Environmental regulation of the activities of manufacturing enterprises is one of the main mechanisms for solving of the problem of preventing and reducing the negative impact on the environment. The modern principles of this mechanism are based on the concept of the best available techniques (BAT). The choice of BAT remains the key issue, and solving it should take into account numerous criteria by which none of the competing technologies has obvious preferences. This adds relevance to the task of developing new ecological-economic-mathematical models and methods for evaluating alternative options and identifying BAT. We have considered the problem of implementing one of the main stages in determining BAT: analysis and generalization of a large number of information obtained from different sources on input and output flows of alternative technologies (emissions, discharges, wastes, raw materials, energy consumed). The quality of the information has key importance, but it is rather difficult to determine objective data on the characteristics and potential complex impacts of technologies. Decision makers have to be critical about the data quality and compare data from various sources using quantitative methods of uncertainty estimation, but nowadays determining flow levels mostly depends on expert assessment. Information received from various sources can be unstable at the initial stages of using the technology. It is necessary to determine the values of the flows corresponding to the time period when the alternative technologies have been sufficiently tested, that is, the flow values become stable and can be used for the BAT comparison and selection procedure. The traditional probabilistic approach to analysis and processing of large amounts of data is not applicable in this case, since the laws of distribution of random data are unknown. A quantitative method for estimating, analyzing and processing information based on the information entropy measurement is proposed to compare the data from various sources. The result of its application is the determination of sustainable values, obtained from various data sources about the environmental impacts of technology, which can be reasonably applied in the process of assessment of environmental effectiveness of technologies. The procedure of determination of stable values of the input and output flows of alternative technologies is explained in the illustrative example. We have demonstrated ways of using the obtained information for solving the task of multi-criterial choice of BAT in the case of the traditional approach to representing the parameters of the task, which operates with ordinary numerical values, and in the case of the representation of parameters by diffuse quantities in terms of fuzzy set theory.