Fill in the Blanks (Reading & Writing)

Reservoir managers must balance competing demands, releasing enough water downstream to —supplysupplyingsuppliedsupplies farms and cities while retaining sufficient reserves for drought years. During periods of heavy rainfall, operators sometimes must release water early to prevent the dam from —overflowingoverflowoverflowedoverflows, even if this means discharging water that could have been stored. Long-range weather forecasting has become essential for —planningplanplannedplans these decisions months in advance.