RIVERVIEW — If a big storm hits and the Alafia River rises quickly, water supply officials want to capture that rain.
So the Southwest Florida Water Management District has extended an emergency order allowing the area's main water wholesaler to take extra water from the river without seeking special authorization.
The order had been scheduled to expire on Dec. 31. Instead, it will last through Sept. 30.
But the withdrawals won't take place at all unless the Alafia rises — a lot.
"Right now the river's far too low to take any water from," Swiftmud spokesman Michael Molligan said Wednesday.
During November, the river's flow was about 88 percent below normal, according to Tampa Bay Water, the regional water supply agency.
The new order allows Tampa Bay Water to take up to 60-million gallons of water per day, or 19 percent of the flow, from the Alafia without seeking special authorization.
But the withdrawals can take place only when the river's average daily flow is at least 124 cubic feet per second. These days, it's about 50 cubic feet per second, Molligan said.
Using river water, once it becomes available, would reduce the amount of groundwater the agency needs to meet demands. Studies have shown that temporarily withdrawing water from the river does not significantly threaten its ecology, Swiftmud said.
Tampa Bay Water needs to be able to pump from the Alafia because it cannot use the full storage capacity of the C.W. Bill Young Regional Reservoir in southeastern Hillsborough County.
The reservoir was designed to hold 15-billion gallons of water, but after the summer rainy months it held just 6.5-billion gallons. As of Dec. 15, it was down to 3-billion gallons.
Tampa Bay Water has been drawing on that supply since mid September to meet demand during the dry winter months and to allow engineers to investigate cracks that have appeared in the reservoir's soil cement layer.
Tampa Bay Water gets its water from several major well fields, local rivers and a desalination plant. It supplies Hillsborough, Pinellas and Pasco counties, as well as Tampa, St. Petersburg and New Port Richey. Other cities around Tampa Bay receive at least some water from those six systems.
Faced with dwindling demands and the driest months of the year, water officials recently have tried to augment supplies, enacted conservation measures and urged local governments to crack down on water wasters.
Richard Danielson can be reached at Danielson@sptimes.com or (813) 269-5311.