Freshwater - State and impacts (Luxembourg)

The state and impacts, drivers and pressures need to be examined from different angles: water supply, groundwater and surface water quality and flooding.

Water supply

The usage intensity of available resources in households, industry and agriculture is relatively low compared to other developed countries, reflecting the low level of abstractions for agriculture. Daily household consumption is 140 litres per capita. There is little loss through leakage and many of the water supply systems have been upgraded over the last 10 years.

Ground water provides 57 % of the 47 million m³ of drinking water used annually in Luxembourg. In the southern industrial region, industries and utilities must draw from the water table of the Luxembourg sandstone aquifer, located in the centre of the country, and from the Esch-sur-Sûre reservoir in the north to cover their water needs. Under the Water Act, there must be a balance between depletion and renewal of underground water sources so that they will be in good condition no later than 2015. The preference given to surface tapping over groundwater pumping eliminates the risk of over-exploitation of the sandstone aquifer, which supplies more than half of the country’s drinking water. On the other hand, the Esch-sur-Sûre reservoir, which provides 43 % of the water supply to public utilities in Luxembourg, is in a critical state of eutrophication.

While the demand for water from industry has decreased with the improvement of industrial processes, notably in the metallurgy sector, household consumption has increased by 1.35 % per year over the last 15 years, reflecting the country’s strong demographic growth and the steady increase in cross-border workers.

Surface water quality

According to the Water Act, all surface water bodies must be protected, improved or restored to meet the definition of “good status” by the end of 2015. However, it is estimated that at least 72 % of surface water bodies (watercourses and reservoirs) will not meet the 2015 chemical and biological quality targets under the EU Water Framework Directive. While the pollution level in watercourses has decreased slightly in recent years, 39 % of watercourses are still heavily polluted and 54 % moderately polluted.

With regard to new contaminants, the watercourses of the Alzette and the Mess, located in industrialised and heavily populated environments, have been found to contain xenobiotic pollution from antibiotics, analgesics and hormones. There are several xenobiotic pollutants coming from diffuse pollution that are found in all major watercourses. These pollutants can not be eliminated by the existing purification plants.

Groundwater quality

Under the terms of the Water Act, all bodies of groundwater must be protected, improved and restored to “good status” by the end of 2015. The main groundwater pollutants are nitrates and pesticides. The nitrogen content at the national level has decreased considerably since the early 1990s, dropping from 200 kg N/hectare to 111 kg N/hectare in 2004 (last available year). However, a recent study showed that 40 % of the surface area that drains into drinking water sources discharges water containing 25-50 mg/l of nitrates. Moreover, some of the sources show a clear trend towards deterioration. At the national level, half of the nitrogen input comes from the use of chemical fertilisers, and a third from livestock effluents; the rest is atmospherically deposited. In up to 90 % of the monitored ground water sampling sites pesticides are detected, sometimes at concentrations that exceed the threshold value of 100 ng/litre. This indicates that not only is the Luxembourg sandstone aquifer more vulnerable to pollution than the aquifers of neighbouring regions, but also that there is a lack of protection for the abstraction areas.

Flooding

Flooding is the most serious natural hazard in Luxembourg, both because of the damage it causes and because of the number of municipalities affected. In recent decades, Luxembourg has suffered numerous bouts of flooding, in 1983 along the Moselle and in 1993, 1995 and 2003 in the Sûre basin. Since 1995, the Government has been covering 50 % of the cost of flood control measures.