LAKE SIMCOE

Ice fishing huts on the lake


Photo: J.Overton, K.Nicholls, M.Dickman and M.Foy

 
 

A. LOCATION

• South Central Ontario, Canada.
• 44:5-44:5N, 79:0-79:0W; 220 m above sea level.

B. DESCRIPTION

Lake Simcoe is southern Ontario's largest body of water excluding the Great Lakes. It serves as an important recreational resource for cottagers, anglers, campers and boaters. The population of the lake's basin was approximately 190,000 people in 1985. During the summer, there is an influx of 40,000 to 50,000 cottagers who occupy the 12,000 cottages surrounding the lake. Seventy percent of these cottagers rent or own boats and 35 marinas provide a moorage for the larger boats and yachts that can then access the Trent-Severn Canal System waterway which connects Lake Simcoe to Georgian Bay (via the Talbot River), Lake Huron, Lake Ontario and the Rideau Canal System which allows boats to reach the nation's capital and from there, the Ottawa River and the St. Lawrence.

Lake Simcoe's shoreline is composed of 55% cobble, 35% sand and 10% organic muck. The lake is located within the eastern portion of the Simcoe Lowlands where well-drained till soils predominate. Along the northern and western shores of the lake, the lowland consists of a narrow bouldery terrace confined by a low bluff. The southern and eastern shores are characterized by poorly drained sandy loams and large organic deposits located along the major river courses.

The lake's basin is drained by 35 tributary inflows with 5 major rivers draining approximately 60% of the watershed area. Annual mean discharges for the major river systems range from 2 to 4 m3 s-1. Peak flows range from 20 to 60 m3 s-1 and usually occur during the spring melt period.

The 1980 survey of Ontario sport anglers indicated that Lake Simcoe received more fishing effort than any other Ontario inland lake. During the winters of 1980-1983, 400,000 to 500,000 angler-hours were spent on the lake during each winter and 2,000 to 3,000 ice fishing huts were rented during each year. Lake Simcoe's proximity to major urban centres in the Oshawa-Toronto-Hamilton corridor is primarily responsible for the intense sport fishery that exists on the lake, which is located about 50 km from Toronto and is within an hour's drive for over half the population of Ontario.

Water quality in the lake has been affected by an excessive supply of phosphorus which has stimulated an over-growth of aquatic weeds and algae in certain parts of the lake. This results in critically low dissolved oxygen levels in deep portions of the lake which in turn has been linked to a decline in whitefish and lake trout populations within the lake. Beginning in 1975, lake shore municipalities. Ontario ministries and conservation authorities responsible for Lake Simcoe began working together to study the lake and in 1979 they published the Lake Simcoe-Couchiching Basin Environmental Strategy which evaluated measures designed to reduce phosphorus inputs to the lake. This strategy also established baselines for physical, chemical and biological data, some of which are described below. Considerable reductions in point source phosphorus loading have been achieved in recent years. Present-day inputs (1989) may be near acceptable levels (2, 3, 4, 5, 7, 8).
 

C. PHYSICAL DIMENSIONS (5, 9)

 

Surface area [km2]	725
Volume [km3]	11.6
Maximum depth [m]	41
Mean depth [m]	15
Water level	Regulated
Normal range of annual water level fluctuation [m]	0.4
Residence time [yr]	16
Catchment area [km2]	2,840

 

D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL

• Bathymetric map: Fig. NAM-42-01.
• Names of main islands: Georgina, Thorah, Snake, and Fox (1).
• Number of outflowing rivers and channels (name)

1 (Atherly Narrows, mean flux 37.1 m3 s-1)(5).
• Others

Number of inflowing rivers and channels (name) 3 (Talbot R., 4.35 m3 s-1), (Holland R., 3.9 m3 s-1) and (Pefferlaw Brook, 3.78 m3 s-1)(5).

D2 CLIMATIC

• Climatic data at Orillia, 1989 (6)

 

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Ann.
Mean temp. [deg C]	-9.3	-12	-2.8	4.6	13	16.2	20.4	19.2	14.6	7.4	2.3	-5.9	5.6
Precipitation [mm]	89	63	59	64	70	79	83	82	82	85	82	95	932

 

• Number of hours of bright sunshine (Toronto): 2,045 hr yr-1.
• Solar radiation (Toronto)[MJ m-2 day-1](6)

 

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Ann.
5.2	8.2	12.1	16.1	19.8	22	22	18.7	14	9.2	4.8	3.9	13

 

Fig. NAM-42-01
Bathymetric map (Q).

• Water temperature [deg C]

 

Station K45, 1984 

Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0	-	-	-	-	4.8	14.8	17.2	22.2	13.7	12.0	-	-
5	-	-	-	-	4.8	14.5	17.3	22.2	14.5	12.0	-	-
10	-	-	-	-	4.8	12.1	15.6	22.2	15.1	12.0	-	-
15	-	-	-	-	4.8	9.3	13.9	15.1	15.2	12.0	-	-
20	-	-	-	-	4.8	7.7	8.5	9.9	10.4	12.0	-	-
25	-	-	-	-	4.8	7.6	8.2	8.2	7.5	12.0	-	-
30	-	-	-	-	4.7	7.6	8.0	8.1	6.7	12.0	-	-

 

Fig. NAM-42-02
Water temperature at one meter above the lake bottom at 3 stations in Lake Simcoe (2).

• Freezing period: December-March.
• Mixing type: Dimictic.
• Supplementary note

A very gradually sloping thermocline forms between 13 and 20 m each summer and remains there from June to September.

E. LAKE WATER QUALITY

E1 TRANSPARENCY [m]

Mean Secchi depth at the open water location station K45 was 4.4 m for 1981- 1985. That for the same period in Cook Bay was 2.9 m (2)

Station K45, 1981-1985 

1981	1982	1983	1984	1985	Average
4.5	4.4	3.9	4.5	4.8	4.4

 

E2 pH (2)

 

Station K45, 1981-1982 

Depth [m]	1981	1982	Average
0	8.3	8.45	8.38
30	-	8.0	8.0

 

E3 SS [mg l-1]*(2)

 

Station K45, 1982-1985 

Depth [m]	1982	1983	1984	1985	Average
0	329.4	318.0	334.6	335.1	329.6
30	345.8	331.7	346.2	344.7	342.1

* Cond 25.

E4 DO [mg l-1](2)

 

Station K45, 1985 

Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
0	-	-	-	12.0	12.0	9.6	8.1	7.9	8.8	9.2	-	-
5	-	-	-	12.0	12.0	9.6	7.6	7.8	8.8	9.2	-	-
10	-	-	-	11.9	12.1	9.4	6.9	7.8	8.6	9.2	-	-
15	-	-	-	11.8	12.2	9.6	6.7	5.6	8.4	9.2	-	-
20	-	-	-	11.8	12.1	9.9	5.9	3.9	6.6	9.2	-	-
25	-	-	-	11.8	11.9	8.9	4.9	3.7	1.4	9.2	-	-
30	-	-	-	11.8	11.8	8.8	2.4	3.7	0.9	8.9	-	-

 

Fig. NAM-42-03
Dissolved oxygen, transparency [m] and temperature profile [deg C] at Station K45, 1980 (11, 12).

E6 CHLOROPHYLL CONCENTRATION [mg l-1](2)

 

1981	1982	1983	1984	1985	Average
2.1	1.6	1.6	2.2	2.6	2.02

 

E7 NITROGEN CONCENTRATION

• NO2-N, NO3-N, NH4-N and Total Kjeldahl-N [mg l-1]

 

Depth [m]	NO2		NO3		NH4		TKN
	0	30	0	30	0	30	0	30
1982	0.005	0.015	0.045	0.135	0.039	0.015	0.39	0.40
1983	0.002	0.007	0.009	0.072	0.021	0.005	0.40	0.36
1984	0.002	0.003	0.041	0.082	0.074	0.012	0.62	0.37
1985	0.002	0.007	0.028	0.113	0.069	0.075	0.51	0.48
Average	0.003	0.008	0.031	0.101	0.051	0.027	0.46	0.40

 

Fig. NAM-42-04
Inorganic nitrogen concentrations measured 1 m above the bottom.

E8 PHOSPHORUS CONCENTRATION

• PO4-P and Total-P [mg l-1]

 

Depth [m]	PO4		Total unfiltered P
	0	30	0	30
1982	0.003	0.009	0.012	0.031
1983	0.003	0.007	0.021	0.030
1984	0.002	0.010	0.017	0.023
1985	0.002	0.008	0.020	0.025
Average	0.0027	0.009	0.017	0.027

 

Fig. NAM-42-05
Euphotic zone total phosphorus concentrations at stations C1, CS and C9 in Cook Bay and in the Holland River, 1980 (11).

E10 PAST TRENDS

The levels of dissolved oxygen in the deeper basins of the lake began falling in the 1960's and improvements were noted in the 1980's following the implementation of phosphorus abatement strategies (12).

F. BIOLOGICAL FEATURES

1971-1979

F1 FLORA (9)

• Emerged macrophytes: Typha latifolia, Typha angustifolia, Scirpus spp.
• Floating macrophytes: Lemna minor, Wolffia sp.
• Submerged macrophytes

Potamogeton pectinatus, Elodea canadensis, Myriophyllum spicatum.
• Phytoplankton

Ceratium hirundinella, Stephanodiscus hantzschia, S. astreaea, Melosira granulata, M. ambigua, and Cryptomonas spp. are the dominant taxa at most stations in Lake Simcoe. During late summer, Anabaena flos-aquae forms dense surface blooms reaching densities of 0.06 mm3 l-1 in Cook Bay which is the most eutrophic part of the lake (2). Dinobryon, Mallomonas, Scenedesmus, Pediastrum, Aphanizomenon, Coelosphaerium, Lyngbya, Oscillatoria, Euglena, Trachelomonas and Phacus never reached more than 5% of the total annual (May- October) algal biomass (11).
• Benthic algae: Cladophora, Dichtomosiphon tuberosus, Chara.

Fig. NAM-42-06
Seasonal distribution of phytoplankton density for the 7 most abundant classes at stations K45 and E51, 1980 (2).

F2 FAUNA

• Zooplankton

The rotifers were not abundant. Surface tows in the fall (October) of 1982 revealed Karatella cochlearis, K. quadrata, Syncheata, sp., Brachionus spp.
and Polyarthra. sp. (15). The common copepods were Senecella calanoides, Epischura lacustris and Diaptomus sicilis (calanoid copepods); Cyclops bicuspidatus thomasi and Mesocyclops edax (cyclopoid copepods); and Daphnia galeata mendotae and Bosmina coregoni coregoni (dadocerans)(15).
• Benthos

Micropsectra sp., Phanopsectra sp. (chironomids); Pisidium conventus and P.
casertanum (clams).
• Fish (8)

Lake trout* (Salvelinus namaycush), Large mouth bass* (Micropterus salmoides), small mouth bass* (Micropterus dolomieui), northern pike (Esox lusius), whitefish (Coregonus clupeaformis), white sucker (Catosomus commersoni), American smelt (Osmerus mordax) walleye or yellow pickerel (Stizostedion vitreum), ling or burbot (Lota lota), rock bass (Ambloplites rupestris), yellow perch (Perca flavescens).
* Economically important.

F4 BIOMASS (11)

• Phytoplankton [mm3 l-1]

 

Station K45, 1981 

30 Apr	20 May	12 Jun	1 Jul	12 Aug	23 Sep	14 Oct
0.23	0.42	0.79	0.38	0.25	0.57	0.38

 

F7 NOTES ON THE REMARKABLE CHANGES OF BIOTA IN THE LAKE IN RECENT YEARS (8)

Whitefish populations are decreasing and there is some year-class inferred evidence that the whitefish population is not reproducing.

G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA (15)

 

1982 

	Area [km2]	[%]
Natural landscape	-	37
- Woody vegetation	158
Agricultural land	-	61
- Crop field	984
- Pasture land	214
Others	-	2
Total	1,356	100

 

• Types of important forest: Red pine.
• Main kinds of crops

Hay, corn, small grains (wheat, oat, barley and rye) and row crops as onion and carrot.
• Levels of fertilizer application on crop fields: Moderate.
• Trends of changes in land use in recent years (16)

Housing developments have increased most rapidly with agricultural developments next.

G2 INDUSTRIES IN THE CATCHMENT AREA AND THE LAKE (16)

 

1986 

	Gross product during the year (Canadian $=US$)	No. of establishments	Main products or major industries
Primary industry
- Crop production	127,000,000	2,500	Vegetables, grain, milk, cheese, beef and poultry
- Animal husbandry
- Fisheries*	20,000,000		Whitefish
- Others			Sport fishery*

* Information from R. Desjardin, OMNR Biologist, Central Region.

• Numbers of domestic animals in the catchment area

Cattle 63,000, sheep 11,500, swine 62,000, poultry 910,000, milk cows 20,000, horses 4,800.

G3 POPULATION IN THE CATCHMENT AREA (16)

 

1985 

	Population	Population density [km-2]	Major cities (population)
Urban	87,095*1	1,371	Barrie Newmarket
Rural	132,905	47
Total	220,000*2	76*3

*1 All cities with a population greater than 30,000.
*2 This figure does not include the 50,000 seasonal residents of the cottages in the catchment area.
*3 This figure would increase to 93òÓ5 km-2 if seasonal residents were included.

H. LAKE UTILIZATION

H1 LAKE UTILIZATION (2)

Source of water, sightseeing and tourism (no. of visitors in 1985: 50,000), recreation (swimming, sport-fishing and yachting) and fisheries.

H2 THE LAKE AS WATER RESOURCE

 

	Use rate* [1,000 m3 day-1]
Domestic
- Brock Township	7.27
- Mara Township	4.0
- Georgia Township	4.56

* Capacity of Plant.

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS

I1 ENHANCED SILTATION

• Extent of damage: Serious.

I2 TOXIC CONTAMINATION

• Present status: Detected but not serious.

Mercury levels in L. Simcoe fish by species and size (from "Guide to Eating Ontario Sport Fish," 1978).

 

Species	Fish size [cm]
	15	15-20	20-25	25-30	30-36	36-46	46-56	56-66	66-76	76
Large mouth bass	-	A	A	A	A	A	B	-	-	-
Small mouth bass	-	A	A	A	A	B	B	-	-	-
Yellow perch	A	A	A	A	A	-	-	-	-	-
Northern pike	-	-	-	A	A	A	A	A	A	A
Walleye	-	-	-	A	A	A	B	B	C	D
Lake trout	-	-	-	-	A	A	A	A	A	B
White sucker	-	-	-	-	A	A	A	-	-	-
Whitefish	-	-	-	A	A	A	A	-	-	-
Rock bass	-	A	A	A	A	-	-	-	-	-
Ling	-	-	-	-	-	-	-	A	B	B

Key to mercury levels [ppm]:
A: <0.5
B: 0.5-1.0
C: 1.0-1.5
D: >1.5
-: projections not made for this size class.
Fig. NAM-42-07 (14)
Spatial distribution of mercury in the surface sediments of the lake.

• Past trends (11)

Mercury concentration in fish collected in the lake.

 

Species	Year	No. of fish	Hg concentration [ppm]			Length of fish [cm]
			Mean	Min.	Max.	Mean	Min.	Max.
Walleye (Pickerel)	1970	22	0.27	0.07	0.96	51.9	30.7	75.2
	1971	12	0.55	0.18	2.04	53.5	30.0	71.6
	1975	15	0.73	0.15	1.28	60.7	48.0	74.0
	1976	50	0.98	0.18	1.70	66.2	36.6	80.1
	1977	27	0.60	0.10	1.60	53.8	29.0	75.0
Lake trout	1970	20	0.39	0.16	0.58	72.5	54.1	82.8
	1975	16	0.24	0.13	0.39	62.3	55.0	71.0
	1976	12	0.35	0.18	0.56	69.9	57.2	85.3
	1977	20	0.48	0.20	0.93	66.6	49.5	87.0
Whitefish	1915*1	6	2.4*2	1.4*2	4.9*2	38.0	35.4	44.5
	1928*1	6	0.08	0.06	0.11	39.9	36.8	42.3
	1952*1	10	0.06	0.05	0.09	19.3	17.5	23.3
	1970	11	0.06	0.04	0.08	44.3	35.6	49.0
	1971	12	0.04	0.03	0.07	43.8	40.4	47.7
	1975	13	0.03	0.02	0.05	46.9	44.0	51.0
	1977	20	0.03	0.01	0.07	52.2	50.8	54.5
Large mouth bass	1971	12	0.25	0.14	0.50	30.8	19.3	42.2
Small mouth bass	1970	24	0.48	0.17	1.44	32.1	22.6	41.4
	1971	12	0.27	0.13	0.82	31.1	19.3	48.3
	1975	10	0.13	0.09	0.18	29.1	19.0	34.5
	1977	30	0.25	0.06	0.93	29.3	19.4	43.5
Cisco	1928*1	8	0.16	0.11	0.21	25.3	20.7	29.2
	1952*1	9	0.16	0.13	0.19	20.0	18.3	21.3
	1969*1	15	0.14	0.09	0.19	26.0	23.0	29.1
	1970	9	0.06	0.05	0.08	23.2	22.5	24.5
	1977	26	0.13	0.09	0.17	32.8	26.8	40.3
Rainbow smelt	1970	10	0.08	0.05	0.11	20.9	16.8	24.9
Emerald shiner	1971	4	0.08	0.06	0.11	7.6	5.1	10.0
Rock bass	1952*1	3	0.20	0.18	0.24	22.2	21.7	22.7
	1970	12	0.14	0.10	0.24	17.4	13.5	21.3
	1975	10	0.16	0.08	0.25	21.5	17.0	25.0
Yellow perch	1952*1	4	0.12	0.10	0.13	14.5	13.4	15.5
	1967*1	4	0.29	0.19	0.36	17.5	15.8	21.1
	1970	15	0.17	0.10	0.27	25.6	20.1	32.5
	1971	12	0.30	0.15	0.80	25.8	20.6	31.8
	1975	12	0.21	0.06	0.49	23.8	14.0	30.0
	1977	22	0.23	0.07	0.42	24.7	12.0	31.0
Northern pike	1967*1	2	0.13	0.12	0.14	43.4	-	-
	1971	12	0.19	0.12	0.44	69.8	54.9	96.5
	1975	3	0.16	0.05	0.31	63.0	43.0	86.0
	1977	22	0.20	0.07	0.47	67.4	51.2 105.0
Ling (burbot)	1970	10	0.39	0.14	0.55	69.8	33.0	81.3
	1975	5	0.53	0.45	0.65	76.8	70.O	86.0
	1977	15	0.44	0.15	0.98	59.4	43.7	79.0
White sucker	1952	4	0.04	0.03	0.05	30.6	23.8	35.9
	1970	12	0.17	0.09	0.23	43.0	38.4	46.5
	1971	12	0.09	0.05	0.14	41.4	35.0	48.0
	1975	6	0.14	0.07	0.19	43.5	39.0	46.0

*1 Specimens from Royal Ontario Museum.
*2 Mercury contamination of preserving fluid suspected.

I3 EUTROPHICATION

• Nuisance caused by eutrophication (8)

Unusual algal bloom In 1971 a surface bloom of Anabaena flos-aquae was observed for the first time. This continued in the late summer and early fall of subsequent years. In 1983, the two main sewage sources were diverted from Lake Simcoe and it is believed that this will reduce by half, the algal biomass by 1990.
Cladophora is the dominant on-shore alga on the cobblestone beach just east of the Orilla sewage treatment plant. Cladophora reaches its highest densities in June, July and August at a depth of 0.5-1.0 m.
• Supplementary notes (15)

On August 1,1970, federal regulations reduced the phosphorus content as P2O5 in laundry detergents from approximately 50% to 20%. Additional regulations which were proclaimed by the federal government of Canada on January 1, 1973 further decreased the phosphorus content to 5%.

I4 ACIDIFICATION

• Extent of damage: None.

J. WASTEWATER TREATMENTS

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA

(d) Measurable discharge of pollution load into the lake with limited wastewater treatment.

J3 SANITARY FACILITIES AND SEWERAGE (19)

• Municipal wastewater treatment systems

No. of secondary treatment systems: 1 (conventional method with phosphorus removal).
No. of other types: 1 (conventional lagoon with seasonal phosphorus removal).

K. IMPROVEMENT WORKS IN THE LAKE

K1 RESTORATION

Sewage diversion began in 1983

K2 AERATION (10)

Aeration studies in the deep basins have been considered.

L. DEVELOPMENT PLANS

The number of marinas and housing developments continue to expand.

M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS

M1 NATIONAL AND LOCAL LAWS CONCERNED

• Names of the laws (the year of legislation)
1. Canada Fisheries Act
2. Canada Navigable Waters Protection Act
3. Canada Water Act
4. Canada Environmental Contaminants Act
• Responsible authorities
1. Ontario Ministry of the Environment (0. M. E.)
2. Ontario Ministry of Natural Resources (O. M. N. R.)
3. Environment Canada) Main items of control
• Main items of control
1. Municipal and industrial discharges of wastes and waste waters
2. Consumption withdrawal
3. Sport and commercial fishery
4. Habitat protection and water related resources

M2 INSTITUTIONAL MEASURES

1. Environment Ontario, Central Region, and Aquatic Biology and River Systems Sections
2. Lake Simcoe Region Conservation Authority
3. Ontario Ministry of Natural Resources- Central Region
4. Ministry of Tourism and Recreation, Ontario

M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES

1. Fisheries Research Section, Fisheries Branch, Ontario Ministry of Natural Resources
2. Water Resources Branch, Ontario Ministry of the Environment

N. SOURCES OF DATA

17. Questionnaire filled by Drs. K. Nicholls, J. Overton (Aquatic Biology Section, Ontario Ministry of the Environment), M. Foy (Water Quality Branch, O. M. E.) and M. Dickman (Biological Sciences Department, Brock University).
1. Surveys and Mapping Branch, Department of Mines and Technical Services, 1:50,000 scale maps. Government of Canada.
2. MOE (1985) Lake Simcoe Environmental Management Strategy (OMAF, OMOE and OMNR); Final report and recommendations of the steering committee. Suite 700, 150 Ferrand Dr. Don Mills, Ont. M3C 3C3.
3. Garlaw, J. & Trumbly, B. (Central Region, Parks Canada) Trent-Severn Waterways Recreational Boating (705-742 9267).
4. MOE (1979) The Lake Simcoe-Couching Basin Environmental Strategy.
5. McCurry, P. Water Levels and Monthly Stream Flow. Water Survey of Canada (519-821 0110).
6. Environment Canada. Canadian Climate Normals, 1951-1980. Atmospheric Environment Service.
7. Humber, J. (1985) Lake Simcoe Environmental Management Strategy, Water Quality Characteristics of Lake Simcoe (1980-1984). Technical report #B.1. Suite 700, 150 Ferrand Dr. Don Mills, Ont. M3C 3C3.
8. MOE (1979) Lake Simcoe-Couching Basin Environmental Strategy. Suite 700, 150 Ferrand Dr. Don Mills, Ont. M3C 3C3.
9. MOE (1975) Lake Simcoe Basin: A Water Quality and Use Study. Ontario Ministry of the Environment. Suite 700, 150 Ferrand Dr. Don Mills, Ont.

M3C 3C3.
10. Lake Simcoe Conservation Authority (1987) To Determine the Predictability of Hypolimnetic Dissolved Oxygen Depletion in Lake Simcoe as Related to Water Temperature, Nutrient Loading and Other Limnological Variables. Report prepared by W. J. Snodgrass and J. Holubeshen of Beak Consultants Ltd.
11. MOE (1982) Water Quality Characteristics of Lake Simcoe 1980. Ontario Ministry of the Environment, Suite 700, 150 Ferrand Dr. Don Mills, Ont.

M3C 3C3.
12. Wilson, J. P. (1987) The use of statistical models to document environmental change in the Lake Simcoe Basin. Ph. D Thesis, University of Toronto, Dept. of Geography.
13. Lake Simcoe Environmental Management Strategy Reports. A (Land sub- group) 5 reports and B (Lake sub-group) 4 reports.
14. 0. M. E. (1978) Mercury in the Lake Simcoe Aquatic Environment. Water Resources. Planning Unit, Planning and Co-ordination Section, Water Resources Branch.
15. Dickman, M. (1982) Limnology class (Biol. 363) survey of the macrophytes and zooplankton of Lake Simcoe. (unpublished data).
16. Michalski, M. F. P., Johnson, M. G. & Veal, D. M. (1973) Muskoka Lakes Water Quality Evaluation: 0. M. E. Report No. 3, Eutrophication of the Muskoka Lakes. Brock University Library DOC, CA2, On, EV, M74, No. 3.
17. Ontario Ministry of Natural Resources (1978) Guide to Eating Ontario Sport Fish.
18. Rawson, D. F. (1930) The Bottom Fauna of Lake Simcoe and Its Role in the Ecology of the Lake. Univ. of Toronto Studies. Publication No. 40 of the Ontario Fisheries Research Laboratory. 183 pp. and 5 plates.
19. Ontario Ministry of the Environment (1981) Municipal Water and Wastewater Works in Ontario.
20. Evans, D. O., Houston, J. J. & Meredith, G. N. (1988) Status of the Lake Simcoe whitefish, Coregonus clupeaformis, in Canada. Canadian Field Naturalist, 102: 103-113.
21. MacCrimmon, H. R. & Skoke, E. (1970) The Fisheries of Lake Simcoe. Ontario Department of Lands and Forests. Toronto, Ontario. 140 pp.
22. Johnson, M. G. & Nicholls, K. H. (1988) Temporal and spatial trends in metal loads to sediments of Lake Simcoe, Ontario. Water, Air and Soil Pollution, 39: 337-354.