This article examines the possibilities of improving the ecological condition of small Rivers on the example of the upper part of the Prut River in the vicinity of Yaremche (Ivano-Frankivsk region, Ukraine). The previously published data of the article authors and other researchers that the amount of pollutants in River water in this area has increased, in particular, phosphorus compounds, has been confirmed. It is shown that the incompletely purified waste waters of Yaremche, which contains an excess of phosphate ions, has a significant impact on this fact. Based on their own previous research and current work, the authors propose to remove these ions using a natural sorbent based on bentonite, activated by microwaves in various ways. Experiments have shown that microwave activation of this sorbent increases the coefficient of phosphate ions extraction from waste water significantly higher compared to natural bentonite. An approximate technological scheme of waste water purification from excess phosphates after the main standard purifying cycle is suggested.