November 14th, 2025What can you do about an evaporating dam?

By Kerri Goschnick, Land Management Extension Officer

As we head into the warmer months, it’s essential to monitor your water storage regularly. This helps you understand how much water stock is drinking and what you may be losing through evaporation or leakage.

See if you can identify which is having the greatest impact – water used through stock consumption or water lost through evaporation or leakage. Have you simply run out of water because there has not been sufficient rainfall to produce the required runoff?

To generate runoff into storages, rainfall events typically need to exceed 20mm.  If your grass height is over 50 mm, you may need 60 mm or more per event. Many regions have not had these types of events for some time.

Identifying and managing leakage

Leakage from dams often shows up as wet spots or clumps of green grass in a small area during the drier part of the year. This can occur when dry dams fill quickly but dam walls haven’t fully re-saturated. If you suspect leakage, consider using treatment products but choose carefully, as many are soil-type specific. You will get the best value when you take this into account.

If you treat your dam, ensure the dam is properly fenced to exclude all stock. Storage treatment products can range from $1,000–$10,000 and should only be used when you are certain that your storage is leaking.

Also, consider safety by adding steps or structures to the inside batters to help animals or people exit safely without damaging the treated batter or liner.