Rural water supplies in an area of South Otago have fallen to critically low levels.
The Clutha District Council has called for an urgent drop in usage on the North Bruce Rural Water Scheme to avoid supply cuts.
The scheme supplies 950 farms and houses north of Balclutha, from Lovells Flat to Waihola.
The council said the reservoir was critically low and it suspected a major leak somewhere was compounding the problem of very dry conditions.
The council has banned any unnecessary watering by people connected to the scheme.