The average rainfall it receives, 700 mm, gives it an estimated annual flow of 12 hm³.

The Zolina reservoir, a former artificial leachate deposit from the disappeared potash mines, belongs to the Sadar basin, although, due to the concentration of salts, its waters and sludge are kept confined within its containment dike.

Although of artificial origin, the reservoir is being colonised by species typical of halophilic environments, which make it of environmental interest.

The Sadar is a small river, with a low flow, which is very well embedded in the terrain and hardly presents any flooding problems.

[6] In 2019, the Public University of Navarre carried out a project to preserve the environment of this river, installing information panels on the fauna and flora that surrounds it as it passes through the Arrosadía university campus in Pamplona, as well as carrying out a clean-up of the river banks.