The volume of water used in the Basin rises to about 3.861 Mm³ of which 91% comes from the mobilization of the surface waters. This volume allows for the irrigation of more than 345.000 ha, the production of 1630 1866 of energy in average year, the provision of drinking water supply for 5 million inhabitants and a minimum flow to guarantee the healthiness of water courses.

Water use (million m³)

Use	Surface water	Groundwater	Total
Irrigation	3250	257	3507
Water supply and industry	100	89	189
AEPI transfer	165		165
Total	3515	346	3861

The global demand in drinking and industrial water from water resources of the basin is about 354 Mm³ of which 20 Mm³ for the rural area and 30 Mm³ for the isolated industry.

This demand is satisfied thanks to 265 Mm³ from the superficial waters and 89 Mm³ from the underground waters.

The great centers supplied from water resources of the basin are Beni Mellal, Khouribga, Oued Zem, El Jadida Casablanca, Settat, Berchid Safi and Marrakech

Needs in irrigation water from resources of the Oum Er Rbia are 3507 Mm3/year (2533 Mm³/year for the great hydraulic works and 974 Mm³/year for the small or middle hydraulic works - SMH).

The hydraulic equipment established in the basin allowed a remarkable irrigation development: the irrigated surface in great hydraulic from the Oum-Er-Rbia waters is 308.500 ha (including 35.400 ha currently equipped in the Central Haouz). As for the SMH, irrigated surface is 36.000 ha.

The cities of Casablanca (close to 4 millions of inhabitants) and of Marrakech (close to a million of inhabitants), which are cities situated out of the Oum Er Rbia Basin, depend for drinking water supply on waters transferred from this basin.

The water volume currently transferred, for cities situated out of action zone (Casablanca, Settat, Berchid and Marrakech) is about 165 Mm³/year distributed as follows :

• 120 Mm³/year for Casablanca, Settat and Berchid from the Al massira complex;
• 45 Mm³/year for the Marrakech city from the Hassan 1er-Sidi-Driss complex

The hydroelectric power stations of the Oum Er Rbia, associated to dams, occupy the first place in the national hydroelectric production. The currently installed power in the hydroelectric factories of the Oum-Er-Rbia basin not included the STEP of Afourer, is 623 MW (50% of the national hydroelectric park). These factories produce in average 1866 GWH (60 to 72% of the national hydroelectric production)