Paul T. Yillia

Abstract: Njoro River (60 km) is a high altitude second order stream in southwestern Kenya. The stream is the main source of water for Lake Nakuru National Park, a Ramsar site and a renowned tourist destination for wildlife. The stream is also important for the riparian inhabitants that depend on it for their daily water needs. Nevertheless, considerable land use change has occurred in the catchment within the last three decades with expected consequences on the water quality, ecology and hydrology of the stream and the receiving lake. But the inherent response by the stream to the interactions between human interventions and the natural landscape variables within the catchment has not been aptly investigated. As a result, the catchment was systematically studied between February 2005 and May 2008. The overall objective of the study was; (i) to link current land use/cover in the catchment to pollution in the stream; (ii) to describe the loading, transportation and transformation of pollutants in the stream; and (iii) to suggest realistic management measures to prevent or curb pollution in the stream. Eleven sampling sites (3–5 km apart) were routinely monitored on a monthly, semi-monthly and/or diurnal basis as dictated by several specific objectives. Monthly and semi-monthly sampling occurred between December 2005 and December 2006. Diurnal sampling occurred at 6 hrs intervals in response to the diurnal pattern of visits to the stream by people and livestock. Visits were enumerated by making head counts at several water abstraction points (WAPs) from 6–7 p.m. A suite of water quality parameters was investigated. Stream flow; total suspended solids; turbidity; alkalinity; total hardness; physico-chemical parameters; BOD5; micronutrients and; bacteria indicators (HPC, TC, Escherichia coli and intestinal enterococci), were analyzed with the aid of standard analytic procedures on site and/or at the laboratory of the Department of Biological Sciences at Egerton University on the left bank of the stream at the middle reaches. Stream flow was intermittent and seasonally periodic with three distinct flow regimes and a complete cessation of flow at the lower reaches during dry periods. Pollution levels in the stream were spatially and temporally variable. Cluster analysis revealed two significant site clusters separately for each of the three hydrological periods. Ambient levels of pollutants at the upper forested catchment were significantly (p < 0.05) lower compared to the middle or lower reaches, where commerce, farming and settlements dominated. Site specific analysis for temporal variability showed that generally, ambient levels of suspended solids, total P and the microbial indicators increased significantly (p < 0.05) during wet weather whereas conductivity, total N, PO4-P, NH4-N and NO3-N decreased concurrently. Several water quality indicators displayed strong associations and efficacy for site segregation based on pollution levels. The observed positive and significant correlation (p < 0.05) between microbial indicators, suspended solids, turbidity and total P suggested possible common source(s) associated with specific land use/cover within sub-catchments. Analysis of the net flux of pollutants at a reduced spatial scale identified the densely settled and heavily farmed areas around Egerton University and Njoro Township as the most vulnerable sub-catchments. The least vulnerable was the predominantly forested Upper Njoro River Catchment. The principal sources of pollutants were WTP outfalls, surface runoff from farmland and residential areas and, the in-stream activities of people and livestock. Nonetheless, the potential for self-purification was evident especially within the 5 km restricted stretch between Egerton University and Njoro Township, where the estimated rate of removal/retention of major contaminants was remarkably high, in particular during dry weather. However, the systematic removal/retention during dry weather was obliterated as stream flow increased in wet weather. This was associated to within-channel sediment wash-out, as well as runoff from commercial farms in the vicinity as was evident with the increase in suspended solids and total P especially during transient rainstorms within this stream reach. Two forms of transient pollution events were identified at the middle reaches. Transients induced by rainstorms yielded significantly (< 0.05) higher levels of pollutants compared to short-lived episodes provoked by the diurnal in-stream activities of people and livestock. The transient yield of suspended solids, BOD, total P and total N in excess of base flow during storm-induced transients was particularly striking (780, 8.4, 0.5 and 0.1 t/d, respectively) with all pollutants going through a slight anticlockwise circle of improved water quality within 48–72 hrs of the descending limb of the stream hydrograph. Both transient events were symptomatic of within-channel processes but storm-induced transients were exceedingly important for the catchment mobilization of pollutants compared to the in-stream activities of people and livestock. In-stream activities occurred at water abstraction points (WAPs) along the stream and included waste deposal, watering of livestock, washing of clothes and vehicles, swimming, bathing and abstraction of water for domestic use. The daily total abstraction during in-stream activities at the middle reaches was 120–150 m3.day-1 during dry weather being considerably lower in wet weather. More than 60% of the abstraction was done by adult male water vendors. Vended water from the stream was sold at US$ 3.5–7.5 per cubic meter and vendors earned between US$ 3–6 a day. During dry weather, abstracted water contributed approximately 40–60% of the total daily consumptive water use in the riparian area. However, > 30% of the morning stream flow was abstracted thereby upsetting stream flow in the lower reaches. In-stream activities also affected the water quality of the stream. The microbial water quality, in particular, deteriorated significantly (p < 0.05) downstream of activities increasing by at least 1–2 log units during in-stream activities. Similarly, levels of TSS, turbidity and BOD5 increased significantly (p < 0.05) but mean levels of micronutrients were not significantly (p > 0.05) different even though levels were consistently higher downstream. The pooled data was explained largely by three significant principal components, namely; recent pollution, metabolic activity and residual pollution. The empirical upstream–downstream site parity/disparity that was observed reflected the diurnal periodicity of in-stream activities and the concomitant pollution they caused. Consequently, the potential health risk (PHR) at the WAPs for bathing and drinking exceeded acceptable health risk (AHR) levels. PHR was 2–3 times higher with the Cabelli (1983) Intestinal Enterococci (IE) model compared to the U.S. EPA (1994) Escherichia coli (EC) model. Reducing the current PHR levels of > 4% of the exposed population to U.S. EPA bathing AHR levels of 0.7% (EC) and 1.9% (IE) would require at least 2–4 log reductions of IE and EC densities and further reductions to achieve the WHO recommended drinking water AHR level of 0.1% of the exposed population. This would necessitate specialized treatment techniques and comprehensive catchment management measures to protect the WAPs. It was concluded that the hydrology and water quality of the stream, in particular, at the middle and lower reaches is critically affected by various human interventions in the catchment. But the response of the stream to the interventions is principally governed by current land use/cover, the diurnal periodicity of human activities and the seasonality of the hydrological regime. This knowledge could be useful for pollution management. Measure could include: (i) improving wastewater treatment efficiency to minimize loading from point sources; (ii) small-scale actions at various locations in the catchment to minimize the transfer of pollutants from diffuse sources; (iii) restricting access within certain stream reaches to control in-stream activities of people and livestock and; (iv) improving water and sanitation facilities in the settled areas of the catchment.

Abstract: Two transient pollution events were monitored in a pastoral stream in southwestern Kenya to evaluate their relative contribution to diffuse pollution. Peak loads of pollutants during storm-induced transients were within 3-4 orders of magnitude higher than the short-lived (30-60 minutes) diurnal episodes provoked by in-stream activities of people and livestock. Transient yields were striking during storm-induced events; 778,000, 8,400, 550 and 100 kg day(-1) for suspended solids, BOD(5), total P and total N, respectively, compared to wet weather base flow (150, 30, 0.8 and 1.4 kg day(-1), for the same parameters, respectively). Two forms of concentration-discharge relationships were observed: increases in concentration for turbidity, suspended solids, BOD(5), total P and the faecal indicator bacteria at the peak of the stream hydrograph, and concurrent decreases in concentration for conductivity and total N. Following each storm-induced transient event, a marked improvement in water quality was observed within 48-72 hrs of the receding limb of the stream hydrograph before the next base low was established. It was concluded that storm-induced transients are exceedingly important for the mobilization of pollutants from diffuse sources but both transient events affect stream-channel processes, especially water quality, with the possibility of attendant consequences on the health of riparian inhabitants.

Abstract: US-based models for recreational water quality were applied to characterize the potential health risk (PHR) of infection with gastroenteritis (GI) and highly credible gastroenteritis (HCGI) illnesses from single exposure at several water abstraction points (WAPs) along the Njoro River in rural Kenya. Ambient geometric mean densities of Escherichia coli (EC) and intestinal enterococci (IE) were generally high (2–4 log units of cfu/100 ml) and risk levels were grossly in excess of acceptable health risk (AHR) levels for bathing and drinking. PHR was 2–3 times higher with the Cabelli (IE) model (Equation (2)) compared to the US EPA (EC) model (Equation (1)). Risk levels varied among WAPs in concomitance to the spatial and seasonal variability of ambient EC and IE densities. With the Cabelli IE model, PHR of HCGI illness on single exposure to the dry weather 95th percentile IE density for bathing was 2.5% of the exposed population at Logoman compared to 5.2% at Turkana Flats, 4.9% at Kenyatta or Nessuit and 4.6%, 4.5% and 4.2% at Treetop, Segotik and Njoro Bridge, respectively. PHR was 5% on exposure to the wet weather 95th percentile IE density at all WAPs, excepting Treetop with 4.3%. Relative risk levels increased by at least 30 and 70 times for GI and HCGI illnesses, respectively, from drinking (250 ml) raw stream water, rising erratically in wet weather by >80% of the dry weather risk at Logoman, >30% at Njoro Bridge and Kenyatta and 10–15% at Segotik, Nessuit and Turkana Flats. By stipulating freshwater bathing water quality guidelines of 126 and 33 cfu/100 ml for EC and IE, respectively, US, EPA upholds maximum AHR levels at 0.7% and 1.9% for EC and IE, respectively. Hence, reducing current PHR levels at the WAPs to the US, EPA bathing AHR levels would require at least 2–4 log reductions of IE and EC densities with even further log reductions to achieve the WHO recommended drinking water AHR level of 0.1%. This would necessitate specialized treatment, in particular point-of-use treatment at the household level, as well as the implementation of comprehensive catchment management measures to protect the stream and the WAPs.

Abstract: Emissions and riverine loads of pollutants were estimated for five sub-catchments in the Njoro River Catchment, Kenya to isolate specific areas for interim pollution management. The most vulnerable sub-catchments were the densely settled and heavily farmed areas around Egerton University and Njoro Township with the restricted area between them demonstrating a remarkable potential to retain/remove most of the pollution emitted in the Egerton University area. The least vulnerable sub-catchment was the predominantly forested Upper Njoro River Catchment whereas the recently settled and increasingly farmed Lower Little Shuru was moderately vulnerable. The method provided a scientific framework for the rapid assessment of catchment vulnerability to prioritize areas for remediation.

Abstract: The influence of periodic in-stream activities of people and livestock on the microbial water quality of the Njoro River in Kenya was monitored at two disturbed pools (Turkana Flats and Njoro Bridge) at the middle reaches. A total of 96 sets of samples were obtained from the two pools in six weeks during dry weather (January–April) in 2006. On each sampling day, two trips were made before and during in-stream activities and on each trip, two sets of samples were collected upstream and downstream of activities. This schedule was repeated four times each for Wednesday, Saturday and Sunday. Samples were processed for heterotrophic plate count bacteria (HPC), total coliform (TC), presumptive Escherichia coli and presumptive Enterococci. Additional samples were analysed for total suspended solids (TSS), turbidity, BOD5 and ammonium-N. The microbial water quality deteriorated significant (p < 0.05) downstream during activities at both pools. A similar trend was observed with the chemical indicators (TSS, turbidity, BOD5 and ammonium-N). The two groups of indicators demonstrated high capacity for site segregation based on pollution levels. Pollution levels for specific days were not significantly different (p > 0.05). This was incompatible with the variability of in-stream activities with specific days. The pooled data was explained largely by three significant principal components – recent pollution (PC1), metabolic activity (PC2) and residual pollution (PC3). It was concluded that the empirical site parity/disparity in the levels of microbial and non-microbial indicators reflected the diurnal periodicity of in-stream activities and the concomitant pollution they caused. However, microbial source tracking studies are required to distinguish faecal sources. In the meantime, measures should be undertaken to regulate in-stream activities along the stream and minimize the movement of livestock in the catchment.

Abstract: For shallow streams in sub-Saharan Africa, in-stream activities could be described as the actions by people and livestock, which take place within or besides stream channels. This study examined the nature of in-stream activities along a rural stream in Kenya and established the inequality in water allocation for various livelihood needs, as well as the negative impact they have on dry weather stream flow and chemical water quality. Seven locations along the stream were studied in wet and dry weather of 2006. Enumeration consisted of making head counts of people and livestock and tallying visitors at hourly intervals from 6 a.m. to 7 p.m. To estimate water abstraction, filled containers of known volume were counted and the stream was sampled to examine the impact on water quality. Water samples were obtained upstream and downstream of in-stream activities before (6 a.m.) and during (11 a.m., 6 p.m.) activities. Samples were analyzed for suspended solids, turbidity, BOD5, total nitrogen and total phosphorus. The daily total abstraction at the middle reaches during dry weather was 120–150 m3 day−1. More than 60% of abstraction was done by water vendors. Vended water from the stream was sold at US$ 3.5–7.5 per m3 and vendors earned between US$ 3–6 a day. Abstracted water contributed approximately 40–60% of the total daily consumptive water use in the riparian area during dry weather but >30% of the morning stream flow was abstracted thereby upsetting stream flow in the lower reaches. The daily total water abstraction correlated positively (R2, 0.98) and significantly (p < 0.05) with the daily total human visit, which was diurnally periodic with two peaks, occurring between 9 a.m. and 10 a.m. and from 4 p.m. to 5 p.m. This diurnal pattern of visits and the corresponding in-stream activities affected water quality. In particular, suspended solids, turbidity and BOD5 levels increased significantly (p < 0.05) downstream during in-stream activities. It was concluded that the positive contribution of in-stream activities, in particular, water abstraction to livelihoods and the daily water needs was overshadowed by the apparent disregard of the impact on stream flow and water quality. Therefore, measures are required to control in-stream activities along the stream but authorities should be mindful of the implications of any management strategy on the livelihoods of the riparian inhabitants.

Abstract: In rural sub-Saharan Africa, small scale water abstraction could be described as the manual withdrawal of water usually from the banks of shallow surface water systems by people with the aid of 10-and/or 20-litre containers mainly for domestic use. The gender composition of human visitors during water abstraction at the middle and upper reaches of a predominantly rural stream (Njoro River) in southwestern Kenya was analyzed. Abstraction started at dawn with adult females accompanied by girls. But adult males who were mostly water vendors dominated, contributing > 65% of the daily total visits on weekdays. The number of children at the stream in the morning, as well as early in the afternoon of weekdays was < 15% but they accounted for approximately 40% of the evening total and > 7% of the daily total visits on weekends. The dominance of adult males coupled with the low participation of children, especially on weekdays suggested that water abstraction in the Njoro area was not an important activity for most children. This information could be relevant for the development and/or refinement of policy and targeted programmes on water supply in the area.

Abstract: Africa continues to struggle to make progress in supplying water and sanitation to its people. Often the challenges can be overwhelming and the looming threats of climate change, increased urbanisation and expansion of urban slums make action all the more urgent. Innovative Practices in the African Water Supply and Sanitation Sector is a must read for practitioners who are interested in sustainable water management. Its rich collection of practical African case studies covering innovative ways to approach such diverse topics as financing, capacity building, community ownership and management, through to water loss reduction, provides a variety of entry points for governments and NGOs to take action. Donors, governments and practitioners should take notice as replication and upscaling of local initiatives, such as those presented in this book, are the way to success for water and sanitation in Africa.

Abstract: Africa continues to struggle to make progress in supplying water and sanitation to its people. Often the challenges can be overwhelming and the looming threats of climate change, increased urbanisation and expansion of urban slums make action all the more urgent. Innovative Practices in the African Water Supply and Sanitation Sector is a must read for practitioners who are interested in sustainable water management. Its rich collection of practical African case studies covering innovative ways to approach such diverse topics as financing, capacity building, community ownership and management, through to water loss reduction, provides a variety of entry points for governments and NGOs to take action. Donors, governments and practitioners should take notice as replication and upscaling of local initiatives, such as those presented in this book, are the way to success for water and sanitation in Africa.

Abstract: To assess the spatial and seasonal dynamics of pollutants along the Njoro River, water samples were taken from 11 sites at 14 days interval from January through December in 2006. Samples were processed for microbial indicators, micronutrients, suspended solids, turbidity, BOD5 and the physico-chemical parameters. Mean (±SD) dry weather levels of conductivity, TSS, BOD5, total P, NH4-N, and total N increased significantly (p < 0.05) from 127±21, 8.7±3.2, 2.9±0.9, 0.1±0.0, 0.1±0.0, and 0.5±0.2 mg.l-1, respectively, at Logoman at the forested upper reaches to 406±106, 14.3±5.1, 17.3±1.3, 1.4±1.1, 0.6±0.3 and 1.0±0.1 at Canning below WTP effluents at the middle reaches. Median indicator bacteria densities were generally within 4–7 log units for heterotrophic plate count bacteria and total coliforms, and within 2–4 log units for presumptive Escherichia coli and presumptive intestinal enterococci with slightly higher levels at the middle and lower reaches compared to the upper stream reaches. Site specific analysis for seasonal variability of water quality indicators suggested loading, as well as dilution of pollutants during wet weather. Ambient levels of suspended solids, total P and bacteria indicators increased significantly (p < 0.05) at most stream sites during wet weather, whereas conductivity, total N, PO4-P, NH4-N and NO3-N decreased concurrently. Several parameters displayed strong associations and capacity to segregate sites with the classification of two distinct site clusters for each hydrological period even though clusters for short wet weather were scrambled and indistinct at RDCC (rescaled distance cluster combined) < 6. The observed positive and significant correlations (R = 0.43–0.87; p < 0.05) between microbial indicators, suspended solids and total P indicated possible common source(s), presumably WTP effluents, runoff from agricultural and residential plots and within stream channel activities of people and livestock. A reduction of the current number of sampling sites and the number of water quality variables investigated was proposed. This could reduce the current cost of sampling and processing by half and the time spent sampling by at least 3 hrs without comprising the quality and spatial outlook of the water quality data.

Abstract: Two contrasting transient pollution events were monitored at the middle reaches of Njoro River in southwestern Kenya to evaluate the temporal dynamics of diffuse pollution related to such events. Peak loads during storm-induced transients were within 3–4 orders of magnitude higher than short-lived (30–60 minutes) diurnal episodes provoked by in-stream activities of people and livestock. Clockwise concentration-discharge hysteresis were observed for Turbidity, TSS, BOD, total P and the faecal indicator bacteria, whereas anticlockwise loops were detected for conductivity and total N. Transient yield of TSS, BOD, total N and total P in excess of base flow during storm-induced transients was striking: 65, 0.7, 0.05 and 0.01 kg/ha/day, respectively, with all pollutants going through a slight anticlockwise loop of improved water quality within 48–72 hrs of the receding stream hydrograph following a storm. It was concluded that even though both transient events were symptomatic of within-channel processes, storm-induced transients were exceedingly important for catchment mobilization of pollutants from diffuse sources.

Abstract: A systematic review is presented of recent research advancements on the Njoro River Catchment (NRC), south-western Kenya. Particular emphasis is placed on evaluating published and unpublished scientific literature on the biophysical landscape and the alterations caused by population growth, human activities and land use change in the last three decades. Also the relevance of this knowledge for broader catchment management is examined and an attempt is made to identify possible knowledge gaps that could be hindering management efforts. Undoubtedly, the situation in the NRC is critical – a typical manifestation of the immense social and environmental challenges facing natural resources managers in this part of Kenya. However, substantial information on several disciplines already exists to aid management efforts. Indeed there is knowledge dearth especially on a sustained long-term basis in almost all disciplines but current information gaps need not hinder management efforts as these gaps do not amount to the ostensible general paucity of information that is often widely blamed for the management ineptitude in the catchment.

Abstract: Displaced from the countryside during the decade long civil war, they settled in the hilly south end of Mayenkeneh and were faced with inadequate water and sanitation facilities. But they organized themselves to protect a natural spring source by constructing a water abstraction facility that merits replication. The story begins with a prologue and ends with an epilogue, both narrating the water chronicle of a typical household in Mayenkeneh Prologue: Since 1993, Mama Hannah, the amiable and prayerful wife of a retired diamond mine worker lives with her husband TN and six grandchildren in a modest house at Mayenkeneh in the east end of Freetown, Sierra Leone. The accommodation is furnished with a flush toilet, a shower and a tap in the kitchen. There is an additional tap outside the house. But since they moved in, not a single drop of water has flowed from any of the taps nor have they ever used the flushing mechanism in the toilet. "The unit works perfectly but we are not bothered with it because there is never any running water" Mama Hannah said. "We have learnt to flush the toilet by simply pouring water directly in the toilet basin. As sad as it is, we are now used to it" she added. It is already nine o' clock on a Sunday morning and there is not a single drop of water in the house. Yesterday, her grandchildren, SM and Fayia could not bring sufficient water home from a protected spring nearby – the only consistent and dependable source of drinking water for a community of over 50000 residents. There were so many people at the spring, as it is often on Saturday. So the two boys could barely manage to fill two 20-litre jerry-cans for a household of eight. Mama Hannah is not used to insufficient water at home and she is always complaining. She grew up in the countryside at Kpongoma Village on the banks of the Moa River, one of seven major river systems draining the country. As a child, she remembers bathing each evening at the shores of the river and in the morning obtaining drinking water at ease from an unprotected spring nearby. When her husband worked at the mines (DIMINCO) at Yengema in the east of the country, life was pretty good. In addition to a fairly good salary, there was a year-round supply of electricity and running water. Both the shower and the flush toilet in their modest apartment worked perfectly all year-round. "There was not a single day when water had to be brought home by my children", she recalls. This is because at the mines, portable water supply and sanitation was never an issue. Thanks to the fringe benefits her husband received as an intermediate staff at DIMINCO. However, when rebels struck the mines on their last daughter's birthday on October 23 in 1992, life changed unconstructively for Mama Hannah and her husband. Her husband lost his job and they had to move with their grandchildren to Mayenkeneh, a peri-urban community at Calaba Town in the east end of Freetown. Epilogue: According to recent reports, Sierra Leone is way off-track to achieving the water and sanitation target of Millennium Development Goals (MDGs) (Oxfam, 2006; DFID, 2007). Mama Hannah does not know what the MDGs are and she is not bothered. Instead, she prays and hopes for improvement in the general living condition. But she has since lost hope of returning to the now defunct mines at Yengema. Instead, she dreams of relocating to her husband's birthplace at Wiema Village in Kailahun District. "If at least some degree of pre-war normalcy could return to that part of the country, I am prepared to move". She said. But it is past five years since the war officially ended and life in Kailahun District is still miserable and intolerable. The whole district is a ruined land with crippling poverty and a crumbled infrastructure. It is the district with the highest incidence of poverty with most people living in abject poverty (Oxfam, 2006). There is no electricity. The roads are bad and largely inaccessible and the healthcare facilities are dismal. Even though the water supply facilities are being resuscitated, only 14% of the population has access to safe drinking water and basic sanitation remains grimly poor according to the 2003–2004 Sierra Leone Integrated Household Survey (Oxfam, 2006). In Wiema Village, for instance, there is only one village well and sanitation facilities are disgustingly inadequate for over 100 residents, nearly all of whom may have never seen or used a flush toilet before. Consequently, it seems for the time being, Mama Hannah must cope with limited water at home in Mayenkeneh. "Living here is very difficult but it may be better compared to life in the village. She said. "The war lasted too long. My husband lost his job and all we had worked for. But I thank God that we are alive and well". She concluded as her grandson Fayia returned home staggering with a 20-litre jerry-can of water from the community spring in the hilly south end of Mayenkeneh. At least, she has some water to bath just in time for the Sunday morning service at a church nearby.

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Abstract: Water samples were obtained from the main water abstraction points (WAPs) along Njoro River in 2005/2006 to evaluate the microbial water quality and the associated health risk for various activities. Bacteria levels were generally high, staying within 4–7 log units for heterotrophic plate count bacteria (cfu.ml-1) and total coliform (cfu.100 ml-1), and within 2–4 log units (cfu.100 ml-1) for presumptive Escherichia coli and intestinal enterococci. The corresponding potential health risk (PHR) levels were grossly in excess of acceptable health risk (AHR) levels for bathing (1.9%, U.S. EPA) and drinking (0.1%, WHO). PHR levels at the WAPs ranged from 0.3–0.5% for washing and irrigation, 1.3–2.6% for religious baptism, 2.7–5.2% for full-contact recreation, including bathing and swimming, and 6.7–13.0% for drinking a glass of water (250 ml) from the stream. Except for Logoman at the forested upper catchment with 53.7%, PHR was 80–100% for all WAPs when the recommended daily intake for adults (2000 ml/p/d) was computed. It is evident that without treatment, Njoro River is unsuitable for many uses as the stream constitutes a potential health risk to the exposed population. Point-of-use treatment at the household level is advised for drinking and bathing but extra studies are required on the best available technology in the region.

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