zone III corresponds to a portion or the whole of watershed that feed the catchment if one is interested respectively to punctual or diffuse pollution (Achidi et al., 2010). It is elaborated in order to protect reservoir against persistent pollutants (Garouni and Merzouk, 2006).
Depending that one want to fight against punctual/accidental or diffuse pollution,the zone III or distant protection perimeter will correspond respectively to a portion or all the catchment. This zone was widened to the whole basin because of scattering of high vulnerability zones. Similarly, the relief less hilly and agriculture that occupies 43% of total watershed area are as parameters that require protection measures are applied to the entire watershed. It should be therefore appropriate to regulate inner this, fertilizer use in coherence with protective measures. Sensitization campaigns of different users of basin should be led in order to attract their attention about the stake of reservoirs.