WICCOPEE — It's easy to drive past the Gildersleeve Brook without noticing where it crosses Route 52 in East Fishkill, at the entrance to John Jay High School.

Since 2002, when IBM Corp. started manufacturing innovative new microchips at its plant here, the Gildersleeve Brook has received the region's largest load of water pollutants reported to the federal government — 2.56 million pounds in 2004.

IBM and the Department of Environmental Conservation said the stream is not being harmed. There's no proof.

The DEC classifies streams based on its determination of their "best use." Discharges are regulated to keep streams in their designated conditions so they can support those uses. Pollution loads allowed in smaller streams like the Gildersleeve Brook are designed to protect the stream even if its flow drops to levels expected during 10-year droughts, IBM spokesman Steve Cole said.

"We would not expect any significant impacts from our discharge on the Gildersleeve Brook or any of the downstream creeks," Cole said.

IBM's nitrates stem from its treatment of ammonia. A $12 million treatment plant is poised to remove ammonia from the waste stream in weeks, limiting ongoing pollution of the brook. A second $4 million plant is being designed to do the same for copper.

David Burns, former watershed coordinator for the Dutchess County Environmental Management Council, was a lead author of the Natural Resource Management Plan for the Fishkill Creek Watershed, completed last year.

Data analyzed

The report analyzed available science about the 193-square-mile watershed. No data came from Gildersleeve Brook or immediately downstream of its confluence with the Fishkill Creek, Burns said. Most of the data was gathered prior to 2002.

Nitrates provide the nitrogen needed for life. Over-fertilized, though, algae and plants can alter the aquatic food web in ways that can make the stream inhospitable to cold-water fish such as trout. Dead and dying algae can also sink to the bottom and rob water bodies of oxygen as they decay, in a process called eutrophication.

The Fishkill Creek watershed report noted some low oxygen and eutrophication concerns upstream of dams on the Fishkill Creek. The cause was assumed to be sewage or agricultural runoff.

"To some extent, the impact is going to be greater on a small stream than on a larger stream, particularly at low-flow conditions," said Tom Lynch, a Marist College biology professor. "It will affect fish, and it will affect larger invertebrates like crayfish."

Lead is toxic to the nervous system and can accumulate in the tissues of living things. Copper is an essential nutrient that can be toxic in high concentrations.

The Fishkill Creek management plan noted elevated lead levels in crayfish around Beacon, and attributed it to defunct industries in the city.

"I think there's definitely a need for more testing," Burns said. "I can't say whether it's going to be an adverse impact or not."

On the Web

Natural Resource Management Plan for the Fishkill Creek Watershed: [FishkillCreekWatershed.org/mgtplan.htm]