Second Marsh

• From the 1930's to the 1970's significant impacts to the marsh including pollution, sedimentation and habitat loss occurred as a result of dredgeate deposits from Oshawa Harbour, upstream urbanization, development of adjacent lands, and effluent from a water treatment plant.
• Between the 1960's and 1990's there were several ownership changes, a proposal to turn the marsh into a port, and prolonged studies and battles to save the marsh.
• In the 1990's ownership of the marsh was returned to the City of Oshawa and a Marsh Management Plan was developed in 1992.
• Following the development of the Marsh Management Plan (1992) restoration works began including moving the outlet back to the west side of the marsh; installing flow deflection islands, native plantings, and carp barriers; and the establishment of trails, lookouts, and signage.
• In 1999, the Marsh Management Strategy was developed and additional restoration work began which included the construction of an earthen dyke to divert the creek around the marsh, installation of a fish passage structure and installation of a 2-way pump.
• Subsequently the marsh was drawn down in 2004 which mimicked low water levels not seen since before Lake Ontario water level regulation. This acted to expose the seedbank, stimulate vegetation growth and improve water quality.

Drawing down water levels mimic natural conditions that historically occurred in Lake Ontario during alternating periods of high and low water levels. This process is a best management practice used to optimize the health and diversity of wetlands by kick starting biological activity. Drawing down the marsh water levels helps to:

• stimulate seed germination, root development and increased vegetation growth and diversity by exposing the plant seeds in the mudflats to sunlight;
• release nutrients locked in the marsh muck;
• improve water quality by reducing turbidity; and
• improve fish habitat and fish community while reducing invasive fish population such as common carp and goldfish.

Alternating periods of high and low water levels that naturally occurred historically in Lake Ontario supporting the health and a high diversity of habitat within Second Marsh.

Since 1960, water levels on Lake Ontario and the St. Lawrence River have been artificially managed removing the periods of very low and very high water levels. This has generally resulted in the loss of wetland habitat, structural complexity, and species diversity within many coastal wetlands along Lake Ontario.

The drawing down of water within wetlands is a common tool used in wetland rehabilitation projects. It mimics historic natural coastal conditions that help to maintain a healthy and productive wetland ecosystem. Low water levels provide optimal conditions for the germination of a diverse array of wetland plants, which supply food and habitat to a variety of wildlife.

As more water is held in the marsh, the productivity of plants and invertebrates also increases, providing an abundant food source important to many wetland dependent species, including waterfowl.

Resident species are well adapted to dynamic changes in water levels that occur naturally in marshes. Deeper areas are not drained completely allowing refuge habitat for various species including fish, reptiles and amphibians and invertebrates. Water levels are gradually lowered over a number of weeks allowing fish to move into refuge areas.

Recent monitoring by CLOCA clearly show invasive Common carp are the most abundant fish species in Second Marsh. Common carp are widely regarded as a destructive invasive species which tend to thrive in low quality water environments. Common carp multiply quickly and because of the way they eat, sucking up residue from the bottom and spitting it out, they stir up bottom sediments and uproot aquatic plants. This causes plants to die which in turn leads to fish and wildlife dying or leaving the marsh because there isn't enough food.

Removing the carp and completing the drawdown will improve the overall marsh health. During the drawdown period, some of the carp may not survive, however those left behind will not pose a hazard to the marsh or wildlife and will even provide food for scavengers such as turkey vultures, herring gulls and raccoons.

The drawdown will use new pumps installed by D.U.C. thanks to funding from D.U.C. and Ontario Power Generation. The pump will operate for approximately 4 weeks depending on site conditions, spring rains, etc. During this time, most of the water will be pumped out of the Marsh, except for a deeper portion in the southeast portion of the marsh.

Visitors will notice changing conditions within the marsh over the coming year. The changes are typical of natural conditions that would have been seen prior to human influences. Throughout the project, visitors will see an abundance of local and migrating waterfowl, shorebirds, raptors, songbirds and other wildlife to attract to the mudflats to feed and rest.

Spring 2016

• Pumping will begin in April.
• It will take approximately 4 weeks to pump the water out to ensure optimal conditions for re-vegetation.
• Starting in the spring, visitors will see very dry conditions known as mudflats attracting shorebirds in the spring and summer, right through to reflooding.
• Bob Mills Boardwalk and nature trail will remain closed to visitors and warning signage will be posted. Visitors can still access the Waterfront Trail (Ed Kroll Memorial Walkway).

Summer 2016

• The dry conditions are necessary to allow for natural germination of vegetation.
• Monitoring of vegetation growth and site conditions will occur.
• If necessary, additional pumping out after heavy rains or the pumping in of water to irrigate new growing vegetation may occur during this period.
• Improvements to the carp gate will be made to prevent the invasive species from accessing the marsh and to prevent vandalism.

 Fall 2016

• Re-flooding, either passively, if lake levels are sufficient or by pumping, will begin in late-September to bring water levels back to their seasonal average.
• Water levels will be kept shallow in order to prevent overwinter drowning of newly germinated aquatic plants. 

Spring 2017

• Water levels will begin to increase to a level that supports vegetation growth.

Fall 2017

• Water levels will increase to normal levels.

The process for drawing down water levels and re-flooding mimics natural low and high water conditions that occur seasonally over one year cycle. Low water conditions would be experienced from May to September. During this time, dormant seeds of aquatic plants will germinate, creating a green carpet of new growth across the marsh. Nutrients will be released from decaying old plant material. Ongoing habitat assessment and other monitoring will determine future management programs.

To undertake such a project the following approvals were obtained:

• Approval for Alterations to Shorelines and Watercourses - Central Lake Ontario Conservation

• Permit to Take Water - Ministry of the Environment

• Species at Risk Act - Ministry of Natural Resources

• Fisheries Act - Department of Fisheries and Oceans

Much of the eastern portion of the trail network has been closed to users since 2015 due to the condition of the boardwalk and bridge. There has been some habitat damage occurring where sections of the boardwalk are incomplete and users are trampling the understory seeking a drier path. The portion of the trail to the west of the berm and east of Farewell Creek leading to the Waterfront Trail was closed in 2010 due to damage from severe repeated spring flooding.

In addition, the area surrounding Bob Mills Boardwalk and nature trail is dominated by ash trees infested with Emerald Ash Borer (E.A.B.), an invasive insect that kills all ash trees. Once dead, ash trees are at risk of breaking or falling and can pose a danger to people. To ensure public safety, the boardwalk and trail will remain closed. Staff will be working to develop a management plan that will take into consideration the sensitive nature of the area.

Access to the Waterfront Trail (Ed Kroll Memorial Walkway) will remain open.

Misuse of the trail network and the site - including bypassing barricades, hunting, fishing, use of the highly sensitive barrier beach and the presence of dogs on/off leash - continues to be a problem.

Visitors are reminded that the marsh is a highly sensitive ecosystem given the rare species of birds and animals that make the marsh their home.

To ensure the continued enjoyment of the marsh by others and the health of the ecosystem, visitors are reminded to respect the following restrictions:

• No motorized vehicles (including snowmobiles, motor bikes and A.T.V.s)
• Please do not litter; use the containers
• No camping
• No excessive noise
• No hunting, fishing or boating
• No dogs (except on the paved Waterfront Trail)
• Stay out of restricted areas

Recently the City has begun to shift attention to managing the hazards posed by dead or dying trees infested with E.A.B. within woodlots and natural areas. Safety is the most important issue when determining when to remove an Ash tree since standing dead ash trees rapidly decompose and become hazardous within a few years after death. Trees within woodlots generally do not have to be removed unless they abut roads, private property, infrastructure, public pathways, and trails or otherwise pose a hazard.

Unfortunately the woodlot that surrounds Oshawa Second Marsh consists of approximately 95% ash trees. In 2016, it became clear that much of the ash tree canopy within the woodlot was dead or dying. To limit risks of falling trees and branches, access to the the nature trail network within the marsh was closed to public use. To limit risks along Colonel Sam Drive ash trees that are dead or dying and pose a hazard will be removed. The process will be selective cutting with limited impact on other vegetation and trees. Some trunks will be left standing and debris left on the ground for habitat. The City has consulted with both the Ministry of Natural Resources and Forestry and has obtained the necessary permit from C.L.O.C.A. to undertake the work. The City is working with its partners on future restoration work.

Through ownership of Oshawa Second Marsh, the City of Oshawa can ensure the responsible management and conservation of the marsh, provide the public with access and connection to the natural heritage features along the waterfront, as well as promote and maintain the social, cultural, economic, and environmental benefits associated with marsh.

By maintaining partnerships within the steering committee the City of Oshawa gains expertise and financial support in the successful management and rehabilitation of the marsh, ensures a healthy ecosystem which supports and reduces the impacts on municipal infrastructure and private property, and facilitates the sustainable management of the marsh into the future.

Restoration projects implemented by Ducks Unlimited Canada provide valuable improvements to the marsh including improved water quality, diversity and quality of wetland vegetation, quality of habitat for fish and wildlife, and recreation and nature appreciation opportunities. The infrastructure that they have put in place helps to keep out invasive carp and enables drawdowns to mimic pre-regulation water level fluctuations to promote a more natural, dynamic, healthy wetland.

Part of the mandate of Friends of Second Marsh is to enable the community to enjoy the natural heritage the wetland provides, while safeguarding it at the same time. Friends has developed and implemented the C.U.E. principle (Caring comes from Understanding comes from Experiencing) to nurture a sense of stewardship in members of the community. Opportunities to experience the wildlife area are provided in a number of ways including an extensive trail system for hiking, boardwalks to protect sensitive ecosystems, and lookouts to provide views of the wetland and surrounding area.

In order to provide people with some up close, hands-on experience with nature, a number of interactive programs, for both students and the public, are run at various times throughout the year. By necessity, part of the safeguarding effort also involves restricting certain activities in certain regions of the wildlife areas so as to protect sensitive ecosystems and wildlife species.

The monitoring work conducted by Central Lake Ontario Conservation and Environment Canada is essential to establish baseline conditions and assess the ecological conditions and overall health of the marsh. As a result of this work, there is a long-term dataset that enables the detection of changes over time and identification of trends. Monitoring helps to identify species at risk and species at risk habitat, and the presence and extent of invasive species. All of this information is used to determine restoration and management needs and supports education and stewardship initiatives. Ongoing monitoring allows for the assessment of the success of restoration actions.