Is it time to look into Weweantic with fresh eyes? What does Weweantic have to offer us? What do we, in 2005, have to offer Weweantic?
Come take a look with us into the area surrounding the Horseshoe Pond Dam. This man made boundary, is the key to the future of the largest river system in the Buzzards Bay Watershed, a key which if thoughtfully turned will open a door to reveal unexpected treasures. What might these treasures be? To find out we need only to look thoughtfully into this hidden gem of the Buzzards Bay Watershed.
Differentiating between looking "at" something and looking "into" something is a worthwhile exercise here at Weweantic. In the above paragraphs I specifically use the phrase "look into," rather than "look at", for a purpose. To often we look at things whether they are places or people, and come to conclusions based on outward appearances or preconceived notions. Looking thoughtfully "into" something is a different exercise.
My experience into this section of Weweantic began about ten years ago, in 1996, when a fishladder was proposed for the Horseshoe Pond Dam. At first glance it seemed a harmless plan. It would only require a notch to be cut in the concrete face of the dam and the addition of a few aluminum steep pass segments. Along with these minor alterations a new spill gate for the damís spillway would have to be installed to maintain enough of an impoundment for the fishladder to pass fish. The former spillgate had been removed by the dam owner thirty odd years ago, which allowed the impoundment to fluctuate as flow conditions dictate. Although this plan would have a favorable impact on the targeted specie, the alewife, it did not fully consider or look thoughtfully into the overall diversity of Weweantic.
It may sound strange but the future of Weweantic hinges on the three foot square hole where the dams spillgate once was.
From what I have gathered, Mr. Robbins, the damís late owner, removed the spillgate of the Horseshoe Pond Dam sometime in the 1960's. He did so to prevent flooding in the brook trout hatchery he established on Patterson Brook, a small spring stream at the upper reach of the Horseshoe Pond Dam impoundment. It was Mr. Robbins objection to a new spillgate being put on the dam that ended the 1996 fishladder effort.
When Mr. Robbins removed this spillgate, he opened a new chapter in the history of Weweantic. For the previous two hundred years, Weweantic above the dam had been an impoundment maintained for the sole purpose of turning the wheels of industry. Before the gatesí removal the dam had maintained a fairly constant water level in the impoundment. Water was impounded to the tree line of the surrounding woods, with no saltwater intrusion. What had been part of a diverse fluctuating upper estuary before the dams construction, became a freshwater impoundment with far less diverse habitat and species. When Mr. Robbins removed that spillgate, the impoundment above began to fluctuate again, breathing its first breaths of its estuary since the days of horse and buggies.
The value of fluctuating water levels and the resulting saltwater intrusion must not be overlooked here. It is no secret that the constantly fluctuating water levels of estuaries and free flowing systems create a diversity of habitats, followed naturally by a diversity of species.
Over these past ten years my children and I have spent countless hours looking into the environs of Weweantic, at and around the Horseshoe Pond Dam. Although we may lack the credentials to draw scientific conclusions, our observations leave no doubt that this is a very unique place, which presents us with unique restoration opportunities.
Low tide below dam
High tide below dam
Looking upstream from the Horseshoe Pond Dam August, 05 low flow.
Same view Sept 05, after rains raised the impoundment.
If the spillgate on the dam was replaced the water level would remain fairly constant at the level in the Sept 05 photo above. It is pretty enough to look at but offers little in diversity of habitat.
Looking upstream through the spillgate of the dam at high tide.
The Horseshoe Pond Dam is somewhat unique because it is built within the tidal zone. Using the benefit of these tides we can restore tidal flow, maintain seasonal water level fluctuations, allow easy passage of all sea run fish species, and still maintain enough of the impoundment to support a modest run of alewives. In other words, we can restore the upper estuary of Weweantic (Horseshoe Pond).
Follow the links to photo's to see how the tide works at the Horseshoe Pond Dam.
Alewives find their way above the pond by way of the channel which was used by the mill complex to power the mill. It is not an ideal set up. The entrance way to the channel is a couple hundred feet below the dam, therefore it can be difficult for them to locate. The alewives tend to follow the strongest flow which brings them to the base of the dam where they are vulnerable to the ever present poachers. Despite this draw back the channel functions fairly well as passage for alewives. Over the past several years we have observed a respectable run of adult alewives coming upstream. Spring of 2005 was an exception, as observed elsewhere adult alewife returns appeared quite low. We have also observed schools of juvenile alewives in the pond during summer months.
Alewives may also access the pond through the spillgate hole during periods of high spring tide cycles. Although there is no upstream flow above the dam during high spring flows, it appears high lunar tides stem the flow from the pond enough to allow alewives to swim through to the pond.
Photo's of bypass channel... HERE
Like the alewife, rainbow smelt are an anadromous fish, which spawn in freshwater and return to salt. Rainbow smelt spawn earlier than the alewife, in 2005 eggs were visible in late March and early April below the dam.
Because of the dam smelt have limited spawning habitat in Weweantic. The only area they lay their eggs is within a hundred feet downstream of the dam. The problem for the smelt here, is the tide. Smelt, by nature move up the river on the high tide to overcome swift water and obstructions. They also must spawn in fresh or low saline water. Because they cannot get past the dam they lay their eggs below it, within the the tidal zone, therefore at low tide their eggs are on dry ground. Under normal circumstances the smelt would move above tidal influence to spawn. After an evening spawn at Weweantic thousands of tiny smelt eggs can be seen lying dead among the rocks after the tide recedes.
Dead smelt eggs clustered on the stream bed at low tide April 05 Weweantic
Follow this link for additional Weweantic tidal info.... HERE