While dams along the Saugatuck River may create recreational opportunities and scenic waterfalls, they also can pose dangers to wildlife.

That's why Nature Conservancy volunteers are donating time to monitor fish spawning activities at the Wood Dam, located a couple hundred yards up river from the bridge along Kings Highway North. A "fishway" -- a sort of underwater ramp to help fish hurdle the dam -- must be maintained and monitored.

According to Sally Harold, director of migratory fish projects for the conservancy, there are 4,000 dams of various sizes in rivers and waterways throughout Connecticut. For saltwater fish that require swimming upstream into their native freshwater spawning grounds in order to reproduce -- among them certain types of salmon, herring and lamprey -- the dams present a serious problem.

"There are many, many reasons why dams still remain," Harold said, though few of them directly relate to their historic role in generating energy. "They're expensive to remove," she said, for one thing, and many are privately owned. Yet while there is often grant money available for removing dams -- or for installing fishways and other measure to aid fish migration -- some property owners choose not to make any changes.

"It's a real challenge," Harold said. She notes that while several dams working backward up the Saugatuck have been fitted to accommodate fish, including the one at Lee's Pond, a last remaining dam in upper Weston prevents fish from getting within three miles of the Saugatuck Reservoir -- their intended destination.

"Maybe someday the guy who bought that property will decide he loves us and do something," Harold said. "It takes a long time for generational changes to happen," she said, noting that after a century of being saddled with these restrictions, the numbers of some fish have significantly decreased.

"People don't understand what dams do to affect river health and the fish population," she said.

"Taking care of the environment is really important to me," said Tim Fornero of Westport, who is volunteering for a second year on this project.

The work is simple, he said. "There's a cage and really what you do is you count the fish in the cage and you clean the cage."

Another volunteer is Lisa Tryon of Bridgeport, a science teacher at Stratford High School. "This is a chance to do science, rather than just teach it," said Tryon, who has volunteered on other conservancy projects that involve invertebrate counts.

Access to the Wood Dam is through Aquarion Co. property, which is closed to the public. The surrounding area, which includes a large flat section of flood plain and a range of towering trees, is largely untouched despite being near Westport's downtown.

Volunteers at the site were introduced to an electronic fish-counting device, which keeps track of each fish passing by one of eight electronic sensors underwater. The sensors don't identify the kind of fish, but keeping track of the numbers helps environmentalists learn and confirm if they correspondent to what is happening upriver at other dams.

On a regular basis the volunteers will return to the site during the spring, summer and fall, verify that the access ways are clean and operational, and keep the count going. If at all possible, they make note of the species they may see.

"We have no documentation of blueback herring in this river," Harold said, noting that species is not doing well.

Volunteer Kat Hastings of Stratford said of the project, "I like volunteering, I like community service and I like being outside."

Clay Minor of Norwalk is volunteering for a third year. "I like being outside and I feel it's a contribution," he said. "And it's a great organization."