Significant Pressures: Urban Waste Water
Urban Waste Water Treatment Plants and agglomeration networks (UWW) have been identified as a significant pressure in 20 % (291) of all water bodies that have been determined as being At Risk of not achieving their WFD objectives.
Of these 291 water bodies, 250 are rivers, 15 are lakes, 23 are transitional waters and three are coastal waters (Table 1).
Six of these water bodies have High Environmental Status (HES) objectives. One of these water bodies, Island_030 in Galway is impacted only by UWW while the remaining HES water bodies are impacted by multiple pressures (Figure 1).
Water quality problems in water bodies impacted by Urban Waste Water
Direct discharge of nutrients from urban waste water treatment plants and discharge from combined storm overflows (CSOs) or storm water overflows (SWOs) are the most common water quality problems associated with urban waste water. Emissions of elevated concentrations of phosphorus and ammonia from UWW impact rivers and lakes while emissions of nitrogen and phosphorus impacts transitional and coastal waters while elevated concentrations of microbes impact bathing and shellfish waters.
Table 1. Number of At Risk water bodies with Urban Waste Water (UWW) as a significant pressure
|Waterbody (WB)||Number of WBs||Number of At Risk WBs||Number of WBs with UWW as a significant pressure||% of WBs with UWW as a significant pressure||% of At Risk WBs with UWW as a significant pressure|
Possible Solutions and the Next Steps
The River Basin Management Plan (RBMP) outlines the actions that will address the release of nutrients from urban waste water in the 2nd RBMP Cycle. These actions include a €1.7 billion investment by Irish Water in waste water projects, programmes and asset maintenance including €12 million for expenditure on smaller plants which have been identified as significant pressures. In addition, drainage areas plans will be completed for 44 urban areas by 2021. Although this will not directly translate to water quality improvements by 2021, it will help prioritise areas where leaking sewers and misconnections are an issue and where effort should be targeted next.
Find out more:
You can view the individual water bodies where urban waste water is a significant pressure on www.catchments.ie/maps
You can view a map of sewage treatment locations in Ireland on gis.epa.ie/EPAMaps/SewageTreatment
For planning and policy, including measures, see www.bit.ly/rbmp20182021