4. Conclusion
Climate change impacts within river systems include changes in runoff, river flow and groundwater storage. In addition to these quantitative aspects, some water quality parameters are also expected to change. With respect to biogeochemical water quality, most climate change impacts can be attributed to changes in stream water temperature. The impact of climate change on stream water temperature is highly dependent on the future evolution of air temperature as well as on other meteorological and physical parameters. The present study showed that projected air temperature increase of 2˚C - 5˚C was very consistent across the province of New Brunswick and that the water temperature would most likely increase in the range of 70% of air temperature increase. This information was based on a long-term data and modeling analysis at Little Southwest Miramichi River. These changes will have an impact on dissolved oxygen concentrations and instream biological activities. The present study showed that dissolved oxygen (DO) was the only parameter (from the available water quality data in New Brunswick) which was correlated to water temperature. Therefore, a Tw-DO relationship was established for each river in order to predict future water quality index based on both water temperature and dissolved oxygen. Therefore, future water temperature was project for each river and corresponding WQI were calculated. The present study concluded that the water quality in New Brunswick Rivers was not projected to deteriorate significantly under climate change (from a drinking water perspective) based on the two methods and criteria used in the present study. Nevertheless, it should be pointed out that the present study makes the assumption that other water quality parameters will remain constant in the future under climate change. How- ever, climate change may results in these parameters changing by other processes that increased air temperature. For instance, if climate change increases runoff, it is very likely that some parameters, particular those related to soil erosion, will also change in the future. In addition, the present study dealt with drinking water quality parameters and criteria. If the water quality was studied for other purposes, e.g. aquatic habitat conditions,the selected criteria as well as thresholds would be very different than the one used in the present study. Under these conditions it is very likely that the results would be different. For instance, a good body of research is showing that from an aquatic habitat perspective, some New Brunswick rivers are currently experiencing close to lethal water temperatures (30˚C) in summer. Such high temperatures may not have a great influence on drinking water quality, but may have a significant impact on Atlantic salmon population as well as for other cold water species.