It's bioaccumulation of toxin that mankind eats that worries
The amount of selenium in the water is taken up into the microorganisms and they in turn accumulate the selenium to a higher level. Then a small minnow eats the microorganisms and they bio accumulate more selenium in their bodies. Then a crappie or blue gill eat the minnows and again the amount of selenium is increased in the bluegills body. Then a largemouth bass or a cat fish eats the bluegills (notice the S as in Plural) and they increase the selenium another ten fold. But the time we eat ten bass or ten catfish the amount of selenium in the human body is 1,000,000 time higher than it is in the water. So the more fish you eat the more selenium you get in your body.
To get that much selenium into your body by just drinking the water would take a lot of water. Which is why they test the fish tissue to make sure that people know and understand the dangers. It's your choice whether to eat the fish or not. But at least you have been warned and you are more educated in the potential dangers.
The problem is that it take time and the more fish you eat the more likely you will have selenium building up in your body. So the danger is not immediate. It's delayed and that's the danger. You get a false sense of security as you don't die immediately after eating some fish. But the more fish you eat the more in danger you get from the selenium in your body.
[QUOTE=jcb;560409]I have no idea where Danville's water intake is. Of course human concerns outweigh fish's concerns.[/QUOTE]
Sample grids are probably used to get the samples points
Scientist will grid off an area and assign number to different grid coordinates. Then a random number generator program is use to chose sample points on the grid. That way the sampling is truly random and unbiased. They will use lift nets to sample fish in those areas.
Fish can move great distances in a short time and they tend to school together by species and age. So a real good sampling grid would have to take that into consideration. Remember that 90% of the fish only occupy about 10% of the water at any on time.
But if they sample fish from areas that fishermen are most likely to catch fish then that would be a good way to find out if the fish we fishermen are likely to catch are contaminated or not. It's not an exact science but it the best that we can do giving the circumstances.
But if a single fish can accumulate enough selenium in it's body in it's life time then other fish could do the same thing. Remember they all school together a lot. So catching one fish out of the school would be a good indicator of what the other fish are doing in the same school. Schools of fish tend to feed on the same prey items and in the same areas.
I too have the same type of questions that pappy had in his taking the other side just for the sake of knowledge.
Heavy metals tend to accumulate in the bottom of the lake. If the selenium is coming out of the coal that's dumped near the water then it would be concentrated in that area for sure. But the biomass will tend to take up the selenium and then spread it though out the water column. And we know that it tend to accumulate in the fish or other organisms. Then they move around. Water flowing may not always move the fish in the direction of the water flow as fish are mobile. I'm not sure how strong the current is or this area so I'm talking in general.
They should try to catch and sample some of the trout to find out if they too are contaminated with the selenium. River's can tend to dilute the selenium and wash it down stream into other areas.
And there is no telling what was in those 55 gal drums before they were used to float docks. Scary stuff there. But at lease they were hopefully not full of what ever was in them at one time. Only the residue remained in the barrels hopefully. Still that could add to the problem of the contamination. The problem is that the testing people would have to know what was in the barrels before forming a testing plan to see if those contaminates are in the fish too.
But who's going to eat the fish if they have known high levels of selenium and smaller amounts of other toxin in the fish? The selenium alone would be enough to prevent me from fishing and eating fish in these waters.
You have to balance the cost of the sampling plan and the testing against the need to test the fish for human consumption. We can't afford to test for thousands of possible contaminates as it would be cost prohibitive.
[QUOTE=crappiepappy;560619]I'll play devil's advocate on this (but not to diminish the severity of the problem) :
I'd like to know -
How many fish were tested
What species of fish were tested
Where those fish were taken from
Seems to me, considering the location of the power plant being so close to the dam ... and the water flow towards the dam ... that a lot of that "polluted" water should be localized.
And something else that may prove to be a problem, if in fact the polluted water IS being washed thru the dam, is that the Dix River trout population would be receiving as much or more chemical pollution as the area between the coal ash drainage & the dam.
And chemical pollution from the power plant is only one factor ... considering all the stuff that's dumped into the lake (from all parts of it), and the hundreds of old 55gal drums that have been sunk in that lake, containing who knows what. Remember ... originally, most docks were floated by 55gal drums, long before styrofoam blocks were used. And many of those were sunk, after getting loose from those docks, so as to not be a hazard to water traffic.[/QUOTE]