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4Empowerment presents

Glenn Longley
Chat with Hydrologyst, Dr. Glenn Longley.

April 12, 2001

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Tom: What is the worst common pollutant?

Dr. Longley: Well, in surface waters, it is probably organic matter. In urban areas I would suspect it is runoff from construction areas, could be sediment, could be runoff from streets. Also, we have many pets that are loose in the city, they produce fecal material. That fecal matter gets into the storm drains, and is washed to the streams, and it's amazing how much that does matter in terms of organic loading in our streams.

Jim: What is a harmful pollutant that is not so obvious?

Dr. Longley: I'd like to mention groundwater, probably one of our worst situations. For many years we had underground storage tanks for gasoline at many gas stations, and those storage tanks for the gasoline, many of them were metal, they had metal pipes going to them, and through the years--many of them were in the ground for thirty or more years--and many of them would begin to leak. That would leak the organic matter in the gasoline, and that would get into the groundwater. Not only that, we had other places like dry cleaners that stored their solvents in underground storage tanks, and these were very noxious materials that you would not want in your groundwater. Unfortunately, for example here in San Marcos, we have an area near the river that is being listed as a Superfund site, that probably has resulted from some dry cleaning tank of a cleaner's that has long been shut down but is now showing up those solvents in springs that are running into a small creek that runs into our river here.

Tommy Tidwell: What do you think caused the Golden Algae (Prymnesum parvum) bloom in Lakes Possum Kingdom and Grandbury in north Texas? This is a rare occurrence and it has killed large numbers of fish. There must be some unusual circumstance to cause this.

Dr. Longley: As I understand it, this particular algae is normally associated with our coast, and if I remember correctly, Possum Kingdom is much saltier water than some other areas. And because it is more saline, or salty, than other freshwaters, I think it has allowed this algae to bloom. Another area that this has occurred is in the Pecos River in West Texas, and the Pecos River is known to be salty, it runs across some natural salt deposits, and picks that salt up. And as a result, the algae are able to live, and grow rapidly in those areas, both Pecos and Possum Kingdom. Possum Kingdom, if I remember correctly, is in the Brazos River basin, which is in the upper end, and has some natural salt springs and salt deposits, again that contribute salt to the river system.

Ray Parraz: How many rivers are seriously polluted in Texas?

Dr. Longley: You know, I don't know the exact number. I do know the Texas Natural Resource Conservation Commission, or TNRCC, does either an annual or every three year inventory of water quality in Texas streams. And one could determine the answer to that question by going to their website, which you could find through the Texas government website.

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