How Water Carryover Works: State-by-State Rules for the Murray-Darling Basin

What carryover does

Carryover lets you hold unused water allocation in your account at 30 June (end of the water year) and use it the following season. Instead of losing water you paid for, you roll it forward. It appears in your account on 1 July alongside any new allocations announced for the coming year.

Before carryover existed, unused allocation was forfeited at season end. Now it is one of the most powerful tools in water management — particularly for cross-season arbitrage. Buy allocation cheaply in a wet year's seasonal trough, carry it into a drier year, and use or sell at significantly higher prices.

The numbers make this concrete. Zone 1A allocation averaged $36/ML in the wet-year trough of WY2022/23. By WY2025/26, the same megalitre was worth $258/ML. Carryover is the mechanism that lets you bridge that gap.

Victoria: the most generous system

The rules

Victorian water share holders can carry over up to 100% of their entitlement volume. Hold 200 ML of HRWS? You can carry up to 200 ML. It is automatic — you do not need to apply. Whatever unused allocation sits in your VWR account on 30 June rolls into the next season.

The catch: spillable water

Carried-over water in Victoria is classified as spillable. If storages fill and spill during winter or spring, your carryover can be reduced or zeroed out. The VWR calculates a system-wide spillable water balance and, in a spill event, forfeits carryover proportionally across all holders.

This is the single biggest risk of Victorian carryover. In La Nina flood years (2021-2023), Eildon hit capacity and spillable accounts took losses. In drought years, spill risk is negligible — Eildon in the mid-40s (current level) is not going to spill.

The LROS declaration

The LROS (Low Risk of Spill) declaration is made by the storage manager, not by you. Each season the NVRM assesses whether storages are likely to fill. Once a Low Risk of Spill is declared, water in spillable accounts becomes available to use or trade.

In dry years the declaration typically comes early in the season. In wet years it can come late — or not at all — which means carried water can sit locked in your spillable account for months while you wait.

The decision that does sit with you has a hard deadline: 30 June. Whatever is in your account at season end rolls forward automatically, so hold-versus-sell must be settled before then. Once the season ticks over, you are committed to the new season's spill risk.

Goulburn vs Murray spill risk

Zone 1A carryover is held against Eildon (3,334 GL). Zone 6/6B carryover is deemed held in Murray storages (Hume 3,005 GL + Dartmouth 3,856 GL = 6,861 GL combined). The larger Murray buffer means Zone 6 carryover historically faces lower spill frequency than Zone 1A. If you have a choice about where to park carryover, the Murray system offers slightly better protection in wet sequences.

NSW: carryover limits and account limits

NSW regulated rivers run a different framework, set valley by valley in each water sharing plan. The NSW Murray is the one most relevant to southern-basin traders.

The rules (NSW Murray)

General security holders can carry over up to 50% of entitlement volume into the new water year. On top of that sits an account limit of 110% of entitlement — water that would push your account above the limit is forgone and re-allocated to other licence holders.

For a 1,000 unit general security licence: carry up to 500 ML across 30 June, and never let total account credits (carryover plus new allocation) exceed 1,100 ML. Monitor your account through the season, particularly if late allocation announcements push you near the limit.

Key differences from Victoria

• Lower carryover cap — 50% in the NSW Murray versus Victoria's 100%
• No spillable water risk — carried NSW water is not exposed to spill forfeiture
• Hard account limit instead — credits above 110% of entitlement are forgone
• No waiting on an LROS declaration before carried water is usable
• Rules differ by valley — the Murrumbidgee and northern valleys set their own limits

South Australia: the tight cap

SA allows private carryover for Murray water access entitlement holders, but with a significantly lower cap than Victoria.

The rules

DEW SA (Department for Environment and Water) sets the carryover limit at approximately 20% of entitlement volume for Class 3a water access entitlements. Hold 500 ML of entitlement? You can carry over up to 100 ML.

This is far more restrictive than Victoria's 100% cap. SA irrigators cannot bank large multi-year positions the way Victorian operators can.

Capacity limits

SA carryover is also subject to total system capacity. If DEW determines the system cannot deliver carried volumes alongside new allocations, restrictions may apply. Check DEW SA announcements each year — the cap can change.

Strategic carryover: the cross-season trade

The classic carryover strategy:

Buy in a wet year trough. March-June in a wet season, allocation prices bottom out. Zone 1A hit $21/ML at the WY2022/23 trough. Buy surplus allocation at these levels.

Decide before 30 June. Carryover is automatic, but the hold-versus-sell decision is locked in once the water year ends. Review your position in May-June.

Enter the next season with water. On 1 July, your carried water is in your account. You have supply before a single new allocation is announced. If the following season opens dry, you are holding water worth 3-10x what you paid.

Sell at peak. January averages 70% above June. In a drought transition year, the multiple can be far higher.

The WY2022/23 to WY2025/26 cycle: bought at $36/ML, worth $258/ML eighteen months later. A 500 ML carryover position cost $18,000 and was worth $129,000 at the WY2025/26 average. This is why institutional holders (Kilter Rural, Duxton Water) use carryover as a core income strategy.

When to carry vs when to sell

Carry when:

• Spill risk is low (storages below 60%)
• Seasonal outlook favours dry (El Nino, positive IOD)
• You want early-season supply certainty next year
• Prices are below long-run average and likely to recover

Sell instead when:

• Storages are near capacity and spill is probable
• La Nina is forecast (prices likely to stay low next season too)
• Late-season prices are attractive enough to lock in profit now
• You need cash flow before 30 June

In the current environment (Eildon in the mid-40s, an El Nino likely emerging, and models favouring a positive IOD by spring), carrying into WY2026/27 is strongly favoured. Spill risk is negligible and next season's pricing outlook is bullish.

Common mistakes

Drifting past 30 June without a plan. Carryover happens automatically, but that is not the same as having a strategy. Holders who never weigh hold-versus-sell end up carrying water into a wet year's spill risk, or dumping surplus into the thin June market. Review your position with your broker in May.

Carrying too much in a wet year. Large carryover positions when storages are at 80%+ capacity face serious spill risk. The upside of holding is limited (next season is probably also wet and cheap) while the downside is real (partial or total loss). Sell into the late-season market instead.

Ignoring state differences. Victoria's 100% with spill risk, NSW Murray's 50% carryover with a 110% account limit, SA's 20% limit — these are completely different frameworks. If you hold entitlements in multiple states, each requires its own carryover strategy.

Relying on IVT for carryover sales. If you carry Zone 1A water planning to sell to Murray buyers next season, remember that IVT may not be open when you want to sell. Build a within-zone selling strategy as backup.

For more on how zones interact, see our trading zones guide. If you want to carry water but do not hold entitlements with sufficient volume cap, ask about carryover parking — parking allocation on another holder's entitlement specifically for carryover purposes.

Frequently asked questions

Can I carry over water I bought on the temporary market?

Yes. Once allocation is in your account, carryover rules apply regardless of where it came from. Purchased allocation carries over exactly like allocation generated by your own entitlement.

Is carried-over water the same as new allocation?

In Victoria, carried water is spillable while new allocation is not. This matters if a spill event occurs. In NSW there is no spillable mechanism — carried water simply counts toward your carryover and account limits.

Can I trade carried-over water?

Yes. Carried-over water in your allocation account can be sold on the temporary market at any time during the following season, subject to normal trading rules for your zone.

Does carryover cost anything?

No separate fee in most systems. You continue paying fixed entitlement charges regardless. The real cost is opportunity cost (capital tied up) plus spill risk in Victorian spillable accounts.

Should I carry or sell and re-buy next season?

If you expect prices to rise (dry outlook, low storages), carrying saves you money. If you expect another wet year (prices stay low), selling now and re-buying fresh allocation next season may be smarter. Your broker can help you weigh storage levels, climate signals and your risk tolerance.