A hybrid approach for identifying the seasonal variation of groundwater quality, source apportionment and health risk in a coastal area driven by natural and anthropogenic factors.

The objective of this study was to evaluate seasonal fluctuations in groundwater quality, determine the effects of different stressors on this resource, and recognize the potential pollution sources in a coastal region of southern Vietnam. Eleven samples collected in Ben Tre province during the dry and wet seasons were then analyzed for sixteen parameters, including pH, total dissolved solids (TDS), salinity, total hardness (TH), ammonium (NH₄⁺-N), nitrite (NO₂ˉ-N), nitrate (NO₃ˉ-N), sulfate (SO₄²ˉ), chloride (Clˉ), iron (Fe), manganese (Mn), lead (Pb), mercury (Hg), arsenic (As), coliforms, and Escherichia coli (E. coli). Pearson correlation analysis, principal component analysis (PCA), and cluster analysis (CA) were employed. The results indicated that total dissolved solids, salinity, total hardness, Clˉ, E. coli and coliform were detected as contaminants in groundwater samples. The trend of fluctuations in the parameters was mostly higher in the dry season. Which Mn and coliform significantly fluctuated between the dry and wet seasons. Activities in industrial-craft areas, landfills and seawater-intruded areas negatively impacted groundwater quality, typically TDS in industrial-craft areas, coliform and E.coliat the landfill area. Six principal components obtained from PCA could explain 93.6% of the variance, and all parameters are responsible for variations in groundwater quality. Geology, discharged wastewater, landfill leachate, agricultural activities, and saltwater intrusion can be considered representative factors. CA grouped the collected samples into four clusters based on the similarity in water properties. The analysis results showed that the locations in each cluster have outstanding water quality characteristics, clusters I and III have high TDS characteristics, cluster II has coliforms, and cluster IV sets of locations with high salinity. This study is promised to partially fill the gap in comprehensive information on groundwater quality in the coastal province so that policymakers can develop sustainable water management strategies in the future. Doi: 10.28991/CEJ-2023-09-03-01 Full Text: PDF

Agricultural production, urbanization, and other anthropogenic activities, the major causes of surface water pollution in China, have dramatically altered hydrological processes and nutrient cycles. Identifying and quantifying the key factors affecting water quality are essential for the better prevention and management of water pollution. However, due to the limitations of traditional statistical analysis methods, it is difficult to evaluate the spatial changes and interactions of influencing factors on water quality. In addition, research on a national scale is difficult, as it involves large-scale and long-term water quality monitoring work. In this study, we collected and collated the monthly average concentrations of four water quality parameters, dissolved oxygen, ammonia nitrogen, chemical oxygen demand, and total phosphorous, based on data from 1547 water quality monitoring stations in China. The combined pollution level of the water quality was assessed using the water quality index. Based on the water quality characteristics, water quality monitoring sites in the dry and wet seasons were grouped using k-means clustering. Eleven environmental factors were evaluated using geodetector software, including six human factors and five natural factors. The results showed that there are high-risk areas for water quality pollution in the eastern and southeastern coastal regions of China in both the dry and wet seasons and that surface water pollution in China is highly spatial heterogenous in both the dry and wet seasons. Among the anthropogenic factors, urban land area is the main factor of water quality pollution in the dry season, and the explanation rate of spatial heterogeneity of integrated water quality pollution index is 20.3%. The number of poultry farms and the area of farmland explained 12.4% and 12.1% of the integrated water quality pollution index in the wet season. The nonlinear relationship between these three anthropogenic and natural factors and their interaction exacerbated water quality pollution. Based on this analysis, we identified the key factors affecting surface water quality in China during the dry and wet seasons, evaluated the achievements of the water environmental protection policies in China in recent years, and proposed future management measures for the effective prevention and control of water quality pollution in high-risk areas.

This study examined the concentration levels of physico-chemical profiles of groundwater quality of communities in Southern Ijaw Local Government Area of Bayelsa State, Nigeria. The seasonal variation of groundwater quality were evaluated. Fifteen (15) communities within the LGA were selected and groundwater from hand-dug well (HDW-15samples) and borehole (BH-15samples) was sourced during the wet season (July) and dry season (March) and analyzed for seasonal variations. The difference in the mean of the parameters investigated during the dry and wet season revealed the difference in concentration level as influenced by the season attributes. The HDW showed a very strong correlation in wet and dry season physicochemical properties as well as no significant difference in the physicochemical properties of groundwater at both seasons. Also, the results of borehole water sample showed a very strong correlation in wet and dry season physic-chemical properties with no significant difference in the physicochemical properties of water at both seasons. There are similarities in various natural and anthropogenic activities influencing the concentrations during both wet and dry seasons. The mean values of parameters such as pH, TDS, TSS, Bicarbonate, Cl, SO34, NO2, Ca, Mg, K and P are within the permissible limit of WHO and NSDWQ during both seasons except TC.

The study analysed the spatial and temporal contamination levels of fresh water resources by saline intrusion in the Douala coastal area. Water samples were collected from 19 stations. 3 stations were selected from the mangrove area and 16 stations were selected from the rest of the area partitioned into four transects (coastal transect, inner transect 1, inner transect 2 and inner transect 3). Sampling was done repeatedly during the wet and dry seasons. They were analyzed for physico-chemical parameters according to the American Public Health Association methods. Geostatistical analysis was used in mapping the water properties. Considerable levels of actual electrical conductivity values (208.91 to 660.63 and 45 to 7540 μS/cm for the wet and dry seasons, respectively); calcium (0.06 to 85 and 4 to 256 mg/L for the wet and dry seasons, respectively); sulphate (0 to 103 and 0 to 99 mg/L for the wet and dry seasons) and total dissolved solids (15.79 to 1467 and 20 to 3750 mg/L for the wet and dry seasons, respectively) were observed for ground water in the study area based on spatio-temporal assessment. From the output grid, it could be deduced that the south eastern region had a hint of salt water intrusion (SWI) contamination of fresh water resources with actual value highs of electrical conductivity (1790 and 820 μS/cm) for the dry and wet seasons, respectively. Calcium highs (140 and 16 mg/L) for the dry and wet seasons were obtained at the central part of the study area. The spatial distribution of calcium highs extends from the central zone of the study area in the dry season and the south eastern zone in the wet season. The southern region is more vulnerable to contamination by calcium ions during this season. An up to date scope for surveillance monitoring and forecasting regarding the deterioration of coastal aquifers is recommended. Modelling of aquifers shifts for the coastal zone should be instituted as a means of ensuring efficient fresh water resources evaluation and utilization. An indepth study of the geochemical characteristics of ground water of the coastal zone could determine factors that most significantly impact on fresh water resource quality.

Seasonal variation of groundwater quality in Jimeta-Yola area was investigated using selected chemical contaminants. The results indicated that pollutant loading occurred in the dry and rainy seasons. The groundwater is fresh and varied from slightly acidic to alkaline in both the dry and rainy seasons. The mean values of BOD, COD and chloride exceeded the recommended standards of drinking water quality in the rainy season from the shallow and deep aquifers (hand-dug wells and boreholes). Nitrate and ammonium ion mean values in both seasons in shallow and deep aquifers exceeded the recommended limit of WHO. The mean coliform number counts exceeded the WHO recommended limit in both seasons in shallow and deep aquifers. The spatial distribution of EC and TDS reveal that the leachates from the dumpsites are significant source of groundwater contamination. The variation in contaminant distribution is influenced by depth to water and well depth. There were increase in COD, BOD, nitrate, phosphate and chloride, and decrease in ammonium ion and coliform with water depth in shallow aquifer in the dry season, and COD, nitrate, ammonium ion, phosphate and chloride increase with water depth, and decrease in BOD and coliform in the rainy season. COD, ammonium ion and chloride increase with well depth, and decrease in COD, BOD, nitrate, phosphate and coliform in deep aquifer in the dry season while COD, BOD, nitrate, ammonium ion, phosphate and chloride decrease in the rainy season. Coliform showed no depth control during the same period. In the dry season in leachate samples, contaminants revealed perfect correlation and nearly perfect correlation in the rainy season. The contaminants in all the aquifers revealed strong positive correlations in both seasons which are an indication of common source. Factor analysis indicates that groundwater chemistry is controlled by anthropogenic activities, salinity, ammonification and natural mineralization. It is recommended that safe waste disposal practice should be encouraged and drilling of boreholes to deeper levels is also suggested.

The Zhuoshui River alluvial fan is one of the most important groundwater and agricultural areas in Taiwan. Abundant groundwater resources are the main source of domestic water supply and irrigation water. However, groundwater recharge and groundwater quality have been greatly affected under extreme climate and hydrological conditions. Hence, the quality of groundwater has been a topic of concern to the public. In this study, groundwater level and groundwater quality data of the Zhuoshui River alluvial fan from 2008 to 2020 were used to divide the wet and dry season groups according to the sampling dates. An independent samples t-test was used to evaluate the differences in the mean groundwater level and the mean concentration between the wet and dry seasons. The test results show that there was no statistically significant difference in the mean groundwater level between the wet and dry seasons. This may result from the time lag effects of groundwater recharge. Except for groundwater temperature, bicarbonate, and total organic carbon (TOC), there were no significant differences among the mean concentrations of other groundwater quality parameters in Aquifer 1 and Aquifer 2 between the wet and dry seasons. In terms of the alluvial fan location, although the soil texture, land utilization, cropping systems, and hydrogeology of the proximal, mid-, and distal fan may affect groundwater quality variations, it seems that only Aquifer 1 is affected by surface water infiltration, resulting in significant differences in mean groundwater temperature, mean concentrations of major ions, and nitrate between the wet and dry seasons, whereas Aquifer 2 is less affected. At the same time, owing to the geological conditions and intensive cultivation in the Zhuoshui River alluvial fan, nitrate and arsenic could represent a high risk to the public’s health if groundwater is used as a source for domestic water supply or irrigation water in the distal fan area, whether in the wet season or dry season. Meanwhile, due to global climate change and uneven droughts and floods, the hydrological conditions of the so-called “wet season” and “dry season” are obviously different from those in the past. Compared with precipitation, groundwater level may be a better indicator for understanding variations in groundwater quality.

This research work was aimed at analyzing the data of the seasonal variation of groundwater quality in the Federal University of Agriculture Abeokuta (FUNAAB) environment using descriptive statistics and a covariance matrix analysis of the data set for both rainy and dry seasons to see the effect of the water quality parameters on each other. Cluster analysis was also carried out on the data set to check the level of the Euclidean distance between the water quality parameters. The data used for this analysis was secondary data obtained from groundwater sources (ten wells) within the University environment during the rainy and dry seasons respectively. It was observed that there is a slight variation in the quality of groundwater in the FUNAAB environment as regards the dry season and the rainy season. In the result of the cluster analysis, the water quality parameters are clustered into seven groups for the dry season and eight groups for the rainy season which indicate that the dissimilarities in the data set increase during the rainy season. It was observed that for the dry season covariance data, 36% of the values have a negative relationship within themselves and 64% has a positive relationship, as compared to the rainy season data which possesses a 31% negative relationship and a 69% positive relation. This implies that there is only a 5% variation in the entire data set of the dry season and the raining season as regards the interdependence of the water quality parameters on each other.
 Keywords: Groundwater, Physico-Chemical, Water Quality, Wells

Biotic and abiotic properties most closely associated with subtropical forest soil respiration differ in wet and dry seasons: A 10-year in situ study

In the Pearl River Delta (PRD), river water quality deteriorates continually due to the population increase and ongoing industrialization and urbanization. In this study, a water quality management paradigm based on the seasonal variation is proposed. For better exploring the seasonal change of water quality, wavelet analysis was used to analyze the division of dry and wet seasons in the PRD during 1952–2009. Then water quality seasonal variation in 2008 and relevant impact factors were analyzed by multivariate statistic methods as a case to make some management measures. The results show that there are some differences of dry and wet seasons division among different years. Wet season mainly appear from April to September, which occupy the largest proportion among the 58 years (about 70%) and then followed by the wet season from May to October (about 13.8% of the total years). As to the water quality of 2008, significant differences exist between dry and wet seasons for 17 water quality parameters except TP, ${\rm NO}_{3}^{- } $, Fe2+, and Zn2+. Levels of parameters pH, EC, CODMn, BOD5, ${\rm NH}_{4}^{ + } $, ${\rm SO}_{4}^{2- } $, and Cl− in dry season are much higher than those in wet season. In dry season the variations of river water quality are mainly influenced by domestic sewage, industrial effluents, and salt water intrusion. While in wet season, except the aforementioned pollution sources, drainages from cultivated land and livestock farm are also the main factors influencing water pollution. Thus, water quality management measures are proposed in dry and wet seasons, respectively. The results obtained from this study would further facilitate water quality protection and water resources management in the PRD.

This study focuses on assessing the seasonal variation in groundwater quality within the Al‐Hoceima region, specifically examining physicochemical parameters and bacteriological indicators of water fecal contamination. The sampling campaign took place during the wet and dry seasons of 2019 and 2021. In situ measurements were conducted on 37 groundwater samples to determine the physicochemical parameters, while bacteriological analyses were performed using Escherichia coli (E. coli) as a fecal contamination indicator. The findings demonstrate significant variations in physicochemical parameters across seasons and reveal fecal contamination of the groundwater, predominantly indicated by increased levels of E. coli during wet periods. Possible contributing factors include water surface runoff and percolation processes. Additionally, the result showed a high concentration of E. coli expected 240 CFU/100 mL. Pollution was higher in the dry season than in the wet season. These results underscore the poor quality of the water in the Al Hoceima region, necessitating treatment before consumption.

The southwestern mountains of Hainan Island are the southernmost region with tropical karst landform in China. The frequent alternation of dry and wet seasons leads to the loss of the mineral nutrients of limestone, creating karst fissure habitats. Plants living in karst fissure habitats for long periods of time have developed local adaptation mechanisms correspondingly. In the paper, hydrogen–oxygen stable isotope technology was applied to determine the water-use sources of Impatiens hainanensis in the dry and wet seasons, hoping to expound the adaptation mechanism of I. hainanensis in karst fissure habitats to the moisture dynamics in the wet and dry seasons. In the wet season (May to October, 2018), the air humidity is relatively high in the I. hainanensis habitat; in the dry season (November 2018 to April 2019), there is a degree of evaporation. In the wet season, fine-root biomass increases with soil depths, while coarse-root biomass decreases with soil depths; in the dry season, fine-root biomass is lower and coarse-root biomass is higher compared with the wet season. It was found that the average rainfall reached 1523 mm and the main water-use sources were shallow (0–5 cm) and middle (5–10 cm) soil water, epikarst water, and shallow karst fissure water during the wet season; the average rainfall reached 528 mm, and the deep (10–15 cm) soil water and shallow karst fissure water were the main water-use sources during the dry season. Fog water has a partial complementary effect in the dry season. The differences in the distribution of root biomass and each source of water in the wet and dry seasons of I. hainanensis also reflect the different water-use strategies of I. hainanensis in the wet and dry seasons. In both dry and wet seasons, I. hainanensis formed a water-use pattern dominated by soil water and shallow fissure water (0–15 cm) under the influence of the “fissure-soil-plant” system in the karst region.

Context Due to considerable declines in African wildlife populations, most large African mammals are managed inside protected areas. Protected areas come in various sizes, and have different environmental features, climates and management strategies (i.e. ‘hands-on’ or ‘hands-off’) that can influence an animals’ homeostasis. White rhinos (Ceratotherium simum simum) are found almost exclusively within protected areas where population sizes are driven by natural factors and poaching pressures. Aims Our aim was to understand the effect of natural and anthropogenic factors on the adrenocortical response of white rhinos within three protected areas. Specifically, we wanted to understand how poaching pressure, protected area size (<500 km2), season (wet and dry) and rainfall patterns were responsible for driving adrenocortical activity in white rhino. Methods To understand the relationship between rhino adrenocortical responses and different environmental and anthropogenic stressors, we quantified glucocorticoid metabolites in faecal samples (fGCM) collected from four populations within three protected areas (i.e. two small parks, one big park) during the wet and dry seasons. Key results We found differences in seasonal fGCM concentrations, with a 42% increase during the dry season, and no differences in fGCM concentrations between the high and low poaching areas. Additionally, we found fGCM concentrations in samples from the small parks were respectively 38% and 42% higher than in samples from the large park during both the dry and wet seasons compared. Conclusions Our results suggest that white rhinos may experience physiological stress in smaller parks, especially during the dry season when resources are limited. Implications By mitigating stress associated with reduced access to resources and spatial constraints, managers may better promote the viability of large mammals in small protected areas.

Water samples collected from fifteen hand dug wells in November (dry season), 2011 and July (Wet season), 2012 using random sampling technique. In situ parameters were measured for pH, electrical conductivity, total dissolved solids using portable meters. Heavy metals were analyzed for; Fe, Cu, Zn, Cd, Pb, and Cr using Atomic Absorption Spectrophotometer (AAS). The study aimed at examining the spatial variations in groundwater quality around dumpsite in Igando using paired sample T-test statistical technique. The result shows that the measured pH values were below the minimum WHO standard for drinking water quality in wet and dry seasons in about73.3% and 26.7% respectively. Also, approximately, 13.3% of EC, and 6.7% exceeded the prescribed standard limit of WHO in dry and wet seasons respectively. Concentration of Fe exceeded drinking water quality in all the sampling locations during wet season and only about 46.7% in dry season. Pb, Zn, and Cu exceeded WHO limit in about 86.7%, 80%, and 26.7% respectively in dry season. Concentration of Pb, Cd , Cu and Cr were under detection limit in all the locations except at locations G2 for Cu in wet season. The paired samples statistics and correlation revealed that the mean values of all the parameters were higher in dry season with the exception of Fe. No significant correlations exist among the paramet er for both seasons at p<0.05. The paired T-test show significant seasonal variations among four heavy metals including Fe, Cd, Pb and Zn.The study concluded that, samples in dry season are of low quality compared to wet. The study recommends public enlightenment on solid waste disposal, controlled anthropogenic activities, and treatment /recycling of waste to prevent heavy metal from leaching unto the sub-surface.DOI: http://dx.doi.org/10.3329/jesnr.v6i1.22063 J. Environ. Sci. & Natural Resources, 6(1): 179-186 2013

以艾比湖流域主要入湖河流为研究对象，在5月（丰水期）和8月（枯水期）分别沿博尔塔拉河（博河）和精河进行采样，采用平行因子模型（PARAFAC）和三维荧光区域积分法对水体三维荧光特性进行研究并对其与水质的关系在枯、丰水期下的变化进行探讨.结果表明①河流DOM在枯水期与丰水期都含有C1（240、425 nm） UVC类腐殖质，C2（225、290 nm）紫外区内络氨酸类有机物，C3（230/280、330 nm）蛋白类有机物，C4（265、260 nm）腐殖质类共4种组分.通过对水体三维荧光进行区域积分可以看出DOM荧光成分的占比在不同时期的变化.博河在枯水期时EEM光谱中的区域Ⅲ富里酸含量低于丰水期，枯水期时区域Ⅱ芳香类蛋白质、区域Ⅳ可溶性微生物代谢物以及区域Ⅴ类腐殖质酸高于丰水期；对于精河来说，区域Ⅱ芳香类蛋白质和区域Ⅳ可溶性微生物代谢物在枯水期的含量高于丰水期，区域Ⅲ富里酸和区域Ⅴ类腐殖质酸的含量枯水期低于丰水期，这表明水体腐质化程度较高.②本研究选取了一些常规的荧光指数来描述枯、丰水期水体的荧光指数特性.经研究发现，精河的荧光指数、自生源指数和腐殖化指数在不同时期的变化幅度较小，而博河的变化幅度较大.③将荧光指数与水质参数进行相关性分析并建模，结果表明枯水期自生源指数（BIX）与化学需氧量呈显著正相关，相关系数R=0.688；丰水期时BIX与铵态氮浓度呈显著负相关，相关系数R=-0.493.通过对比分析艾比湖主要入湖河流的三维荧光光谱特性与水质在枯、丰水期时的关系进一步表明水体中DOM的特性以及在枯、丰水期下的差异，为艾比湖流域的治理改善提供一定的理论支持和参考依据.;This study takes the main lakes in Lake Ebinur Watershed as the research object, and samples along the Bortala River and Jing River in May (wet season) and August (dry season). The PARAFAC analysis method and the three-dimensional fluorescence region integration method is used to study the three-dimensional fluorescence characteristics of water and its seasonal variation with water quality. The results show that:1)In both dry and wet seasons, river DOM contains C1 (240, 425 nm) and C4 (265, 260 nm) kind of humus, C2 (225, 290 nm) uranium-like organic matter compounds. It found that fulvic acid is lower, while the aromatic protein, soluble microbial and humic acid were highest in dry season than wet season in Bortala River. The concentration of the aromatic protein and soluble microbial in dry season was higher than in wet season, and the fulvic acid and humic acid in dry season was lower than in the wet season in Jing River, based on fluorescence regional integral (FRI) analysis and the regional standards related to water quality and fluorescence. This indicates that the degree of decomposition in water is relatively high; 2)In this study, some conventional fluorescence indexes were selected to describe the fluorescence index characteristics of water in wet and dry season. It found that the three indexes (FI, BIX, HIX) of the water quality of Jing River and Bortala River in dry and wet seasons showed slight changes, comparing to larger changes in the Bortala River. In general, the change of water quality of Jing River and Bortala River in dry and wet seasons is mainly influenced by microbial activities and human activities; 3) In terms of the correlation coefficients of water quality parameters and fluorescence indexes in different seasons, the results showed that the relationship between BIX and COD concentration was best and a significant positive correlation in dry season(R=0.688, P<0.01). Secondly, there is a significant negative correlation between BIX and ammonium nitrogen concentration in wet season (R=-0.493, P<0.05). The study provides theoretical support and reference basis for the improvement of the governance of Lake Ebinur Watershed, which further proved that exogenous characteristics and the differences in different periods of DOM sources in the water.

Impacts of natural and anthropogenic factors on microbiological water quality indicators along an urban riverine tropical wetland &amp;#160;Flavia Byekwaso1,3,6, Guenter Langergraber2, Gabriele Weigelhofer1,3, Rose Kaggwa4, Frank Kansiime5,&amp;#160; Thomas Hein1,31 University of Natural Resources and Life Sciences, Vienna (BOKU), Department of Ecosystem Management, Climate and Biodiversity, Institute of Hydrobiology and Aquatic Ecosystem Management, Gregor-Mendel-Strasse 33, 1180 Vienna, Austria2 University of Natural Resources and Life Sciences, Vienna (BOKU), Department of Landscape, Water and Infrastructure, Institute of Sanitary Engineering and Water Pollution Control, Muthgasse 18, 1190 Vienna, Austria3 WasserCluster Lunz, Dr. Kupelwieser-Promenade 5, 3293 Lunz am See, Austria4National Water and Sewerage Corporation, P.O. BOX 7053, Kampala, Uganda5 Makerere University, Department of Environmental Management, P.O. BOX 7062, Kampala, Uganda6 Ministry of Water and Environment, Climate Change Department, P.O BOX 20026, Kampala, UgandaABSTRACT&amp;#160;Water quality monitoring is essential for understanding seasonal variations in microbiological indicators and their implications for public health. Waterborne bacteria and pathogens are a significant cause of human diseases, especially in developing countries.&amp;#160; The study aimed to understand the factors that cause seasonal changes in the concentrations of microbiological water quality indicators along a riverine tropical wetland. In total, 144 water samples were collected for 12 months at six sites along Lubigi wetland in Kampala, Uganda, receiving varying stormwater and wastewater inputs from urban water infrastructure during the dry and wet seasons. Water samples were analysed using specific microbiological assay tests for Escherichia coli, faecal coliforms, heterotrophic plate counts, Enterococcus and Salmonella species. Generally, the highest concentrations of microbial contamination were detected during the dry season at all sites. There was a decreasing trend in microbial contamination for all the selected five microbiological indicators with increasing distances from the sources of stormwater and wastewater inflows in the upstream reaches towards the downstream areas of Lubigi wetland. Nitrogen compounds, Escherichia coli, faecal coliforms, Enterococcus and Salmonella species originated from stormwater, whereas wastewater discharges delivered primarily phosphorus compounds, organic matter and heterotroph plate counts. E. coli and heterotrophic plate counts were positively correlated with water temperature and salinity. E. coli, faecal coliforms and heterotroph plate counts were positively associated with Biological Oxygen Demand (BOD5). Escherichia coli, faecal coliforms and Enterococcus species were positively correlated with NH4-N. Escherichia coli, faecal coliforms, and heterotrophs dominated with high concentrations during the dry seasons, while Enterococcus and Salmonella species were more prevalent in the wet season. Escherichia coli, faecal coliforms and Salmonella showed insignificant logarithmic reductions during both seasons, showing when the carrying capacities of Nsooba main channel and Lubigi sewage treatment plant systems were exceeded. Enterococcus species showed no reduction in both seasons, which implied continuous high in-stream contamination. Heterotrophs showed significantly higher logarithmic reduction during the wet season than in the dry season. This suggested a concentration reduction during the wet season and loading/increase in the dry seasons. Our research findings may be used by the public health sector to understand relationships between the occurrence of surface water quality microbiological indicators and the prevalence of diseases through strategic seasonal monitoring and evaluation in Kampala and the region.