Central Coast’s water storage levels hit ‘uncharted territory’ at 88.4 per cent capacity

The Central Coast’s total water storage jumped 12 per cent in less than two weeks at the height of the floods with the region’s biggest dam on track to ‘spill’ for the first time in history.

Just shy of 400mm of rain so far this month alone has skyrocketed Central Coast water storage to its highest levels ever.

With long range weather forecast painting a bleak picture for the east coast’s big wet spell to hang around for some time yet, potentially for the rest of autumn, the silver lining sees the region’s dams full to bursting for the first time.

Mangrove Creek Dam is at a record level, even higher than it was pictured here in July 2018

Fifteen years after the coast’s total water storage hit an all time low of 11.19 per cent in February 2007 — when residents were urged to shower with buckets and the council was clambering for a desalination plant — the region has this week recorded a total storage of 88.41 per cent.

And the region’s biggest dam, Mangrove Creek, has hit 88.37 per cent for the first time since it opened in 1982.

It comes after a capacity for Mangrove Creek Dam was lifted from 80 per cent to 100 per cent last year following legislative changes to dam safety regulations and a risk-based assessment.

Before then Central Coast Council would stop transferring water into Mangrove Creek Dam when it reached 75 per cent capacity and not let the capacity exceed 80 per cent during rain events.

Mangrove Creek Dam increased by 1.9 per cent — or 3340ML, the equivalent of 1335 Olympic swimming pools — from November 1 to February 3 after 371.4mm of rain was recorded at Mangrove Mountain weather station.

The dam has jumped more than 12 per cent from 77.2 per cent after 436.6mm of rain was recorded at the dam, the majority of which in the last week of February and first week of March.

The dam’s previous highest level was 76 per cent in February 2016.

In February 2007 Mangrove Creek Dam’s water intake tower was left high and dry when levels dipped below 10 per cent. Picture: Mark Scott

With the La Nina weather pattern expected to deliver more above average rainfall until at least May, the Central Coast Water Authority is bracing for Mangrove Creek Dam to hit 100 per cent capacity and `spill’ for the first time.

“If we continue to get rain it will get to 100 per cent (capacity),” one senior staffer said.

“This is uncharted territory.”

The spillway at Mangrove Creek Dam, which has never reached 100 per cent capacity. Picture: Peter Clark

The Central Coast has recorded some huge rainfall figures for March with 409.4mm recorded to 9am on March 28 at Mangrove Mountain, 483mm at Kulnura and 544.6mm at Gosford.

This is up to three times the mean rainfall of 159mm of rain usually recorded in March at Mangrove Mountain and 141mm of rain at Kulnura.