The studies were made on the surface water and groundwater sources, the existing and future water production yields of the Riga city. The forecasts about water demand in Riga by year 2010 are estimated as 200 000 m**3 dE-1, with a variation coefficient of 1.13. Total water yield is estimated as 410 000 m**3 dE-1, with a storage coefficient of 2.05, which is considered as sufficient. It is proposed that in future 50% of drinking water for Riga will be abstracted from groundwater and 50% will be produced in the Daugava surface treatment plant.

The article deals with the regeneration process of water resources capacity of the wells in the Baltezers region using mechanical and chemical treatment. The methods of this treatment process are described in detail.

The work contains the description of the current technical conditions of the water resources of the Baltezers region and drinking water consumption in Riga during 2003-2010.

Estimating water quality of rivers, lakes and other water bodies, their contamination is being modelled according to the quantitative changes of pollution factors and their appearance conditions. Water contamination is being determined considering one or another value of contamination factors. The modelling of the impact of pollution factors on water quality becomes problematic when the values of the factors can be estimated only approximately or cannot be estimated at all. It is rather difficult to define qualitative estimation of water contamination factors in comparative terms (scanty impact, average impact, etc.) applying only quantitative mathematical methods. In this case the method of fuzzy logic may be of great help. Fuzzy logic enables us to formalise the comparisons of the ojects or phenomena under discussion as well as eliminates the contradictions between qualitative and quantitative methods. Those two methods supplement each other and can be easily applied together. The objective of the study was to estimate the possibilities of fuzzy logic application for the evaluation of stream water quality.