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Ottawa Caves & Discoveries

“There is no question the Ottawa Valley caves are the longest underwater caves in Canada (so far), but they are also significant Canadian caves in their own right,” said Dr. David Sawatzky, a retired Canadian Armed Forces lieutenant-colonel, doctor, diver and expert on cave diving, who spent over 15 years mapping the Ottawa River caves.

“I must say, having explored the Ottawa Valley landscape for some 45 years both in a professional and private capacity, I’ve never seen a place like this and I think it is an extraordinary and important conservation opportunity,” said Ottawa Riverkeeper co-founder Daniel Brunton.

The Ottawa’s Wrap Around the Westmeath Peninsula

From the little-used Provincial Park in the west to the exciting whitewater of the Rocher Fendu Rapids in the east, the river’s large sweep around the Westmeath Peninsula provides both magnificent beauty and awesome power. New research is bringing new information about the area to light.

The Westmeath Provincial Park:  See Naturalist Guide  and Westmeath Provincial Park, Ottawa Citizen, July 2013.   In the late 1980’s a site and management plan was set forth for the Westmeath Park with citizen input.  These development plans have not gone further and this over 600 ha. wonderful natural environment park remains almost an unknown asset to the area with little usage.  To view Plan click on: Westmeath Provincial Park Management Plan

The Longest Underwater Caves in Canada

Ottawa Underwater Caves at the Westmeath Peninsula

“Gervais Caves” and “Three Island Caves” of the Ottawa River

Reid & Fitzpatrick Islands sit in the Ottawa River Channel with a huge cave complex beneath

The largest underwater cave system in Canada is in the Westmeath Peninsula under the Ottawa River islands and channels. The cave systems’ length is 10,674 m. and the systems’ deepest point is  11.6 m. beneath the surface.

‘I’m not afraid of dying’: Cave diver’s latest obsession is underneath the Ottawa River

Jill Heinerth has charted some of the world’s deepest underwater caves in Florida and Mexico. She’s now exploring closer to home. Author of the article: Andrew Duffy Published Nov 03, 2023 Ottawa Citizen..  

In the Fall of 1995 the local weekly newspaper of the Westmeath Peninsula, “The Cobden Sun”, covered the cave dives of Dr. David Sawatzky  and diving partner Ric Browning, as they explored the system of underwater caves in the Paquette Rapids area of the Ottawa River’s channel, north of the Village of Westmeath, ON.

At the time, studies were underway by the then Ministry of the Environment and Energy, to chose candidate areas for the location of landfill dumps. Editor Marie Zettler’s editorial that week was entitled “Ludicrous”, as indeed it was to contemplate locating a dump over the permeable  limestone bedrock of the Peninsula.

NOTE:  A MUST-READ BACKGROUND PIECE:  Marie Zettler’s Cobden Sun in-depth article; please open the PDF:  october-1995-ottawa-river-caves-cobden-sun, kindly submitted here by Linda Bromley.

The two major caves systems are: 1. Three Island Cave; 2. Gervais Cave. 

“The labyrinth measures more than 10 kilometres in length under several islands throughout the Ottawa River, and includes a four-kilometre section on the Ontario side of the river known as the Gervais Caves.

Three Island Cave (part on Quebec side) made #7 and Gervais Cave (part on Ontario side) made #13 on the List of Canada’s 100 longest Caves. 

Ottawa River Map of Caves drawn by David Sawatzky

«The caves lie under a large peninsula on the Prov. Ontario, under several islands, and under the Ottawa River within the Prov. Quebec. There are two major sinks and at least five major resurgences.»

Dr. David Sawatzsky, a former military physician, and many volunteers helped map these underwater caves. These explorer-adventurers scuba diving into these treacherous caves have written up their findings. Three papers from the 1990s:  OR Canadian Caver 1990, and OR Canadian Caver 1997, and OR Canadian Caver 1998.

The Ottawa Citizen newspaper interviewed Dr. Sawatsky in 2006: Caveman of the Ottawa March 2006.  More recently the newspaper ran this  article  by Tom Spears: Nature Conservancy.

The NCC’s website has pictures of both a sinkhole and a spring plus a full description of the ecological significance of this area of Canada CLICK on their logo to the right.

Gervais Caves, Ottawa River

Ottawa River Caves to be bought by Nature Conservancy

Arnprior Chronicle-Guide – November 27, 2014

Did you know that Ottawa River Valley is home to the longest underwater cave system in Canada?

Beneath the surface of the Ottawa River lies a subterranean wonderland seldom seen by the human eye – the Ottawa River Caves. The labyrinth measures more than 10 kilometres in length under several islands throughout the Ottawa River, and includes a four-kilometre section on the Ontario side of the river known as the Gervais Caves.

The Nature Conservancy of Canada is currently in negotiations to buy a 75-acre (30-hectare) shoreline parcel that contains most of the entrances to the Ontario portion of this remarkable series of caves in the Westmeath area up river from Arnprior.

A not-for-profit land conservation organization, the Nature Conservancy of Canada, owners of the Gillies Grove, must raise the final $87,000 for this project by Jan. 5, and it is asking for the help of people, corporations and foundations to meet this goal.

The most important features of the property are the karst landscape and sinkholes associated with the Gervais property. Karst landforms are an important variant of landforms created by flowing water. Water is routed underground via solutional cave systems instead of flowing at the surface in normal river channels.

At least 13 of these sinkholes are connected to the Ottawa River through this extensive network of underwater caverns. Fish such as sturgeon, walleye and smallmouth bass can be found hiding in the nooks of the caves.

Above ground, the Gervais property is just as impressive. This site is full of life – home to over 135 native vascular plant species and a number of at-risk plant species, including the endangered butternut tree, the provincially-rare Hooker’s orchid, regionally-rare moonseed and Hitchcock’s sedge. The mature forest features exceptionally large examples of Eastern white cedar, including two trees over 90 centimetres in diameter that are many centuries old.

The Ottawa River supports a rich diversity of freshwater mussels and at least 13 species of mussels have been recorded in this area. Freshwater mussels filter bacteria, microscopic algae and organic material contained in the water, which improves water quality and contributes to the aquatic ecosystem.

The endangered and rare hickorynut freshwater mussel can be found in the Ottawa River and in order to filter food and consume nutrients, mussel larvae must attach to a fish, called a host. Hickorynuts attach to lake sturgeon to consume their nutrients from the fish’s body until they transform into juvenile mussels and fall off.

“Our conservation work is driven by leading edge science that helps us identify the most important places in Canada for protection. The Gervais property in Ottawa Valley is one of these places worth conserving,” said Nature Conservancy of Canada Ontario regional vice-president James Duncan.

“By investing in conservation we are ensuring that our natural world remains a home for wildlife, a haven for recreation and a vital resource that cleans the air we breathe and the water we drink.”

“I must say, having explored the Ottawa Valley landscape for some 45 years both in a professional and private capacity, I’ve never seen a place like this and I think it is an extraordinary and important conservation opportunity,” said Ottawa Riverkeeper co-founder Daniel Brunton.

Brunton conducted site assessments of the Gervais property as an independent ecological consultant.

“We spent a total of 752 hours underwater surveying the caves. There is no question the Ottawa Valley caves are the longest underwater caves in Canada (so far), but they are also significant Canadian caves in their own right,” said Dr. David Sawatzky, a retired Canadian Armed Forces lieutenant-colonel, doctor, diver and expert on cave diving, who spent over 15 years mapping the Ottawa River caves.

Ecologists say the caves are the highest priority conservation property in the Ottawa River Valley representing nationally significant earth and life science features, as the property supports nationally and provincially designated species at risk and regionally significant vegetation and flora.

Since 1962 the Nature Conservancy of Canada and its partners have helped to protect more than 2.7 million acres (over 1.1 million hectares) coast to coast, including 178,000 acres (72,034 hectares) in Ontario.

Two interesting blogs from the NCC site:

Cave diving in the Ottawa River, Canada, September 28, 2015, by  Australian diver Peter Buzzacott.

Exploring the remarkable Gervais Property November 26, 2014  by Ottawa Valley Naturalist Daniel Brunton.

Rare Hickorynut Mussel in its natural setting. Photo by Andre Martel, the Canadian Museum of Nature, 2014.

Plentiful But Rare Hickorynut Mussels

A short distance downstream at the western end of Lake Coulonge, (a widening of the Ottawa’s channel), sit islands off the Quebec shoreline named the Finlay Islands; an area well-known to local fishermen. Opposite on the Ontario side, a long sand spit  is a destination for boating families in summer. This deep channel held a surprise for researchers.

From the blog by André Martel, researcher, on the Canadian Museum of Nature website: The Rare Hickorynut Freshwater Mussel Finds a Haven in the Ottawa River   and Scuba Diving for Freshwater Mussels in the Ottawa River.

The Finlay Islands Ecological Reserve

27 July 2006 Map by land surveyor Denis Fiset. The 94 hectare Finlay Islands are flooded each spring and so have never been inhabited year round. It is now off-limits to visitors.

Lying in the Ottawa’s channel, as it widens to become Coulonge Lake, are the low-lying Finley Islands.  The Quebec provincial government has designated the Finlay Islands as an unique protected conservation area.

The field research done on the islands, by Quebec’s  Ministry of Sustainable Development, Environment and Parks , lists their characteristics. Since flora and fauna don’t pay attention to provincial boundaries, these species are found throughout the Ottawa River’s relatively wild shoreline, as it wraps around the Westmeath Peninsula.

This inventory of species is of benefit to highlight how many found here are considered to be in decline or endangered elsewhere. This section of the Ottawa’s course is still environmentally clean and highly valuable as natural habitat. Only authorized persons are allowed to enter the reserve.

Excerpt taken from quebec-startegy-for-protected-areas-finlay-islands-ecological-preserve, January 2007.


The ecological reserve status assigned to the Finlay Islands permanently ensures the protection of the biological diversity of land composed of well-preserved marshes and swamps, thick forest stands and dry beaches forming rare wildlife habitats. There are six species on the islands likely to be designated as threatened or vulnerable species, a number of indications of the presence of species of turtles and several species of amphibians and birds.

  1. Official toponym

The official toponym of the Chênaie-des-Îles-Finlay ecological reserve “Réserve écologique de laChênaie-des-Îles-Finlay” refers to the presence on the islands of a stand of bur oak (Quercus macrocarpa), a forest community extremely rare in Québec.

  1. Plan and description

2.1. Geographic location, boundaries and dimensions

The Chênaie-des-Îles-Finlay ecological reserve is located in the territory of Municipalité de Waltham, Municipalité régionale de comté de Pontiac, in the Outaouais administrative region, and consists of theparts of the Finlay islands in the Outaouais river at an elevation higher than 106.68 metres. The territory is designated as parts of islands 52 and 54 in reference to the cadastre of Canton de Waltham, registration division of Pontiac. In reference to the original survey, the territory forms part of the Outaouais river islands fronting Canton de Waltham.

The land in the reserve covers an area of approximately 94 hectares. It is located on the plan prepared on 27 July 2006 by land surveyor Denis Fiset which appears as Schedule 1.

2.2. Ecological overview

The ecological reserve forms part of the Ottawa Plain (provisional name) natural region which lies within the natural province of the St. Lawrence Lowlands.

2.2.1. Representative elements

Climate:  The land of the ecological reserve lies within the sugar maple–bitternut hickory bioclimatic domain. It is characterized by a moderate, subhumid climate with a long growing season. The average annual temperature is 4.5º , average annual precipitation is 1,065 millimetres and the average growing season is approximately 201 days.

Geology: The basement rocks of the Finlay islands are formed of Ordovician rocks including limestone, dolomite, mudrock and sandstone. The basement rocks have no influence on the soils or vegetation because they are covered by Quaternary fluviatile deposits of sand, gravel and clay. On the southern island (island 54), the wind is believed to have caused the deposits to shift to form an eolian deposit which then became colonized by vegetation.

Archaeology: There has been no archaeological work on the Finlay islands to date. The islands have enormous archaeological potential, however, because the Outaouais river is a major waterway which provided an east-west transportation link for generations of Amerindians. Archaeological research carried out in recent years has shown the potential of the Aux Allumettes island area slightly west of the Finlay islands. The archaeological sites that may be discovered in the area will be extremely fragile because they are generally close to the surface and as a result any disturbance of the soil could partially or completely destroy them. The ecological reserve will ensure their preservation.

Vegetation: Silver maple predominates on the fringe of the marshy areas of the Finlay islands where the soils are subject to seasonal flooding. Red ash (Fraxinus pennsylvanica), black ash (Fraxinus nigra), bur oak (Quercus macrocarpa) and American elm (Ulmus americana) are frequently found in these forest communities while the herbaceous layer is formed exclusively of sensitive fern (Onoclea sensibilis).

The silver maple stands give way to red oak stands slightly upslope on the sites which are not affected by annual flooding. The latter forest community is largely dominant, covering over three quarters of the Finlay islands. The stand of bur oak grows at the higher elevations on the Finlay islands. The main companion species in the oak stand are silver maple (Acer saccharinum) , yellow birch (Betula alleghaniensis), black ash (Fraxinus nigra), butternut (Juglans cineréa and basswood (Tilia americana).

Pine stands are found in the better-drained areas, including the eolian deposit. These stands are on the southern island (island 54). White pine (Pinus strobus), red pine (Pinus resinosa) and jack pine (Pinus banksiana) are the dominant species in these softwood forest communities along with a range of other pioneering species.

Fauna:  Various species of amphibians, birds and mammals have been inventoried on the Finlay islands.

Amphibians:  The inventories have confirmed the reproduction of the spring peeper, leopard frog and green frog. The presence of bull frogs, blue-spotted salamanders, American toads and gray treefrogs has also been observed.

Birds:  A total of 44 species of birds were observed on the Finlay islands while the inventories were being conducted: great blue heron, Canada goose, wood duck, American black duck, broad-winged hawk, red-tailed hawk, spotted sandpiper, great horned owl, ruby-throated hummingbird, belted kingfisher, yellow-bellied sapsucker, downy woodpecker, hairy woodpecker, northern flicker, eastern woodpecker, leastflycatcher, great crested flycatcher, eastern kingbird, yellow-throated vireo, warbling vireo, red-eyed vireo, blue jay, American crow, black-capped chickadee, red-breasted nuthatch, white-breasted nuthatch, veery, American robin, cedar waxwing, yellow warbler, yellow-rumped warbler, blackburnian warbler, pinewarbler, black-and-white warbler, American redstart, northern waterthrush, chipping sparrow, song sparrow, rose-breasted grosbeak, red-winged blackbird, common grackle, brown-headed cowbird, Baltimore oriole and American goldfinch.

Reptiles:  During field trips, no turtles or snakes were observed despite the presence of much ground material where snakes would normally be found. Turtle egg laying has been confirmed through the observation of five predated nests found on the dune on the southern island..

Mammals:  During inventories, red squirrel, beaver, muskrat and white-tailed deer were noted. Traces of white-tailed deer, muskrat, raccoon and black bear and feces of black bear, raccoon and white-tailed deer have also been noted, confirming the presence of at least six species of mammals, without counting the four species of small mammals observed: the short-tailed shrew, masked shrew, meadow jumping mouse and white-footed mouse.

2.2.2. Outstanding elements

At least five threatened or vulnerable plant species likely to be so designated have been inventoried on the Finlay islands to date. They are the white oak (Quercus alba), woolly hudsonia (Hudsonia tomentosa), Cyperus lupulinus subsp. macilentus, Sporobolus cryptandrus and Polygonella articulata. These plants have all been observed on the eolian dune deposit found on the southern island. The habitat of a sixth plant species that is part of the group of threatened or vulnerable species, Gratiola aurea, has also been ands.

The Finlay islands have considerable wildlife potential because of two species of turtle, namely the spiny softshell (Apalone spinifera), designated as threatened, and the map turtle (Graptemys geographica) which is found on the list of wildlife species likely to be threatened or vulnerable. The presence of the map turtle on the islands was reported in the 1990s.

2.3. Occupation and land uses 

The land is public property and no rights have been granted within the boundaries of the ecological reserve.

  1. Protection status 

Ecological reserve status will allow a representative sample of the large sand-covered islands characteristic of the Outaouais river to be integrally preserved on a permanent basis.

  1. Activities framework 

The activities carried on within the boundaries of the Chênaie-des-Îles-Finlay ecological reserve are governed by the Natural Heritage Conservation Act (R.S.Q., c. C-61.01). This conservation plan does not specify any prohibited activity other than those prohibited in the ecological reserves under the Act; nor does it authorize any other activities, or set any additional constraints on the activities permitted by the Act.

4.1. Prohibited activities 

General prohibitions under the Act

As provided in the Natural Heritage Conservation Act, the main activities prohibited in an area to which ecological reserve status has been assigned areforest management within the meaning of section 3 of the Forest Act (R.S.Q., c. F-4.1); mining, and gas or petroleum development; mining, gas and petroleum exploration, brine and underground reservoir exploration, prospecting, and digging or boring; the development of hydraulic resources and any production of energy on a commercial or industrial basis; hunting, trapping, fishing, earthwork and construction activities, agricultural, industrial or commercial activities and, generally, any activity likely to alter the state or nature of ecosystems.

No person may be in an ecological reserve, except for an inspection or for the carrying on of an activity authorized under the Act.

The Minister of Sustainable Development, Environment and Parks may, however, give written authorization on the conditions the Minister determines for any activity consistent with the purposes of an ecological reserve or with its management.

4.2. Activities governed by other statutes 

As stated above, certain activities consistent with the purposes of an ecological reserve, such as educational and scientific research or management activities may be conducted with the prior authorization of the Minister. That authorization from the Minister does not imply an exemption from the permit or authorization requirements of other statutes or regulations that apply to the ecological reserve.

4.3. Supervision of activities 

The Minister of Sustainable Development, Environment and Parks is responsible for the application of the Natural Heritage Conservation Act, and is therefore responsible for management of the ecological reserves established under that Act. The Minister supervises and monitors the measures in the Act as they relate to activities permitted in protected areas. In addition, the Minister has authority over the land which forms part of the domain of the State.

The Rocher Fendu Set of Rapids Known as the Best Whitewater Rapids in Eastern North America

Just to the east of the old Westmeath peninsula lies a turbulent zone showing  the Ottawa’s enormous might –  crashing and plunging through and over the Canadian Shield granite outcrops. The name Rocher Fendu means “split rock”. Within this zone, the waterway has been set aside as the Ottawa River Provincial Park.  Its powerful natural features of  spectacular white water and an untouched stretch of shoreline are the prime features of this waterway park. There are no visitor facilities in this waterway park. Visitors should be highly skilled in wilderness trekking and white-water rafting.  A number of whitewater rafting companies take thousands of visitors through this area every year; an adrenaline rush in the Whitewater Capital of Canada.

Taken from Whitewater News.ca.

Unknown numbers of drownings have taken place when men tried to run these rapids. The Algonquin and native peoples in earlier times, the explorers, adventurers, and voyageurs with their huge cargo canoes or the lumbermen taking the logs through to market; all have seen members perish. Today’s recreational adventurers have also lost their lives. A stone of remembrance has been erected at the river shore, close to the Fletcher’s Road unopened road allowance, to commemorate this heavy toll in the white water.

Inspiration Point Commemorative Stone, Roche Fendu Rapids, Township of Whitewater Region.

This is a beautiful, reflective spot to access on x-country skis or snowshoes in winter or to hike to in summer. Cheryl Spotswood who shot this photo and video finds it peaceful and lovely with only the sounds of the water. Open her beautiful video:  Ottawa River at Inspiration Point.

No matter what the era,  all who have seen the river know it drains  land blessed with nature’s beauty and demands mankind’s covenant of good stewardship.

Ottawa River Designated a Canadian Heritage River

In 2005 a very valuable piece of work on the history and heritage of the  Ottawa River was published in support of  the Ottawa River’s Nomination Under the Canadian Heritage Rivers System. This background study document is the most comprehensive ever made available on all aspects of the river. Any student or admirer of the Upper Ottawa Valley should read Chapter 2, in particular, as well the rest of this very important document.

If you never read another document about the Ottawa River, choose  this document as  the one you have taken time with. Its teams of writers and researchers have delivered it ALL.

The political support by all levels of government for the Canadian Heritage Rivers designation is now here and the Ottawa has  now been named for the honour of being a Heritage River.  The Government announcement:  Ottawa River Designated a Canadian Heritage River;       Ottawa River Finally Gets Heritage River Designation

The Ottawa Valley contains thousands of archaeological sites, few of which have been studied in detail. The ancient history of the Ottawa Valley below Mattawa reaches back to when the Ottawa River was quite literally forming, and spans across millennia. During this time, the peoples of the Ottawa Valley developed an intimate relationship with the land and distinct cultural characteristics, including a rich ceramic tradition. At the same time, artifacts from the Ottawa Valley demonstrate wide trade and communication networks that existed up to 6000 years ago, enabled by the Ottawa River and its tributaries. Despite the relative lack of archaeological research in the Ottawa Valley, the data which we do possess provides brief but exciting glimpses into ways of life which have been constantly changing and adapting. Page 17 Summary from Ottawa River’s Nomination Under the Canadian Heritage Rivers System.

The Ottawa River was the pathway for much of the early European exploration of North America, truly a gateway to the continent. In search of a passage to the Orient, French and later English and Scottish explorers began their travels by paddling up the Ottawa River, including the illustrious Jolliet, Mackenzie and Franklin. The most famous of French explorers in Canada will be remembered for their exploits and discoveries along the Ottawa River, beginning with Champlain and his emissaries who mapped and named many features of the river after founding Quebec in 1608. Other well-known figures in Canadian history including Nicollet, Radisson, La Vérendrye, Dulhut and De Troyes, traveled west along the Ottawa River to establish trade relationships with First Nations communities, laying the groundwork for the fur trade, a period that is central to the history of Canada. Page 52 Summary from Ottawa River’s Nomination Under the Canadian Heritage Rivers System.

Ottawa River Watershed Area

“The Ottawa River  (French name: Rivière des Outaouais), (Algonquin name: Kitchissippi), is a river in the Canadian provinces of Ontario and Quebec. For most of its length, it now defines the border between these two provinces. The river rises from its source in Lake Capimitchigama, in the Laurentian Mountains of central Quebec, and flows west to Lake Timiskaming. From there its route has been used to define the interprovincial border with Ontario.

From Lake Timiskaming, the river flows southeast to Ottawa and Gatineau, where it tumbles over the Chaudière Falls and further takes in the Rideau and Gatineau rivers.

The Ottawa River drains into the Lake of Two Mountains and the St. Lawrence River at Montreal. The river is 1,271 kilometers (790 mi) in length; it drains an area of 146,300 km2, 65% in Quebec and the rest in Ontario, with a mean discharge of 1,950 m3/s.” – From Wikipedia

The Ottawa River sits in the middle of the ranking of Canadian Rivers – click on chart to enlarge.

From Environment Canada’s website:   http://www.ec.gc.ca/eau-water/

According to Wikipedia;  this mighty heritage river boasts 16 major tributaries and flows past 45 towns and villages.  The peoples coming to settle its banks or cut the valuable timber of its hinterlands saw it as a means of transportation and commerce.  Now its value lies in recreation, tourism, and hydro generation.

This mighty system with a drainage basin twice the size of New Brunswick still has some way to go to get back to anywhere near a pristine condition. In July 2015, Globe & Mail columnist Roy MacGregor sets out the sorry state of the Ottawa River in The Story of the Ottawa River: Priceless and Precarious .

Visit the Ottawa River Regulation Planning Board website to see all the water flow information and management statistics and documents for this mighty river. This website also tracks the reservoir capacities along the system and gives readings of inflow and outflow.