Lake Capacity Assessment

FOCA continues in our role as active contributors to sound lake management, including ongoing upgrades to lake capacity planning, through a process referred to as Lake Capacity Assessment (LCA).


It has long been recognized that nearshore development can have an impact on the integrity of the natural biota, and water quality. As development occurs on inland lakes, there are economic, social and community impacts as well. At a certain point, the lake can be said to be “at capacity” meaning further development would degrade its condition.

Why should cottagers care about LCA? Protection of water quality is essential to protecting the environmental, recreational, economic, and property value of a lake. Therefore, it is in the best interest of cottagers‟ associations and residents living on lakes to safeguard their water resources. LCA is one way that municipal planners can help protect the water quality of lakes from excessive development along their shores.

The following is a “visual essay” created by FOCA in 2014, to explain the importance of lake capacity. 

Our members live within the landscape, and are an integral part of the rural community. What is our comfort level with waterfront development? How much is “too much”? Where is the perfect balance? Which of the following images reflects your vision of an “ideal” cottage lake?

Every waterfront property owner has a role to play in protecting water quality, through actions taken on our own properties.

Download and circulate FOCA’s Fact Sheet about LCA and LCM (PDF, 2 pages)

Download FOCA’s 2014 summary about Lake Capacity Assessment: Protecting the water quality of Ontario’s inland lakes: A closer look at the impacts of shoreline development on water quality (PDF, 2 pages)

Take the following steps on your own waterfront property:

  1. Maintain a properly functioning septic system. Have your septic system pumped as needed, to remove the build-up of solids and scum, and have the system checked for any required maintenance on a regular basis. If you are converting a cottage into a permanent dwelling be sure to check the capacity of the septic system. Exceeding the capacity of your septic could result in the remobilization of phosphorus in the soil.
  2. Reduce your water use at the cottage. Excessive water use is the most common cause of septic failure. Cut down on the amount of water entering your septic system by installing low flow toilets and showerheads, and taking laundry home to wash.
  3. Encourage your municipality to implement mandatory septic inspections. Even if your municipality has not taken this step, your Association could make arrangements for an inspector to come to your lake and see multiple properties at once.
  4. Naturalize your shorelines (e.g., vegetated buffer strips, retain wetlands, remove harden shore structures like retaining walls) to help control soil erosion and the runoff of nutrients to the lake and nearby rivers and streams.
  5. Limit impervious surfaces including roofs, parking areas and patios, to reduce runoff to nearby waterbodies.
  6. Adopt strong stewardship programs to educate other lake users on ways to promote good water quality (e.g., promote the use of phosphorus free products).
  7. Encourage enhanced septic system setback limits. The current minimum setback requirement in the Ontario Building Code (OBC) is 15 metres, although some municipalities have implemented bylaws that dictate longer distances. The MECP recommends a minimum clearance of 30 metres between a septic system and the water’s edge.

Over 30 years ago, the Province of Ontario undertook a lakeshore capacity Study which resulted in the establishment of a Lake Capacity Model (LCM), based largely on phosphorus levels.

The Ontario Ministries that undertook the Study were the Ministry of Municipal Affairs & Housing (MMAH), the Ministry of the Environment (MOE; now the Ministry of Environment, Conservation & Parks – MECP) and the Ministry of Natural Resources (MNR, now the Ministry of Natural Resources and Forestry – MNRF).

The other study components that were considered (wildlife, fisheries, land use, microbiology) while important, were utilized much less directly in practice.

One of the key goals of the LCM is to determine the maximum allowable total phosphorus (TP) concentration that would protect lake water quality, since a main goal of the Province’s original Study was to “provide a planning tool to assist in evaluating the effects of cottage development on inland lakes.

This was intended to address the problem that “Community planners and other professionals involved in the preparation of planning policies for lakeshore development …have always found it difficult to determine objectively the impact of development on the natural environment.”

Overall, according to the “Committee Report” module (1 of the 7 modules): “environmental predictions will always be based on incomplete scientific knowledge. While it may be tempting to seek greater precision, the crucial concern for planners is not whether the predictions are perfect but whether they are the best estimate of the future environmental repercussions of lakeshore cottage development.

Read FOCA’s update to members about the “new” Lakeshore Capacity Model”, written in this excerpt from the 2000 Lake Stewards Newsletter! (PDF, 1 page)

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As it stands today the only “hard and fast” (quantitative and defensible) component of modelling and making determinations about “capacity” of a waterbody are those that relate to phosphorus levels.

Today, we find ourselves still trying to apply good planning on the waterfront, while facing continued development pressure on increasingly marginal shorelands and ever-increasing intensity of building (size, and amount and intensity of use) at the waters’ edge.

We are also faced with addressing complex environmental, and community sustainability goals, and ever more challenged to manage “good planning” based on a singular predictive chemical parameter (phosphorus).

In addition to needing more sophisticated approaches and defensible planning parameters, FOCA has working with MECP and others to try to adopt best practices, including approaches that might also consider:

  • density of shoreline development/overcrowding
  • amount of available developable land
  • recurrent water quality problems and/or algal blooms
  • specific fishery management objectives, i.e. Lake trout, splake, walleye, or (aquatic or terrestrial) species at risk
  • aesthetic (human/community) considerations such as  light pollution, noise pollution, boating traffic
  • other planning tools including site plan control, tree cutting and site alteration by-laws, septic re-inspection program
  • safety
  • site characteristics including steepness, potential erosion, vegetation cover, etc.

FOCA helped in various capacities in a provincial review of the Ministry of the Environment Lakeshore Capacity Model, and has worked with our member associations and planning practitioners to productively consider its use in good planning.

FOCA continues to work with MECP and other partners to build a more robust tool(s) to ensure planners and community members alike that we will not plan cottage country on an ad hoc basis, through death by a thousand cuts, with no longer-term big picture framework.

We look forward to continuing the important work on our shared interest in sustainable waterfront communities on Ontario’s inland lakes.