1School of Environment and Earth Science, Maseno University, Maseno, Kenya 2School of Public Health and Community Development, Maseno University, Maseno, Kenya3Lake Victoria Basin Commission Secretariat, Kisumu, Kenya*Corresponding author: nyambs06@yahoo.com

Influence of anthropogenic activities on microbial and nutrient levels along the Mara River tributaries, Kenya

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EurAsian Journal of BioSciencesEurasia J Biosci 8, 1-11 (2014)http://dx.doi.org/110.5053/ejobios.2014.8.0.1

Water pollution is a major global problem that requires continuous evaluation and revision of policies related to its use and protection. Polluted water is regarded as the leading cause of deaths and diseases worldwide, and it accounts for more than 14,000 deaths daily (Larry 2006). A number of factors continue to negatively impact natural water resources across the world, many of which primarily result from anthropogenic activities. Although sources of surface water pollution are numerous, anthropogenic activities have been singled out as among the most important and of great concern, while urbanization and industrialization are regarded as most effective (Anonymous 2003a). It is estimated that over 90% of wastewater from

various sources especially from domestic, industrial and agricultural activities is discharged into rivers, lakes and other aquatic systems across the world (Anonymous 2012a), while about 18% of the world’s population, or 1.2 billion people (i.e., 1 out of 3 in rural areas), defecate in the open (Anonymous 2008a).

Rivers often get polluted by human activities, even as they remain the only reliable source of water for domestic use (Anonymous 2012a). The World Health Organization (Anonymous 2004a) estimates that every year about 2.2 million people die from

Received: November 2013Received in revised form: February 2014

Accepted: April 2014Printed: May 2014

INTRODUCTION

AbstractBackground: A number of factors impact negatively on natural surface water resources across theworld. Although sources of surface water pollution are numerous, anthropogenic activities havebeen singled out as among the most important and of great concern. The aim of this study was toassess the influence of anthropogenic activities on nutrients and microbial levels along the Amalaand Nyangores tributaries of the Mara River in Kenya.Materials and Methods: Four sampling sites along each tributary were specifically selected fromwhich water samples were collected and analyzed for nutrients by use of spectrophotometrictechniques, and coliform bacterial presence by a multiple tube fermentation technique.Results: Higher levels of total phosphorus were recorded along the Nyangores than the Amalatributary (P= 0.02). Significant differences in phosphorus levels were recorded between differentsites along the Nyangores tributary (P=<0.001) and also along the Amala tributary (P= 0.0036).However, total nitrogen levels varied only within sites along the Nyangores tributary (P<0.0001) butnot along the Amala tributary. Similarly, Escherichia coli and total coliform levels varied significantlywithin Nyangores tributary sites. Sites with frequent and direct human and livestock contact hadhigher microbial and nutrient levels, indicative of a localized pollution effect.Conclusions: The findings imply that the health of local communities who depend on this water fordomestic use might be compromised. As such, regular monitoring, strict enforcement ofenvironmental protection laws, public education and proper sewage disposal is recommended.Keywords: Coliform bacteria, domestic waste, Mara River, pollution, urban center.

Anyona DN, Dida GO, Abuom PO, Onyuka JO, Matano AS, Kanangire CK, Ofulla AVO (2014) Influenceof anthropogenic activities on microbial and nutrient levels along the Mara River tributaries, Kenya.Eurasia J Biosci 8: 1-11.

http://dx.doi.org/110.5053/ejobios.2014.8.0.1

Douglas Nyambane Anyona1*, Gabriel Owino Dida2, Paul Otieno Abuom1, Jackson Odhiambo Onyuka2, Ally-Said Matano3, Canisius Kabungo Kanangire3, Ayub Victor Opiyo Ofulla2

©EurAsian Journal of BioSciences

diarrheal diseases; 90% of these deaths are among children, mostly in developing countries. Bloomfield et al. (2009) concur that diseases resulting from contaminated water comprise 80% of the total disease burden in some poor countries. The WHO (Anonymous 2004a) estimates that one-third of deaths in developing countries are caused by consumption of contaminated water, and on average as much as one-tenth of each person’s productive time is sacrificed to waterborne diseases. Likewise, the WHO (Anonymous 2008b) estimates that up to half of all hospital beds in the world are occupied by victims of water contamination.

Although clean water is a valuable natural resource essential for human health and ecological integrity, most fresh water bodies are increasingly being degraded by anthropogenic activities, thus, exposing the water users to a higher risk of waterborne diseases (Bloomfield et al. 2009). Unfortunately, important water quality concerns persist in most developing countries in Africa as a result of increased livestock and anthropogenic activities. Access by livestock and people to river banks is very common in most developing countries, particularly among the poor rural communities or those living in informal urban settlements where most households do not have access to tap water. Visits to rivers are often periodic but frequent especially during dry periods when alternative sources of water such as groundwater and dams are irregular, lacking or inaccessible. During such visits, several activities are performed, among them livestock watering, bathing, swimming, waste disposal, washing of clothes and vehicles among others, which often contribute to water quality degradation (Yillia et al. 2009). The in-stream anthropogenic activities usually constitute a major source of diffuse pollution that can influence nutrient levels and water quality (Zamxaka et al. 2004). Insufficient communal sanitation facilities such as toilets especially in informal settlements of developing countries in Africa often give way to open defecation along the river banks, in drains and open spaces. This results in fecal matter being intermixed with household refuse that finally ends up in aquatic ecosystems through surface runoffs.

Many urban centers in Africa either lack sewerage systems or operate inefficient systems that serve only a small proportion of the urban population (Anonymous 1996). Even where sewers exist they are often blocked leading to overflow of raw sewage into streets and open spaces, providing suitable grounds for disease-causing pathogens. Such discharges can significantly compromise water quality in aquatic systems, which may pose serious health risks, more so when the water is meant for domestic use (Anonymous 2004b).

Rapid population growth and urbanization amid economic stagnation in Kenya have resulted in an increased proportion of people living in absolute poverty in urban and peri-urban areas (Anonymous 2003b). A study on sanitation and hygiene among women living in informal urban settlements by the Central Bureau of Statistics (Anonymous 2003b) showed that only 42% of the women disposed of children fecal matter hygienically into a toilet or latrine. The rest either rinsed it away in rivers or threw it outside their dwelling place intermixed with other household waste. Poor human waste disposal methods and fecal droppings from livestock are routes through which fecal matter can gain entry into aquatic systems, thus introducing pathogens, nutrients and organic matter (Vikaskumar et al.

2007).

Studies by WHO/UNICEF (Anonymous 2004b) showed that sewage is the largest contaminant of water masses around the world causing increased microbial contamination, nutrient enrichment and subsequent eutrophication of surface waters as was also observed by Kanu and Achi (2011). Byamukama et al. (2005) acknowledged that fecal matter may present a significant health risk to the public. Scott et al. (2002) on the other hand reported that the level of risk depends on the origin and level of contamination. Human excreta are regarded as a major risk to public health as they often contain human-specific enteric pathogens. Microbial contamination of surface waters can also trigger the spread of many other infectious diseases such as

cholera, dysentery, typhoid, hepatitis,

cryptosporidiosis, ascariasis, and even

schistosomiasis among others (Anonymous 2000).

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Mulot and Bomet urban centers, like many other centers in Kenya, are experiencing rapid population growth characterized by poor urban planning, informal settlements, limited amenities, poor waste handling capacity, poor sanitation and lack of sewage treatment facilities (Anonymous 2007a). The two towns also differ in size and population. This implies that the Mara River tributaries serve not only as critical sources of water for domestic use for the locals, but also as conduits for waste and raw sewerage that often contaminate water resources (Karani and Mutunga 2004). However, the extent to which the waters are polluted and the potential risk they pose to human health cannot be ascertained without focused analysis to determine pollutant levels. This study sought to assess pollutant levels by use of fecal indicators of water quality including total coliform and Escherichia coli as well as nutrient levels (total nitrogen and total phosphorus). Since half of the world’s population (47%) lives in urban areas (Anonymous 2002a), many rivers that flow through such areas are often highly polluted, more so those flowing through informal settlements. This study will therefore be of general importance and can be widely applied to other river systems faced with similar challenges to those of the Mara River.

Study area

The Mara River Basin lies between longitudes 33°

88' E and 35° 90' E and latitudes 0° 28' S and 1° 97' S, at altitudes of between 2,932 m at the source in the Mau Forest Escarpment to 1,134 m at the discharge point into Lake Victoria (Fig. 1). It covers a surface area of about 13,504 km2 (Mati et al. 2008). The two perennial tributaries, Amala and Nyangores, originate from the western Mau escarpment in the Rift valley in Kenya and flow through the towns of Mulot and Bomet, respectively, before forming a confluence and flowing further down as the Mara River. This eventually discharges its waters into Lake Victoria at Mosirori swamp in Musoma in Tanzania (Mati et al. 2008).

Research design and sampling sites

This descriptive cross-sectional study was carried

out between the 4th and 8th of July in 2011. The

sampling sites were selected based on their

characteristics and location along the two perennial

Mara River tributaries of the Amala and Nyangores.

In total, eight sampling sites were chosen; four along

each tributary. The sampling sites on each tributary

were distributed as follows; three within the towns

(Bomet town - along the Nyangores tributary and

Mulot town - along the Amala tributary) to capture

the influence of anthropogenic activities within

urban centers and a fourth site located at the upper

catchment spring, that discharges its water into each

tributary to act as a control. Water samples were

collected for nutrients and coliform bacterial

analysis in replicates of three and five, respectively,

from each sampling site.

Determination of total phosphorus and total

nitrogen

Total Nitrogen (TN) and Total Phosphorus (TP) were determined on unfiltered water samples following the methods outlined in APHA-AWWA (Anonymous 2005). Total nitrogen was determined using the persulfate digestion method, while total phosphorus was determined by the ammonium molybdate method.

Determination of total coliform and

Escherichia coli

Five replicate water samples for coliform bacterial determination were collected from below the water surface at intervals of 10 m along each tributary using sterile 250 mL glass bottles. The bottles were inverted downwards against the water current, with the hand kept downstream from the neck to avoid contamination. The samples were stored in an ice-packed box and delivered within the six-hour holding time to the Longisa Sub-District Hospital Microbiology laboratory for microbial analyses. Coliform abundance in the water samples was estimated using the most probable number (MPN) procedure by the multiple tube fermentation technique, which involved three successive steps, namely presumptive, confirmed and completed tests (Feng et al. 2002).

A summary of the resulting characteristics of the

data were given by descriptive statistics presented

as means and standard deviations, while variation in

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MATERIALS AND METHODS

nutrient and coliform bacterial levels between sites

along the Amala and Nyangores tributaries were

determined using One-way analysis of variance

(ANOVA), followed by post hoc separation of means

by use of the Duncan Multiple Range Test (DMRT), to

establish the significant differences between sites.

Regression analysis was used to describe

relationships between nutrients and coliform

bacteria, while the Student’s t-test was used to

deduce the possible differences in nutrients and

coliform levels between the Amala and Nyangores

tributaries. Statistical analyses were performed

using SAS V9.0 software. A P<0.05 was chosen as the

significance level.

Nutrient (phosphorus and nitrogen)

concentration

The mean total phosphorus was significantly

higher along the Amala tributary compared to the

Nyangores tributary (Student’s t-test, P= 0.02).

However, total nitrogen levels did not show any

significant differences between the two tributaries.

Considering each tributary separately, the mean TN

levels varied significantly between sites along the

Nyangores tributary (F (3,7)= 530.71, P<0.0001).

Further, DMRT confirmed that TN was significantly

higher (1967±6 μg/L) at the exit point from the town

of Bomet along the Nyangores tributary, but it was

lowest (1230±19 μg/L) at the upper catchment

spring (Fig. 2). Likewise, mean TP levels varied

significantly between sites along the Nyangores

tributary (F (3,7)= 77.47, P= <0.001). Significantly

higher TP levels (685±6 μg/L) were recorded at the

exit point from Bomet along the Nyangores

tributary, while the lowest (404±16 μg/L) was

recorded at the upper catchment spring, draining

into the same tributary (Fig. 3).

At the Amala tributary, the mean total

phosphorus levels varied significantly between sites

(F(3,7)= 28.83, P= 0.0036). The Duncan Multiple

Range Test further showed that mean TP levels were

significantly lower at the upper catchment spring

compared to other sites located within the

urbanized area (Mulot town) along the Amala

tributary (Table 1, Fig. 4). However, no significant

differences were observed in TN levels between

sites along the Amala tributary (P= 0.245). Even

though total nitrogen level was relatively higher

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RESULTS

Fig. 1. Map of study area showing the location of thesampling points along the Amala and Nyangores tributariesof Mara River.

Fig. 2. Mean total nitrogen levels in water samples fromdifferent sites along the Nyangores tributary, Kenya (n= 8). Means with different superscripts are significantly different at

P<0.05.

Fig. 3. Mean total phosphorus levels in water samples fromdifferent sites along the Nyangores tributary, Kenya (n= 8). Means with different superscripts are significantly different at

P<0.05.

along the Amala than Nyangores tributary, the

difference was not significant (Student’s t-test, P=

0.06). Total nitrogen levels showed a steady increase

downstream along both the Amala and Nyangores

tributaries (Table 1, Fig. 5).

Total coliform bacteria (MPN/100 mL) along

the Nyangores and Amala tributaries

The mean total coliform level was 531 MPN/100

mL along the Amala tributary and 272 MPN/100 mL

along the Nyangores tributary (Fig. 6). One-way

ANOVA indicated significant variations in total

coliform bacteria between sites along the Nyango-

res tributary (F(3,19)= 6.91, P= 0.003). The Duncan

Multiple Range Test further showed site-specific

significant differences between the upper catch-

ment spring and those sites located within the

urbanized area (Bomet) along which the river flows.

As expected, total coliform bacterial levels increa-

sed downstream along the Nyangores tributary

(Table 2).

Along the Amala tributary, the highest mean total

coliform level (1100±0 MPN/100 mL) was recorded

at the middle point of Mulot, while the lowest

(225±220 MPN/100 mL) was at the upper catchment

spring that drains into the same tributary (Fig. 7).

There was a significant difference in total coliform

between sites along the Amala tributary (F(3,19)=

5.09, P= 0.012), with DMRT further indicating that

total coliform levels at the middle point of Mulot

was significantly higher than at all other sites (Table

2). The mean coliform levels between the two

tributaries were, however, not significantly different

(P= 0.103).

Escherichia coli levels along the Amala and

Nyangores tributaries

Escherich ia coli levels varied significantly

between sites along the Nyangores tributary

(F(3,19)= 31.82, P<0.0001), with DMRT further

showing that E. coli levels at the upper catchment

spring were significantly lower compared to all other

sites located within Bomet along the Nyangores

tributary (Fig. 8). Generally, sections of the Nyango-

res tributary flowing through Bomet recorded

relatively high E. coli levels compared to the upper

catchment spring that discharges into the same

tributary. Along the Amala tributary, however,

higher E. coli levels (27.5%) were recorded at the

upper catchment spring compared to those

recorded at the lower sections of the tributary. E.

coli proportions showed a close range of between

23.5% and 27.5% across all the sites, and no

significant differences were observed between sites

along the tributary (P>0.05). Overall, regression

analysis on nutrients and E. coli showed that total

nitrogen (R2= 0.6886, n= 8, P= 0.01) was predictive of

E. coli abundance along both tributaries combined,

but was not predictive of total coliform along the

Mara River tributaries.

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Table 1. Total nitrogen and phosphorus levels along theAmala and Nyangores tributaries.

*Means with different superscripts in the same column aresignificantly different at P<0.05. (Data analyzed by Duncan’sMultiple Range Test).

Table 2. Mean total coliforms (MPN/100 mL) along theAmala and Nyangores tributaries.

*Means with different superscripts in the same column aresignificantly different at P<0.05. (Data analyzed by Duncan’sMultiple Range Test).

Fig. 4. Mean total phosphorus levels in water samples fromdifferent sites along the Amala tributary, Kenya (n= 8). Means with different superscripts are significantly different at

P<0.05.

This study was novel in evaluating the role of

anthropogenic activities on water pollution along

the Mara River. It is indicative that most polluted

sites were those frequented by livestock and people

for various purposes. Many factors and sources were

identified as contributors to the high bacterial levels

along the Mara River tributaries. Overdependence

on the Mara River waters by the communities living

along the riparian community exposes humans to

increased risk of contracting waterborne diseases.

Given the expected scale of urban population

growth in the coming decades, continued growth in

the number of urban poor will pose a fundamental

challenge to urban-flowing rivers around the world.

This will most likely expose more people, especially

those in developing countries, to increased risks of

waterborne diseases. The findings of this study are

therefore not only of local or regional interest but

can be generalized to other lotic systems in both

developing and developed countries, the majority of

which are now faced with more or less similar

challenges as those facing the Mara River Basin.

Nutrient (phosphorus and nitrogen) and

coliform bacterial levels

The Mara River tributaries, like many other rivers

worldwide, serve as valuable sources of water for

various uses, key among them being domestic use.

However, increased anthropogenic activities

continue to negatively impact on water quality

making it unsafe for human consumption. More

disturbed sites, especially those located within the

urbanized areas (Mulot and Bomet) along the Amala

and Nyangores tributaries, respectively, had higher

nutrients (total nitrogen and phosphorus) and also

total coliform levels compared to those located at

the upper catchment springs. This was a clear

indication of the potential contribution of

anthropogenic activities to nutrient enrichment and

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DISCUSSION

Fig. 5. Mean total nitrogen levels in water samples fromdifferent sites along the Amala tributary, Kenya.

Fig. 6. Mean total coliform levels in water samples fromdifferent sites along the Nyangores tributary, Kenya.Means with different superscripts are significantly different at

P<0.05.

Fig. 7. Mean total coliform levels in water samples fromdifferent sites along the Amala tributary, Kenya.Means with different superscripts are significantly different at

P<0.05.

Fig. 8. Proportion of Escherichia coli levels along the Amalaand Nyangores tributaries, Kenya.

microbial pollution of the Mara River waters. In the current study, the nutrient levels recorded ranged between 430 μg/L and 832 μg/L for TP and 1230 μg/L and 2201 μg/L for TN across both tributaries. These were almost similar to those recorded at the Yarra River located in Victoria bay, Australia in a longitudinal study (1994-2009). Precisely, the TN levels ranged between 190 and 5150 μg/L, while TP values between 100 and 870 μg/L in four of the five stations sampled along the river. This was also the case for the Mara River Basin where an increase in population, land use development in the catchment and inappropriate application of fertilizers in farms were cited as the largest generators of nutrients recorded in the Yarra River (Anonymous 2009).

Sources of nitrogen and phosphorus that find their way into the Amala and Nyangores tributaries are numerous and can range from livestock and agricultural activities at the upper catchment areas to urbanization and in-stream human activities like use of detergents during washing of clothes and utensils and bathing in the river as well as poor human waste disposal. High protein intake in the human diet is also regarded as a contributor of nitrogen in water especially if the human waste is poorly disposed (Anonymous 2002b); thus, this must not be ruled out as a possible contributor of nitrogen into the Mara River. While acknowledging the increased role that anthropogenic activities play in water quality degradation, a study by Liu et al.

(2008) singled out human wastes as the second biggest source of nitrogen load into aquatic systems after agricultural fertilizers. However, atmospheric deposition is also an important source of nitrogen into aquatic systems, although it is more pronounced in lentic than lotic systems (Baron et al. 2009). Small-scale agricultural activities evident in the upper Mara River catchment and along the river channel in which fertilizers and manure are used are also presumed to contribute to nutrient enrichment of the Mara River waters. Likewise, livestock activities along the riverbanks could also have contributed to the nutrients as well as coliform bacteria in the water through waste deposition either along the banks or in the river channel.

Consistent with the current findings, previous

studies by Shindo et al. (2006) and more currently by Matano et al. (2013) also found a correlation between high levels of total nitrogen and phosphorus with increased levels of E. coli along the Mara River tributaries. They both attributed this to land use types and wastewater discharged from adjacent terrestrial ecosystems. It was highly suspected that untreated wastewater and sewage discharge from informal urban settlements and lack of sufficient sanitation facilities could also have contributed greatly to the high coliform levels observed along the Mara River tributaries. This proved to be the case when the relatively populated and highly disturbed middle part of Bomet, along the Nyangores tributary and exit point from Mulot, along the Amala tributary, were found to contain high levels of total phosphorus, total nitrogen and total coliform bacteria, compared to the relatively undisturbed upper catchment spring draining into the Nyangores tributary.

These findings are consistent with those of APHRC (Anonymous 2002c), in which the informal settlements along the Nairobi River also characterized by a high population and insufficient sanitation facilities contributed considerably to its water quality degradation. Bashir and Kawo (2004) also showed a close link between effluent discharge from highly populated informal settlements and high nutrient levels and microbes in adjacent aquatic systems, while WHO (Anonymous 2002b) reported that lack of provision of septic tanks and sewage systems can lead to surface water pollution. The significant variation in total coliform levels observed between sites along the two tributaries could, therefore, be a result of localized small-scale variability in water quality, driven largely by in-

stream anthropogenic and livestock activities at specific points along the river continuum.

Escherich ia coli, which are indicators of fecal

contamination in surface waters, varied significantly

between sites along the Nyangores tributary with

the highest levels recorded at points flowing

through the urbanized area (Bomet), while the

lowest were at an undisturbed upper catchment

spring that discharges its water into the Nyangores

tributary. This provides further evidence of the

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contributory role that anthropogenic and livestock activities play in water quality degradation. A previous study by Frenzel and Couvillion (2002) also established a significant positive correlation between fecal bacteria and high human population density in urban watersheds. Okoko et al. (2012) attributed increased levels of E. coli at some points along the River Awach in Kisumu County, western Kenya to localized contributions through anthropogenic activities. Livestock grazing along the river and use of certain sections along the river as their watering points can also contribute to E. coli bacterial loading in the river water either directly through deposition of animal waste into the river, or indirectly when animal waste deposited on land or spread manure on agricultural fields surrounding the aquatic system is swept into surface water bodies by surface runoff. Since E. coli bacteria from humans and other warm-blooded animals tend to die rapidly outside the body, their presence in Mara River water is a clear indication of a localized and more recent contamination and, thus, a greater risk factor to inhabitants of the Mara River Basin who depend on the water for domestic use.

The distribution of E. coli along the Nyangores and Amala tributaries was not uniform nor did it increase or decrease exponentially downstream. Instead, E. coli levels varied highly with more disturbed areas recording relatively higher levels compared to less disturbed areas. This was probably due to the small-scale variability in water quality, emanating from point source pollution that was driven mainly by anthropogenic activities. Noble et al. (2004) attributed the spatial variation in bacterial levels to initial loading and the disappearance rate which is a function of time and distance of travel from the source, as well as other external and internal factors such as temperature, competition, toxicity, predation and solar radiation. This can to some extent explain the spatial variability of coliform bacteria observed at certain points along the Amala and Nyangores tributaries.

The most significant finding in this study,

however, was the relatively high (27.5%) E. coli

proportions at the upper catchment spring draining

into the Amala tributary, previously thought to

contain clean water. The high E. coli levels at this particular point of the spring should be of great concern because of the critical role the spring plays as the main source of water for domestic use by the surrounding inhabitants. The US EPA (Anonymous 2012b) recreational water quality criteria put the concentration threshold for culturable E. coli at a mean of 126 cfu per 100 mL measured using EPA Method 1603 or any other equivalent method that measures culturable E. coli in a sample of water meant for recreational purposes. However, the thresholds are put at nil or 0 (zero) for waters meant for human consumption. This implies that while the Mara River waters can be used for recreational purposes, they may not be safe for drinking.

Apart from human activities, livestock activities coupled with the gently sloping and largely bare landscape around this particular spring could be facilitating the transfer of waste into the spring contributing to high E. coli levels. Kelsey et al. (2004) attributed fecal contaminants in surface water systems to storm water runoff from urban and agricultural land uses. Likewise, a longitudinal study by Toothman et al. (2009) in North Carolina, in the United States of America, singled out urban storm water runoff as the major contributor to fecal coliform bacterial loads in the surface waters.

As watershed areas are developed for residential, commercial, industrial, and transportation land uses, the quality and quantity of freshwater in rivers is substantially altered due to increase in the impervious layer. This is because many types of pollutants, originating from a variety of sources, accumulate over impervious urban surfaces and are subsequently washed into water bodies during and immediately following rainfall events, severely degrading water quality and harming aquatic life. This is however serious in areas like Olympia, Washington where the impervious layer covering over 63% has been recorded (Schueler 1994) compared to the Mara River region where the impervious layers are very minimal. For instance, a recent land cover map of the Nyangores Basin showed that the basin was covered by 64% cropland, 26% forest, 9% bushland, and 1% tea (Anonymous 2007b). Surface waters in such areas are likely to be

influenced more by agricultural pollutants and

sewage than urban surface runoffs.

Regression analysis showed that total nitrogen was predictive of E. coli, along the two Mara River tributaries. These findings are consistent with those of Burkholder et al. (2007) and Mallin et al. (2000), which reported significant relationships between fecal bacteria and nutrient concentrations due to a common source or a random arrival of nutrients and E. coli in the same area. The detection of E. coli at various sections of the Mara River tributaries was a strong indication of the possible presence of other potentially harmful enteric pathogens as was also reported by Mireille et al. (2011) in their study on the prevalence of pathogenic strains of E. coli in urban streams in Cameroon.

The continued use of water from the Mara River

tributaries for domestic purposes without

knowledge of its sanitary quality, therefore,

continues to expose the Mara River Basin

inhabitants to an increased risk of contracting

waterborne diseases such as cholera, typhoid, and

hepatitis among others. It is, thus, necessary to

educate communities residing not only within the

Mara River Basin but also within other river basins

especially in developing countries, on basic hygienic

and sanitation practices aimed at curbing water

pollution and, therefore, reducing waterborne

diseases. In addition, all water collection points

including springs need to be protected to curb

backflows that may lead to source contamination,

while anthropogenic activities such as washing of

soiled baby clothing and bathing directly in the river,

or defecating along the banks should be

discouraged. Similarly, discharge of untreated

sewage into the river channel should also be curbed.

These recommendations are not only restricted to

the Mara River Basin, but can also be applied widely

to many other aquatic systems across the world that

are faced with similar issues.

We acknowledge the Lake Victoria Basin

Commission Secretariat for providing funds for this

study, Maseno University and Kenya Marine and

Fisheries Research Institute for providing the

required infrastructure and technical support during

sample collection and nutrient analysis and Longisa

District Hospital administration for use of their

laboratory for microbial analysis.

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Anonymous (1996) Urban environment and health in ECA member states. Economic Commission for Africa, AddisAbaba.

Anonymous (2000) Measuring preferences on health system performance assessment. World Health Organization,GPE Discussion Paper No. 20, Geneva.

Anonymous (2002a) World urbanization prospects: the 2001 revision. UN Population Division.http://www.un.org/esa/population/publications/wup2001/WUP2001_CH1.pdf (Date accessed 16.8.2013)

Anonymous (2002b) World health report: reducing risks, promoting healthy life. World Health Organization, France.http://www.who.int/whr/2002/en/whr02_en.pdf (Date accessed 14.7.2013)

Anonymous (2002c) Population and health dynamics in Nairobi informal settlements. African Population and HealthResearch Center, Nairobi.

Anonymous (2003a) The 1st UN world water development report: water for people, water for life. United Nations WorldWater Assessment Programme (UN WWAP). http://www.unesco.org/water/wwap/wwdr/wwdr1/ (Date accessed5.9.2013).

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Health Organization and UNICEF, Geneva, New York.

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