1.1.1.WATER RESOURCES Fifty-six per cent of the average annual rainfall is lost to evapotranspiration. The internal renewable water resources (IRWR) are 9.4km3/year, with 5.5 and 3.9km3/year for surface and groundwater respectively. Approximately 44 per cent of these IRWR are considered exploitable or reliable. Of the total reliable yield of 4.09km3/year, 80 per cent is contributed from limestone aquifers, 4 per cent from alluvial aquifers and 16 per cent from surface water runoff. About 20 per cent from the limestone aquifers is extracted through wells, mainly in the River Cobre and River Minho. However, in other basins, the water is generally available as base flow and is exploitable through run-of-river developments. There are two major raw water storage facilities, both located in St. Andrew. The Mona Reservoir, with intakes at the Hope and Yallahs Rivers, has a storage capacity of 3.67 million m3. The Hermitage Reservoir, with intakes at Ginger River and Wag/Morsham River, has a storage capacity 1.78 million m3. The last assessment of water resources in Jamaica in 1997 indicated total exploitable water resources of 4085 million m3/yr with groundwater providing 3419 million m3/yr and surface water providing 666 million m3/yr. In 1997, production from both sources totaled 939 million m3/yr leaving a balance of 3163 million m3/yr for development. However, the state-owned National Water Commission (NWC) is hampered in its commitment to make water accessible to every Jamaican because of the financial hardships being faced by the government. It is estimated that Jamaica is using less than one-fifth of total available water. Approximately 10 per cent of the island’s water resources have been lost to saline intrusion and pollution (Springer, 2005). According to CEPAL (2005), some 87 per cent of Jamaica's water supply is obtained from groundwater sources. Even so, only 25 per cent of the available resources is actually in use. Despite the attention given to abstraction wells, contamination of groundwater is evident. Associated with this phenomenon are saline contamination as a result of the withdrawal of groundwater in quantities in excess of the safe yield; poor well-head designs; caustic soda contamination from ponding of red mud wastes from the bauxite/alumina industry; nitrate contamination from soak-aways built for sewage disposal; and organic and bacteriological contamination from disposal of dunder and other effluent from the sugar/rum industry.

(Water Risk Filter)