The new concept of bioremediation  of anthropogenic water bodies and quarry wastewaters treatment by phytoextraction and phytotransformation in the Subarctic conditions is presented.  This technology is based on transformating  the man-caused water reservoirs  into nature-like  marsh ecosystems.  At the first stage,  a new patented method for advanced waste treatment using floating bioplate was developed and implemented. After implementing  the bioplate, the concentration of ammonium ions in water decreased by 53-90%, nitrate nitrogen reduced by 15-20%. At the second stage, the floating bioplate technology was modified into the highly efficient purificating marsh ecosystem, which allowed to cover the waterbody  territory to the greatest possible extent. The technology is based on the creation of phytomats enabling in the accelerated mode to form plant blocks of three different types. They are aimed both at local grassing down, and at swamping deep and shallow areas of sediment ponds. In forming phytomats, two soil substitutional substrates (thermovermiculite  and wood sawdust) and regionally-optimized  assortment of 24 plant species are used. The proposed technology does not require energy, chemicals and soil components which are scarce in the region. The predominance of natural ecosystem  processes in the formed phytocenoses allows to achieve maximum efficiency, and the use of available materials contributes to minimizing the costs of creating and maintaining the system. The introduction of this technology and formation of the artificial phytocenosis  with the area of about 30% of the man-caused  reservoirs territory made it possible to increase the efficiency of wastewater treating from mineral nitrogen compounds  by 22%.