**Author details**

difficult to predict the evolution of river ecosystems in the context of global warming. The observed increase in nitrites-nitrates in the last 10 years reinforces the need for the Québec Government to develop an efficient management program which would significantly reduce the massive nitrogen fertilizer inputs in agriculture. In addition, this management program should include the respect of legal water quality standards for nitrogen wastes in rural and

As already pointed out by Hudon [12], flow variations exert a strong influence on the physicochemical characteristics of Ottawa River waters. This influence was observed in St. Lawrence River waters affected by the Ottawa River. However, this influence does not affect all characteristics in the same way. Depending on this influence, these characteristics may be grouped into three categories. The first category comprises water temperature and total nitrogen, the values of which vary seasonally as a function of water levels. The second category comprises variables that vary significantly over a single season, resulting in marked increases in

, TP, *a*CDOM340nm, and suspended particles), summer (NO<sup>3</sup>

(Cond). Finally, the third category comprises variables whose mean values do not change

Comparison of data at the decadal scale revealed a clear warming of waters, a significant increase in nitrite-nitrate concentrations, but a significant decrease in phosphate concentrations. These changes confirm the trend observed since 1979 in many Quebec Rivers [34]. Mean concentrations of these chemical parameters in 2006 were higher than standard limits set for river waters by the Ministère de l'Environnement du Québec as compared to those measured in 1994–1996. In order to assess the ecological integrity of rivers in Québec, there is an urgent need for the implementation of a monitoring program which would allow for the development of solutions to reduce the negative impacts of global warming on the functioning and evolution of river ecosystems. We also recommend reinforcing the strict application of exist-

We gratefully acknowledge Captain François Harvey and the crew of the RV *Lampsilis* for their invaluable support during the expedition on the St. Lawrence River. We thank A.-L. Larouche, J.-F. Lapierre, C. Martin, D. M'Radamy, P. Thibeault, and A. Veillette for help in the field and in the laboratory. This research was funded by the Natural Sciences Research Council of Canada (NSERC ship time and discovery programs) and the Fonds Québécois de la Recherche sur la Nature et les Technologies (FQRNT) to J.-J.F. Québec-Océan's logistical support during sampling is greatly acknowledged. This is a contribution of the Groupe de

and PO4

), or fall

city areas. These standards already exist but are barely applied.

12 Achievements and Challenges of Integrated River Basin Management

significantly as a function of water levels ((*K*d (PAR)) m−1 and TURB).

ing water quality laws for nitrogen wastes in rural and city areas.

Recherche Interuniversitaire en Limnologie (GRIL).

**5. Conclusion**

the spring (NO<sup>2</sup>

**Acknowledgements**

Jean-Jacques Frenette and Ali A. Assani\*

\*Address all correspondence to: ali.assani@uqtr.ca

Environmental Sciences Department, University of Quebec at Trois-Rivières, Trois-Rivières, Québec, Canada
