Paddling is not only about pushing limits, but also about getting out there. Rivers are the ultimate means of transport into the unspoilt parts of nature, and not only that, they are the veins of life for humankind. It is therefore of utmost importance that rivers and their surroundings are protected.
Although paddlers seldom pollute the rivers, it is still necessary to mention some aspects of environmental impact. It makes common sense that nothing that could be harmful to any living organism should be thrown in or near water, but for unknown reasons some people regard rivers as open drain systems that will carry everything away to who knows where.
As a general rule, everything that is taken on a river trip should be removed when you leave, as is the case with any other nature trail. To simplify matters, reduce litter at the source by re-packing and by keeping to simple menus.
Human waste should be disposed of properly to avoid water pollution and minimise the possibility of spreading diseases. Where the group size is relatively small and the group frequency is low, bury the waste away from the river and place the used toilet paper in paper bags, which are either taken home or burned thoroughly. Where group sizes are larger, human waste should be removed entirely using a Porta-Potti kind of system (typically on commercial overnight trips on a river like the Orange).
In high-volume rivers, urinate directly into the flowing current. In low-volume rivers, urinate on the banks below the flood water line.
Use the following guidelines when camping on the riverbank: Camp on beaches or non-vegetated areas below the flood water line, or on existing sites above the flood water line; avoid fires, and when it is really necessary, use existing fire-rings where possible; use durable ground for the kitchen and minimise the number of times any part of the site is used; avoid making new trails and naturalise the site when you leave.
In a more general sense: any form of human intervention concerning rivers is normally negative. This is equally true of weirs, low-level bridges and dams. Most of them are extremely dangerous, so rather stay away from them. As far as dams are concerned: studies completed in leading First World countries show that the negative impact on the eco-systems involved in the specific environments of the dams far outweigh the presumed economical benefit the dams may generate. This is such a serious issue, that some dams are been destroyed to try to recover the damage already done. In developing countries, however, most decisions concerning dams are taken for political reasons with single-minded impact-studies having been done. Paddlers are in the position to voice their opinion concerning dams and they should do so whenever the opportunity arises.