Introduction of allochthonous species may have noticeable affects on populations communities of native species, ecosystem, but also could result in socio-economic consequences. Therefore, creating and applying risk assessment protocols of aquatic invasive species is a main step in supression of biological invasions. SBC index is used for estimation of biological contamination.

The paper deals with the essential of economic insurance within the whole economy procedure in the water management companies. As it is well known, the fundament of insurance is risk itself. The risk, by its appearance, power and intensity, has its impacts on processes, objects and activities in the water management. That is why is very important to know and apply knowledge, awareness and comprehension about risk management in the field of water management. Any sort of risks must be analyzed, planned, controlled, organized, prevented, repressed, averted and fixed in order to decrease detriments and disadvantages. The best way to preclude all predicted and unpredicted tribulations and costs is to go all-out for the rules of covenanted and unsolicited types of insurance. The paper also gives a brand - new approach to bypassing risks within management by the system of covenanted and unsolicited insurances.

The paper presents the results of different methods of sequential extraction of metal in sediment of the Great Backa canal in order to obtain data on the total, available and potentially available contents of heavy metals as well as risk assessment in aquatic systems. Based on the results of sequential extraction of metals was found that sediment does not have the risk to the environment in terms of Cr, Cu and Pb concentration while the contents of Ni, Zn and Cd sediment indicates a moderate risk. Results of sequantial extraction of metals indicate that the risk to the aquatic ecosystems decreases in risk assessment based on the pseudo total metal content in the sediment. Thus the results suggest that not all detected metals are bioavailable and that not only on the basis of total metal content of the actual risk may be overestimated.