Seattle Public Utilities Mami Hara, General Manager/CEO

Yard Care

Clean water tip

How can you fertilize and help keep our waters clean?

  • Use fertilizers sparingly. Many plants do not need as much fertilizer or need it as often as you might think.
  • Don't fertilize before a rain storm.
  • Consider using organic fertilizers; they release nutrients more slowly.
  • Use commercially available compost or make your own using garden waste. Mixing compost with your soil means your plants will need less chemical fertilizer and puts your waste to good use. Commercial compost and soil amendments may be available from your solid waste or wastewater utility as well as your local garden store.
  • For more information on fertilizing alternatives and composting, call your local Cooperative Extension's Master Gardeners program or the Garden Hotline at (206) 633-0224 or

What's the problem with fertilizer?

Fertilizer isn't a problem -- if it's used carefully. If you use too much fertilizer or apply it at the wrong time, it can easily wash off your lawn or garden into storm drains and then flow untreated into lakes or streams.

Just as it does in your garden, fertilizer in lakes and streams makes plants grow. In water bodies, extra fertilizer can mean extra algae and aquatic plant growth.

Too much algae harms water quality and makes boating, fishing and swimming unpleasant. As algae decay, they use up oxygen in the water that fish and other wildlife need.

Related links

Natural Lawn and Garden Care