Several years of below-average rainfall have produced record-low flows in the Pungoe River , Beira's only surface water supply. While sufficient in quantity to meet Beira's supply needs, these low flows fail to prevent saltwater from reaching the intake, some 77 km from the mouth of the estuary. At best, this means water can be pumped from the river only during periods of low tide. At times, however, the water is saline under all tidal conditions, and the intake pumps must be shut off. During October and November 1992, the situation was so extreme that the entire system was shut down for nearly seven weeks. Total water produced in 1991 was about two-thirds of the system's capacity and in 1992, it fell to less than half. The lack of rainfall needed to recharge the groundwater aquifers combined with the periodic closure or intermittent operation of the water system also has placed added burdens on the shallow wells used by the majority of the population. Water levels have dropped; salinity has affected many wells; and the general quality of the well water has worsened. Only 30 percent of the permanent population is served by sewers. This lack of coverage and the poor quality of the sewers contribute to the groundwater contamination.