Carrying Capacity

Lake Density

The District of Muskoka Official Plan requires that:

"C.3 The growth permitted by the Plan will be monitored and reviewed on a regular basis to ensure that the carrying capacity of the natural environment is not significantly affected in the adverse and the development pattern as identified in the Plan is achieved in a fiscally and socially sound manner."

The Official Plan of the Town of Huntsville has historically approached limits to lake
development in the form of minimum frontage requirements and minimum lot
size to control the effect of development on the recreational water quality.  These are important, but it needs to be remembered that these deal with lot size, not the overall density of the lake, and therefore only approximate the actual carrying capacity for a "typical" lake.  Unfortunately, this approximation is inadequate in the face of highly irregular or long, narrow lakes which have a very small surface area in comparison to their available shoreline length.

The current Official plan recognizes this shortfall.

"8.13.4 It is recognized that environmental, physical and social factors other than recreational water quality may also present limits to the amount of development that would be desirable for a particular lake. Therefore, the preparation of specific Lake Plans in consultation with waterfront communities is strongly encouraged to address these matters on an individual lake basis."

The size of the lake itself as a public area - in particular its surface area - is relevant for various recreational uses of the lake, just as the combination of the size of the lake and its depth (and hence the volume of the lake) is relevant for understanding the ability of the lake to absorb nutrients such as phosphorus from development on the shore.[1]A model developed by Ministry of Natural Resources called the "Lake Alert System" sets limits on lake development by considering, among other things, the surface area of the lake (or more accurately the net usable surface area[2] of the lake) in relation to the amount of development on the lake. The underlying principle is that during the summer residents are likely to use the lake for various purposes.  Hence there is a need to consider the volume of use that the lake as a whole can sustain (e.g., for canoeing, sailing, water-skiing, swimming, etc.). Locally, this recreational carrying capacity model has been adopted in the Official Plans of Magnetawan, Perry Township, Highlands East (Haliburton), and Sequin. It is referenced (without specific densities) in the Official Plans of Gravenhurst and Kearney.

This model takes the total surface area of the lake and subtracts from it the surface area that is within 30 metres of the shore.  For a small lake, 4 hectares per dwelling would be required, for a medium sized lake 2.4 hectares would be needed, and for a large lake, the proposal would set 1.6 hectares per dwelling as the minimum amount of usable surface area of the lake.  Obviously these limits are somewhat arbitrary "rules of thumb."  At the same time, it is easy to see that at some point any lake could become too crowded to sustain safe and pleasant recreation.

As shown in the next table, by this criterion, the four lakes covered by this lake plan are all over-developed.  These figures do not take into account the actual amount of usable surface area for boating purposes. Lake Waseosa, for example, contains three islands each of which, because of the added shoreline, reduces the amount of usable surface area for boating. 

These calculations also do not take into account the fact that one developed lot on Waseosa contains Camp Huronda. Camp Huronda counts as only one property but has hundreds of residents during the crucial summer months and is planning on increasing this number considerably over the next few years because of the number of diabetic children who want to attend the camp has increased over the years and the camp is the only permanent camp for diabetic children in Ontario. Furthermore, Camp Huronda provides an important opportunity for the personal development of these children by providing an environment where they can participate in the normal outdoor activities enjoyed by other children under the supervision of professionals trained to accommodate their needs. A key factor in the success of this camp is the pastoral setting of Lake Waseosa. As these children learn to sail and canoe on this relatively small lake, it is crucial to ensure that there is sufficient "space" on the lake for them. 

Table: Surface area per residence (including approved building lots) on Lake Waseosa and associated lakes

Lake	Total surface area in hectares	Number of Properties	Number of Residential Buildings	Current total Surface area per property (in hectares)	Conclusion
Waseosa	156.3	137  (Not including island properties. Includes Camp Huronda and Factor's lodgings as one property)	135 (including Bear Island cottage and Factor's lodging but not including sleeping cabins in Camp Huronda. )	1.14	Over-developed
Palette	15.3	53*	45	0.29	Over-developed
Ripple	18.1	32		0.56	Over-developed
Jessop	28.9	25	17	1.15	Over-developed
Clark**	26.7	25	Unknown	1.07	Over-developed

            * Includes two cluster developments of 12 lots that share a common access point

            ** Included solely because it is in the immediate watershed of Lake Waseosa

It should be noted that we have been extremely conservative and have used total surface area of each lake, not the total usable surface area (i.e., only the surface area beyond 30 metres from the lake.  Had we calculated the usable surface area, the amount of usable surface area per dwelling would be even lower than it is and even further from what is seen as the appropriate limit for development.

The conclusion that one should draw from this table is a simple one: The creating of additional dwellings on any of the lakes for which we have data would put each of these lakes even further from the minimum standard that has been proposed.  These lakes already have too much development on them in terms of the use of the surface of the lake.

Boat Density Study

The District of Muskoka Official Plan makes reference to the issue of boat density:

"D.21 Increased boating density on many lakes is a significant issue. Discussions with senior levels of government should be undertaken to address issues of congestion, speed and use.

F.4 To maintain and enhance the quality of Muskoka's other resources by, among other matters:

...

b) maintaining and improving public access to and opportunities for public enjoyment and use of the lakes and rivers of Muskoka in a manner which is compatible with established uses and the recreational carrying capacity of these waterways."

A common method of determining the recreational carrying capacity is by measuring the boat density - ie: the surface area of water per boat. While some  authorities use an area per boat regardless of use, this study utilized a sliding scale approach that allocates less surface area for certain activities and more for others. For example, a powerboat towing a water-skier requires more space than a powerboat alone. This approach is particularly suitable for small to medium sized lakes and narrow lakes were the available space for maneuvering when towing or tacking is limited.

Methodology

In 2006, the LWRA conducted a survey of lake residents on Ripple, Pallet, Jessop and Waseosa lakes with a response rate of 38%. Of the respondents, 47 property owners indicated that they own and operate at least one power craft and 18 residents indicated that they own and operate at least one sail craft. Using our respondents' boat ownership a representative sample those on the lake indicates a total of at least 124 power and 47 sail craft distributed among current owners of developed lake front lots on the four lakes.  Of the power craft, 66% of respondents indicated that they use their boats for water-skiing.

There are two assumptions made for the purpose of this study: First, that an owner will only be operating one boat of any class at any given time. It seems unlikely that a household with two power craft will have two being operated simultaneously. Second, it is assumed that no more than 10% of available craft in any given class will be operating on the lake even during peak periods. These assumptions represent typical use according to studies previously conducted for the MNR.

Canoes, kayaks, peddle boats and row boats have been ignored as they generally operate within the 30 meter shore zone from which power boats are excluded. Obviously, this is a conservative assumption, since they are often seen in the middle of the lake. Similarly, there has been no allowance made for craft not owned by lake residents being operated on the lakes. As there are no public launch facilities available for craft larger than a canoe or kayak it is very unusual for outside boats to be operated on these waters.

In order to account for future load from previously approved building lots, a direct ratio of approved, undeveloped lots to existing lots was applied to the total for each lake. This calculation has was updated in 2011 to reflect additional lot severances approved in the intervening years. Lake Waseosa presents a special case as home to Camp Huronda, a camp for diabetic children. The camp's 7 sail craft were added to the projected load.

The surface area and perimeter of each lake was extracted from Ministry of Natural Resource records and the Land Information Ontario mapping system. Since powerboats are restricted to a minimum distance of 30 meters from shore and since sail boat keels are similarly restricted by depth, the average usable area was calculated using the formula [{(2*(Area/Perimeter)-30)^2}/{4*(Area/Perimeter)-60}*Perimeter]. Lake Waseosa is also home to 3 islands. The largest, ˜Treasure Island', comprises a land area of 9.26ha. The 30-meter exclusion zone was calculated and subtracted from the usable surface area. The two smaller islands were not subtracted from the area as they lie in part within 30 meters of either the mainland or ‘Treasure Island'. Similarly, boating hazards (rocks and shoals) have not been taken into account in the calculations. Those portions lying outside the 30-meter zone would have the effect of reducing net available space still further (See map - Appendix A3). The resulting area is shown as "Usable Area (EST.)" in the tables below.

Results

Determining the required space is not an exact science. While there are several well-respected studies on the subject, their conclusions differ slightly as to the exact numbers. Four such studies are by Kusler (1972)[3], Jaakson (1989)[4], Wagner (1991)[5] and Warback (1994)[6].  An average of their findings was calculated as follows:

	Power boating	Water-skiing	Sailing
Kusler		16.18ha
Jaakson	8.09ha	8.09ha	4.05ha
Wagner	10.12ha	10.12ha	10.12ha
Warbach	12.14ha	12.14ha	12.14ha
Average	10.12ha	11.63ha	8.77ha

The calculations indicated a total potential load of 25 power and 10 sail craft on Palette Lake; 16 power and 6 sail craft on Ripple Lake; 15 power and 5 sail craft on Jessop Lake and 84 power and 39 sail craft on Waseosa.

Lake Name	Area (ha)	# Vacant	# Developed	Total	Usable	# of Power	# of Sail
	Lots	Lots	Perimeter (m)	Area (EST.)	Craft	Craft
Palette Lake	15.314	3	39	1738	12.7	25	10
Ripple Lake	18.124	4	23	2317	14.6	16	6
Waseosa Lake	156.245	15	124	14800	122.6	84	39
Jessop Lake	28.879	8	16	2510	25.1	15	5

Based on the survey results, power craft use was weighted between cruising and water-skiing to determine the totals. As stated, a peak loading of only 10% of these totals was multiplied by the average requirement determined above to determine a total requirement for each lake in the study.  

Lake Name	Usable	ha for	ha for	ha for	Total	Surplus/
Area (EST.)	Powerboat	Water-skiing	for Sailing	Required	Shortfall
Palette Lake	12.7	12.428	19.261	8.432	40.1	-27.4
Ripple Lake	14.6	8.078	12.520	5.141	25.7	-11.1
Waseosa Lake	122.6	41.638	64.530	34.108	140.3	-17.7
Jessop Lake	25.1	5.965	11.561	4.730	22.3	2.8

Conclusions

Palette, Ripple and Waseosa are far above the carrying capacity for boating. In fact, Palette already has twice as many boats as can safely be accommodated. The situation on Waseosa may be equally dangerous, since the children from Camp Huronda are just learning to sail and cannot be expected to have developed any great degree of proficiency during their two-week session. Of all the lakes, only Jessop appears to have some room left but it should be recognized that even one additional craft on the lake at peak times would put it over the threshold. 

These findings confirm the density calculations derived from the guidelines of the Ministry of Natural Resources: Three of these four lakes are over-developed and Jessop is at capacity. 

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[1]  It should be noted that Town officials and its consultants and District officials and its consultants have, from time to time, stated that it is advisable to move beyond using phosphorus runoff as a planning limit since it is possible that some time in the future reliable phosphorus containing septic systems will be developed.

[2] "Usable" surface area would exclude the surface within 30 metres of the shore where, for example, boating could not take place.  Hence two lakes with the same total surface area, but different shapes, could have very different usable surface areas.  For example, two 100 hectare lakes - one a perfect circle and the other a long narrow lake - would differ in usable surface area since the long narrow lake would have a substantial portion of its surface area in close proximity to the shore and therefore unavailable for boating activities such as waterskiing.

[3] Kusler, Jon A. 1972. Carrying Capacity Controls for Recreation Water Uses. Upper Great Lakes Regional Commission.

[4] Jaakson, R., M.D. Buszynski and D. Botting. 1990. Carrying capacity and lake recreation planning. The Michigan Riparian, November 1989

[5] Wagner, Kenneth J. 1991. Assessing Impacts of Motorized Watercraft on Lakes: Issues and Perceptions. Proceedings of a National Conference on Enhancing States' Lake Management Programs. Northeastern Illinois Planning Commission.

[6] Warbach, J.D., M.A. Wyckoff, G.E. Fisher, P. Johnson and G. Gruenwald. 1994. Regulating keyhole development: Carrying capacity analysis and ordinances providing lake access regulations. Planning and Zoning Center, Inc.