Council acts to reduce levels of harmful phosphorus in County lakes and streams

March 16, 2009

Summary

Patterson initiative limits use of fertilizers that choke oxygen out of waterways

Story

Phosphorus is an element vital to plant growth, but too much phosphorus can also be harmful to aquatic life. The Metropolitan King County Council today unanimously adopted an ordinance that limits one of the major man-made sources of phosphorus in the ecosystem: lawn fertilizers.

“Research proves that phosphorus suffocates the plants necessary for a healthy aquatic ecosystem, but it is not irreversible,” said Councilmember Julia Patterson, prime sponsor of the ordinance. “We have the opportunity, through this legislation that I wrote, to reverse the trend of increasingly unhealthy lakes, rivers, and streams.”

Phosphorus is a common element in many lawn fertilizers, and high concentrations of phosphorus in aquatic environments have the potential to encourage rapid and extensive growth of water-based vegetation and algae, leading to oxygen depletion and the smothering of aquatic life. Phosphorus has also been found to cause more frequent and intense algae blooms, which may become toxic. These toxic algae blooms have been associated with pet deaths and skin irritation and gastrointestinal issues in humans.

The ordinance, which will not take effect until 2011, limits the non-agricultural use of phosphorus fertilizers in unincorporated King County. It prohibits the use of fertilizers— whether or not they contain phosphorus—on impervious surfaces like driveways or sidewalks. Phosphorus fertilizers can be used in the first calendar year of a new lawn or where a soil test shows low levels of soil phosphorus.

Golf courses may continue to use phosphorus fertilizers if they have a plan for the prevention of water runoff. The use of biosolids and mulches will be allowed even though they may contain phosphorus.

“Reducing the use of phosphorus fertilizers will make our lakes safer for people and fish,” said Councilmember Larry Phillips, co-sponsor of the ordinance and Chair of the Regional Water Quality Committee. “Limiting use of phosphorus fertilizers will help educate the public about the environmental harms excess phosphorus levels pose to our waterways and make consumers aware of the effective, inexpensive non-phosphorus fertilizers that are readily available.”

The ordinance includes outreach efforts to inform the public about the limits on fertilizer use and alternatives that can be used to maintain healthy lawns. King County TV will partner with the Department of Natural Resources (DNRP) to develop a video feature that will play on KCTV throughout 2010. DNRP will also identify opportunities for grant funding and partnerships to support education and outreach efforts, and encourage local cities to implement similar legislation.

“There is a growing interest and concern in the safety of the products we use, the foods we eat, and their impact on the environment,” said Patterson. “Because many people are unknowingly damaging nearby lakes and streams, it is important that public education be the primary tool in changing the fertilizers we use. This legislation focuses on education and outreach to cities and residents, in order to help them better understand the dangers of phosphorus in fertilizers.”


Read the legislation