Global Journal of Science Frontier Research, H: Environment & Earth Science, Volume 23 Issue 2

outside and only sample (B) fell within the WHO guid- ance limit of 6.5 – 8.5. Though the pH of drinking water has no direct health effects, levels outside the WHO range of 6.5 – 8.5 could indirectly affect the quality of drinking water by either resulting in acidic water for pH less than 6.5 or bitter taste for pH values greater than 8.5. The differences in the pH of the various samples may be due to the characteristics of the source waters influenced by both natural and anthropogenic factors ture, waste disposal and acid precipitations. iii. Turbidity Turbidity of the dam water samples for all the sample points varied from 7.0 to a very high turbidity value of 10.0 NTU. The lowest turbidity value of 7.0 NTU was recorded for two samples (B and C) and the high- est value of 10.0 NTU was recorded for sample A (Table 2) Table 2: Mean Values of Physico-Chemical Parameters and Nutrients Analyzed at the Dam From the results, turbidity of all the samples ex- ceeded the WHO recommended acceptable limits of 0.00-5.0 NTU. Turbidity directly influences the colour of water and there is a general increase in colour with in- creasing turbidity values. The excessive turbidity in water correlates with the very high apparent colour. This makes water purification processes such as flocculation and filtration difficult making treatment expensive [30]. High turbidity can inhibit the effects of disinfection against microorganisms and enable bacterial growth. Ideally disinfection is effective at turbidity below 0.1 NTU. Turbidity is an important parameter which gives an indi- cation of the effectiveness of the treatment processes especially with the coagulation or sedimentation and the filtration. iv. Total Dissolved Solids (TDS) Mean total dissolved solids concentrations ranged from 34.0 to 35.2 mg/L for all three samples with the highest value recorded at sample A and the lowest at sample B (Table 2). These amounts of TDS measured in the monitored samples were within acceptable levels recommended by WHO. [31] stated that the palatability of water with TDS level less than 600 mg/L is generally considered to be good whereas water with TDS greater than 1200 mg/L becomes increasingly unpalatable. This indicates that all water samples that were taken were suitable for drinking in terms of palatability because all are within the recommended standards. v. Colour Colour is an important physical property of wa- ter because of its implications for water supply, and the need to reduce it to acceptable levels by water treat- ment is highly recommended. Increase in the colour of water in reservoirs results in increase in treatment cost. Colour in natural water usually results from the leaching of organic materials and is primarily the result of dis- solved and colloidal humic substances, primarily humic and fulvic acids. Colour is also strongly influenced by the presence of iron and other metals, either as natural impurities or as corrosion products. Highly coloured water may be due to decaying vegetation. Apparent co- lour ranged from 3.30 to 6.10 Hazen units for all sample points with the highest at sample point A and the lowest at sample point B. All three samples were within the WHO limit of 15 HU (Table 2) vi. Electrical Conductivity Electrical conductivity gives an account of all, the dissolved ions in solution. The mean conductivity of all water samples ranged from a least value if 68.70 μ S/cm at sample point C to a considerably high mean value of 70.50 μ S/cm at sample point A (Table 2). The acceptable WHO limit of conductivity is 0 – 1000.00 μ S/cm. Generally, conductivity of clean water is lower but as it moves down the earth it leaches and dis- solves ions from the soil and also picks up organic from biota and detritus [32]. Generally, the conductivity values recorded for the samples from the dam does not pose any potential health risk for consumers. They were all within the acceptable limit prescribed by WHO limits. vii. Alkalinity Total alkalinity ranged from 20.0-23.0 mg CaC0 3 /L for all three sample points within sample period with the highest value recorded at sample point B and the lowest at sample point C. These values were within the WHO limit of 0-500.00 mg/L (Table 3). There was however no Phenolphthalein alkalinity for all three points sampled. This is because all the pH values were below 8.3 (pH<8.3) hence all alkalinity values were Methyl Orange alkalinity (Table 3). Alkalinity values provide guidance in applying the right amount of chemicals to the treatment of drinking and waste water. High alkalinity means the drinking water will have the ability to neutral- ize acidic pollution and hence keeps the water’s pH constant. Water with very high alkalinity is not detrimen- Sample Point Total Dissolved Solids (TDS) mg/L Apparent Colour HU (PtCo) Turbidity NTU Fe 2+ mg/L WHO Limit 1000.00 0.00 – 15.00 0.00 – 5.00 1.0 Sample Point A 35.20 6.10 10.00 0.63 Sample Point B 34.00 3.30 7.00 0.44 Sample Point C 34.40 3.50 7.00 0.53 such as washing of clothes back into the dam, agricul- © 2023 Global Journals 1 Year 2023 82 Global Journal of Science Frontier Research Volume XXIII Issue ersion I VII ( H ) Assessment of Water Quality of the Nalerigu Dam in the East Mamprusi Municipality of the North East Region of Ghana