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Second Marsh

Turtle

Oshawa's Second Marsh is a 137 hectare provincially significant coastal wetland that provides considerable habitat for wetland dependent wildlife. It is particularly known as an important breeding and migratory stopover area for birds.

The Oshawa Second Marsh watershed is highly influenced by human activity and its surrounding land use. Watershed inputs, stream bank erosion, invasive species, and regulated water levels on Lake Ontario, impact water quality and quantity within the marsh. The changing nature of the wetland due to these external influences requires ongoing management and monitoring to ensure the health of the ecosystem.

History

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.

Restoration and Protection Projects

To preserve the health of Second Marsh, the Marsh Management Steering Committee have joined forces to undertake restoration and protection projects at Oshawa's Second Marsh.

Since the City of Oshawa obtained ownership of Second Marsh in the 1990s, a number of successful restoration and rehabilitation projects resulted in an improvement of the health and diversity of the marsh. The most successful restoration project occurred in 2004 when water levels within the marsh were mechanically lowered (drawn down) and allowed to naturally recharge (flood). The drawdown was very successful in improving the overall health and diversity of the marsh.

Recent monitoring has begun to show the establishment and spread of several invasive species including Emerald Ash Borer, Common Carp, Goldfish, Common Reed, European frog-bit, and Flowering Rush.

Based on the results of ongoing monitoring the following projects will be undertaken in 2016 and 2017:

the drawing down of marsh water levels to improve water quality
the installation of signage and fences to restrict access to the trail network within Second Marsh to limit hazards associated with the potential of falling branches and trees infested by Emerald Ash Borer
the development of a plan to deal with ash trees infested by Emerald Ash Borer
ongoing management and monitoring of the wetland

Drawdown Updates

View the virtual tour of Second Marsh. The tour shows perspectives of the marsh taken late June. Check out the photo gallery below and read the summary of the transformation of Second Marsh.

Photo Gallery: Second Marsh will appear here on the public site.

April 2016

The slow pumping of water out of the marsh has begun with each partner organization taking a week to check the pumping system and the water level. The process is gradual but so far the new pumps are working great and the weather has been good.

May 2016

The water level is almost completely down exposing the floor of the marsh (mudflats) normally covered by water. Some pockets of water remain in deeper areas of the marsh that will provide refuge habitat for various species including fish, reptiles and amphibians and invertebrates. The pumps were turned off during the 6th week of pumping because the water levels are almost completely down. This is great progress. Thanks to all the volunteers from C.L.O.C.A., Ducks Unlimited and Friends of Second Marsh who are assisting with the daily monitoring. Volunteers will continue to monitor to ensure that major rain events do not impact the current condition. As the mudflats warm and dry you will start to see the seed bed germinate. This is also a great opportunity to watch for shorebirds.

June 2016

The water levels are at a point where the pumps are being turned on every few days to drain water draining from the higher points. If it rains the pumps will be turned on to manage water that may accumulate during the rain event. With all this sunshine we should start to see vegetation start to germinate in the exposed mudflats. There is lots of activity in the marsh with birds feeding and turtles nesting. Please remember to take care when walking and enjoying the marsh, it is environmentally sensitive.

July 2016

What a difference a few weeks makes. The hot dry summer has helped to dry up the remaining water within the marsh. The exposed mud flats are dry and cracked but if you look close enough you will see the signs of seed germination thanks to the sunshine. Native wetland plants like cattails, soft stem bulrush, arrowhead and smartweed are beginning to sprout. The renewed vegetation enhances the biodiversity of the marsh and will help to maintain a healthy wetland ecosystem for wildlife and migrating birds. In addition to the abundant plant life the exposed mudflat has also attracted a number of rarely seen bird species including sandpipers and other shorebirds that migrate from the Arctic including lesser yellowlegs, Wilson's phalarope, least sandpiper, American avocet and the endangered piping plover.

August 2016

The marsh has seen an incredible transformation over the last few months. The vegetation has grown considerably and is now a lush carpet of native wetland plants. Some plants, including the smartweed pictured in the photo gallery, has grown to just over 7 feet tall.

Visitors who are used to entering the marsh along the trail and maintenance road will notice that access has been restricted. This is due to the hazards caused by Emerald Ash Borer infestation. Emerald Ash Borer is an invasive insect that kills all ash species. Since the majority of tree species within the marsh are ash the impacts on the tree canopy will be significant leading to a change in the natural conditions within the woodlot and nature of the trail network. As the trees die they become hazardous to trail users. To eliminate the hazards of falling trees and branches the City has closed access to this area installing signage and fencing. For your safety please respect the signage. Visitors can watch the progress of the drawdown by visiting the McLaughlin Bay Wildlife Reserve where they can access the viewing tower from the western parking lot located at the Headquarters of General Motors of Canada Limited off of Colonel Sam Drive.

September 2016

Ducks Unlimited explored Second Marsh from the air using an unmanned aerial vehicle or drone to capture high-resolution
imagery and High Definition video. The drone will also help to develop terrain models.

Fall 2016

Ducks Unlimited worked hard through the Fall to do repair work to the fishway. Ducks Unlimited is continuing to monitor water levels and hope to have 6-12 inches of water throughout the basin this spring.

Winter 2017

You will begin to see changes in the woodlot that surrounds the marsh. Unfortunately the woodlot that surrounds Oshawa Second Marsh consists of 95% ash trees. In 2015 it was identified that much of the woodlot consisting of mostly ash trees had been infested with Emerald Ash Borer. Emerald Ash Borer (E.A.B.) has had a devastating impact on our street trees and woodlots across the City. Once infested with E.A.B. the tree quickly becomes brittle and hazardous to public safety.

To limit risks of falling trees and branches, access to the the nature trail network within the marsh was closed to public use in 2016. This January the City will begin removing ash trees that are dead or dying within the hazardous area adjacent to Colonel Sam Drive. 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.

Ongoing Monitoring Program

Monitoring of Second Marsh will continue on an ongoing basis and be reported as part of the Durham Region Coastal Wetland Monitoring Project (D.R.C.W.M.P.). The D.R.C.W.M.P., which monitors water quality, fish and bird community, frog/toad community, submerged aquatic vegetation and aquatic macro-invertebrates within the marsh, will continue to provide valuable information on the condition and health of the marsh. Monitoring through the D.R.C.W.M.P. will allow for continued adaptive management of Second Marsh.

Frequently Asked Questions

What are the benefits of the drawdown?

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.

By mimicking natural conditions the process ensures wetlands continue to be healthy and productive long into the future. Once the vegetation is established re-flooding occurs to bring water levels back to their seasonal average. This is perfect timing for the fall migration of many waterfowl, shorebirds, raptors and songbirds as they look for staging areas like Second Marsh to feed and rest.

Why does the water need to be drained from the marsh?

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.

What will happen to the fish and aquatic life in the marsh during a drawdown?

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.

How will the water be removed?

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.

What changes can we expect to see at Second Marsh during the drawdown?

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.

How long does it take for water levels to be lowered?

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.

What approvals are needed to do this work?

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

Why are the nature trails closed?

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.

What can I do to help keep the marsh healthy?

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

Why is the City removing trees?

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.

Partnerships

The Marsh Management Steering Committee is composed of members from the City of Oshawa, Ducks Unlimited Canada, the Friends of Second Marsh, Central Lake Ontario Conservation and Environment Canada. There are also many volunteers without whose help many of the monitoring, stewardship and restoration initiatives would not be possible.

City of Oshawa

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.

Ducks Unlimited Canada

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.

Friends of Second Marsh

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.

Central Lake Ontario Conservation

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.