In Estonia, this habitat type includes those sections of rivers and streams that have remained in a natural or near-natural state. Of particular note are the watercourses starting from the uplands, where there are waterfalls and rapids with rocky gravel bottoms. Also valuable are the cold-water rivers starting from large springs and plain rivers flowing in a natural meandering bed, which form old rivers and where there are also rapids or fast-flowing sections with a rocky gravel bottom.
In most cases, such rivers create diverse habitats inhabited by species-rich and valuable river biota (including animals and plants of rare and/or endangered species). The rivers and streams included in this habitat type must be clean enough that species sensitive to pollution could also live there.
Rivers passing through the cliffed coast in Northern Estonia and forming picturesque ancient valleys with sandstone outcrops in Southern Estonia deserve special protection.
Includes the habitat type 6121 (watercourse site type) according to Paal.