The Grand River Conservation Authority is starting a review of the future of the upper Rockwood Dam on the Eramosa River in the Rockwood Conservation Area.
The review, a class environmental assessment, will include opportunities for members of the public to comment on plans for the dam. The structure is about one metre high and it is located at the top of a two meter waterfall.
The dam is one of two in the park and is adjacent to the ruins of the old Harris Mill. It was likely built in the 1860s, around the same time as the mill.
Naomi Moore, the project manager for the study, said in an interview on Monday that there are three options for the GRCA, and it wants to hear what people think.
The options are:
– do nothing, which could lead to a small failure, and, depending on the damage when it goes, a possible lawsuit;
– rebuilt the dam; or
– remove it entirely.
That last option, she said, would like improve the water quality in that stretch of the Eramosa River.
The dam has two concrete abutments and three piers. Sets of logs (called stoplogs) are placed between the abutments and piers to block the flow of water in the Eramosa River. When the logs are in place, they create a pond that is about one metre deep and two hectares in area.
The stoplogs have reached the end of their 25-year life span and replacements would cost about $10,000. The GRCA removed some of the logs in 2006. Since then, vegetation has grown up in the previously flooded area. Moore noted that the water quality improved marginally, too.
She said the pond was only one metre deep, and that allowed the water to get heated. Cold water is preferred in streams because it contains more oxygen. A cold water river is a health river.
Part of the process will be to investigate the impact of that dam on water quality. The Eramosa is a coldwater river, however the presence of the dam creates a pond where the water warms up before moving downstream to the larger pond at the centre of the conservation area.
There is another dam owned by the GRCA downstream of the dam under study, and a privately owned dam upstream of the dam under consideration.
Any repairs to any of them requires federal permission.
Moore said the dam under study has a waterfall, and people generally like that effect. Even with the dam removed that would remain, but she added the study is just beginning and no decisions will be made until all the data, including public comments, are in.
More information on the project will be available on the GRCA website at www.grandriver.ca.
Those interested in providing written comments or receiving future notices concerning the study should contact Naomi Moore, project co-ordinator, at 519-621-2763, extension 2293; fax 519-621-4945; or by e-mail nmoore@grandriver.ca.
