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The negative impact of urbanisation on river and lake systems in European cities is wide-ranging and multi-faceted. The impacts go beyond the historical issue of water pollution and extend to structural changes of the once-more natural rivers and lakes. The ways urbanisation has affected urban rivers and lakes include (based on ECRR, 2015):

• Water quantity impacts: Decreased flow and reduced groundwater levels through abstraction as well as increased flow from surface run-off, increased frequency of floods and reduced infiltration affect the quantitative status of rivers and lakes in cities.
• Water quality impacts: Wastewater discharges and increased run-off from impervious surfaces such as roads, roofs and gardens, and contamination from household and industrial stormwater overflows degrade water quality.
• Physical structure impacts: Artificial walls replace natural river banks, barriers disrupt connectivity or in many cases the river is hidden underground (covered rivers).
• Geomorphological impacts: Urban rivers lack the space to erode their banks and deposit sediment or connect to their floodplain, which leads to altered morphology. Bridges, pipes and other infrastructure alter the width and depth of rivers, and their courses are changed by straightening and bypassing.
• Impacts on the ability to support wildlife: Natural corridors, riparian zones and in-channel habitats are lost.
• Removal of riparian vegetation: This reduces organic input, habitat complexity, increases river temperature and reduces bank stability.
• Invasive species: Urban areas often suffer from introduced non-native species that become dominant and cause damage to the environment.

Urbanisation also has a notable impact on channel ecology, made obvious in terms of decrease in biotic richness and increased dominance of pollution- and flow-tolerant species. As urban centres have expanded in size and number, negative impacts on freshwater ecosystems have become more severe and widespread (summarised by Everard & Moggridge (2011)).