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 | Lake Rehabilitation Project East Lake (Lac de l'Est) in Quebéc, Canada, 2007  CanadianPond.ca
Products Limited was
approached by the local lake association of Lac de L'est to find a solution to
the problems of the lake; degrading clarity, algae, high phosphate levels, odors
etc. Initial evaluation by our pond experts determined that one thing the lake
was in need of was increased water circulation and aeration. It was also prescribed
to use floating islands in the lake to assist in the sequestration of unwanted
nutrients from the lake. The association began fund raising, local government
and businesses added financial support to the project, and in August 2007 a 250
square foot floating island was installed.
A combination of treatments were used during the Lac de l'Est project in the summer of 2007; an aeration system and a 250 foot square floating island. The island was was positioned and anchored above the rising bubbles from the linear runs of Bubble Tubing on the lake bed as research has shown the island efficiency increases in the presence of aeration. Natural, friendly bacteria were also added to the site to accelerate the treatment. The combined action of these different tools permits not only the digestion of organic muck on the lake bottom, but also improvement of water clarity and quality and the creation and diversification of aquatic habitat. While
the exterior surface size of the island is only 250 square feet (23 square meters)
it actually represents the equivalent filtering value of approximately one acre
(4400 square meters) of wetlands. This is due to the matrix that makes up the
floating island which is constructed of recycled materials into a mesh that actually
creates a intricate and densely packed system for beneficial biofilm to grow.
Rehabilitation
& creation of aquatic habitats in a lake The plantation of a number of trees in the watershed and along the shoreline, and the recommendation that residents use detergents without phosphates, are several other initiatives taken by the Lake association members, encouraging everyone to do their part to help the lake. The project to install the island and aeration system is the first part of a larger restoration plan for this lake. The addition of similar systems at different water intakes throughout the lake, where streams from within the larger watershed feed the lake, is envisioned for the next few years. All these efforts will without a doubt prove effective for improving water quality for the lake, and for reducing invasive aquatic plants. Study
Protocol and Analysis The measures inside this zone to be carried out include: changes in water depth, sediment depth, water clarity with the use of a Secchi disc, and phosphorous and chlorophyll levels in the water. The data will be collected at regular intervals and the results will be analyzed in a report given to the Ministry of Sustainable Development, Environment and Parks (MDDEP) after two years of data collection. The
zone in the lake identified for treatment was characterized by severe sedimentation
and problems with invasive aquatic plants, namely Milfoil and Elodea, both non-indigeneous
to the region. The
aeration systems used in this project are designed to function all year round,
but in order to minimize the dangerous risk of thin ice, the Lac De L'est system
will be shutdown in winter to allow ice to form properly. The Floating Island
The large cavities allow planting of shrubs, while the circular holes allow water to access plant roots through capillary action within the island structure. These holes will be compacted with Biomix, a special soil used for floating islands. The
Biomix dirt provided with the island is specifically formulated for durability
and stability and should not be replaced with regular dirt. Ordinary dirt will
wash away quite rapidly, not providing the necessary stability for establishing
new plant growth. In this photo, see how the different sections are joined together. Volunteer assistance was greatly appreciated for launching an island of this size in one day. The installation of a floating island project is a great community affair. Thanks to the volunteers who gladly participated in the launching of this island project. Their presence allowed our team to respond directly to questions and also to fully explain the functioning of the island in relation to its design and in conjunction with lake bottom aeration.
Towing the island to its desired location is easy using any boat. The island can be anchored into location using concrete blocks or boat anchors. Nature
will take no time to move in to this new piece of real estate. Within hours of
launching this island, a great blue heron was spotted on the Lac de L'est island.
The
project of installing a floating island and an aeration system on a public lake
like Lac de l'Est requires following the proper environmental norms of the region
on one part, and securing the funds to purchase the products on the other part.
The presented project may seem minor, but it is important to note that this project represents the first project of a floating island installation on an open lake in Quebec! And also if it weren't for the Lac de L'Est Association ( l'Association Sportive et de Bienveillance du Lac de l'Est) and its volunteers who were very active participants of environmental improvement, this wonderful project would likely never have seen the light of day! As
well as taking the necessary steps with the environment ministry ( MDDEP ministère
du développement durable, de l'environnement et des parcs), the ministry
of wildlife and the local authorities, it was also necessary for the lake association
to raise the funds to purchase the products installed in the lake. Here is a highlight of the major contributions which made this floating island/aeration project possible:
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The
actual surface area available for microbes on the island is many many times larger
than the physical footprint of the island which is why the filtering capacity
is so substantial.
The
study area was determined in consultation with the volunteers of the Lac de L'Est
Association, and delineated by buoys on the lake.
This
particular aeration system is from Vertex Water Features one of North America's
leaders in aeration technologies and close partner of CanadianPond.ca Products
Limited. This customized aeration system involves two double piston compressors
of 1/3 HP each, four lines of 100 feet (30m) of 1/2 inch bubble tubing which were
installed parallel to the shoreline and under the island. 
When
any aeration system is functioning in winter, you may notice a section not frozen
in the ice. If the weather is really cold, the ice may appear thick and is actually
not, especially if covered by a recent snowfall. All ice near aeration systems
is dangerously thin. 
The
250 square foot floating island comes in 3 sections that require assembly on land.
Before the soil was added in preparation of plantation, all joiners were properly
secured. The island here is 250 feet square. For ease of work and launch, all
pieces were placed on top a tarpaulin before assembly.
The
attachments for joining the three island sections together are provided with the
islands; regular or rubber hammers can be used for assembly. 
For
this island project, a carpet of indigenous plants and some individual aquatic
plants were used. A combination can also be used; plants, seeds and carpet or
even sod (although sod is not normally favored for creating habitat). 
