Nutrients, Sprays & Chemical Applicants Guide

Within this guide, you will more information on nutrients & lakes, the most common nutrients impacting lakes, actions you can take to manage nutrients and chemical sprays and applicants on your property, and more! You can toggle to any of the applicable sections via the buttons below.

Types of Lakes

One important thing to note is that all lakes have some level of nutrients in them naturally. In fact, lakes can even be classified based on their levels of naturally occurring nutrients. Some lakes have more nutrients than others because of their specific features, such as lake depth, area, watershed size, underlying bedrock and climate conditions, while others have less. To classify the differences between these lakes, scientists established the Trophic State Index which is based on nutrient level and the resulting level of productivity in a lake. There are three main lake types under this classification system: oligotrophic, mesotrophic and eutrophic. Oligotrophic lakes are usually deep (around 80-100 feet) and have low levels of phosphorus and other nutrients. Eutrophic lakes are naturally the shallowest (around 20 m or less) and contain the most nutrients, especially phosphorus. Mesotrophic lakes are in the middle of the spectrum - they are medium in depth (around 60 feet)and have more nutrients than oligotrophic lakes but less than eutrophic lakes. You can learn more about the different types of lakes by clicking through the drop-down below.

Types of Nutrients

The most common nutrients that runoff into our lakes are phosphorus, calcium, and nitrogen. You can learn more about these nutrients, their sources, and the threats they pose by clicking through the drop-down below!

Algal Blooms

Not all algae is bad! It is important to note that algae is essential for the survival of fish and that a lake can have an algal bloom solely from natural causes. In fact, the process of eutrophication (often associated with algal blooms) during which the lake bottom fills in with sediment and decomposing plant matter is a lake’s way of aging. This process happens over tens of thousands of years as the lake is converted into a wetland and finally into dry land. However, humans are exacerbating the occurrence, frequency and duration of algal blooms across the world, far beyond what is typical for an ordinary aging lake - in this situation climate change is not the only culprit.

When nutrients are added to a lake through unnatural sources it can contribute to changes in the lake ecosystem, its water quality, habitats and species, in a process called eutrophication. The excessive amount of nutrients promotes the growth of algae beyond its natural levels. When this happens, algae will utilize a substantial portion of the oxygen in the lake, "choking" that lake and the rest of its aquatic life of oxygen while creating an "algal bloom" in the process. Algal blooms can have detrimental impacts to lakes, including:

  • Disruption to food web dynamics: Too much plant cover provides more hiding spaces for prey and puts predators at a disadvantage. Plants and algae can also cover nesting areas and fish spawning beds.
  • Anoxic (lack of oxygen) conditions and raised pH of water: High rates of photosynthesis during plant growth removes dissolved inorganic carbon from the water, raising the pH and interfering with the chemosensory ability of organisms. Decaying plant matter also consumes dissolved oxygen from the water. Both decrease water quality and place aquatic organisms and fisheries at risk.
  • Outcompeting native plants by algae and invasive species: Native plants may be taken over by algae and invasives, depriving the ecosystem as well as all the organisms that rely on the specific native plants.
  • Destruction of swimming areas and drinking water: Excessive algae and other plants clog intake pumps as well as deteriorate the water quality by making lakes foul-smelling, cloudy-looking and potentially toxic to swim in and drink.
  • Decreased lake biodiversity: Our once-thriving native species struggle to live in such nutrient-rich, anoxic conditions, and often die as a result. We lose biodiversity from the lake when certain species cease to survive. The die-off of plants also takes oxygen out of the water - and the cascading effects  continue.
  • Removal of calcium sources such as trees from a lake basin can contribute to algal blooms because the number of diatoms (small water creatures whose bodies are made from calcium) decreases and these microscopic animals eat algae helping to keep levels in check.

Algal blooms can be particularly dangerous if blue-green algae (a type of cyanobacteria) starts to proliferate because some species within this algae strain can produce toxins (e.g., microcystins and anatoxin-a) which pose a serious threat to humans and animals. You can identify a potential blue-green algae bloom by observing the following:

  • Odour of mown grass from alive cyanobacterial cells, or foul odour from decomposing cells coming from the lake usually in mid-late summer and into the fall.
  • Blue-green colour (but can sometimes appear as olive green to red in colour) in the water that looks like spilled paint or gelatinous floating mats

If you suspect that you have a blue-green algae bloom, you should call the MECP Spills Action Centre at 1-866-663-8477. In the meantime, you should assume that the water is toxic - do not drink any water from the lake, let your pets near the water, eat any fish from the lake or swim in it (even nearby inhalation of fumes from the cyanobacteria can be harmful, so keep a safe distance). It is important to note that boiling the water and treating it with ultraviolet light DOES NOT make it safe to drink if blue-green algae is the problem. For more information on blue-green algae and other algae and aquatic plants, refer to the Algae and Aquatic Plant Education Manual produced by the Rideau Valley Conservation Authority.

Managing Your Nutrients, Chemicals Sprays & Applicants

Believe it or not, you have already made the first step in managing nutrients - understanding them helps you better recognize their sources and effects on your lake so you can determine further action. For example, after learning about algae and phosphorus inputs in your lake from previous sections, you may remember a time when your water looked abnormally green. Looking around your lake, you might realize that there are a lot of manicured lawns that use fertilizer. Putting together what you learned about the use of fertilizers and algal blooms, you may suspect that this is one of the contributors. So what can you do? Fortunately, there are many simple measures that you can take to steward your property and manage nutrients going into your lake. These include the following:

  • Use phosphate-free cleaning supplies, detergents and soaps. This is as easy as checking the label on the bottles before you buy them. Plant-based soaps are the best option. To be extra eco-friendly, opt for biodegradable bottles as well! In addition, ensure that all bathing and washing is done on permeable land (not hard surfaces) and as far away from the shore as possible, or 60 m at the minimum. This will ensure that the water and soap enters the ground and has time to be filtered and degraded by the soil before it reaches the lake. Even natural soaps must be processed by the land before they enter the water.
  • Avoid the use of fertilizers, but if you must use them, avoid ones that contain phosphates (look for the “phosphate free” checkmark label). Another good alternative is fertilizer that is coated with a biodegradable material which uses a controlled-release method to minimize leaching of nutrients into surrounding soil and lake water.
  • Avoid the use of herbicides and pesticides. Often a native plant garden (which is always low-maintenance) with clean natural soils, is your best defence against invasive weeds and insects. In addition, weeds can often easily be removed manually, as with most insect pests. However, if herbicides or pesticides must be used, use ones that are proven safe (for the environment and human health). Make sure to check the Ontario Government’s Allowable List of Pesticides and follow the Ontario Pesticides Act and Ontario Regulation 63/09 and local by-laws if using pesticides and herbicides. There are also many plant-derived herbicides on the market right now that contain organic concentrates such as clove oil, vinegar and citric acid. You can even make your own to save on costs! An easy recipe is: 1 litre of water, ½ cup of lemon juice, ½ cup of vinegar, 2 tablespoons of salt and 2 tablespoons of dishwashing liquid. Spray on broadleaved plants to remove them.
  • Contribute to water quality monitoring (algae, nutrient, water clarity, etc.). Property owners can take water samples to look for chlorophyll A, a proxy for algal content in your lake, as well as nutrient contents. Refer to the FOCA Guide to Citizen Science at the Lake for a more detailed description of how you can conduct monitoring and sampling on your lake.
  • Limit salt applications to your driveway by regularly shovelling or plowing snow and chipping away ice. If some areas are particularly icey, opt for sand instead of salt, or an environmentally-friendly de-icer such as calcium magnesium acetate, but remember to use both sparingly. You can also sweep up the sand in the spring so it does not contribute to sediment loading in the lake. Another alternative is cat litter. Also wood ash can be used as an anti-slip agent, which can support healthy calcium levels in the lake.
  • Add calcium to the soils on your property in the form of wood ash. Not only will your plants love it but so will all of the creatures in the lake! Wood ash from burning hardwood trees in household stoves can increase the pH, calcium, magnesium and potassium concentrations (among others) in soil, plus help add calcium to the lake environment when it runs off or is leached into the water. But be careful - wood ash should really only be added if your soil’s pH is below the optimal neutral pH of 6.5 - 7. In general, you should always test your soil pH before considering adding wood ash because if you add too much you can risk making your soil too alkaline (high pH value). However, soil that is already within the optimal pH range can still withstand wood ash addition without affecting the pH level too much over a long period - this way you can still reap the benefits of added nutrients. The general application amount for soil with a pH of 6.5 is no more than 20 pounds (or a 5-gallon bucket) per 1,000 square feet of soil once per year (typically in the fall). The ash should be mixed into the soil in the top 2-4 inches. Be careful not to spread the ash around seedlings or acid-loving plants such as raspberries and blueberries as this could harm them. In The Land Between bioregion, most properties will naturally have more acidic soils, and thus can withstand additions of calcium without becoming too alkaline.
  • Manage erosion and runoff with permeable surfaces, downspouts, rain barrels and water gardens. Sustainable Drainage Systems (SDS) are natural systems such as water gardens which help to direct runoff and rainwater down into the ground, instead of over the land. Water is filtered naturally and runoff, sediment loading and nutrient input in lakes are reduced. They  also help to recharge groundwater drinking supplies. In order to achieve a SDS, try:
    • Planting native rain gardens and/or grassy swales in areas where water pools or runs naturally
    • Replacing impermeable surfaces (i.e. paved driveways, patios, decks, staircases, etc.) with permeable surfaces (i.e. gravel driveways, interlocking brick, mulch and gravel seating areas, raised permeable walkways, etc.)
    • Redirecting downspouts into rain barrels - the collected water can be used to water your garden on drier days
    • Creating pooling areas (ex. rock pits) for runoff to collect and infiltrate the ground
  • Reduce organic matter entering the water. Although it is best to leave the leaves in place and refrain from keeping a manicured lawn, if you do generate grass cuttings, leaf piles and weed piles, try to keep them away from the water’s edge by at least 30 m. If these sources of organic matter find their way into the water in these concentrated amounts, they will decompose and add extra nutrients to the water, potentially fuelling harmful algae and reducing water clarity.
  • Keep a healthy and maintained septic tank. Your septic tank should be pumped and inspected regularly to ensure it is in proper working order and does not contain too much sludge that might overload the tank and contribute to leaks. If leaking, your septic tank can contaminate groundwater drinking sources, as well as lake water that we use for recreation. The frequency at which you will need to pump out your septic depends on your tank size, frequency of use and nature of use, but in general, most need to be emptied every 2-3 years. To keep your septic system functioning properly, avoid using antibacterial soaps since septic systems rely on a healthy amount of bacteria to process and decompose waste - antibacterial soaps can kill these helpful bacteria. In addition, do not place heavy or non-permeable structures, such as patios, on top of your septic bed - the load may cause damage to the tank or may make the soil impermeable over the leaching bed. You should also avoid driving over the leaching bed, compacting the soil, and planting trees over or near it since roots can damage the system or interfere with water movement and processing (smaller plants, flowers and vegetables are okay to plant though). You will know if your leaching bed is not functioning properly if the ground seems wet and spongy above it - this may mean that it is being overloaded or that the liquid is unable to leach properly. You can consider installing an effluent filter on your septic tank to reduce clogging of solids in the leaching bed. In addition, try to direct rainwater away from the leaching bed and do not water the lawn or ground above it - if the leaching bed area is too saturated it will not be able to absorb and treat wastewater. There are approved alternative septic systems that can be used to treat wastewater in a closed or tiered wetland system.
  • Direct livestock away from water bodies to limit erosion and contamination of water. Trampling of shoreland vegetation by livestock will contribute to erosion, runoff, sediment loading and nutrient levels in the water. In addition, the waste generated from livestock can carry harmful bacteria (E. coli and a parasite, Cryptosporidium) as well as nutrients which contribute to algal blooms and reduced water quality for swimming and drinking. To avoid this, redirect grazing areas sufficiently far away from the water’s edge using fencing and provide an alternative water source such as a trough. In addition, you can plant filter and buffer strips along the pasture edges that are closest to the water to help limit nutrient and contaminant input. You can obtain help with implementing these changes in the form of incentives through the Environmental Farm Plan program offered by the Ontario Soil and Crop Improvement Association
  • Try to keep pet waste away from the shoreland and from drainage ditches.

Geese & E.Coli

Livestock are not the only animals that contribute to contaminating lake water. In fact, the average lakeside residence has to worry more about one particular wild animal instead - the Canada Goose. Geese are tundra species and colonize areas that resemble these flat open landscapes - many unnatural shorelands mimic the tundra and attract geese. Geese pollute the water with excess nitrogen, phosphorus and pathogens through up to 2 pounds of fecal matter produced per day. One of the most concerning pathogens is Escherichia coli (E.coli) which lives in their digestive tract and is excreted in their waste matter. In problem areas where geese frequent the shoreland, large amounts of fecal matter, and therefore E.coli, can enter the water and pose a risk to humans - if ingested in drinking water or during swimming it can cause nausea, vomiting and diarrhea.

Another pathogen in geese fecal matter is a parasite, schistosomes, that can cause swimmers’ itch. This parasite lives in birds, but also semi-aquatic mammals, and snails. Once in human skin, the parasite eventually dies but can still cause an allergic reaction leading to a skin rash.

So how do we prevent geese and their poop from contaminating our lawns and lakes? Since geese prefer fertilized, short grass with an open view near the water, the best thing you can do is to re-naturalize your shoreland so that it no longer resembles the tundra open landscapes that geese prefer. Specifically, you can:

  • Allow tall native grasses, sedges, wildflowers and shrubs to grow, or even plant some of your own. The row of vegetation should be a minimum of 3 m but ideally 30 m wide, located right along the water’s edge and feature a dense array of native plants at least 60 cm tall - if the geese cannot see through the row of vegetation then they will not enter it since they need open sightlines to spot predators.
  • Limit the amount of manicured lawn space on your property or separate your lawn into patches and recreational areas that are smaller than 20ft x 20ft. You can plant native gardens between designated open lawn areas to deter geese, reduce runoff and nutrient loading into the lake, and provide habitat for wildlife -all at once!
  • Plant more native trees and/or tall shrubs to block geese' flight paths in uplands areas (Geese will land in open water if nearby). If the geese see that they cannot safely land and/or take off from your property they will likely not come in the first place.
  • Do not feed geese, as they will not leave an area so long as they are getting fed. In addition, feeding bread to geese can harm their health as it is not easily digested and provides little to no nutritional content.
  • Fertilized lawns are sources of carbohydrates for geese. Avoid using fertilizers and you will reduce palatable sources of food as well as limit nutrients that could reach the lake.

Please note that the killing and capturing of geese, as well as interfering with their nests (unless otherwise listed as an exception under the Migratory Birds Regulations), is prohibited under the Migratory Birds Convention Act, 1994 (MBCA).

Additional Reading & Resources

Algae and Aquatic Plant Education Manual, produced by the Rideau Valley Conservation Authority

ASHMuskoka, produced by the Friends of the Muskoka Watershed

A Shoreline Owner’s Guide to Healthy Waterfronts, produced by the Federation of Ontario Cottagers’ Associations

A Shoreline Owner’s Guide to Lakeland Living, produced by the Lakeland Alliance

Calcium Concentrations in Lakes, produced by the Muskoka Watershed Report Card.

Canada Geese on Your Shoreline Property, produced by the Love Your Lake Program (Canadian Wildlife Federation and Watersheds Canada)

Chen, L. (2018). Environmentally friendly fertilizers: A review of materials used and their effects on the environment. The Science of the Total Environment, 613-614, 829–839.

Chislock, M. F., Doster, E., Zitomer, R. A. & Wilson, A. E. (2013) Eutrophication: Causes, Consequences, and Controls in Aquatic Ecosystems. Nature Education Knowledge 4(4):10. Retrieved here.

Geese and Your Shoreline Property, produced by Peterborough Green-Up

Guide to Using Wood Ash as an Agricultural Soil Amendment, produced by Olivia Saunders from The University of New Hampshire Cooperative Extension

Handbook: Canada and Cackling Geese: Management and Population Control in Southern Canada, produced by Environment Canada

Horner, B. (1992). Environmental evaluation of calcium magnesium acetate for highway deicing applications. Resources, Conservation and Recycling, 7(1), 213–237.

Information About Blue-Green Algae, produced by the Government of Ontario, Ministry of Environment

Inland Ontario Lakes Designated for Lake Trout Management, produced by the Ontario Ministry of Natural Resources and Forestry

Livestock Access to Watercourses Factsheet, produced by the Government of Ontario, Ministry of Agriculture, Food and Rural Affairs

Strayer, D., & Findlay, S. (2010). Ecology of freshwater shore zones. Aquatic Sciences, 72(2), 127–163. Understanding Lake Data, produced by Byron Shaw, Christine Mechenich and Lowell Klessig at the University of Wisconsin–Extension, Cooperative Extension

The Muskoka Watershed Report Card, produced by the Muskoka Watershed Council

The Threat of Calcium (Ca) Decline for the Life in Muskoka (& Haliburton) Lakes, produced by Norman Yan at York University

Quality in the Kawarthas, Kawartha Conservation's guide provides best practices for each season to help reduce runoff of pollutants into the lake.

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