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

Types of Nutrients

Algal Blooms

Managing Your Nutrients, Chemicals Sprays & Applicants

Geese & E.Coli

Additional Reading & Resources

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.

More about oligotrophic lakes

Oligotrophic lakes are usually deep (around 80-100 feet) and have low levels of phosphorus and other nutrients. They support little aquatic plant growth. These are cold-water lakes that can support Trout and Whitefish due to having high dissolved oxygen content. Lake Trout lakes are of particular importance to The Land Between and Ontario as a whole since only about 1% of lakes (i.e. ~ 2,300 lakes) in the province contain Lake Trout, but this represents a total of 20-25% of all Lake Trout lakes in the world (Ontario Ministry of Natural Resources and Forestry [MNRF], 2015). Lake Trout are great indicators of the health of fragile aquatic ecosystems since they are a sensitive species adapted to a very specific range of environmental conditions. They are also highly sensitive to human disturbance, such as exploitation, nutrient input from cottage septic systems, acidification, invasive species introductions, and habitat destruction. As a result, approximately 5% of Ontario’s Lake Trout populations have already become extinct (MNRF, 2015). Oligotrophic Lake Trout lakes are typically found on the Canadian Shield or northern edge of The Land Between, with underlying bedrock and little soil.

More about mesotrophic lakes

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. They can therefore support more aquatic plant growth and fish like Walleye and Bass, but occasionally have Lake Trout as well, and can experience natural algal blooms at the surface. Mesotrophic lakes have clear water and many plants growing in the littoral zone.

More about eutrophic lakes

Eutrophic lakes are naturally the shallowest (around 20 m or less) and contain the most nutrients, especially phosphorus. For this reason, they have abundant vegetation growth, murkier water, and support warm-water fish species like Perch. They may also have more frequent or widespread natural algal blooms.

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.

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!

Phosphorus

The primary nutrient in fertilizer-type inputs is phosphorus typically in the form of phosphate. Phosphate naturally occurs in low levels and is usually a limiting factor for plant growth (i.e. plants typically need both nitrogen and phosphorus to grow, but nitrogen usually occurs at higher levels), therefore even small additions of phosphorus are enough to significantly encourage the growth of plants. In fact, just one pound of phosphorus in the water is enough to grow a whopping 500 pounds of plants! This excessive nutrient loading not only encourages the growth and proliferation of algae and weeds, but also monocultures of invasive plant species such as Phragmites - in turn resulting in cloudy water, reduced water quality, and cascading effects in the food chain (disruptions and changes to entire species populations). For instance, as these plants die and decompose, they use up vast amounts of dissolved oxygen from the water, leaving very little for other aquatic species. The end result is massive die-offs of fish and other aquatic organisms, such as tiny water animals (benthic macroinvertebrates), crayfish, and molluscs.

Nitrogen

Nitrogen is the second most important nutrient for aquatic plant growth, but it is usually found at higher levels in lakes than phosphorus (the ratio ranges from 10:1 to 15:1). Naturally, a large amount of nitrogen is stored in our atmosphere as N₂ gas (approximately 78% of the air we breathe), but similar to phosphorus, human land use alterations such as the use of fertilizers, manure, sewage, animal waste and farming have contributed significant additional amounts to our water and soil. These additions of nitrogen can take multiple forms, including ammonium (NH₄⁺), ammonia (NH₃), nitrite (NO₂^–), and nitrate (NO₃^–). Did you know that your own urine has ammonium in it? Urine and human waste in septic systems, if not maintained properly, can leach into the soil and reach the lake where it affects aquatic life. In nature, ammonium and ammonia get converted into nitrites by bacteria in the soil and water. Nitrites can then be converted by other bacteria in the presence of oxygen to nitrates, the most common form found in lakes. However, it is important to note that all forms of nitrogen can be used by plants to produce energy - and more importantly, all forms of nitrogen can pose a risk if present in excess.

In drinking water, nitrates are odourless and colourless and can be found in wells due to leaching from the soil. If consumed, they can inhibit the ability of our red blood cells to carry oxygen to other organs in our bodies. This lack of oxygen can lead to nitrogen poisoning if severe enough and can even affect pets and turn babies blue with a condition called methemoglobinemia that causes brain damage and even death. In lake ecosystems, it can have similar health effects on fish and other aquatic species. Also, excess nitrogen has many of the same consequences as excess phosphorus does - both promote proliferation of algae, aquatic plants, and weeds which consume dissolved oxygen from the water, interfere with trophic interactions, and also take over foraging, spawning and nesting habitats.

Calcium

Do you remember those milk commercials that started popping up in the 1980’s - the ones that advocated for drinking milk to build big, strong bones and prevent osteoporosis? Although they have been widely debated since then, the fact remains that the main nutrient, calcium, is essential for all forms of life. It helps build teeth, bones, and shells (exoskeletons) in all sorts of animals, and it is even consumed by plants. In fact, calcium makes up about 1% of trees, 2-8% of fish, and over 20% of clams and crayfish! Hard-shelled animals, such turtles and molluscs especially rely on it - and we rely on them to keep our waters clean!

Unfortunately, acid rain in the 60’s and 70’s depleted calcium from our environment, creating an environmental illness that scientists have coined “ecological osteoporosis” (environmental calcium decline). In fact, lakes in The Land Between and Muskoka have declined in calcium content by 25-40% over the last 40 years. This is due to a century of harsh acid rain, poor logging practices (which remove calcium-rich trees), forest fire suppression, and shoreland development. To make matters worse, the problem is much more prevalent where the soils are thin and located on granitic bedrock which has little calcium to begin with - much of the Land Between. This means that our lakes are less able to buffer against acid rain due to having less calcium in our waters.

Today, levels of acid rain aren’t as bad as they used to be because we have managed to reduce air pollution (sulfur dioxide levels) by 55% since 1980. This means that less leaching of calcium is occurring now. However, paleo-ecological Cladoceran records suggest that calcium levels are still lower now than they were before acid rain leached it away. How is this possible? It is actually rather simple - we already have less calcium in our soils and waters due to intense historical leaching, among other factors, and now we have less input of calcium from precipitation and dust, forest fires which produce calcium-rich ash, and from natural shorelands with intact forested edges. Therefore, it doesn’t matter that we have less acid rain leaching calcium in this part of Ontario, because we have very little calcium here presently, and what we do have is easily affected by acid rain, even if it is less acidic today than historically.

So how does this lack of calcium affect lakes and aquatic organisms? Unlike phosphorus and nitrogen that can wreak havoc if they are in excess, calcium can be detrimental if there is not enough. For example, Daphnia are microscopic animal plankton or “water fleas” made up of around 5% calcium which forms their main body shell - and thus need calcium to survive. In fact, calcium must be present in the water at about 1.5 - 2 mg/L to support the development of their carapaces (shells), or else they will not be able to grow. Daphnia are a great food source for many fish and they also help keep our waters clean by acting as our lakes’ “lawn mowers”, eating algae as they swim. However, they have already disappeared from some lakes in the Land Between due to too little calcium. When this happens, it becomes easy for algae to grow unimpeded by these natural predators. In this sense, the depletion of calcium in lakes is also causing algal blooms, just like excess nitrogen and phosphorus do.

Aside from Daphnia, other aquatic species, including clams, amphipods and crayfish, are also in decline due to limited calcium supplies in lakes. Predators of these species are expected to decline as well due to these diminishing food supplies. Even humans are affected by calcium deficiencies in lakes - Daphnia are being replaced with the jelly-clad water flea, called Holopedium, which can clog water filters on intake pipes at lakeside residences.

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. https://doi.org/10.1016/j.scitotenv.2017.09.186

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. https://doi.org/10.1016/0921-3449(92)90018-W

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. https://doi.org/10.1007/s00027-010-0128-9 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.