Summer Hill Creek, which connects Spring Creek Reservoir to Suma Park Reservoir, has provided just three megalitres in the past 12 months, the equivalent of half a day's water supply.

At the same time, the council is required under licence to release 1.75 megalitres a day from Suma Park into Summer Hill Creek for irrigation purposes, which would stop when storage hits 25 per cent capacity.

With Suma Park relying on the Macquarie River pipeline, bores and stormwater harvesting to top up its supply, council staff have applied for two measures.

The first, subject to approval from the Department of Planning, Industry and Environment, would cut the release of water to visible flow once storage drops below 50 per cent, so irrigators could still draw water.

Estimates have concluded the measure would add 500 megalitres, or two months' supply.

A second measure, also with the department, would involve lowering the trigger point to use the Macquarie Pipeline.

Currently, water can be pumped when the river flows faster than 119 megalitres a day, factoring in a 10 per cent safety buffer.

The trigger point was calculated based on historical flows, which did not take into account dams and other licences added since.

Staff found a newer model factoring in the infrastructure better predicted the flows through the river and by relying on it and eliminating the buffer, the trigger could lower to 70 megalitres.

If the lower trigger point was already in place, the council could have pumped 147 days in the 2018-19 year rather than 94 days, providing an extra 636 megalitres a year.

Mayor Reg Kidd praised the council's water engineers for the investigations they had undertaken.

"All that monitoring about maintaining environmental flows, that's important for the ecology of the stream, but just as important for how much water we need in Orange," he said.

"[The proposed changes] make good sense because we don't know what summer will bring and it won't interfere with environmental flows, it's a good balance."

He said school students were monitoring their water use, showing the message was getting through.