The Low that formed off the northern NSW coast delivered more rain than forecast Saturday night. Since 9am Saturday morning, 70.6mm has fallen at the Lismore Airport, making the total rainfall since 3pm Thursday 202mm.

The Bureau of Meteorology says the Wilsons River should peak at 6.8m on Sunday morning, just below the moderate flood level of 7.2m. At 12 midnight the Wilsons River at Lismore was recording 4.6m.

Lismore City Council has 32 gates along the levee that council staff close at various stages depending on the river level.

The first three gates at Upper and Lower Hollingworth Creek (South of Kyogle Road and at Riverview Park) and Gasworks Creek are closed when the river reaches 4m.

All other gates are closed in a specific sequence when the river reaches or is predicted to reach 5, 6 and 7m. The final gates under 11 Molesworth Street are closed at 9m.

Timing of the closure of some gates can vary depending on whether cars are still parked in the Kirklands Riviera, Rowing Club, and the Upper and Lower Hensley carparks behind the levee wall.

LCC Pumps

There is a range of large and small pumps that are activated during a flood event to extract rainwater from within the levee walls and pump it into the Wilsons River.

Once the river height reaches 5.2m, the Browns Creek gate is closed and the first pump automatically kicks in. If the height reaches 5.4m, the second pump automatically starts.

They both operate until the height of the river drops below 5.4m, when Pump 2 stops, with Pump 1 continuing until the height drops to 4.8m.

If the height rises again to 5.2m, the cycle restarts and will do so while ever the gates are closed. It is designed to keep the level below 6m, keeping Dawson and Uralba streets open.

Each pump has a capacity of 3,000 litres per second.

The Gasworks Creek gates are closed at 4m and also have two pumps that operate on the same principle as Browns Creek pumps, but start at different heights.

Pump 1 starts at 6.4m and Pump 2 at 7m. Both stop when the level drops to 5.5m. Each pump has a capacity of 2,000 l/s.

The forecast for Sunday is for possible rainfall as the low moves off the coast of northern NSW. The Bureau predicts rainfall of 0 to 7mm with an 80% chance of rain.