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The river Ganges, the National Heritage, and the lifeline of millions of Indians, unfortunately, ranked the second most polluted rivers of the world in 2017. This review reveals the current trends of the water quality of the Ganges assessed around 36 stretches during 2012-2016, to indicate an improvement around 6 (16.7%), deterioration around 14 (38.9%), and non-significant changes around 16 (44.4%) stretches. An increase in dissolved oxygen and a decrease in biochemical oxygen demand were observed at six stretches (Devprayag [S 5 ], Rishikesh upstream [S 7 ], Varanasi upstream [S 19 ], Mokama upstream [S 25 ], Mokama downstream [S 26 ], and Munger [S 27 ]). The total and fecal coliform contamination decreased at seven stretches (Rudraprayag [S 2 and S 3 ], Devprayag [S 5 and S 6 ], Rishikesh [S 7 ], Varanasi upstream [S 19 ], and Munger [S 27 ]) due to improved hygienic conditions, but it increased subsequently at eight stretches (Haridwar [S 8 ], Kanpur [S 15 ], Raibareili [S 16 ], Prayagraj [S 17 and S 18 ], Patna [S 24 ], Berhampore [S 30 ], and Serampore [S 31 ]) due to improper defecation and mass bathing during 2007-2016. Dissolved oxygen level declined significantly, and biochemical oxygen demand increased (> 3 ppm), alarmingly at places receiving heavy untreated sewage water. The water quality of the Ganges was good up to Rishikesh, because of an undisrupted flow of the uncontaminated water from the higher altitudes (≥ 372 m) with higher forest cover, lower temperatures (< 21 °C), and higher dissolved oxygen (≥ 8.5 ppm) and due to the dissolution of antipathogenic chemical constituents of the medicinal herbs, pollutant degrading alkaline phosphatase, and bacteriophages. The present review is a systematic collection of data on river pollution, its scientific analyses, and its relationship with 6Ps (namely population, poverty, pollution, precipitation, plantation, and periodicity). Not only that, but the river water restoration measures have also suggested through the novel interlinked water working groups for implementing integrated water management strategies.

Urbanization and related environmental pollution have strong effects on stream systems by inducing short duration high-peak floods, raised levels of nutrients and contaminants, altered channel geomorphology, sediment dynamics, and reduced biotic richness. The main purpose of this current study is to detect stream contamination levels in a mid-sized Hungarian city by comparing the results of two separate years (2011, 2018). Discharge, channel geomorphology, and water quality parameters were measured, and load-based contamination was calculated for the city's main watercourse (Gaja Brook). The pH, CaCO 3 , texture, and heavy metal contents – Cd, Co, Cu, Ni, Pb, and Zn – were reanalysed in the sediment for both investigated years. For comparison, enrichment factors were used to determine sediment accumulation. As a complex parameter, biological water quality was also determined using BMWP and MMCP protocols in 2018. The results show that conductivity and the nutrient concentrations were higher, but the discharge values were lower in 2011 than in 2018. The nitrate load doubled both times in the brook between the first and the last sampling sites. The enrichment factors decreased or stagnated when the values of the two years were compared, but severe enrichment of Cd was detected in the middle of the city and south of the city. The aquatic macroinvertebrate fauna structure defined clean, but slightly impacted watercourses north and south of the city as well, but the abundance and presence of sensitive taxa differed at the sampling sites. Székesfehérvár has better than expected water quality, which can be attributed to the good ecological states of the hydromorphology and the streamside zone. Image 1 • Accumulation of some trace metals can be observed in sediments in urban regions. • WWTP outflow showed adverse impact on water quality. • Conductivity, nutrient concentrations and loads increased due to the urban area. • Unmodified streambeds have positive effects on biological water quality. [ABSTRACT FROM AUTHOR]