Dairy farm borehole water quality in the greater Mangaung region of the Free State Province, South Africa

Short communication Dairy farm borehole water quality in the greater Mangaung region of the Free State Province, South Africa L Esterhuizen1*, A Fossey2 and JFR Lues1 School of Environmental and Agricultural Sciences, Faculty of Health and Environmental Sciences, 1 Park Road, Bloemfontein 9301, South Africa 2 Biotechnology, Faculty of Health and Environmental Sciences, 1 Park Road, Bloemfontein 9301, South Africa 1 Abstract Most dairy farm effluent is discharged onto pastures and land by irrigation and poses a risk of enriching groundwater including borehole drinking water. Nitrate, coliforms and Escherichia coli (E. coli), in particular, may cause disease in humans and animals drinking contaminated water. The aim of this study was to obtain an understanding of the status of borehole drinking water quality, including physical, chemical and microbiological properties, on 75 dairy farms in the greater Mangaung region of the Free State, South Africa. Borehole drinking water samples were collected during autumn and spring of 2009 and the physical, chemical and microbiological parameters analysed and compared to the required standards prescribed by the South Africa National Standards (SANS) 241 of 2006. Most farms were compliant; however for combined nitrate and nitrite N, 37 of the farms exceeded the prescribed limit. Similarly, for total coliforms, 45, and for E. coli, 22 of the farms exceeded the acceptable limits. Nine of the farm boreholes were contaminated by N and E. coli. On two of the farms four of the chemical parameters exceeded the prescribed limits, including those for N; both farms were, however, compliant for E. coli. The results of this study suggest that further research on water and waste management on dairy farms in the Manguang region of the Free State should be conducted. Keywords: Water quality; borehole drinking water; water standards; E. coli; coliforms; nitrate Introduction * To whom all correspondence should be addressed.  +27 51 507-3850; fax: +27 51 507-3435; e-mail: Received 31 March 2011; accepted in revised form 19 September 2012. of agricultural activities on groundwater and surface water (Monaghan et al., 2009) is becoming more of a concern worldwide (Santhi et al., 2006). For example, elevated concentrations of ammoniacal nitrogen and phosphate found in receiving watercourses from farm effluent are harmful to both farm animals and the indigenous wildlife, if used as drinking water sources, and to the aquatic micro- and macro-fuana within such water bodies. Equally of concern is the potential for groundwater sources to become contaminated, as such water is consumed as drinking water often without any further treatment. Therefore, it is important that farm effluent is adequately treated and stabilised before being allowed to discharge to water or disposed of to land (Willcock et al., 1999). South Africa is a water-scarce country and the central region, which includes the Free State Province, is an arid area. In the Mangaung area of the Free State, surface water is limited to a few seasonal streams and the low-flowing Modder River. The majority of dairy farms in this area are not close to any surface water source and utilise groundwater (borehole water) for all dairy activities and for drinking water. Groundwater is the main source of potable water for the majority of rural and farming communities in South Africa. These communities often have no other available water source (Van Tonder, 2009). A study on the handling practices of dairy effluent in South Africa by Strydom et al. (1993) showed that most farm effluent was discharged onto pastures and land by irrigation. With the increasing growth of the dairy industry together with the risk posed by dairy effluent, there is no doubt that measures to protect groundwater sources should be instituted. However, information about the impact of dairy effluent on groundwater is limited (Harter et al., 2002), particularly so in South Africa. The aim of this study was to obtain an understanding of the http://dx.doi.org/10.4314/wsa.v38i5.20 Available on website http://www.wrc.org.za ISSN 0378-4738 (Print) = Water SA Vol. 38 No. 5 October 2012 ISSN 1816-7950 (On-line) = Water SA Vol. 38 No. 5 October 2012 803 Dairy farming is a major contributor in the agricultural sector of South Africa, making a significant contribution to the economic development and sustainability of the country. Farm configurations are diverse, ranging from small enterprises with a few milk-producing cows to large industrialised farms comprising more than a thousand cows. All dairy enterprises utilise water for all of the steps of the dairy industry, including cleaning, sanitisation, heating, cooling and floor washing. Dairy wastewater or dairy effluent is characterised by physical, chemical and microbiological parameters (Danalewich et al., 1998). In particular, it is known to have high biochemical and chemical oxygen demand, high levels of total dissolved solids including fats, oils and grease, and nutrients such as ammonia phosphates. As such, it must be treated (stabilised) appropriately before being discharged to the aquatic environment or re-used by disposal to land. Faecally-derived pathogens, such as the Escherichia coli (E. coli) strain O157:H7, can impact water quality and human health, especially when the water is consumed without prior treatment (Oliver et al., 2009). It is well known that surface run-off from land during excessive periods of rainfall or discharge from dairy farms can pollute groundwater drinking water sources and have a significant adverse environmental impact on receiving surface waters (Atalay et al., 2008; Kay et al., 2008; Van der Schans et al., 2009). The harmful effect 804 43.50 0 0 1.0 37 9.6 ( ) = SANS limit of variable not to exceed; sd = standard deviation; * = United States Public Health Standard Limit. ** = WHO Guidelines for drinking-water quality (2011); standards of health concern. 47.0 6 3 0.40 301.0 0 0 4.3 57.4 2 7 33.0 72.0 3 6 81.5 0 7.68 Median No. farms exceeding 10.8 55.5 + 54.1 1.5 + 1.60 0.04 0.2 11.2 + 11.7 80.3 + 100.6 10.5 0.02 0.44 + 0.30 304.2 + 145.7 3.6 0.3 10.5 + 23.6 71.8 + 85.7 15.7 9.5 43.4 + 35.8 90.7 + 67.2 24.0 95.4 + 48.6 Mean + sd 30.0 7.1 7.64 + 0.3 Min 376 5.46 68 533 1.43 1314 158 740 237 406 353 8.30 Max - 50 mg/ℓ 5 mg/ℓ 1.5 mg/ℓ WHO standard** - - N (<10 mg/ℓ) Cl (<200 mg/ℓ) F (<1.0 mg/ℓ) CaCO3 (<150 mg/ℓ) K (<50 mg/ℓ ) Na (<200 mg/ℓ) Mg (<70 mg/ℓ) Ca (<150 mg/ℓ) Electrical Conductivity (<150 mS/m) Generally, the physical and chemical properties of the borehole water of the 75 farms were within the prescribed SANS 241 (2006) limits, except for N (Table 1). The 10 mg/ℓ limit for N was exceeded by 49.3% of the farm boreholes, also demonstrated by the mean value as well as the median value being greater that the SANS 241 (2006) limit. When the N concentrations were compared to WHO (2008) standards, only 2 farm (...truncated)