An annual assessment of the functioning of the filter systems filled with polypropylene and gravelite profiles, located in the river bed, to reduce total suspensions and biogenic compounds in the water before it was directed to the city lake was carried out. It has been shown that, due to poor maintenance and a small number of cleaning operations, the efficiency of the system has decreased considerably comparing to the period of correct operation. This was mainly related to the exhaustion of the ability to retain the main biogenic element – phosphorus. During the monitoring period the facility retained the ability to reduce organic pollutants, suspended solids and nitrogen.