The expert group used following data sets as a help in outlining the estuaries: average stream (places where continuous measurements), results from VELMALA -stream modeling (places without measuring information), depth data, and salinity model on the sea areas. Orthoimagery was used for observing the extent of the sediment plumes and typical vegetation in estuaries, reed belts. Rivers flowing to the dammed artificial lakes were not included into the Estuary data set.

The Lagoon data was created from the orthoimagery and GIS analysis. Lagoons connected to the sea were identified from the aerial images provided by the National Land Survey of Finland and were digitized by utilizing the shoreline data from the chart. Selection criteria were e.g. enclosed nature. Unattached lagoons, gloe lakes, were bordered by using the lake data from the topographic database (National Land Survey of Finland) and contour lines. Water areas lower than 2,5 m asl were selected to add to the lagoon data. Lakes above 2,5 m have most probably been separate lagoons for a long time and therefore interpreted as gloe lakes that are not included into the final lagoon data.