1080 and streams, rivers and lakes

If bait pellets containing 1080 enter a waterway

Any bait pellets containing 1080 that fall into a stream, river or lake are rapidly diluted to harmless levels and almost always undetectable in a waterway after 24 hours.

When a bait pellet containing 1080 falls into water, two things happen:

• the 1080 dissolves and is washed out of the pellet, even before the pellet breaks apart. This process happens quickly, especially in flowing water
• the 1080 washed out of the bait becomes so diluted it cannot work as a toxin.

How pellets become harmless

In laboratory experiments that simulated water flowing over pellets in a stream, about half of the 1080 had been washed out after 5 hours and more than 90% after 24 hours. No 1080 was detected in the water after 36 hours.

Only a very small fraction of a pellet (0.15%) is the chemical 1080 – the rest is cereal, binding agents and flavouring that make it attractive to predators. When wet, baits lose their green colour after 2 days, start to swell and break apart after 3 days, and disintegrate after 4 days.

Microorganisms and plants in the stream then break down diluted 1080 into non-toxic compounds. This usually takes less than 6 days.

1080 poison - what's in the bait?

Keeping 1080 out of drinking water

Every aerial 1080 operation is strictly controlled and must be approved by a medical officer of health or health protection officer before it can go ahead.

This approval includes conditions on excluding waterways that supply drinking water. Drinking water supplies are always safeguarded by buffer zones set by health officers to ensure there is no temporary contamination by 1080. We use sophisticated GPS technology to keep 1080 pellets out of exclusion zones.

Toxic pellet baits containing 1080 are only effective on land, so we avoid wasting them by sowing them over water. However, sometimes baits will be sown over waterways that are not part of exclusion zones, in order to make sure there are no gaps in the treatment area.

Drinking stream water

It is extremely unlikely that stream water will be contaminated by 1080. Bait pellets that land in a stream have their 1080 washed out and diluted very quickly. When it rains after a 1080 operation, rainwater washes most of the 1080 from uneaten baits into the soil, where it is biodegraded by microbes.

1080, the environment and plants

A NIWA field study in 2012 investigated whether 1080 could dissolve out of baits and end up in streams after heavy rainfall.  The study was unable to detect any traces of 1080 in groundwater or stream water, despite using 25,000 times more 1080 than usually applied in an aerial operation.

The only samples that tested positive for 1080 (7 of the 59 samples) came from soil water. These samples contained much lower levels of 1080 than the Ministry of Health standard for drinking water.

1080 and tap water

Nymphs and insects

1080 in water does not affect insects and their larvae such as caddisflies, mayflies and midges (collectively known as invertebrates). Five different studies from 1994–2005 all reported that 1080 had no detectable impact on aquatic invertebrates.

1080 and trout - more about nymphs and insects and 1080

Native fish, eels and crayfish/kōura

1080 in water does not affect native fish or eels. In one research study, 3 species of native fish (longfin eels, koaro and upland bullies) were placed in separate cages downstream of 1080 pellets at 10 times the concentration that was possible after an aerial 1080 operation. No fish died from exposure to 1080.

Crayfish/kōura are not affected by 1080 even if they eat pellets. In a 2006 NIWA laboratory study, kōura were placed in individual cages in stream-like habitat with either a 1080-containing pellet or a cereal pellet without 1080. After 8 days and despite taking small amounts of 1080 into their bodies, no kōura died.

This study also concluded that the risk to humans from eating kōura that had consumed 1080 was virtually non-existent – you would have to eat more than 40 kg of tail flesh in one sitting to have a one in two chance of dying (calculated for an 85 kg adult) .