On January 3rd I started doing a project in another town during the week and didn't get home until after dark. I walk with Kilo every day, and there isn't very much traffic here during that time so we started walking at night. Apparently we are both creatures of habit because even in the dark we followed the same trail that we follow in the day, and without a flashlight. The first night we finished the walk and entered my yard through the pond gate, as usual. It was either overcast or there was no moon, and very dark. I leaned over to take Kilo's halter off and noticed something glowing on the ground on the other side of the gate. I released her into my yard and went back through the gate to the pond side. There were several quarter-sized spots of the substance and they were glowing like a new white t-shirt under a black light, except bluish-green. I remembered the blue glowing material that had traveled through Mexico for several months as a religious icon and had several "radiation" thoughts. I touched one of the spots and soon even tried to pick it up. I finally scooped under one and put it in my hand. I then went to my back door under a light - and there was nothing but dirt in my hand. I was too tired to bother with it that night, and the next night it was there again, and the next, and it was increasing. I told my sister and brother-in-law about it and Bill asked the first relevant question. "Where are you finding the material?" During the night, between the hours of 8 and 10 PM, Kilo and I walk at least one mile, and often two, in all directions, and as much on undeveloped pastures as on roadways. The only place I had observed the phenomenon was on his property - more specifically, in the area that was watered directly from the pond. It reached a point where we were leaving glowing tracks (not footprints, a definite trail) in every unlighted portion of his yard. One night I forced my niece to come into the back yard after dark and she was also amazed. The story actually took a bizarre turn that point and I distanced myself from even thinking about it, but several people saw that as they walked through Bill's backyard by the pond, on a dark night (and the nights during that time were also very wet), a phosphorescent phenomenon would display in the spots where they stepped. One of them told me they had found what was causing it, glow-worms. I never thought about it again until today but tonight I've been searching, and have only found one glow worm reference so far. This article also mentions bioluminescent plankton and then says that almost none are fresh-water.
Finally, an article that discusses bioluminescent earthworms. It states that their bodies don't glow but that they excrete a mucus that does. When they told me that the worms were causing the glow in Bill's yard, they also mentioned that if you rubbed your finger along them, the glow would transfer to your finger. Then if you immediately turned on a flashlight, nothing was visible. It also states that researchers have discovered that the mucus is squirted when the worm is disturbed, such as being handled. This all fits. Being stepped on by people walking around in the dark would be disturbing. Then stalked and captured, even more disturbing. The only part that doesn't fit is, the article is talking about Australia.
Found information about bioluminescent earthworms that relates to this area. This is a slide show. The first slide shows that a bioluminescent earthworm, Genus Diplocardia, can be found here. The forth one is a photo of a species of Diplocardia found in Georgia. The fifth slide is of an earthworm exhibiting almost the same glow (but a little more blue) that we saw. Well, now I probably know what it is, but why? Something about the pond water must attract them because you can almost see a perimeter around the area that it reaches. Will check on it again when the moon wanes.