Looking beneath the surface: how good is our water?
European policymakers have introduced a comprehensive range of legislation to protect our freshwater resources. Most notable is the Water Framework Directive (WFD), which is the most important piece of EU legislation relating to the quality of fresh and coastal waters. The general objective of the WFD is to achieve 'good status' (both ecological and chemical status) for all surface waters by 2015.
Worryingly, poor water quality, water scarcity and physical modifications might prevent a substantial proportion of European water bodies from achieving 'good status' by 2015.
Main pollutant sources: agriculture and the urban environment
Pollution from agriculture remains a major cause of poor water quality in many parts of Europe. Nutrients (nitrogen and phosphorus) from fertilisers, pesticides, pathogenic micro-organisms excreted by livestock, and organic pollutants from manure are washed to waterways, primarily via diffuse pathways.
The urban environment is another key contributor to the freshwater pollution observed across Europe. A range of pollutants are generated in the wider urban environment, including industrial and household chemicals, metals, pharmaceutical products, nutrients, pesticides and pathogenic micro-organisms.
Excessive nutrient levels in water bodies cause proliferation of algal blooms and result in widespread loss of aquatic life. Moreover, chemicals with endocrine‑disrupting properties have been shown to trigger feminising effects in male fish, potentially affecting their fertility. Pesticides and metals can be toxic to aquatic life, while concern is growing about the effects of chemical mixtures found in Europe’s more polluted waters. Much of the pollutant load in freshwaters is ultimately discharged to coastal waters with the potential to impact the marine environment. Poor water quality is also a potential threat to public health through various exposure routes.
Water scarcity and physical modifications affect aquatic habitats
Water scarcity occurs in many areas of Europe, particularly in the south where limited water resources combine with high demand. Over-abstraction and dry periods frequently result in reduced river flows, lower lake and groundwater levels and the drying-up of wetlands, with detrimental impacts on freshwater ecosystems. Excessive abstraction from any one of these types of water body can impact one or more of the others. For example, rivers, lakes and wetlands may all be strongly dependent on groundwater, especially in the summer when it typically provides critical base-flow.
Over-abstraction can also worsen water quality because there is less water to dilute pollutant discharges, while over-abstraction of aquifers in coastal areas often results in salt-water intrusion, diminishing the quality of groundwater.
Over the past 150 years, Europe's freshwaters have been affected by a variety of major modifications. Dams, weirs and sluices have reduced connectivity, rivers have been straightened and canalised, and infrastructure development has disconnected watercourses from floodplains. Such structures and activities have altered many European water bodies, sometimes leaving little space for natural habitats, obstructing species migration, disconnecting rivers from wetlands and changing the water flow.
The road to healthy water ecosystems
Cost-effective measures exist to tackle agricultural pollution. Countries must implement them through the WFD, as well as complying fully with the Nitrates Directive. The forthcoming reform of the Common Agricultural Policy provides an opportunity to further strengthen water protection.
The EU Urban Wastewater Directive (UWWTD) is a vital and successful piece of legislation and Member States need to comply with it fully. It should be complemented by increased control of pollutants at source, reducing treatment needs and thereby cutting energy use. Full-cost pricing for wastewater services will help incentivise controls at source.
In many European cities there is a need to tackle storm overflows, which can discharge a range of pollutants causing rapid depletion of oxygen levels in receiving water. There are already some examples of good practice in Europe, such as the retention of overflows in storage ponds during heavy rainfall, which are subsequently pumped back to the system for treatment.
Europe's water use cannot increase endlessly. Demand must be reduced and policies are needed to achieve this. Measures could include economic instruments; water loss controls; water-reuse and recycling; increased efficiency in domestic, agricultural and industrial water use; and water-saving campaigns supported by public education programmes.
Flood management should shift from its current focus on hard-engineered defence systems to natural measures based more on slowing and storing water in floodplains and groundwater aquifers, and providing adequate space for rivers. The environmental impacts of water engineering projects such as dams and navigation infrastuctures should also be minimised.
Europe has strong water legislation in place. The challenge is now to attain full implementation across Europe. River basin plans for Europe's 110 river basin districts will be a key tool for achieving the objective of ‘good status’ for European waters by 2015.
For references, please go to http://www.eea.europa.eu/articles/looking-beneath-the-surface-how or scan the QR code.
PDF generated on 25 Feb 2017, 04:22 AM