Aim of the study:
The purpose of the article is to present the effects of work on developing a method for determining environmental trough flows that could be implemented as a tool for assessing the degree of possible use of water resources by humans without compromising the functioning of the broadly understood environment. Such a method is considered as an alternative to methods of inviolable flows used so far in Poland, including for example the Kostrzewa method.

Material and methods:
In the first phase of work, the focus was on the living conditions of ichthyofauna and a simple hydrological formula was proposed to estimate the minimum flows in rivers, determined on the basis of the MesoHABSIM habitat model. 34 research catchments, diversified in terms of abiotic and biotic were analyzed, and the method was extended to include environmental requirements of macrosozoobenthos. On this basis, the relationship between environmental flow and water depth was built for macrosoobenthos

Results and conclusions:
A hybrid method was proposed, combining habitat requirements for fish and macrosoobenthos. A set of hydrological formula coefficients was included allowing for each river in Poland and each of the 4 bioperiods a year to calculate the value of the environmental flow provided that the annual SNQ value is known. The authors compared the value of environmental flows obtained by this method with the Kostrzewa method, analyzing 345 water gauges. The summary indicates the weaknesses of the method, resulting from the diversity of the hydrological regime within one biotic type and the effects of averaging the coefficients.