Nutrients

The profile view of aa bioretention feature with associated zones and the processes used to remove excess nitrogen and phosphorous inputs out of incomign overland waer from agricultrual lands (Photo Source: Osman, et al. 2022)

Overview

Nutrients are an essential part of life, however excess amounts of them can harm the environment. Anthropogenic activities can lead to such excessive amount of nutrients in runoff and cause degradation of receiving waters. Phosphorus and Nitrogen are the main nutrients of concern in stormwater runoff. This page provides information on the sources of nutrients, the issues caused by their excess amounts, and strategies to manage them.

Nutrient pollution

The primary concern with excess amounts of nutrients is eutrophication (U.S. EPA 1999). Eutrophication is the process of excessive algae growth due to abundance of nutrients that can cause hypoxic condition in water. Excessive algal growth can cover the surface of water and prevent light penetration. Without light, the desirable aquatic plants die off. The eventual decay of aquatic plants and algae, consumes the dissolved oxygen in the water and creates hypoxic condition that can kill fish and other aquatic animals. Nutrient pollution has been noted as a critical environmental, public health, and economic concern in Canada, Great Lakes, Lake Winnipeg, Lac St. Charles, Lake Simcoe and other water bodies (CWN, 2017). Nutrient pollution can cause environmental imbalance, pose a public health risk for drinking water (USEPA, 2009) and swimming, as inhalation of algae by swimmers or pet can cause hypoxic condition. It can also affect the economy by harming fisheries, tourism, recreation, and increase the treatment cost of drinking water. Historical algal bloom in the Lake Erie during 1960s caused a substantial decline of native aquatic species (CWN, 2017). In 2015 more than 5,000 km2 of Lake Erie was covered by algal blooms rendering the water unsuitable for drinking for residents of Pelee Island, Ontario and Toledo, Ohio (CWN, 2017). In 2011 and 2014, severe nutrient pollution in this lake caused service interruption, equal to $71 million and $65 million USD (Bingham, Sinha, & Lupi, 2015). Reports of nutrient pollution are increasing across Canada causing more beach closures and decline in water quality and fisheries (CWN, 2017).

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Refers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer.

The portion of water precipitated onto a catchment area, which then flows as surface discharge from the catchment area past a specified point.

Water from rain, snow melt, or irrigation that flows over the land surface.

Watercourses and Lake Ontario, to which Stormwater and Combined Sewer Overflows discharge.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.