Killer Weed

It was at Browning Elementary, a neighborhood public school near the Heights, that The Beast first made its appearance.

Ron Jones, a biologist with the local field office of the U.S. Fish and Wildlife Service, had volunteered to help the school build and maintain a Wetlands Demonstration Pond as a teaching tool.

In the fall of 1997, a few months after the small pond opened, he saw that it had become completely covered by a strange, leafy growth that seemed to have appeared overnight. He took a rake and removed all the vegetation.

Last April, he returned to the school. Again the pond was completely overrun with the green plant, which had grown so thick it acted like a tarpaulin, cutting off any sunshine or oxygen to the underwater plants trapped beneath it.

"I had no idea what it was, really," Jones says. "I just knew it was something that was growing phenomenally fast."

As surprised as he was, he soon came in for a bigger shock. School staffers told him that they had completely raked out the pond several times in the months between Jones's visits. Each time the green plant had quickly covered the water again.

A baffled Jones sent samples to area plant biologists. It took a while, but eventually they figured out what the plant was. Salvinia molesta, a South American plant that had lived up to its ominous name by rapidly choking waterways in Australia, Africa and Asia, had made its way to America.

The plant floats on fresh water, pushed around the surface by the wind, with plants sometimes stacking on top of each other to a depth of two to three feet. Reproducing asexually, it essentially clones itself at an extraordinary rate, doubling the water area it covers in a week and wreaking havoc on fragile aquatic ecosystems. In New Guinea, according to one study, a few plants grew within eight years into a mat covering 96 square miles.

Banned from import into the United States, the plant had attempted an abortive foothold here a few years ago, when it was discovered in a small pond in South Carolina and quickly eradicated. The Browning Elementary development was much more severe and serious, but local experts crossed their fingers that somehow the plant had been confined to the school's pond. If Salvinia molesta made its way to any of Texas's lakes or rivers, it could spawn a disaster that would take millions of dollars to fix and might require herbicides that could cause more problems than they solved.

Officials with state and federal wildlife agencies printed fliers and put notices in relevant newsletters saying Salvinia molesta had been found and asking to be contacted in the event of any new sightings. A few false alarms, a couple of private-pond infestations that were easily eradicated, and officials thought they might have dodged a bullet. Maybe molesta would not become the watery equivalent of the fire ant, a pest that had inadvertently been brought into the U.S. decades ago and was now a tiresome fact of Southern life.

In June, Dr. Jim Hyde of the Sabine River Authority was swimming with his family in Toledo Bend Reservoir, a large reservoir that spans the Texas-Louisiana border. He saw a green, leafy plant float by, one that looked like the plant described on the notice sent to employees of his office.

Salvinia molesta, The Beast that no one wanted to tangle with, had made the jump to Texas's public lakes.

No one's sure how molesta, also known as Giant Salvinia, made its way to Texas. Authorities suspect local nurseries, unaware of its prohibited status, sold or even gave away the plant as a fast-growing water-garden accessory. The feds are investigating but have found property owners clamming up when they discover law-enforcement officials asking questions.

More important than how it got here is how fast it will spread. Officials don't know when it will branch out to other lakes and waterways, but they know how it will happen: humans will unwittingly distribute it to local waters that otherwise would never get infested.

As little as a leaf or small chunk of a live molesta is all that is needed to start a new outbreak, a leaf or chunk that could easily attach itself to a boat or be sucked into, and later blown out of, the ballast system of a Jet Ski.

"All it takes is one guy who doesn't wash off his trailer after he goes fishing, and then he moves on to another lake and he takes it with him," says Rhandy Helton, a Texas Parks & Wildlife scientist in Jasper.

Helton and his partner, Larry Hartmann, are counting the days until molesta shows up in Lake Sam Rayburn, one of the most popular lakes in Southeast Texas. Rayburn is a half-hour's drive from Toledo Bend -- on a completely separate river system -- and fishermen who are having no luck on one think nothing of picking up their boats and driving over to the other. Every bass boat tooling down Texas 255 could be carrying the piece of Salvinia molesta that starts a major infestation of Rayburn.