Figure 1: Location of the Pilot Area

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2 Assessment of groundwater contamination in the Ramotswa wellfields, and the effects of small dams in the upstream of Gaborone dam in the Notwane catchment, Botswana Table of Contents 1. Introduction The Pilot area Key and affected parties in the pilot areas The main built and natural elements within the system Major Infrastructure Development Land use practices Institutional structure Ecological sensitivity Major stakeholder priorities Government Priorities Farmers priorities Identification of knowledge gap References... 11

3 1. Introduction Groundwater contamination is a common problem in many countries, especially in high density urban and peri-urban centres where domestic, industrial, agricultural and municipal wastes are unregulated and as a result end up contaminating water bodies, including surface and groundwater. One of the major pollutants common in contaminated groundwater are nitrates, which usually come from septic and other anthropogenic sources (Owens et al, 1992). These sources end up elevating the levels of nitrates that occur naturally in groundwater. Consumption of water containing elevated levels of nitrates can cause low blood oxygen in infants, a condition known as methemoglobinemia or blue baby syndrome leading to shortness of breath, dehydration and diarrhea (Lockhart et al., 2013). The maximum concentration levels set by the World Health Organisation (WHO) for nitrates are 50 mg/l of nitrate ion (or 11mg/l of nitrate-nitrogen) to protect against methemoglobinemia in infants or 3mg/l as nitrite ion (or 0.9 mg/l of nitrite-nitrogen (WHO, 2011). However, in most countries the nitrate levels in drinking water do not exceed 10mg/lor 10 ppm (Lockhart et al., 2013). For Botswana, the Botswana Water Quality Standards Guidelines (BOS 32: 2000) recommend the maximum limit of 45 mg/l and 3mg/l of nitrates and nitrite, respectively. Against this background, it was found that the nitrate levels in the Ramotswa wellfields (a peri-urban area which lies within the radius of km in the southern part of Gaborone city) had reached alarming rates (more than four times above the recommended limit of 45mg/L, Figure 1) in 1996 mainly due to septic and pit latrine leakage into groundwater in Ramotswa (Staudt, 2003). The wellfields were subsequently decommissioned in Recently, in 2013 the Ministry of Minerals, Energy and Water Resources has taken a decision to rehabilitate the wellfields and use them to augment water supply within the Greater Gaborone area owing to severe water shortage in the south eastern part of the country. In addition, Gaborone dam located within the same catchment has not been filling up even after some reasonable rainfall events. Although it has been observed that rainfall has generally declined in Botswana since 1982 (Parida

4 and Moalafhi, 2008), it is also suspected that the decline in reservoir inflows may also be related to land use activities within the catchment, including the existence of some small dams (estimated to be over 200) constructed within the catchment. 2. The Pilot area The Pilot area is located upstream of the Gaborone dam in the Notwane catchment (Figures 1 and 2). It is within the South East District which covers areas such as Tlokweng, Ramotswa, Lobatse and Mogobane, among others. The main rivers are Notwane, Metsemaswaane and Taung which are all ephemeral. The Notwane River is the main tributary into the Gaborone dam, and flows eastwards towards the Limpopo River. Gaborone dam has a capacity of 144 million cubic metres (MCM) and supplies the greater Gaborone area, which covers all towns and settlements around the city. The geology in the Pilot area consists mainly of three lithological supergroup, i.e. Ventersdorp, Transvaal, and the Waterberg (Staudt, 2003). The Transvaal supergroup is of greatest hydrogeological importance: specifically the Ramotswa Dolomite Formation and the Lephala Shales Formation, which are among the highly productive wellfields in Botswana (Tredoux and Talma, 2006). The Ramotswa wellfield extends over an area of 29 km 2, which includes part of the Ramotswa Village (Staudt, 2003). The mean annual rainfall is 475 mm occurring between November and March.

5 Figure 1: Location of the Pilot Area

6 Figure 2: Location of some small dams in the catchment-the lower catchment in Figure 2 (Source: Department of Water Affairs) 3. Key and affected parties in the pilot areas The key and affected parties identified in the Pilot area are diverse, ranging from small scale farmers to large scale commercial farmers and tourism entities. 1. Small scale and large scale farmers Although the majority of farmers are small scale subsistence farmers, the

7 major water users are a few large scale commercial farmers in the Pilot area. Farming activities for commercial farmers include poultry, beef production, feedlots and horticulture while small farmers are restricted to small stock farming. Commercial farmers use private boreholes while small scale farmers depend largely on the farm dams in the catchment. 2. Water Utilities Corporation (WUC) is responsible for bulk water supply for human consumption to the townships in the catchment as well as to the greater Gaborone area. Most of this water comes from Gaborone dam. However, currently Gaborone dam is only 5% with no withdrawal from the dam. Due to this water shortage, the government recommissioned the use of the Ramotswa wellfields in December Water from Gaborone dam is only used to blend the nitrate contaminated water from the wellfields before this water could be supplied to the townships (Figure 3). Figure 3: Reservoirs used to store water from the boreholes and the distribution network for water supply. Water from Gaborone dam is used to dilute this nitrates-contaminated groundwater.

8 3. Department of Water Affairs. It is the custodian of all water resources in the country dealing with the overall development and management of surface and groundwater water. It formulates policies and strategies geared towards improvement of these resources. 4. Ministry of Agriculture (MoA) and Botswana Meat Commission (BMC). The MoA is responsible for all agricultural activities and programmes within the Pilot area. One of these programmes includes development of farm dams for agricultural use by small farmers. There are about 200 farm dams in the Pilot area which were developed in the early 1990s (DWA, 1992). In addition, the MoA owns some farms within the Pilot area. The BMC is also located in the Pilot area. BMC is owned by the government and is one of the major beef exporters in Southern Africa to the European Union markets. It buys cattle from farmers, slaughter them and exports the beef to Europe. 5. Tourism and entertainment sectors. There is one nature reserve in the catchment (Mokolodi Nature Reserve) which is used for wildlife conservation and environmental education. The reserve is connected to the water supply network for human consumption while private farm dams and boreholes are used to supply wildlife and for non-potable use. The catchment also hosts one of the fastest growing entertainment centres in the district known as Lion Park resort which host events of all sorts and sizes. 6. Bamalete tribal authority and Bamalete Land Board. The community has a strong tribal authority who makes sure that the land and resources belonging to the community are protected and used for the benefit of the community. However, all the land in the catchment is owned and managed by the Bamalete land board. There have been cases of alleged conflicts between the community and the Land Board over ownership of land where the former claimed that some of the land in the Pilot area belongs to the Community and not the state. 7. Other interested parties include: a. Department of Environmental Affairs (DEA)-an authority on environmental issues. b. Botswana Tourism Organisation (BTO)-responsible for tourism related activities.

9 c. Department of Waste Management and Pollution Control (DWMPC). 4. The main built and natural elements within the system Currently the Pilot area s major economic activities are public administration, livestock farming and particularly commercial and industrial developments which are concentrated in Ramotswa, Tlokweng, Lobatse and Taung. 4.1 Major Infrastructure Development Amongst the major infrastructural developments existing in the Pilot area is the sewerage networking of Tlokweng and Ramotswa. Further developments include connection of these two villages to the Water Utilities mains. The Pilot area has primary and secondary (high) schools equipped with teachers quarters in all the schools. In addition, there are good health services comprising of hospitals and health clinics. Transportation and communication infrastructure is also of high standard in the Pilot area. 4.2 Land use practices There are several land use practices in the Pilot area, including agriculture, urban and rural areas, tourism, quarries and dams. A significant proportion of the poultry and piggery industries are found in the Pilot area. The area is also characterized by private freehold farms which are a home to middle and high income population most of which work in Gaborone city. The topography is hilly and undulating providing a scenic view across the area. The highest point in Botswana (Otse hill, with an altitude of 1491 m.a.sl.) is found in the Pilot area. The Notwane River is a major source of water linking the Pilot area to the rivers downstream of Gaborone dam. Further downstream, the Notwane River carries treated waste water providing a valuable source of water for small scale horticulture within the eastern periphery of the Gaborone city.

10 4.3 Institutional structure In terms of water resources, the Pilot area is well serviced by the Water Utilities Corporation (WUC), for water supply and waste water collection; Department of Waste Management and Pollution Control (DWMPC); Department of Water Affairs (DWA), the Ministry of Agriculture (MoA) and Bamalete Land Board. The South East District Administration Council (SEDC) is found in the Pilot area. The Council is the main service provider and has the highest employment records in the area as well as valuable immovable and movable assets. 4.4 Ecological sensitivity The main environmental issues emanating from land uses in the area are: 1. Groundwater contamination in the Ramotswa area due to proliferation of pit latrines in the late 1990s. 2. Pollution of surface water sources due to intensive commercial agriculture in the area. 3. Reduction of inflows to the Gaborone dam due to presence of farm dams at the upstream of the dam. 4. Lack of monitoring of farm dams leading to siltation. 5. Land grabbing leading to deprivation of land resources for local people. 5. Major stakeholder priorities 5.1 Government Priorities Gaborone dam is a major water resource infrastructure in the Pilot area. The government is committed to providing potable water to the city and the surrounding townships using water from Gaborone dam. Due to the declining water levels to a record low of 5% (2015), the government has resorted to alternative sources of water, including (i) the utilization of polluted groundwater from the Pilot area, (ii) the use of North-South Water Carrier pipe

11 line spanning a distance of 450 km from the northern part of the country to the southern parts. 5.2 Farmers priorities The farm dams constructed in the Pilot area were meant to assist farmers to supply water to their livestock and for irrigation purposes. These dams are currently not fully utilised by the farmers and some of them have broken down or silted due to lack of maintenance. The other problem is the location of farm dams, as most of the functional ones are either close to or within the settlements, or is within private properties (farms). 6. Identification of knowledge gap Gaborone dam is an important water resource system in the Pilot area used to supply water to the greater Gaborone. The drastic decline in water levels and the current condition of the dam is worrisome. The main drivers and causes of this decline need urgent attention. Similarly, the Ramotswa wellfields are important groundwater resources that can be used to augment water supply in the Pilot area. Protection of these resources from further pollution is urgently needed. 7. References 1. Staudt, M (2003) Environmental Hydrogeology of Ramotswa. Report by the Environmental Geology Division, 47 p., Dept of Geological Survey (DGS), Lobatse, Botswana. 2. Owens, L., Edwards, W., VanKeuren, R., (1992). Nitrate levels in shallow groundwater under pastures receiving ammonium nitrate or slow-release nitrogen fertilizer. Journal of Environmental Quality 21,

12 3. Lockhart, K.M., King, A.M., Harter, T (2013).Identifying sources of groundwater nitrate contamination in a large alluvial groundwater basin with highly diversified intensive agricultural production. Journal of Contaminant Hydrology 151: Parida, B.P., and Moalafhi, D.B. (2008).Regional rainfall frequency analysis for Botswana using L-Moments and radial basis function network. Physics and Chemistry of the Earth 33, World Health Organization (2011).Guidelines for Drinking-water quality. Fourth Edition 6. Tredoux, G., Talma, A.S. (2006). Nitrate Pollution of groundwater in southern Africa. In: Xu, Y. and Usher, B(Eds). Goundwater Pollution in Africa, 15-36, Taylor and Francis Group plc, London, UK. 7. Zwikula, T. (2005). Evaluation of groundwater quality in Ramotswa, southeastern Botswana. Proc. International Workshop on Environmental Geology in semi arid environments, Selibe-Phikwe, November 2004, Department of Geological Survey, Lobatse, pp