MEMPHIS, TN (WMC) - Thursday morning, the Mississippi River stage in downtown Memphis was -3.6 feet.
Even though the river stage reading is on the minus side, there's still plenty of water in the river.
A subject of confusion around the Mid-South is the Mississippi River gauge. The river gauge system was set up at various points along the Mississippi River in the early 1900s. It was devised by river workers and not by hydrologists.
The zero reading on the river gauge is not the same water lever at the various stations along the river. Each station established its own zero level at the lowest point that anyone could remember that the river had been a the time the system was devised.
That is why a flood stage is a different number of feet at different stations along the river. The zero reading is based neither on sea level or the actual depth of water in the river bed.
When the river stage reading in Memphis reaches zero on the gauge, there is still about 70 feet of water under the Hernando-Desoto bridge.
The flood stage in Memphis is 34 feet on the gauge. When the river reaches that level flooding problems occur primarily on the Arkansas side, cutting off access to some roads inside the main levee.
Access to some roads and flooding in low-lying areas on the Memphis side begin to become an issue when the river gets to 36 feet and above. Reaching that 34-foot flood stage can cause water to back into the northern part of downtown as the Mississippi forces a corresponding rise near the mouth of the Wolf River.
However, there is a system of levees and floodwalls in north Memphis to control flooding there.
The highest reading ever recorded on the gauge in Memphis was 48.7 feet on February 10, 1937. More recently, the river reached its second highest crest of 48.3 feet on May 10, 2011.
As for its lowest level, the river has fallen to in Memphis, that was -10.7 feet on July 10, 1988. Thursday morning's reading of -3.6 feet makes it the 27th lowest stage since record-keeping began.