Fertilizers as Water Pollutants

Article Credit: wisconsinlakes.org

Fertilizers, leaves, grass clippings, eroded soil, and animal waste are all sources of nutrients, including phosphorus. Phosphorus is main nutrient that drives eutrophication (premature aging) in most lakes. Relatively small amounts of phosphorus can cause water quality declines. A concentration of 25 parts per billion of phosphorus in water can promote excessive algae growth in lakes.

Phosphorus—an essential nutrient for plant growth—is a common ingredient in many lawn and garden fertilizers. However, the same phosphorus that helps keep lawns green is also the primary nutrient that turns lakes green with algae. Algae blooms can turn lakes into a thick, smelly green soup that is undesirable for swimming and other recreation. Too much algae clouds water and blocks sunlight from reaching aquatic plants; it also lowers the oxygen levels in the water which can cause fish kills.

Soil can retain only so much phosphorus and plants cannot absorb more phosphorus than they can use. Spreading manure and other fertilizers on lake watershed soils already saturated with phosphorus contributes to chronic nutrient loading, as nutrients can run directly into the lake and/or leach into our lakes from groundwater for years.

Excess algae and aquatic plant growth caused by an over-abundance of nutrients can impact boating and other water recreation and increase lake management costs for lake groups.

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Lake Erie: On the Brink of Collapse (Again)

Summer algae blooms are not uncommon, especially when the summer heat moves in, but the toxic algae bloom that caused the issuance of a water ban in Toledo is a sign of Lake Erie’s distress.

Lake Erie became very polluted in the 1960s and 1970s as a result of the quantity of heavy industry situated in cities on its shores.  In the 1970s, patches of the lake were declared dead because of industrial waste as well as sewage from runoff.  It was known as the lake that was dying.  Lake Erie never ‘died’ but sport fish populations were very low, there were algae in the lake and in general the world’s 12^th largest lakes waters were in big trouble.

Lake Erie water is renewed from upstream every 2.6 years, this incredible turn rate for water helped to restore the lake as both U.S. and Canadian officials worked to reduce the algae promoting phosphorus levels.  Phosphorus from wastewater plants, laundry detergent and agricultural all helped to reduce phosphorus and recover Lake Erie as a “Great Lake.”  

However, the success was short lived.  Beginning in 2003 algae blooms were once again plaguing the lake as urbanization and industrial agriculture have produced new and powerful sources of phosphorus runoff.  The toxic algae are not restricted to the Great Lakes. Poisonous algae are found in polluted inland lakes from Minnesota to Nebraska to California, and even in the glacial-era kettle ponds of Cape Cod in Massachusetts.

Unfortunately it has taken the loss of drinking water for half a million people to force people to see what scientists have been saying for years: Lake Erie is in trouble.  State officials told residents to stop using tap water and that boiling the water would only increase the concentration of the toxins.

The man-made three day water ban left residents without water to drink , bath or wash dishes with.  The toxin microcystin produced by the toxic blue-green algae causes health problems such as abdominal pain, vomiting, diarrhea, liver inflammation and pneumonia.  When it comes in contact with skin it can cause rashes, hives and even blisters.  The toxin has been known to cause death in pets and wildlife.

Scientists in Ohio and elsewhere who study Lake Erie’s algae problems say the crisis is solvable.  The first step is limiting the amount of phosphorus that reaches the lake.  Once that happens, the lake will take care of itself with its fast water cycling system.

Action is needed and it’s needed now.  Money has been given to create wetlands and teach farmers ways to reduce fertilizer use and runoff.  More money will be used to encouraged (should be required) to use best management practices when applying fertilizer.  A Nutrient Reduction Strategy paper issued last year cites demonstration projects, voluntary phosphorus reduction goals and watershed plans, but makes no mention of enforceable limits on pollution. Obviously the voluntary reduction isn’t working as Lake Erie slowly collapses.

Wisconsin’s Phosphorus Rule is Approved

In December, 2010 Wisconsin became the first state in the country to adopt phosphorus water quality standards for lakes, reservoirs, rivers, and streams.  The Environmental Protection Agency has approved Wisconsin’s revised rule as a revision to Wisconsin’s federally-approved National Pollutant Discharge Elimination System program under the Clean Water Act.

Under the new rules DNR determines the phosphorus discharge limits based on the condition and quality of a watershed.  Limits can vary depending on whether a waterway is already impaired by phosphorus, among other factors.

Already this summer, many Wisconsin lakes are experiencing algae blooms and excessive aquatic plant growth, both of which are fueled by phosphorus pollution.  The excess nutrients increase the populations of algae, which can multiply in waterways particularly when the water is warm and the weather is calm. 

Algae is typically not harmful to humans, however, some species produce toxins which can affect people by causing illness so swimming and other water activities should be avoided in areas where algal is present.  Blue-green algae blooms have been blamed for the deaths of many dogs which are more vulnerable because they often drink the contaminated water or swallow the algae as they clean their coats. 

Almost 175 Wisconsin waters are officially listed as “impaired” due to excessive phosphorus levels.  The new rules will help clean up those lakes and protect the others.  The new rule is in addition to a smaller effort from 2009 which restricted the sale of fertilizers containing phosphorus and banned the sale of dishwasher detergents with phosphorus.