Methodology and the results of the assessment of the technical state of the concrete water building were introduced in this work, worked out in frames one-stage diagnostics. The weir of the dam of water reservoirs in Zesławice was chosen to the assessment. Apart from the study of the technical assessment of the studied object, indication of the competence effect of persons making the assessments of the technical water building on the result of this assessment was the aim of the work. The assessment of the technical state of the weir was executed according to the methodology proposed by Zawadzki [2005]. The technical assessment of the hydro-building was executed in two phasis. The second phasis of the diagnostics was executed after instructions. In every phasis of the diagnosis was participated eight groups of engineers – the students of the second degree studies in Environmental Engineering and Geodesy Faculty Agricultural University in the Cracow. The change of results was defined for the help of the difference of the sums of the squared residuals, calculated on the basis of the results of the assessments of second and first phasis of the diagnostics. The results of the students assessments were referred to the results of the expert opinion. The conducted technical state assessment of the dam weir of water reservoirs in Zesławice shows on the more less than good state – the assessment according to the expert carries out 3.9. Average from final assessments of first phasis of eight groups carried out 3.1. However in second phasis of the assessment, after the instruction, average from final assessments of the eight groups of students carried out 3.7. It was stated that initiated investigations relating to the impact of the competence of persons making the technical assessments of the water building on the result of this assessment showed, that unsatisfactory knowledge and the lack of experience contributes to lowering the results of the assessment.

71-82