Reservoirs and hydrological alterations cause a regression of native species and the proliferation of invasive ones, which live better in regulated rivers or stagnant waters. Therefore, the restoration of the natural hydrological regime of each river and the reduction of water extractions would favor the recovery of native species. This involves managing agricultural irrigation and flow diversions for hydroelectric production taking into account the needs of fish and other aquatic organisms..

The solution to the lack of river connectivity caused by dams and weirs is a complex subject. The installation of passage devices for fish is one of the possible actions, but they are often ineffective and many species cannot use them properly. A better alternative is to remove obsolete infrastructure, but it is also an expensive solution and sometimes not free of unwanted effects, such as the dispersal of invasive species upstream once the barrier has been removed.

Pollution caused by the discharge of urban and industrial wastewater has traditionally been one of the main problems of our rivers.. However, in general, water quality has improved considerably in recent years with the construction of WWTPs (wastewater treatment plants). In rivers where pollution is still a problem, sewage treatment should continue to be improved.

Invasive species are very difficult to eradicate, but projects to control their populations can be carried out, as has already been done in some places such as Lake Banyoles. Extreme efforts are also needed to prevent further introductions or increase the dispersal of introduced species..