scouring effect. This was then followed up by the October 2017 breach, which involved trimming of the berm and the widening of the tidal funnel. The September 2013 aerial photograph in table 11 is a good example of the mouth state which was achieved by this. This mouth state persisted till the second week of January 2018. 65 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management Table 11 Various mouth states of the Hartenbos Estuary between 1939 and 2015 (Source National Geo-Spatial Information 1939-1991, Google earth 2005-2015). 1939 November 2006 1957 February 2010 1968 October 2010 1985 March 2011 1991 September 2013 March 2005 March 2015 66 Breach Breach Breach Breach Breach Breach Breach Breach Artificial Artificial Breach? Breach? Figure 5 Hourly water level measured above mean sea level (MSL) in the Hartenbos Estuary from 1 March 2014 – 30 July 2015 (DWS Station K1T010). Eight breaching events occurred in this time period with a natural breaching level between 1.8 and 2.1 m above MSL. It is possible that the sudden drop in water level in mid-February 2015 and end-April 2015 occurred due to artificial breaches (Data source: Department of Water and Sanitation). Table 12 Summary of the necessity, costs and benefits associated with planned breaching of the estuary Threat Discussion Threats to human life (as a result of high No threats to human life. Planned breaches will be done with water levels in the estuary at 1.8 m. Surveys of low laying water levels) properties confirm that no properties are at risk at this levels. Threats to immoveable property and No threats to property. Planned breaches will be done with water levels in the estuary at 1.8 m. Surveys of low laying infrastructure (as a result of high water levels) properties confirm that no properties are at risk at this levels. Human health risk (e.g. flooding of sewage No infrastructure containing hazardous substances are at risk of flooding. This has been confirmed by surveys conducted of pump station, septic tanks, chemical storage municipal infrastructure and low laying properties yards, etc.) Potential loss of agricultural resources as a Surveys confirm that no agricultural properties will be at risk. Most agricultural resources are concentrated in the upper result of high water levels reaches of the estuary mouth. Risk to aquaculture facilities as a result of high N/A water levels Loss/impaired access (roads, footpaths, cattle None. crossings) wellbeing and safety and wellbeing Impacts on recreational use (e.g. increased Planned breaches will be done during the day. The estuary will be closed. Planned breaches will be announced in advance. depth/surface area when mouth is closed, People will be warned to avoid the mouth during and directly after the breach. Human Human reduce fishing) Noxious algal blooms During long, closed phases in summer, algal growth is stimulated and can result in accumulation of decaying plant matter in shallow warm water. It is expected that water levels in the estuary will decrease by up to 50% after a breach. However, it must be kept in mind that the WWTW discharges are constant. Also, following a planned breach there will be tidal exchange, which will ensure that conditions are not right for algae blooms. Impact on avifauna abundance, species Important bird habitat Not important for waders, but supports moderate numbers of terns, gulls and water fowl. richness/community composition Experiences in 2017 have showed that there are more birds in the estuary immediately after a breach. Birds then have access to the shallow mud flat areas. Impact of emergency Water fowl do not fly at night and may be washed out to sea if breach is completed at Ecosystem requirements breaching night. Planned breaches will not be done at night. Threat Discussion Impact of NOT conducting a The system will become anoxic (including anoxic sediments) with greater chances of an planned breach avian botulism outbreak. The planned breach will also allow recruitment of marine organisms. Impact on estuarine fish abundance, species Important fish nursery Fish species that have been recorded in the Hartenbos estuary include seven Category IIa richness/community composition species, which are marine species that exclusively breed in estuaries. Two species were resident species which have not been recorded to breed in freshwater or marine environments (Category Ia) while two other species were identified to have estuarine and marine breeding populations (Category Ib). The nursery value of the Hartenbos estuary was estimated between 1.63 and 8.15 million Rand per year (Turpie and Clark, 2007 AEC 2015). Planned breaches will occur during the main recruitment period for fish, it will therefore have a positive impact on the fish abundance. Impact of planned breaching Planned breaching may flush the estuary thus reducing the amount of organic matter that will decompose in the estuary. Evidence suggests that breaching ensures that conditions in the estuary do not become hypersaline. It also keeps the levels of nutrient in balance thereby preventing eutrophic conditions. Impact of NOT conducting a Conditions within the estuary will become eutrophic. There will not be any recruitment of planned breach fish. Conditions will become hypersaline. Fish kills will more likely. Impact on estuarine invertebrate abundance, Invertebrate communities Prior to the construction of the Hartebeeskuil Dam, there mouth had three typical mouth species richness/ community composition states. After the construction of the dam closed mouth conditions persisted for much longer. The only detailed information on invertebrates is the ECRU survey described in Bickerton (1981). The estuary supported populations of tube worms; burrowing sand prawns, mud prawn and pencil bait. Bickerton’s (1981) study asserts that most estuarine organism cannot handle the persistent hypersaline, eutrophic and anoxic conditions , which is associated with prolonged closed mouth periods. Impact of planned breaching Planned breaching will not lead to a permanently open mouth. This is not the intention. A planned breach will ensure that tidal exchange occurs during the summer months when the problems associated with prolonged closed mouth conditions are most acute. The impact of planned breaches will thus be positive. Ecosystem requirements Impact of NOT conducting a Invertebrate kills will most definitely occur as a result of oxygen depletion. Without tidal planned breach influence the areas in the estuary which may support invertebrates, mainly areas near the mouth, will be rendered unsuitable. Threat Discussion Impact on estuarine macrophytes (plants) Botanic importance Overall, the botanic importance of the Hartenbos compared to other estuaries survey is low to moderate (Coetzee et al., 1997). Alien infestation of the riparian habitat is widespread. Supratidal saltmarsh is common and its extent should not decrease. The Hartenbos Estuary has a long history of algae blooms. The hypersaline conditions associated with closed mouth conditions can lead to a die off of estuarine plants. The decaying plant matter add to the already high nutrient load in estuary and it can cause algae blooms. Impact of planned breaching Planned breaching will improve tidal influence during the summer months which will be beneficial for supratidal saltmarsh reproduction. It will prevent the excessive die off of vegetation by alleviating hypersaline conditions. Submerged macrophytes biomass and extent may be reduced temporarily. Impact of NOT conducting a Excess nutrients will result in proliferation of more robust species (can be harmful and planned breach aesthetically unpleasant). Decaying plant matter will contribute to reduced dissolved oxygen levels. Water quality thresholds of concern that Current status Water quality is currently considered to be poor. Prolonged closed mouth conditions have would compromise estuarine ecosystem or become the typical mouth state. Hypersaline, anoxic and eutrophic conditions have thus ecosystem services become common. Excess nutrients are primarily introduced by the WWTW, while upstream sources including agriculture and septic tanks. A lack of tidal influence contributes to the current water quality status. Impact of planned breaching Prolonged closed mouth conditions will be avoided. Hypersaline, eutrophic and anoxic conditions during the summer months will be avoided. Impact of NOT conducting a Prolonged closed mouth conditions will persist. planned breach Eutrophication Current status Eutrophication risk is considered high (Lemley et al., 2014) Impact of planned breaching Tidal exchange has proven to be effective in mitigating and preventing eutrophic conditions Impact of NOT conducting a Eutrophic conditions will almost certainly manifest during prolonged close mouth planned breach conditions. Sedimentation Current status Sedimentation processes have been altered through the construction of the Hartebeeskuil Ecosystem requirements Dam (reduced flooding capacity) and obstructions in the estuary. The ecological releases from the Hartebeeskuil dam has not been sufficient to scour the estuary. This has led to the build-up of anoxic sediments as well as a build up of sediments at the estuary mouth Threat Discussion Impact of planned breaching Planned breaches at high water levels can to certain extent simulate flood events and good scouring of sediments can be achieved. Impact of NOT conducting a Sediments may not be flushed. planned breach Table 13 Summary of the necessity, costs and benefits associated with emergency breaching of the estuary prior to or during the release of large volumes of untreated sewage, as well as during low oxygen events, to alleviate flooding and instances where water quality in the estuary is not fit for contact recreation. Threat Discussion Threats to human life (as a result of high Emergency breaching will be conducted when water levels in the estuary reach heights where low laying properties are at water levels; water quality which is not fit for risk. A breach at 1.8 m gives the MBM sufficient time to make the appropriate arrangements and to do the breach. The recreational use; or when improperly treated breach will reduce water level, so it will not pose a threat to human life. A breach conducted in response to a spill or poor sewerage is about to be or has been released) water quality will reduce the risk and therefore will not pose a threat to human life. Threats to immoveable property and Emergency breaching will be conducted when water levels in the estuary reach heights where low laying properties are at infrastructure (as a result of high water levels) risk. Human health risk (e.g. flooding of sewage Emergency breaching in response a risk of flooding will ensure that water levels do not reach levels where sewerage pump station, septic tanks, chemical storage infrastructure i.e. pump stations or septic tanks spill). yards, etc.) Malfunctioning of the Hartenbos Regional WWTW can result in the release of large volumes of insufficiently treated sewage. This poses a significant health risk to recreational users of the estuary. Emergency breaching is required to flush out and dilute the insufficiently treated releases. Emergency breaches will also alleviate low oxygen events. The estuary is used for contact recreational activities. Breaching has been shown to improve water quality. Potential loss of agricultural resources as a N/A result of high water levels Human wellbeing and safety and wellbeing Human Risk to aquaculture facilities as a result of high N/A water levels Loss/impaired access (roads, footpaths, cattle None known. crossings) Impacts on recreational use (e.g. increased Prior to the construction of the Hartebeeskuil Dam, there were three typical mouth states. After the construction of the dam depth/surface area when mouth is closed, saline conditions and even hypersaline conditions could be observed during low flow periods and closed mouth conditions. reduce fishing) During prolonged closed mouth periods water quality deteriorates to an extent where recreational activities are not possible. The high water levels associated with prolonged close mouth period means that recreational fishing and bait collecting is not Threat Discussion possible. If there is a discharge of insufficiently treated sewerage from the WWTW, it also means that recreational activity is not possible. Emergency breaches will improve water quality so that recreational activities can occur. Noxious algal blooms During long, closed phases in summer, algal growth is stimulated and can result in accumulation of decaying plant matter in shallow warm water. This leads to low oxygen conditions which most often end in fish kills. The daily DO monitoring done during 2016 and 2017 have shown that anoxic conditions are not evident during periods when the mouth is open. Emergency breaches will thus have a positive effect. Impact on avifauna abundance, species Important bird habitat Not important for waders, but supports moderate numbers of terns, gulls and water fowl. richness/community composition Impact of emergency Water fowl do not fly at night and may be washed out to sea if the emergency breach is breaching completed at night. Impact of NOT conducting an The system will become anoxic (including anoxic sediments) with greater chances of an emergency breach avian botulism outbreak. Impact on estuarine fish abundance, species Important fish nursery Fish species that have been recorded in the Hartenbos estuary include seven Category IIa richness/community composition species, which are marine species that exclusively breed in estuaries. Two species were resident species which have not been recorded to breed in freshwater or marine environments (Category Ia) while two other species were identified to have estuarine and marine breeding populations (Category Ib). The nursery value of the Hartenbos estuary was estimated between 1.63 and 8.15 million Rand per year (Turpie and Clark, 2007 AEC 2015). Impact of emergency Emergency breaching may flush insufficiently treated sewage out to sea, reducing the breaching amount of organic matter that will decompose in the estuary. Emergency breaching will lower water levels so that infrastructure is not at risk. Emergency breaching will prevent Ecosystem requirements hypersaline, eutrophic and anoxic conditions. The impact of emergency breaching is thsu positive. Impact of NOT conducting an Fish kills will most definitely occur as a result of oxygen depletion and possibly high emergency breach ammonia levels. Sewerage infrastructure along the river i.e. pump stations and septic tanks will become inundated. Impact on estuarine invertebrate abundance, Invertebrate communities Prior to the construction of the Hartebeeskuil Dam, there was three typical mouth states. species richness/ community composition After the construction of the dam, hypersaline, anoxic and eutrophic conditions could be observed during low flow periods and closed mouth conditions. The WWTW became Threat Discussion operational in 1986 and ever increasing nutrient rich fresh water volumes are being released into the estuary. The prevalence of hypersaline, anoxic and eutrophic conditions is not good for invertebrate populations. Invertebrate community composition, abundance and diversity are unknown at present. Historic records show that burrowing sand prawns, tube worms and pencil bait were prevalent in the estuary. Impact of emergency Emergency breaching will not maintain open mouth conditions but it will alleviate breaching hypersaline, anoxic and eutrophic conditions. Emergency breaching may flush insufficiently treated sewage out to sea, reducing the amount of organic matter that will decompose in the estuary. Impact of NOT conducting an Invertebrate kills will most definitely occur as a result of oxygen depletion and possibly high emergency breach ammonia levels. Impact on estuarine macrophytes (plants) Botanic importance Overall, the botanic importance of the Hartenbos compared to other estuaries survey is low to moderate (Coetzee et al., 1997). Alien infestation of the riparian habitat is widespread. Supratidal saltmarsh is common and its extent should not decrease. Impact of emergency Emergency breaching will reduce water levels. If this occurs in spring and summer it may be breaching beneficial for supratidal saltmarsh reproduction. Submerged macrophyte biomass and extent may be reduced temporarily. Impact of NOT conducting an Increased turbidity due to the sewage spill could supress growth of sensitive submerged emergency breach species due to reduced light availability. Excess nutrients will result in proliferation of more robust species (can be harmful and aesthetically unpleasant). Decaying plant matter will contribute to reduced dissolved oxygen levels. Ecosystem requirements Water quality thresholds of concern that Current status Water quality is currently considered to be poor. Excess nutrients are primarily introduced would compromise estuarine ecosystem or by the WWTW, while upstream sources including agriculture, informal settlements and ecosystem services septic tanks are also contributing to ongoing deterioration. Bacterial contamination harmful to humans generally originates upstream of the WWTW, except when insufficiently treated sewage is released if the plant malfunctions. Impact of emergency In the case of a sewage spill, emergency breaching will flush insufficiently treated sewage breaching out of the estuary and has the potential to reduce the risk of a low oxygen event and associated fish kills. In the case of a low oxygen event (<2 mg/l) not necessarily related to a sewage spill, emergency breaching conducted in accordance with the breaching protocol has the potential to improve DO levels. Threat Discussion Impact of NOT conducting an A sewage spill that occurs during closed mouth conditions will most definitely lead to a low emergency breach oxygen event and associated fish kills and invertebrate kills. Risk of avian botulism may also be increased. If an emergency breach is not done when water levels are high, the chances of flooding is certain as there is a constant discharge of treated effluent into the estuary. Eutrophication Current status Eutrophication risk is considered high (Lemley et al., 2014) Impact of emergency In the case of a sewage spill, emergency breaching will flush insufficiently treated sewage breaching out of the estuary, reducing the amount of nutrients available for algal proliferation and has the potential to temporarily reduce the eutrophication risk. Impact of NOT conducting an In the case of a sewage spill, eutrophication risk is extremely high. In the event of emergency breach prolonged close mouth conditions the risk of eutrophication is also high. Sedimentation Current status Sedimentation processes have been altered through the construction of the Hartebeeskuil Dam (reduced flooding capacity) and obstructions in the estuary. Ecosystem requirements Impact of emergency Emergency breaches in the event of spills will most often result in premature closure of the breaching estuary by the influx of marine sediment, contributing to the accumulation of marine sediments near the estuary mouth. Emergency breaching done in response to high water levels will flush sediments from the system. Impact of NOT conducting an Sediments may become anoxic after the occurrence of constant anoxic and eutrophic emergency breach conditions. Draft Hartenbos Estuary Management Plan Appendices: Mouth Management 7.2.5 Breaching procedure as per the second generation Mouth Management Protocol To ensure successful emergency breaching several hydrological, hydrodynamic, ecological and safety aspects must be considered in the breaching procedure for the Hartenbos Estuary. These are detailed in (Table 11). 7.2.5.1 Emergency Breaching As per this second generation EMP and MMP emergency breach can be triggered by the following situations: 1. When the WWTW is about to release, or has already released, large quantities of insufficiently treated sewage i.e. effluent which may or does not comply with the Water Quality parameters descried in the Water Use Licence, into the estuary due to malfunctioning of the plant; or 2. Dissolved oxygen (DO) concentrations in the estuary are measured at 3-4 mg/l for more than two days, which is followed by a further drop to 2 mg/l or less. 3. When water quality in estuary exceeds the water quality parameters for marine waters in the lead up to or during the peak holiday seasons namely the Easter holidays or December. 4. During the initial phases of an algae bloom which will be identifiable by the distinct change in water colour observed. 5. When water level in the estuary reaches 1.8 m. Note that emergency breaching must if, possible be delayed until it can coincide with spring tide (four days before or three days after the maximum tidal range for the Spring Tide); and when the water metre at the railway bridge measures at least 1.8 m above mean sea level. Breaching cannot be implemented if storm surges are predicted to occur. This is the ideal, however if the emergency event is occurring more than 12 days from spring tide, the breach can be conducted at any water level. Depending on the nature of the emergency, a decision might be taken to delay the breach in order to ensure that the correct water levels are attained for an upcoming planned breach. The breaching procedure for emergency breaching is described in table 13. 7.2.5.2 Planned Breaching As per this second generation EMP and MMP planned breaching of the Hartenbos Estuary will occur as follows: 1. At the end of March / start of April 2. At the end of October Planned breaches will be done a few days prior to spring tide, when water level in the estuary is 1.8 m. 76 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management The breaching procedure for planned breaches are as follows: 1) In the event that the mouth is open 2 and a half months prior to a planned breach, the mouth will be closed via a sand berm. The sand berm will be put in place across the estuary landward of the high water mark. 2) the week prior to spring tide, the berm height on the sea side of the berm described above, will be reduced. Sand will be moved to the northern bank of the estuary. The height of the south western sand spit will also be reduced. 3) two days prior to spring tide, the estuary will be breached at a location approximately 140 m north of the parking lot. 4) The tidal funnel will be trimmed in height prior to the next two spring tide cycles. The decision to conduct an emergency or planned breach will be made by Mossel Bay Municipality in its role as responsible management authority. The chairperson of the Estuary Advisory Forum, CapeNature, DEA&DP, DWS, BGCMA and Eden District Municipality will be informed. The breach will, where possible be monitored by independent environmental control officer. Estuarine specialists should also be consulted throughout this process. Lead authorities involved in the emergency breaching procedure are as follows: Mossel Bay Municipality Eden District Municipality Department of Environmental Affairs and Development Planning Department of Water and Sanitation (in the case of a sewage spill) Department of Agriculture, Forestry and Fisheries CapeNature Breede Gouritz Catchment Management Agency There is often considerable controversy concerning the location where a mouth breaching should take place. Naturally, the position of where the estuary opens changes over time and the correct location that will ensure the most effective emergency breach will vary as a result. The Hartenbos Estuary is a double-sandspit estuary with the major sandspit on the south- western bank and a secondary short sandspit on the north-eastern bank with the lowest point generally occurring somewhere between these two sandspits. These sandspits erode and fully develop depending on hydrodynamic conditions outside and inside of the estuary. Historical aerial photos and other records suggest that under natural circumstances, shortly after a flood, the widened and straightened channel runs along the north-eastern bank opening up into a funnel-shaped tidal inlet close to the north-eastern bank (Table 11) (Bickerton, 1982). This mouth state can be associated with heavy erosion of the north-eastern bank below the railway line (Bickerton, 1982). Secondly, the estuary can take form of an overflowing lagoon, where a narrow channel meanders from the south-western side towards the north-eastern bank, spilling out to sea via a sand delta at the foreshore (Bickerton, 1982). During prolonged closed mouth conditions, the south-western sandspit develops fully, pushing the channel towards the 77 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management north-eastern bank without causing erosion (Table 11) (Bickerton, 1982). A section 30 directive obtained from DEA&DP allowed the removal of the northern section of the south western sand spit. Historical information provided by the Hartenbos EAF suggests that this sandspit has grown significantly in recent years. It is suggested that the height of this berm may have been maintained by mechanical means, although this could not be verified. Experiences in 2017 showed that the trimming of the berm and removal of sand from the mouth meant that the berm height remained at a height where tidal exchange could occur for a prolonged period of time. In addition, the ‘natural berm’ height throughout November and December 2016 was less than 1.4 m. This seen in the water level data for this period. Due to the variable states of the estuary mouth (i.e. berm height dependent on eroding and building of the sandspits), it is recommended that the mouth should be opened by maintaining the shortest route to the sea while also choosing the lowest possible berm height. It is anticipated that consideration of both these factors will lead to artificial breaching near the natural breaching location (i.e. somewhere between the centre of the mouth and the north- eastern bank). It is hoped that this will maximise scouring of sediments from the mouth area while also minimising disturbance of the estuarine habitat. 78 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management Table 14 Hartenbos Estuary breaching procedure. Note that emergency breaching in case of a low oxygen event can only be conducted if all conditions are met. Emergency breach in response to non- Emergency breaching in the Emergency breaching in case of a low oxygen Emergency breach in response to Breaching considerations compliance with WQ parameters for case of a sewage spill event water level reaching 1.8 m recreational Use Threshold of concern, i.e. Large volumes of insufficiently Trigger: DO concentration is measured at 3-4 When the chemical and bacteriolocal When water level in the estuary trigger treated sewage are released mg/l for more than two days and is followed by parameters described in the recreational reaches 1.8 m into the estuary due to the a further drop to 2mg/l or less. water quality guidelines for coastal waters are malfunctioning of the Dissolved oxygen must be measured before exceeded. Note this guideline also cautions Hartenbos Regional WWTW. first light within the first 10 cm of the water against the presence of algae in the system. Non-compliance with permit column at the N2 bridge, approximately 1.8 km conditions, quality of incoming upstream. raw effluent and operation Ideally Breaching can only occur if all other results are all triggers. conditions are met. However, if needed breaching can occur anytime. Minimum breaching level Breach at any water level if Water levels between 1.6 and 1.8 metres above (water level should be as triggered MSL. Breach at any water level When water level in the estuary high as possible before Ideally the breach should be conducted when reaches 1.8 m breaching) water levels are around 1.8 MSL Breaches at this level result in highest scouring capacity, increasing channel depth and outflow velocities. The mouth will be kept open for longer to facilitate the maximum influx of seawater possible. It is recommended that the Mossel Bay Municipality and Cape Nature cooperate to police the berm when low oxygen events occur and water levels are insufficient for breaching. This can prevent unauthorised breaching. Optimum breaching period Breach at any time of year if Breach at any time if triggered and all Breach at any time of the year Breach at any time of the year triggered conditions are met Neap-spring breaching No consideration necessary In an ideal situation the breach should occur at In an ideal situation the breach should occur No consideration necessary considerations spring tide, four days before or three days after at spring tide, four days before or three days 79 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management spring tide. If not possible, then the breach can after spring tide. If not possible, then the occur at any time. breach can occur at any time. Weather conditions Breaching should not occur if storm surges are predicted to occur. Storm surges import marine sediments into the estuary, thereby closing the mouth prematurely Timing of breaching Breach two hours before high tide, or just after high tide to prevent high waves from closing the estuary immediately. No consideration, give preference to next high tide. Warn public to ensure their safety. Consideration must be given to delay breach, depending on the nature of the Day or night time reason for the breach, if it is close to the time when a planned breach is to be done. breaching Excavate a deep and wide trench before breaching to maximise outflow. Breaching trench The mouth should be opened by maintaining the shortest route to the sea (longer channel = greater bottom friction, reduced flow) while also choosing the lowest Location of the breaching possible berm height. It is anticipated that consideration of both these factors will lead to artificial breaching near the natural breaching location (i.e. somewhere position between the centre of the mouth and the north-eastern bank). Ideally, the position and width of the trench would provide enough space for separate ebb and flood tidal channels to develop. 80 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management 81 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management 7.2.6 Key monitoring information Key monitoring requirements prior to, during and after an emergency or planned breaching event are detailed in Table 15. These monitoring requirements are crucial in facilitating responsible and adaptive mouth management. Note that instantaneous measurements taken for the monitoring of a breaching event must be investigated within the context ongoing monitoring results. A comprehensive long-term monitoring protocol is included in Appendix 4 of the EMP. Refer to Figure 6 and Table 16 for the location of the recommended water quality monitoring stations. Table 15 Key monitoring requirements prior to, during and after an emergency and planned breaching event to facilitate responsible and adaptive mouth management of the Hartenbos Estuary. Ecological Monitoring Action Temporal Scale Spatial Scale Component (frequency and when) (No. Stations) Hydrodynamics Record water level in metres Continuous, the existing Existing recorder at the old above mean sea level recorder takes hourly railway bridge DWS K1T010 readings. (operational since 1993) Record mouth state: open, As soon as the need for Mouth opening, closed, closing or emergency breaching has overflowing. been identified. Take at least one photograph Monitor mouth state daily for from the same angle as per one month after the monitoring programme in emergency breaching is Appendix 4. completed. Note whether there is evidence of illegal artificial breaching. Sediment Measure berm height using As soon as the need for Mouth dynamics appropriate technologies. emergency breaching has Establish where the lowest been identified. point of the berm. Bathymetric surveys: Series of After emergency breaching Entire estuary cross section profiles and a (no later than two months longitudinal profile collected at after the breaching event). fixed 500 m intervals but in more detail at the mouth including the berm (every 100 m). Vertical accuracy at least 5 cm. Water quality Salinity and temperature Prior to, and immediately after At all stations except at the profiles the breaching event. head of the estuary. Dissolved oxygen and surface Take daily measurements for At all stations water temperature. at least one month after the need for an emergency breach has been identified. Dissolved oxygen must be measured before sunrise (the DO minimum is expected to occur at night). E. coli and Enterococci Weekly for one month after At all stations insufficiently treated sewage 82 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management Ecological Monitoring Action Temporal Scale Spatial Scale Component (frequency and when) (No. Stations) has been released into the estuary from the WWTW. Biota Monitor occurrence of fish kills Daily for at least one month Entire estuary and avian botulism. after the need for an Fish: Identify species, count, emergency breach has been measure size and weigh dead identified. fish Bird: Identify species and count dead birds. Figure 6 Recommended water quality monitoring stations and location of the water level metre (DWS K1T010) in the Hartenbos Estuary. Table 16 GPS location and status of water quality stations and water level metre in the Hartenbos Estuary. Monitoring station Existing/ New GPS coordinates Head of estuary New 34°6.610'S, 22°5.037'E Transand Existing – Hartenbos Regional Waste 34°6.718'S 22° 5.296'E Water Treatment Works K1H025Q01/Ou Padbrug Existing – DWS & Hartenbos Regional 34°7.098'S, 22°6.150'E Waste Water Treatment Works K1H011Q01 Existing – DWS 34°6.949'S, 22°6.683'E K1H009Q01/Mond Existing - DWS & Hartenbos Regional 34°7.083'S, 22°7.133'E Waste Water Treatment Works 83 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management K1T010 Existing water level meter - DWS 34°7.033'S, 22°6.983'E 7.2.7 Adaptive management through post breaching reporting and consultation sessions Table 17 below summarises the minimum content of a Hartenbos Estuary post-breaching report. The preliminary report should be compiled within about eight weeks of breaching, with data gaps addressed after mouth closure. Table 17 Breaching report requirements for the Hartenbos Estuary. Reporting information Agency Responsible Reason for breaching the estuary Mossel Bay Municipality Ocean information Mossel Bay Municipality State of the tide (spring-neap/high-low tide) Sea conditions (calm/stormy) Estuary information DWS and Mossel Bay Municipality Water level from the DWS meter prior to breaching Water volume before breaching Maximum outflow rate during breaching calculated from water levels and surface area of the system Outflow duration (from water level graph) Lowest water level reached after breaching (from water level graph) Location of the channel Mossel Bay Municipality Position in comparison to the historical channel (establish from photos taken) Channel length Period that the mouth stayed open. Mossel Bay Municipality Bathymetry survey results after breaching compared to previous reports Mossel Bay Municipality compiled as part of the ongoing monitoring of the estuary. Salinity measurements before and after breaching Mossel Bay Municipality Fish kill report Mossel Bay Municipality Assessment report compiled by: Name: Organisation: Date: Contact details: 84 Draft Hartenbos Estuary Management Plan Appendices: Mouth Management 7.2.8 References Bickerton IB. 1982. Report No. 11 Hartenbos (CMS1). In Estuaries of the Cape Part II: Synopsis of available information on individual systems, Heydorn AEF, Grindley JR (eds). CSIR Research Report 425. Stellenbosch; Breitburg DL. 2002. Effects of hypoxia, and the balance between hypoxia and enrichment, on coastal fishes and fisheries. Estuaries 25: 767- 781. CSIR 2014. Long-Term Ecological Monitoring for the Port of Durban: Surveys made in 2013. CSIR Report CSIR/NRE/ECOS/IR/2014/0011/B. Diaz RJ and Rosenberg R. 1995. Marine benthic hypoxia: A review of its ecological effects and the behavioral responses of benthic macrofauna. Oceanography and Marine Biology Annual Review 33: 245-303. Lemley DA, Taljaard S, Adams JB, Strydom N. 2014. Nutrient characterisation of river inflow into the estuaries of the Gouritz Water Management Area, South Africa. Water SA 40: 687–698. Nixon SW. 1995. Coastal marine eutrophication: a definition, social causes, and future concerns. Ophelia 41: 199-219. Pearson TH and Rosenberg R. 1978. Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanography and Marine Biology Annual Revue 163: 229-311. Swartz CD, Knott M, Malan W, Eden JD van. 2000. Biological Phosphate Removal to Meet Strict Quality Requirements for Discharge into Ecosensitive Hartenbos Estuary. Presented at the WISA 2000 Biennial Conference, Sun City, South Africa, 28 May - 1 June 2000. USEPA 2001. Nutrient criteria technical guidance manual: estuarine and coastal marine waters. EPA- 822-B-01-003. Office of Water, Office of Science and Technology, Washington, D.C. USEPA 2003. Ambient water quality criteria for dissolved oxygen, water clarity and chlorophyll a for the Chesapeake Bay and its tidal tributaries. EPA 903-R-03-002. US EPA Region III, Annapolis, MD, Region III Water Protection Division, Philadelphia, PA, and Office of Water, Office of Science and Technology, Washington, DC. Wannamaker CM and Rice J. 2000. Effects of hypoxia on movements and behavior of selected estuarine organisms from the southeastern United States. Journal of Experimental Marine Biology and Ecology 249: 145-163. 85 Draft Hartenbos Estuary Management Plan Appendices: RDM Recommendations 7.3 Appendix 3: Ecological specifications and thresholds of potential concern (TPC) for monitoring parameters listed in Appendix 4 The following table provides “Ecological Specifications/Resource Quality Objectives” and “Thresholds of Potential Concern” (TPC) for the Hartenbos Estuary. “Ecological Specifications/Resource Quality Objectives” are defined as being clear and measurable specifications of ecological attributes (in the case of estuaries - hydrodynamics, sediment dynamics, water quality and different biotic components) that define a specific ecological reserve category, while “Thresholds of Potential Concern” are defined as measurable end points related to specific abiotic or biotic indicators that if reached (or when modelling predicts that such points will be reached) should prompt management action. Note that thresholds of potential concern endpoints are generally defined such that they provide early warning signals of potential non-compliance to ecological specification (i.e. not the point of ‘no return’). Thus, indicators (or monitoring activities) included here incorporate biotic and abiotic components that are considered particularly sensitive to ecological changes associated with changes in river inflow and should be interpreted as such. Table 18 Ecological Specifications and Thresholds of Potential Concern for the Hartenbos Estuary (Category C) (Source DWS 2015). Ecological Ecological Specifications Threshold of Potential Concern Component MAR does not vary by more than 10% Floods (indicated by 1:10 year event) do not Hydrology Maintain at least present day base flows reduce by more than 5% from present. Base flows do not incresae by more than 50% from present Closed mouth state do not decrease by 10% Maintain mouth state to create the from present required habitat for birds, fish, Hydrodynamics Average water level in system >10% from macrophytes, microalgae and water present quality Tidal amplitude (when open) <20% Average salinity along estuary decrease by 5 below baseline average (to be determined) DO <5 mg/l in estuary Salinity distribution not to cause Turbidity >20 NTU in low flow exceedance of TPCs for fish, invertebrates, Secchi in fresher part: <0.5 m macrophytes and microalgae DIN >200 µg/l average (to be confirmed Turbidity and Dissolved oxygen not to through future monitoring) cause exceedance of TPCs for biota DIP > 50 µg/l average (to be confirmed Water Quality DIN/DIP concentrations not to cause in through future monitoring) exceedance of TPCs for macrophytes and Concentrations in water column exceed microalgae target values as per SA Water Quality Toxic substances not to cause exceedance Guidelines for coastal marine waters of TPCs for biota (DWAF, 1995) Concentrations in sediment exceed target values as per W10 Region guidelines (UNEP/Nairobi Convention Secretariat and and CSIR, 2009) Average sediment composition (% fractions) Sediment Flood regime to maintain the sediment along estuary change from baseline (to be dynamics distribution patterns and aquatic habitat measured) by 30% (per survey) 86 Draft Hartenbos Estuary Management Plan Appendices: RDM Recommendations Ecological Ecological Specifications Threshold of Potential Concern Component (instream physical habitat) so as not to Average depth along main channel change exceed TPCs for biota from 30% of baseline (to be determined) Changes in sediment grain size distribution (system expected to significantly fluctuate patterns not to cause exceedance of TPCs in bathymetry between flood and extended in benthic invertebrates closed periods) Changes in average sediment composition and characteristics Change in average bathymetry Phytoplankton >8 µg/l (median) 2 Maintain median phytoplankton/benthic Benthic microalgae >42 mg/m (median) microalgae biomass Phytoplankton >20 µg/l and/or cell density Microalgae Prevent formation of phytoplankton >10 000 cell/ml (once off) blooms Dinoflagellates, chlorophytes and/or cyanobacteria >10% of relative abundance 20% change in macrophyte area (reeds Maintain distribution of macrophyte currently cover 9 ha, saltmarsh 47 ha) habitats Macroalgal blooms cover > 50% of the open Prevent the spread of reeds into open water area water Presence of invasive aquatic macrophytes Macrophytes Prevent and increase in nutrients and (e.g. Azolia, water hyacinth) macroalgae blooms Invasive plants cover > 10% of flood plain Prevent the spread of invasive trees (e.g. Increase in bare areas in salt marsh Acacia spp.) in the riparian zone. because of decrease in moisture and Maintain integrity of salt marsh increase in salinity > 30% of salt marsh Establish presence absence of sand prawn Callichirus kraussi on sand banks in lower estuary If present populations deviate from average Invertebrates Establish abundance of the copepod baselines (as determined in first three Pseudodiaptomus hessei or estuarine visits) by more than 30% congeneric in the zooplankton of the estuary Fish assemblage should comprise the five estuarine association categories in similar proportions (diversity and abundance) to that under the reference. Numerically assemblage should comprise: Ia estuarine residents (20-60%) Ia estuarine residents <20% Ib marine and estuarine breeders (10-30%) Ib marine and estuarine breeders <10% IIa obligate estuarine-dependent (20-40%) IIa obligate estuarine-dependent <20% IIb estuarine associated species (5-20%) IIb estuarine associated species <5% IIc marine opportunists (20-80%) IIc marine opportunists <20% IV indigenous fish (1-5%) IV indigenous fish <1% Fish V catadromous species (1-5%) V catadromous species 1% Cateogory Ia species should contain viable Ia represented only by G. aestuaria populations of at least two species (e.g. G IIa exploited species in very low numbers of aestuaria, Hyporamphus capensis, absent Omobranchus woodii) REI species represented only by G. Category IIa obligate dependents should be aestuaria, Myxys capensis absent. well represented by large exploited species (i.e. A. japonicus, L. lithognathus, P. commersonnii, Lichia amia) REI species dominated by both Myxus capensis and G. aestuaria. Number of birds in any group, other than Maintain populations of original groups of species that are increasing regionally such Birds birds present on the estuary as Egyptian geese, drops below the baseline median (determined by past data and or 87 Draft Hartenbos Estuary Management Plan Appendices: RDM Recommendations Ecological Ecological Specifications Threshold of Potential Concern Component initial surveys) number of species and/or birds counted for three consecutive summer or winter counts. 88 Draft Hartenbos Estuary Management Plan Appendices: Monitoring Protocol 7.4 Appendix 4: Recommended Monitoring Protocol for the Hartenbos Estuary Table 19 provides a list of recommended abiotic and biotic parameters to be monitored for the Hartenbos Estuary. These generic recommendations were sourced from DWS (2015b) and were adapted where necessary to reflect the specific needs of the Hartenbos Estuary and to align future monitoring with existing monitoring wherever possible. Water quality in the Hartenbos Estuary has been monitored by the Mossel Bay Municipality and the Department of Water and Sanitation (DWS) at various stations in the Hartenbos Estuary since 1982. Early detection of low oxygen events, eutrophication risks or bacterial contamination and their appropriate management actions (short to long-term interventions) rely on continued monitoring that is aligned with existing water quality sampling locations and methods of the Mossel Bay Municipality and the DWS. Refer to Figure 6 and Table 16 for the location of the recommended water quality monitoring stations. In line with the recommendations by DWS (2015b), the monitoring programme includes a baseline survey and ongoing monitoring thereafter to assess changes in health of the system over time. Recommendations for monitoring of visitor numbers, profiles and opinions, and angler catch and effort required in terms of the management plan are also included here. The responsibility of the monitoring outlined below falls with the Department of Water Services who are responsible for the National Estuarine Management Project. As per the conditions of the Water Use Licence for the WWTW MBM will continue doing water quality monitoring for a limited set of parameters. Eden District Municipality will also assist with Water Quality Monitoring. It is however critically important that all tiers of the National estuarine monitoring project is rolled out. 89 Table 19 Recommended baseline and long-term monitoring protocols for the Hartenbos Estuary. Monitoring parameters include biotic and abiotic components and are linked to the Ecological Specifications and Thresholds of Potential Concern (Appendix 4) (Modified from the generic monitoring protocol in DWS, 2015b). Ecological Component Monitoring Action Temporal Scale Spatial Scale (frequency and when) (No. Stations) Hydrology Record river inflow at the head of the estuary Continuous Install recorder near the upstream boundary of the estuary Obtain effluent volumes released into the estuary from the WWTW Monthly WWTW outfall point Obtain environmental release volumes from the Hartebeeskuil Dam Monthly Outlet pipe of Hartebeeskuil Dam Hydrodynamics Record water level in metres above mean sea level Hourly Existing recorder at the old railway bridge DWS K1T010 (operational since 1993). Aerial photography (or using high resolution satellite imagery i.e. 5x5 Once-off (baseline), thereafter every three Entire estuary m pixel size, e.g. Google Pro or BirdEye). years. Mouth State: Weekly. Mouth Take at least one photo from the same angle each time. Note whether the estuary is open, closed or overflowing. Note whether there evidence of illegal artificial breaching. Sediment dynamics Monitor berm height using appropriate technologies. Quarterly Mouth Bathymetric surveys: Series of cross section profiles and a Once-off (baseline), thereafter every three Entire estuary. Collected at fixed 500 longitudinal profile years and after large re-setting event. m intervals but in more detail at the mouth including the berm (every 100 m). Vertical accuracy at least 5 cm. Collect sediment grab samples (at cross section profiles) for analysis Once-off (baseline), thereafter every three Entire estuary of particle size distribution (and ideally origin, i.e. microscopic years observations). Water quality Electrical conductivity Monthly New monitoring station at the head of the estuary Salinity and temperature profiles Quarterly At all stations except at the head of the estuary. Dissolved oxygen and surface water temperature. Monthly from 1 April - 1 November, daily from At all stations 1 December – 31 March. Ecological Component Monitoring Action Temporal Scale Spatial Scale (frequency and when) (No. Stations) Take daily measurements for 30 days if insufficiently treated sewage has been released into the estuary. Dissolved oxygen must be measured before sunrise (DO minimum is expected at night) pH, nitrate, nitrite, ammonia, phosphate, total suspended solids. Monthly At all stations. Measure pesticides/herbicides and metal accumulation in sediments Once-off (baseline), thereafter every three to At all stations and depositional areas (for metals investigate establishment of distribution models – see six years if baseline results show (i.e. muddy areas, to be determined) Newman and Watling, 2007). contamination. E. coli and Enterococci Monthly. At all stations Weekly for one month after insufficiently treated sewage has been released into the estuary from WWTW. Microalgae Record relative abundance of dominant phytoplankton groups, Quarterly, preferably for two years. Thereafter Along length of estuary, minimum five i.e. flagellates, dinoflagellates, diatoms, chlorophytes and blue- every three years stations green algae. Chlorophyll-a measurements taken at the surface, 0.5 m and 1 m depths, under typically high and low flow conditions using a recognised technique, e.g. spectrophotometer, HPLC, fluoroprobe. Intertidal and subtidal benthic chlorophyll-a measurements (4 replicates each) using a recognised technique, e.g. sediment corer or fluoroprobe. Macrophytes Map area covered by different macrophyte habitats using recent Once-off in summer (baseline). Thereafter Entire estuary (mapping) Where there imagery. Conduct field survey to record total number of every three years in summer. is salt marsh (minimum three transect macrophytes habitats, identification and total number of sites) macrophytes species, number of rare or endangered species, or those with limited populations. Assess extent of invasive species in EFZ. For salt marsh areas greater than 1 ha, measure percentage plant cover along elevation gradient. Sediment samples collected along the transect and analysed in the laboratory for sediment moisture, organic content, EC, pH and redox potential. In the field, measure depth to water table and ground water salinity. Ecological Component Monitoring Action Temporal Scale Spatial Scale (frequency and when) (No. Stations) Invertebrates Collect duplicate zooplankton samples at night from mid-water Quarterly, preferably for two years (baseline). Minimum of three sites along length of levels using WP2 nets (190 um mesh) along estuary. Thereafter every two years in mid-summer entire estuary Collect sled samples (day) at same zooplankton sites for hyper For hole counts –three sites in each of benthos (190 um). muddy or sandy areas, Collect grab samples (5 replicates) (day) from the bottom substrate in mid-channel areas at same sites as zooplankton (each samples to be sieved through 500 um). Intertidal invertebrate hole counts using 0.25 m2 grid (5 replicates per site). Establish the species concerned (Callichirus kraussi or Upogebia Africana) using a prawn pump. Collect sediment samples using the grab for particle size analysis and organic content (at same sites as zooplankton) (preferably link with sediment dynamics) Fish Ongoing: Ongoing: Ongoing: Record species and abundance of fish, based on seine net and gill Once-off in spring/ summer and autumn/ 3-5 stations (mouth, mid, top) net sampling. Sampling with a small beam trawl for channel fish winter (baseline). Thereafter bi-annually should also be considered. spring/summer and autumn/winter. Fish kills: Seine net specifications: 30 m x 2m, 15 mm bar mesh seine with a Entire estuary 5 mm bar mesh 5 m either side and including the cod-end. Fish kills: Daily for at least one month after Gill nets specifications: Set of gill nets each panel 30 m long by 2 the need for an emergency breach has been m deep with mesh sizes of 44 mm, 48 mm, 51 mm, 54 mm, 75 identified. mm, 100 mm and 145 mm Gill net sampling can be replaced by a large mesh seine (44 mm stretch mesh, 100 m x 2 m). Trawl specification: 2 m wide by 3 m long, 10 mm bar nylon mesh in the main net body and a 5 mm bar in the cod-end Fish kills: Identify species, count, measure, and weigh dead fish. Birds Ongoing: Ongoing: Ongoing: Undertake counts of all water-associated birds. All birds should be Baseline data exists (CWAC data). Continue Entire estuary, continue as per CWAC identified to species level and total number of each counted. CWAC counts bi-annually. methodology. Avian botulism: Identify species and count dead birds. Avian botulism: Entire estuary Ecological Component Monitoring Action Temporal Scale Spatial Scale (frequency and when) (No. Stations) Avian botulism: Daily for at least one month after the need for an emergency breach has been identified. Human use Collect statistics on the profile (origin, sex, age, income category) and Continuous Visitor entry points and key sites of activities of visitors to the Hartenbos Estuary using self-fill in interest questionnaires Survey visitor and local opinions on impacts of key management Every two years Entire estuary interventions. Creel surveys of Catch, Effort and C.P.U.E. for shore-based anglers. Conduct a survey on five randomly selected Entire estuary days per week (include weekends and public holidays) over a two month period during peak holidays (December & January). Repeat every 5 years. Draft Hartenbos Estuary Management Plan Appendices: Monitoring Protocol Figure 7 Recommended water quality monitoring stations and location of the water level metre (DWS K1T010) in the Hartenbos Estuary. 94 Draft Hartenbos Estuary Management Plan Appendices: Monitoring Protocol Table 20 GPS location and status of recommended water quality monitoring stations and water level metre in the Hartenbos Estuary. Monitoring station Status GPS coordinates Head of estuary New 34°6.610'S, 22°5.037'E Transand Existing – Hartenbos Regional Waste 34°6.718'S 22° 5.296'E Water Treatment Works K1H025Q01/Ou Padbrug Existing – DWS & Hartenbos Regional 34°7.098'S, 22°6.150'E Waste Water Treatment Works K1H011Q01 Existing – DWS 34°6.949'S, 22°6.683'E K1H009Q01/Mond Existing - DWS & Hartenbos Regional 34°7.083'S, 22°7.133'E Waste Water Treatment Works K1T010 Existing water level meter - DWS 34°7.033'S, 22°6.983'E 95 Draft Hartenbos Estuary Management Plan Appendices: Monitoring Protocol 7.5 Appendix 5: National response protocol for fish kills Large-scale fish kills have become a common phenomenon estuaries impacted by anthropogenic activities. The most recent fish kills in the Hartenbos Estuary occurred in January 2015 and in March 2016. An understanding of the causes of fish kills that may occur in future is fundamental in order to implement preventative measures to reduce their frequency and magnitude in the long-term. Grant et al. (2014) recognised the need for a nationally applicable response protocol for fish kills to streamline the investigation and reporting of fish kill incidents. This protocol has four phases including the Pre-Incident Phase, the Trigger Phase, the Investigation Phase and the Stand-down Phase. The Protocol should be consulted for detailed explanations and actions to be taken to successfully complete each of these phases. The pre-incident phase of a fish kill investigation represents any stage where no fish kill incident is reported or no fish kill investigation is active, and encompasses a range of ongoing tasks that will develop and maintain a level of preparedness in the event of a fish kill occurring. Such tasks include: • interdepartmental and interdisciplinary communication; • public awareness communication; • obtaining and maintaining fish kill investigation kits and sample containers; • identification and communication with relevant specialists and laboratories able to provide the necessary analyses; and • training. The remaining three phases, i.e. the Trigger Phase, the Investigation Phase and the Stand-down Phase are shown in form of decision tree diagrams in Figure 8. Figure 9 shows a recommended decision tree to establish whether a detailed fish kill investigation is required. 96 Draft Hartenbos Estuary Management Plan Appendices: Monitoring Protocol Figure 8 Fish kill investigation protocol showing steps to be taken during the Trigger, Investigation and Stand-dwon phases (Source: Grant et al. 2014). 97 Draft Hartenbos Estuary Management Plan Appendices: Monitoring Protocol Figure 9 Recommended decision tree for determining the need for a detailed fish kill investigation (Source: Grant et al. 2014). 98 Draft Hartenbos Estuary Management Plan Appendices: Listed Activities 7.6 Appendix 6: Listed activities for which an EIA is required for estuaries in the Western Cape according to the National Environmental Management Act (NEMA) GN R. 983: Listing Notice 1 – Basic Assessment List No. Activity description 17 Development- (i) in the sea; (ii) in an estuary; (iii) within the littoral active zone; (iv) in front of a development setback; or (v) if no development setback exists, within a distance of 100 metres inland of the high- (vi) water mark of the sea or an estuary, whichever is the greater; in respect of- (a) fixed or floating jetties and slipways; (b) tidal pools; (c) embankments; (d) rock revetments or stabilising structures including stabilising walls; (e) buildings of 50 square metres or more; or (f) infrastructure with a development footprint of 50 square metres or more - but excluding- I. the development of infrastructure and structures within existing ports or harbours that will not increase the development footprint of the port or harbour; II. where such development is related to the development of a port or harbour, in which case activity 26 in Listing Notice 2 of 2014 applies; III. the development of temporary infrastructure or structures where such structures will be removed within 6 weeks of the commencement of development and where indigenous vegetation will not be cleared; or IV. where such development occurs within an urban area. 19 The infilling or depositing of any material of more than 5 cubic metres into, or the dredging, excavation, removal or moving of soil, sand, shells, shell grit, pebbles or rock of more than 5 cubic metres from- (i) a watercourse; (ii) the seashore; or (iii) the littoral active zone, an estuary or a distance of 100 metres inland of the high-water mark of the sea or an estuary, whichever distance is the greater – but – excluding where such infilling, depositing , dredging, excavation, removal or moving- (a) will occur behind a development setback; (b) is for maintenance purposes undertaken in accordance with a maintenance (c) management plan; or (d) falls within the ambit of activity 21 in this Notice, in which case that activity applies. 54 The expansion of facilities - (i) in the sea; (ii) in an estuary; (iii) within the littoral active zone; 99 Draft Hartenbos Estuary Management Plan Appendices: Listed Activities List No. Activity description (iv) in front of a development setback; or (v) if no development setback exists, within a distance of 100 metres inland of the high water mark of the sea or an estuary, whichever is the greater; in respect of- (a) fixed or floating jetties and slipways; (b) tidal pools; (c) embankments; (d) rock revetments or stabilising structures including stabilising walls; (e) buildings where the building is expanded by 50 square metres or more; or (f) infrastructure where the development footprint is expanded by 50 square metres or more, but excluding- I. the expansion of infrastructure or structures within existing ports or harbours that II. will not increase the development footprint of the port or harbour; or III. where such expansion occurs within an urban area. 55 Expansion- (i) in the sea; (ii) in an estuary; (iii) within the littoral active zone; (iv) in front of a development setback; or (v) if no development setback exists, within a distance of 100 metres inland of the high water mark of the sea or an estuary, whichever is the greater; in respect of- (a) facilities associated with the arrival and departure of vessels and the handling of cargo; (b) piers; (c) inter- and sub-tidal structures for entrapment of sand; (d) breakwater structures; (e) coastal marinas; (f) coastal harbours or ports; (g) tunnels; or (h) underwater channels; but excluding the expansion of infrastructure or structures within existing ports or harbours that will not increase the development footprint of the port or harbour. 100 Draft Hartenbos Estuary Management Plan Appendices: Listed Activities GN R. 984 Listing Notice 2: Scoping & EIA List No. Activity description 26 Development-- (i) in the sea; (ii) in an estuary; (iii) within the littoral active zone; (iv) in front of a development setback; or (v) if no development setback exists, within a distance of 100 metres inland of the high-water (vi) mark of the sea or an estuary, whichever is the greater; in respect of - (a) facilities associated with the arrival and departure of vessels and the handling of cargo; (b) piers; (c) inter- and sub-tidal structures for entrapment of sand; (d) breakwater structures; (e) coastal marinas; (f) coastal harbours or ports; (g) tunnels; or (h) underwater channels; but excluding the development of structures within existing ports or harbours that will not increase the development footprint of the port or harbour. GN R. 985 Listing Notice 3: Basic Assessment List No. Activity description 4 The development of a road wider than 4 metres with a reserve less than 13,5 metres. (f) In Western Cape: i. Areas outside urban areas; I. Areas containing indigenous vegetation; II. Areas on the estuary side of the development setback line or in an estuarine functional zone where no such setback line has been determined; or ii. In urban areas: I. Areas zoned for conservation use; or II. Areas designated for conservation use in Spatial Development Frameworks adopted by the competent authority. 5 The development of resorts, lodges, hotels and tourism or hospitality facilities that sleep less than 15 people. (a) A protected area identified in terms of the NEMPAA; (b) Outside urban areas within 10 kilometres from national parks or world heritage sites or 5 kilometres from any other protected area identified in terms of NEMPAA or from the core area of a biosphere reserve; (h) In Western Cape: (i) Critical biodiversity areas as identified in systematic biodiversity plans adopted by the competent authority or in bioregional plans; (ii) Outside urban areas, in: 101 Draft Hartenbos Estuary Management Plan Appendices: Listed Activities List No. Activity description I. Areas seawards of the development setback line or within 1 kilometre from the high-water mark of the sea if no such development setback line is determined; II. Areas on the watercourse side of the development setback line or within 100 metres from the edge of a watercourse where no such setback line has been determined; or III. Areas on the estuary side of the development setback line or within an estuarine functional zone where no such setback line has been determined. IV. Areas on the estuary side of the development setback line or within an estuarine functional zone where no such setback line has been determined. 10 The development of facilities or infrastructure for the storage, or the storage and handling of a dangerous good, where such storage occurs in containers with a combined capacity of 30 but not exceeding 80 cubic metres. (g) In Western Cape: i. All areas outside urban areas; or ii. Inside urban areas: I. Areas seawards of the development setback line or within 200 metres from the high-water mark of the sea if no such development setback line is determined; II. Areas on the watercourse side of the development setback line or within 100 metres from the edge of a watercourse where no such setback line has been determined; or III. Areas on the estuary side of the development setback line or in an estuarine functional zone where no such setback line has been determined. 13 The development and related operation of facilities of any size for any form of aquaculture. (d) In Western Cape: i. Areas on the estuary side of the development setback line or in an estuarine functional zone where no such setback line has been determined; ii. In a Protected area identified in terms of NEMPAA; and iii. In an aquatic critical biodiversity area. 14 The development of- (i) canals exceeding 10 square metres in size ; (ii) channels exceeding 10 square metres in size; (iii) bridges exceeding 10 square metres in size; (iv) dams, where the dam, including infrastructure and water surface area exceeds 10 square metres in size; (v) weirs, where the weir, including infrastructure and water surface area exceeds 10 square metres in size; (vi) bulk storm water outlet structures exceeding 10 square metres in size; (vii) marinas exceeding 10 square metres in size; (viii) jetties exceeding 10 square metres in size; (ix) slipways exceeding 10 square metres in size; (x) buildings exceeding 10 square metres in size; (xi) boardwalks exceeding 10 square metres in size; or (xii) (xii) infrastructure or structures with a physical footprint of 10 square metres or more Where such development occurs – (a) Within a watercourse; (b) In front of a development setback; or (c) If no development setback has been adopted, within 32 metres of a watercourse, measured from the edge of a watercourse; Excluding the development of infrastructure or structure within existing ports or harbours that will not increase the development footprint of the port or harbour. 102 Draft Hartenbos Estuary Management Plan Appendices: Listed Activities List No. Activity description (f) In Western Cape: i. Outside urban areas, in: I. A protected area identified in terms of NEMPAA, excluding conservancies; II. National Protected Area Expansion Strategy Focus areas; III. World Heritage Sites; IV. Sensitive areas as identified in an environmental management framework as contemplated in chapter 5 of the Act and as adopted by the competent authority; V. Sites or areas listed in terms of an International Convention; VI. Critical biodiversity areas or ecosystem service areas as identified in systematic biodiversity plans adopted by the competent authority or in bioregional plans; VII. Core areas in biosphere reserves; or VIII. Areas on the estuary side of the development setback line or in an estuarine functional zone where no such setback line has been determined. 18 The expansion and related operation of above ground cableways and funiculars where the development footprint will be increased. (f) In Western Cape: All areas outside urban areas: I. Areas containing indigenous vegetation; II. Areas on the estuary side of the development setback line or in an estuarine functional zone where no such setback line has been determined; or ii. In urban areas: I. Areas zoned for conservation use; or II. Areas designated for conservation use in Spatial Development Frameworks adopted by the competent authority. 21 The expansion of tracks or routes for the testing, recreational use or outdoor racing of motor powered vehicles excluding conversion of existing tracks or routes for the testing, recreational use or outdoor racing of motor powered vehicles, where the development footprint will be expanded. (g) In Western Cape I. Areas on the estuary side of the development setback line or in an estuarine functional zone where no such setback line has been determined; II. Seawards of the development setback line or within 200 metres from the high water mark of the sea if no such development setback line is determined; or III. Areas containing indigenous vegetation; 22 The expansion of facilities or infrastructure for the storage, or the storage and handling of a dangerous good, where such storage occurs in containers with a combined capacity of 30 but not exceeding 80 cubic metres. (g) In Western Cape: i. All areas outside urban areas; or ii. Inside urban areas: I. Areas seawards of the development setback line or within 200 metres from the high-water mark of the sea if no such development setback line is determined; II. Areas on the watercourse side of the development setback line or within 100 metres from the edge of a watercourse where no such setback line has been determined; or III. Areas on the estuary side of the development setback line or in an estuarine functional zone where no such setback line has been determined. 24 The expansion and related operation of facilities of any size for any form of aquaculture. (d) In Western Cape: i. 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