There is an interesting article on Stratfor.com that deals with the issue of terrorist attacks on water systems by contaminating water supplies. The article was written in response to reader questions about an earlier article on the closure of the road that runs across the Dillon Dam in Colorado. Those readers asked why the earlier article dealt only with a physical attack on the dam and not contamination of the water supply
Toxicity is Dose Related
The Stratfor.com authors, Fred Burton and Scott Stewart, do an excellent job in explaining why it is so difficult to adulterate a water supply at the source. They point out that it would take 830,000 gallons of a contaminant added to the 83 Billion gallon reservoir to reach a 10 ppm level of contamination.
Even these authors underestimate the complexity of the operation, saying that it would take 55 tank trucks of material to accomplish that kind of attack. That estimate is way low because they assume each truck would carry 15,000 gallons. Normal tank trucks carry about 5,000 gallons of liquid; so it would take more than 150 tank trucks dumping a contaminant into that reservoir to reach the 10 ppm level. Most deadly toxins take a much higher concentration than 10 ppm to kill people.
Water Treatment Makes it Even More Difficult
To make matters even more difficult for the terrorist there is a complete water treatment and distribution network between the potential contamination at the reservoir and the water tap. The whole purpose of that system it to remove contaminants from the drinking water supply.
The article does a good job of describing how the treatment and distribution network helps to protect the citizens drinking the water from the municipal treatment system. They clearly make the point that an attack upstream of the treatment plant is likely to be totally ineffective in killing people.
Industrial Chemical Contamination
If this is true, why does the government get so concerned about ground water pollution? Cities that use ground water for their drinking water also treat the water. The difference is that the EPA is not worried about contamination that is going to kill people drinking a couple of glasses of water. They are worried about contamination that is going to make people sick with exotic cancers or other diseases after twenty or thirty years of drinking the contaminated water. That is much too long a time frame to be useful to a terrorist.
The Psychological Effect
The authors point out that even a non-deadly attack on water supplies may end up being an effective attack due to the psychological effects on the population. We have come to rely on our water systems for safe drinking water and expect very low contaminant levels. This can be seen by the recent public reactions to ultra low levels of various pharmaceutical residues in city water supplies.
Eco-Terrorist Type Attack
This would not be the type of large-scale, spectacular attack that we have come to expect from al Qaeda related terrorist groups. It would be more in line with the symbolic types of attacks that we have seen from various eco-terrorist groups. To date those groups have not executed attacks that resulted in spectacular deaths, they have instead gone for economic effects to gain their headlines.
To see how effective a pre-treatment water supply attack could be we need only to look at a recent water tower vandalism incident in Las Lomas, CA. There the hatch to a water tower was discovered open in circumstances that indicated an intruder had accessed the tank. At least one test of water quality indicated very low levels of mercury contamination. Even though other tests did not replicate the results (perhaps because the contamination levels were so close to the detection limits of the test) residents were warned and the tank was drained and cleaned.
If the same incident had been accompanied by the publication of a manifesto against chemicals manufactured or used by a local facility the incident would have attracted much more attention. The resultant publicity would fit in well with the objectives of many eco-terrorist groups.
To avoid problems with this type of attack water utilities need to be proactive in explaining all of these facts to their customers before an attack takes place. Articles similar to the one on Stratford.com need to be prepared and sent to customers on a regular basis. Periodic publicity campaigns using local media need to be employed. Once an attack takes place, it will be too late to prepare and use such a campaign to prevent panic.