When Crown Prince Paras was in Pokhara cooling off last week, his speedboat got entangled in clumps of water hyacinths floating on Phewa Lake (pictured below).

If it wasn't for that, there probably wouldn't have been the frenzy of water hyacinth eradications that has been undertaken literally on a war-footing in the past week in this tourist town. The lakeside is now crawling with soldiers in blue and green camouflage fatigues gathering the weeds on boats and loading them on dump-trucks on the shore.

Actually, Pokhara's Restaurant and Bar Association had started a clean-up campaign last month and local luminaries had been involved in taking out the hyacinths. The weeds are spreading too fast for stop-gap cleanups likes this to work, even with the crown prince pitching in. But it's the thought that counts-the very fact that locals are worried about the health of the lake is a positive sign.

Pokharans are bemused by the nationwide notoriety that their famous weed has now earned thanks to a royal celebrity being briefly involved in its cleaning up. In fact, they don't remember anything happening in Pokhara in recent months that has caught mainstream media attention as much as this prolific weed.

However, no one seems to know much about the water hyacinth, except that it spreads at an astounding rate. Beachfronts in Pokhara that are cleaned up the previous day are suddenly choked with the weed the next morning. Even botanist Suresh Shrestha at the Forest Science Research Institute in Pokhara is stumped: "This is one incredible plant, we haven't studied it enough to know how it spreads so quickly."

Another Pokhara-based biologist, Jayadeb Bista with the Fisheries Research Station on the shores of the Phewa, says there is a kind of beetle that is known to feed voraciously on hyacinth. The beetles have been deployed in the United States to eat hyacinth leaves which causes the plants to lose their buoyancy, after which they sink and die. The search is on for the beetle.

Water hyacinths first made their appearance in the lakes around Pokhara only 15 years ago, and have since choked most of the other smaller lakes as well. Within a year, one plant can spread into a hectare area of lake. The weed seems to thrive on the organic pollutants that flow into the lake from the city's drainage system and from the streams that flow into it.

The hyacinths are also a factor in making the lakes of Pokhara valley shrink faster than they would just through sedimentation. In 1993, Phewa was 523 hectares in area, it is now only 452 hectares. Biologists at the Fisheries Research Centre estimate that water hyacinths now cover up to a quarter of the area of Phewa Lake.