It”s not often that a major environmental threat is spotted early enough so that it can be inexpensively and quickly prevented from becoming an ecological disaster.

That is the situation now facing the Delta with a highly invasive weed knows as South American spongeplant. It has been found recently in only a few places, all of which are in California.

The plant grows and spreads at a rate that could devastate the Delta environment in just a few years. “Your jaw drops at what”s going to happen,” said Lars Anderson, a weed scientist at the U.S. Department of Agriculture”s Agricultural Research Service. “The weeds don”t stop.”

Spongeplant floats on the water”s surface and can spread like the hyacinths that used to clog Delta waterways until the state began an aggressive eradication plan, which costs more than $2 million a year. However, spongeplant is potentially far worse than hyacinth for a couple of reasons. It is smaller, making it easier for it to get deeper into pumps and waterworks. Unlike hyacinth, spongeplant is a prolific seed-bearer, which means it would be much harder to eradicate should it take hold in the Delta.

Fortunately, spongeplant has not yet spread like hyacinth did before remedial action was taken. If spongeplant is aggressively attacked now, it can be controlled before it becomes a major problem in the Delta.

Anderson fears that there will be a huge expansion of spongeplant in the next three to five years unless action is taken to stop it.

At present, the weed can be eliminated fairly easily by scooping mats of it out of the water with heavy equipment. As it becomes established, herbicides may be needed.

The problem is that weed control agencies say they do not have the legal authority to spend state money to eradicate the weed. By law, state weed control agencies can spend money to attack only a handful of specified water weeds, including water hyacinth, Brazilian water weed and hydrilla.

State officials worry that diverting money that is used to control hyacinth to attacking spongeplant could cause lawmakers to cut funding.

That fear has so far prevented the state Department of Food and Agriculture from more aggressively searching for and removing spongeplant.

What”s needed as quickly as possible is legislation that funds preventive action now. Assemblywoman Joan Buchanan, D-San Ramon, is considering introducing such a measure next year — the sooner the better.

Delay in dealing with spongeplant is unacceptable. The Delta, which is essential to water delivery to much of California, cannot afford another ecological problem. The rule of thumb is that every dollar spent on the problem in the early stages of infestation could save $100 worth of work that may be needed later.