The harmful environmental effects of mercury have long been documented, and Alabamians have reason to be concerned about the presence of the substance in the waters of their state. An outside review of mercury-related issues and enforcement raises disturbing questions about the monitoring of mercury here.

The Mobile Register paid for testing around a chemical plant in McIntosh that is monitored for mercury pollution. The researchers it consulted found some serious deficiencies in the way the Alabama Department of Environmental Management operates.

The level of acceptable mercury concentration established by ADEM is significantly higher than in most other states. That's troubling enough, but no less a concern is the use of monitoring techniques a Texas A&M researcher called "antiquated" with "crude" detection limits.

Remarkably, the monitoring methods do not appear capable of detecting mercury concentrations that exceed the state's chronic toxicity levels. Put another way, ADEM's limits are high to start with, yet its monitoring isn't sensitive enough to detect even that level.

Glenda Dean, an ADEM official responsible for industrial water issues, told the Register that the state had not required more sensitive testing because the testing would be more vulnerable to "interference" from other chemicals, which could result in inaccurate readings.

That is itself an inaccurate reading, according to the designers of the mercury monitoring protocol used by the federal Environmental Protection Agency. The more sensitive testing approved by EPA is much less vulnerable to interference and false readings than what ADEM uses.

At the McIntosh plant, the major environmental concern is the mercury that washes from the site during rain. Mercury is no longer used there, but stormwater runoff still contains mercury.

ADEM requires the plant to monitor only a "grab sample" -- water taken at one point in the course of a storm. That may or may not be representative of the mercury concentrations at other times during the storm.

The plant only has to monitor two storms per year, down from the scarcely stringent four per year required until last year. Given the amount of rain that falls in our state, that means a lot of unexamined runoff.

The primary concern with mercury is bioaccumulation, the movement up the food chain in increasing concentrations. It becomes more toxic in the process, posing a threat to people by the time an individual eats a fish that ate an insect exposed to mercury.

The measurement of mercury in water, although not insignificant, is not as critical in determining a health threat as the concentration in tissue. Since 2000, every largemouth bass caught by inspectors within 10 miles of the McIntosh plant has exceeded the EPA standard for mercury.

Despite that, ADEM does not declare a stream impaired unless the mercury concentration in fish tissue is three times the level the EPA deems dangerous. That has drawn the attention of the U.S. Fish & Wildlife Service office in Daphne, which issued this statement:

"Fish and wildlife may be adversely affected at levels lower than the level at which Alabama issues consumption advisories. ADEM's fish monitoring data demonstrate that mercury in many of the fish exceed levels that may be toxic to wildlife."

"I think there's a big difference between the pollution that ADEM catches on paper and the actual pollution in Alabama streams," said Adam Snyder, director of the Alabama Rivers Alliance.