Midpoints: Invasion of paradise

The air was heavy with the humidity of mid-August, so steamy that the slightest movement resulted in a sheen of moisture on the brow. Around Ellis Pond, the muggy air was visible, a haze that hung above the still pool, the scent of water and submersed vegetation like some primordial perfume. I walked the overgrown pathway that fringes a portion of the pond, mindful in my flip-flops of the poison ivy that crept and climbed arrogantly into the walkway and up the trunks of trees.

Spying a large bird on a rock across the pond’s expanse, I crept as quietly as possible along the path to get a good look at the creature. A magnificent great blue heron, perched like a gull or a cormorant on a large rock jutting out of the water, stood tall on long, slender legs that are normally partially submerged as it wades in the water looking for food. When it heard my audible exhalation of wonder, the bird launched gracefully into the air, its distinctive neck and impressive wingspan truly awe-inspiring.

Perhaps there was a reason why the large bird was roosting on the rock instead of wading in the water. The pond looked almost solid, more like a mud flat than a sparkling, freshwater pond. Plant growth covered the surface in an unpleasant green carpet, dotted with budded lily pads. This choking aquatic vegetation has a name: Asian water chestnut.

According to the Web site of the Blackstone River Watershed Association, Harvard University Botanical Gardens brought the Asian water chestnut to the United States in the late 1800s. Seeds reportedly escaped from the botanical gardens and, having no natural enemies, the species spread throughout Massachusetts and the Northeastern United States.

The invasive plant’s rooted floating leaves can form dense, impenetrable mats on the water’s surface and its slender stems, feathered with leaves, can reach a length of 15 feet. The nuts, which are armed with four very sharp thorns, are inedible and unrelated to the crunchy morsels found in Chinese take-out food.

An effort is being organized by Norwood’s conservation agent, Al Goetz, to head off the invasion of Ellis Pond by the Asian water chestnut with a band of volunteers on Saturday, Aug. 29, at 9 a.m. Goetz hopes that about a dozen volunteers will show up at the parking area near the Ellis Pond Dam off Walpole Street across from Hannaford Plaza to venture out in non-motorized boats and help rid the pond of the aquatic pest.

It is not the first time that volunteers have gathered to remove Asian water chestnuts from Ellis Pond. On Oct. 17, 2002, the Neponset River Watershed Association mustered more than a dozen volunteers to remove the offending plant life.

Now the Asian water chestnut has again proliferated in Ellis Pond and, left unchecked, would rapidly spread and choke out native species, reducing oxygen levels, which would suffocate fish and produce offensive odors. Goetz is counting on volunteers to aid the Conservation Commission and the Department of Public Works in collecting and disposing of the plants, which will be composted in the town’s Winter Street facility.

“I think there is more there now than we had before,” said Goetz, who has been Norwood’s conservation agent for 13 years. “It continues to expand and we hope to catch it before it gets worse.”

Ellis Pond is a wonderful asset for the town of Norwood, one that at this time is only partially accessible to townspeople. As steward for this beautiful body of water, the town is responsible for making it a clean, safe and viable resource for passive recreation. Even with relatively short notice, it is hoped that enough people will consider coming out to help fend off this predatory plant life and make the pond more hospitable to beneficial plants, fish, and water birds like the beautiful great blue heron.

Norwood resident Candace Leary’s Midpoints column appears Mondays in the Transcript.