which method/approach to take for the deter- nation of reference conditions is dependent on The estimation of reference conditions is crucial the condition of the sites available for a certain in any ecological assessment programme (e. g. lake type: (a) where undisturbed or nearly undis- Moss et al., 1996). These provide the baseline turbed conditions prevail, a validated spatial from which to determine lake change with time, network is preferred; (b) if degraded conditions and are necessary to evaluate a lake s current prevail then the preferred modelling approach status or potential for...