Demonstration indicator: biological quality of lakes
Assessment made on 01 Oct 2003
- WEC 005
Policy issue: Is good surface water ecological status being achieved and the deterioration of aquatic ecosystems and habitats prevented?
Some countries have developed national classification schemes for their lakes. These are generally based on nutrients (mainly phosphorus) and on chlorophyll a concentrations. None of the schemes comply with the requirements of the water framework directive. Even though the national classifications are not comparable with other country classifications, useful information is obtained by comparing the proportion of lakes that are considered and reported nationally to be of less than 'good' quality.
Figure 2.4 is based on examples of current national lake classification schemes. In Ireland and Switzerland there have been significant improvements in lake quality since the 1980s in terms of lake surface area (Ireland) and numbers of lakes (Switzerland). Norway and Finland have many thousands of lakes with Norway in particular having a very small proportion considered as being of bad or very bad quality.
An ecological assessment of lakes in four of the accession countries (Bulgaria, Slovak Republic, Estonia and Turkey) (Figure 2.5), was recently carried out by the World Wildlife Fund (WWF, 2000). Mountain lakes with minimal human pressures scored 'high' ecological status and even some large lake systems like Lake Peipsi in Estonia appear to be in a relatively 'good' ecological state. Unfortunately, some of the lakes are under pressure from pollution, overfishing, or water use for irrigation, industry and drinking.
For references, please go to http://www.eea.europa.eu/data-and-maps/indicators/demonstration-indicator-biological-quality-of-lakes or scan the QR code.
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