ABSTRACT: In the following article, the assessment of mine water from USCB area on the change of water quality in Olza river in years 2000 – 2007 was presented. The impact in this field is confirmed by surface water tests in Poland and Czech Republic. Presented activity is also a great example of long-term and fruitful cooperation between neighboring countries which comes from international agreement in terms of environmental monitoring. Presented results were obtained from Povodí Odry as well as Wojewódzki Inspektorat Ochrony Środowiska (WIOS).