A deep-rooted water hog, once seemingly confined to the Yellowstone and Missouri river shorelines in northwest North Dakota, has spread more than 200 miles downstream.

Saltcedar, blamed for sucking dry streams and smaller lakes in states rife with the exotic plant, has been confirmed as far south and east as Lake Sakakawea's Hazen and Beulah bays.

"It has spread farther down the lake than our wildest suspicions," said Ken Eraas, noxious weed specialist for the North Dakota Agriculture Department. "It's real surprising, real dismaying."

The rub with saltcedar - besides its insatiable thirst - is that it pulls large amounts of salt from the soil and then transfers it through its leaves back onto the ground. This increased surface salinity hinders native plants from taking hold.

"It just takes over," Eraas said.

A small stand of saltcedar, or tamarisk, was first found in North Dakota in 2001 along the Yellowstone River. Further inspection some months later, however, revealed more than 1,500 plants along the river's bank.

Without word of the pests' discovery in other parts of the state, scientists believed it to be isolated in northwest North Dakota.

"Where the plant is and where the plant isn't, we just don't know," Eraas said. "In less than an hour of scouting around (Hazen and Beulah bays) we found over 90 plants."

The plants found in those areas were said to be 3 and 4 years old, which lends credence to one theory about how the saltcedar seeds got there in the first place.

"If you count back three or four years, those were years of high water flow," Eraas said. "There was more water movement, more current back then. So, the seeds being moved by water is certainly a possibility."

Saltcedar seeds, no bigger than flakes of pepper, can also be moved from place to place by wind and waterfowl carrying the hitch-hiking seeds lodged in feathers.

"It wouldn't be unforeseen for seeds to be carried long distances in just one evening," Eraas said. "Goodness knows, we see weather reports in North Dakota of winds of 70 mph."

A herbicide has proven to be an effective agent on this plant first introduced into the United States in the late 1880s as an ornamental tree and windbreak. Some saltcedar stands along the Yellowstone have already been treated with success.

Eraas said county, state and federal agencies are working together to battle the invader.

"We need to do a systematic, comprehensive survey of the lake to see how big the problem is," he said. "Then we'll begin the process of controlling it."

At this point, Eraas said the players feel they can keep the saltcedar under control so it doesn't affect water supplies, recreation, and so on.

"Then we'll shift, hopefully, into a maintenance mode, a continuous monitoring of the shorelines," he said.

In the meantime, scientists wait for the other shoe to fall.

"There is the concern, of course, of the plant spreading to the part of the river between Garrison Dam and Lake Oahe," he said.

(Reach Ron Wilson at 250-8256 or ronw@ndonline.com.)