KINGSTON, Jamaica — The National Water Commission (NWC) says with the current heavy rains, storage levels at the Mona Reservoir and Hermitage Dam have increased by just under 30 million gallons each, but the levels are still below normal.

According to NWC, as of Monday September 16, storage levels have moved from 37.3 per cent to 40.9 per cent at the Mona Reservoir and 40.8 per cent to 48 per cent at the Hermitage Dam.

The water commission said despite the increase, “there are several factors affecting the storage levels and it should not be expected that short periods of rainfall over a few days will immediately erase all the negative effects of about one year of below normal rainfall and inflows”.

With reference to a map of the country released by the Meteorological Service of Jamaica to show rainfall levels for July, NWC noted that the rainfall levels for most southern and eastern parishes were much below normal.

This, the commission said, was also the case for most months of 2019.

It further noted that the following factors influence the reservoir or dam levels in the country:

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[naviga:li]The reservoir or dam levels are primarily determined by the inflows from the various streams, rivers or pipelines that feed into the reservoirs minus the volume of water used from the respective facilities on that day.[/naviga:li]

[naviga:li]Direct rainfall into the reservoir is a very, very small portion of increased storage levels. What matters much more is rainfall above the intakes in the related watersheds – Wag Water River, Hope River and Yallahs River watersheds for the Hermitage and Mona reservoirs. This needs to be sufficient to increase the sustained flows for several days in the rivers connected to the reservoirs. (Rainfall along the coast or away from the catchment areas has no impact on the storage levels.)[/naviga:li]

[naviga:li]The Dam or Reservoir levels are taken mid-morning each day and hence show the movement over the previous 24 hours. The levels published for any particular day would therefore not include inflows from rainfall during the afternoon of that same day or any time after the mid-morning readings have been taken.[/naviga:li]

[naviga:li]The percentages indicated are percentages of large volumes of water – 809 million gallons in the case of the Mona Reservoir and 393 million gallons in the case of the Hermitage Dam. Hence, a mere one per cent increase at the Mona Reservoir represents some eight million gallons more than the volume used to supply customers on the same day, after calculations for evaporation.[/naviga:li]

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