These include, in particular, humus-fed (dystrophic) bog water bodies – brown-water lakes and bog ponds, whose water is acidic (pH 4–6) and quite dark due to the abundance of humic substances. However, in Estonia, this habitat type also includes particularly acidic (acidotrophic) mineral lakes with a strong inflow from forest or bog areas, and mixotrophic water bodies with soft brown water.
Mostly, we have bog lakes and ponds, where the shore vegetation of higher growth is either absent or very sparse, there are no aquatic vascular plants, and there are few plants with floating leaves, but many peat mosses grow on both the shore and the water near the shore.
The water near the shores of mineral lakes with acidic water is inhabited and the floating mat is formed by a community of marsh cinquefoil, bog arum, sedges, and peat mosses. This group includes Lakes Viroste, Pikamäe, Koolma, Partsi Mustjärv and others in Põlva County.
The water of dark and soft-water mixotrophic lakes contains slightly more minerals than the previous ones, and they are a host to bottom-attached plants with inflorescences that are out of the water (elodeids), plants with floating leaves, and, in some cases, quite a lot of water horsetail. This group includes, for example, Lake Valguta Mustjärv in Tartu County, and Lakes Koobassaare and Ubajärv on the edge of the Karula Upland.
Includes the following habitat types according to Paal:
- 6113 (dystrophic waterbody site type);
- 6114 (dyseutrophic waterbody site type).