Evaluating recovery of acidified lakes towards a target based on their pre-acidification status is a difficult task as there are very few biological records for these remote upland systems. The analogue matching approach can be used to identify modern analogues for the pre-acidification status of lakes using the sub-fossil remains of diatoms and Cladocera, which can be used as recovery targets. An 83-lake modern training set was created, with full diatom, cladoceran, hydrochemistry and catchment data for each lake. Fossil samples from 10 lakes of the UK Acid Waters Monitoring Network (UKAWMN) were chosen to represent pre-acidification conditions in those lakes. The closest analogues in the modern training set were identified for each fossil sample by means of the squared chord distance measure. The distributions of the Cladocera in the training set were analysed using a range of multivariate statistical technique. Individual cladoceran species response curves for selected environmental determinands were calculated. A 163-lake diatom training set has been compiled from existing data holdings and the patterns in the data were explored using direct ordination methods. A comparison with the diatom training set from the Surface Waters Acidification Project is also made. Close modern analogues were identified for 8 UKAWMN lakes. The majority of these modern analogues are located in North and Northwest Scotland; areas of low sulphur and nitrogen deposition. Comparison of the hydrochemical characteristics of the UKAWMN lakes to those of the modern analogues showed that the modern analogues had higher lake water pH and alkalinity levels and lower aluminium concentrations. Ionic strength and calcium concentrations in the analogue lakes were similar to observed values in the UKAWMN lakes. These results indicate that the analogue matching approach using diatom and cladoceran remains is a simple, robust and reliable method of identifying modern analogues for acidified lakes in upland areas of the UK
