Defining Chlorophyll-a Reference Conditions in European Lakes

The concept of “reference conditions” describes the benchmark against which current conditions are compared when assessing the status of water bodies. In this paper we focus on the establishment of reference conditions for European lakes according to a phytoplankton biomass indicator—the concentration of chlorophyll-a. A mostly spatial approach (selection of existing lakes with no or minor human impact) was used to set the reference conditions for chlorophyll-a values, supplemented by historical data, paleolimnological investigations and modelling. The work resulted in definition of reference conditions and the boundary between “high” and “good” status for 15 main lake types and five ecoregions of Europe: Alpine, Atlantic, Central/Baltic, Mediterranean, and Northern. Additionally, empirical models were developed for estimating site-specific reference chlorophyll-a concentrations from a set of potential predictor variables. The results were recently formulated into the EU legislation, marking the first attempt in international water policy to move from chemical quality standards to ecological quality targets

NMD project report: Development and evaluation of common Nordic freshwater types 2002–2004

The report presents a Nordic typology system for freshwaters with the aim to facilitate the intercalibration process of Northern lakes and rivers. A common typology system is necessary for the development of comparable ecological quality assessment systems and harmonised ecological quality criteria for surface waters according to the Water Framework Directive. Based on the preliminary Nordic typology system and the selection of pressure types, a set of relevant types of water bodies (Nordic core types) have been selected. The next step was to investigate if intercalibration sites could be selected within the types and to find out which of the sites were situated on the borderlines high/good status and good/moderate status. Based on the relevant pressure types and the results from the compilation and comparison of monitoring data, quality elements, metrics and parameters for intercalibration have been suggested. The report contains also a presentation of the national typologies for freshwaters, and a comparison of the different monitoring methodology for lakes and rivers within the Nordic countries. This work has been taken forward by the Northern Geographical Intercalibration Group after 2004