We recently posted about the possiblity of a pet getting sick from pesticides used on grass in Cal Anderson Park. I sent a mail to the city parks department and asked them about what they put on the grass. Here is what I got. It’s a form response but does include an interesting point — worrying about pets ingesting fertilizer is one thing but there’s also drinking water under there. Hoping all the magic growing elixirs they talk about are as innocuous as they seem. It sounds possible that your doggie might get sick from being on the grass too soon after a fertilizer application. Maybe the parks department can put out a sign to let people know when they’ve fertilized. As for pesticides, they say they’re already signing when they use bug killer.

So, can any green thumb types out there corroborate the city’s claims? Considering the public water resources down below, I tend to believe they’re being careful.

Frequently Asked Questions
About landscape and turf grass management
at Cal Anderson Park

Here are some answers to questions park users commonly ask about our maintenance activities. If you have a concern about the park, please contact Crew Chief Jon Martin or Senior Gardener Jeanie Taylor at 206-684-4750.

What are you putting on the grass?
We apply very specific fertilizers to the grass on the lid over the reservoir. To protect the drinking water supply, Public Health – Seattle & King County and Seattle Public Utilities require that we only use products that are very safe and that will not leach into the enclosed area where the water tanks are located.

We apply a slow release nitrogen fertilizer in a dry form that releases nutrients and is taken up immediately by the grass plants. We also use a liquid phosphorus product combined with other liquid nutrients to promote root and leaf growth and to enhance soil microbial activity. These products are approved because they do not contain toxic levels of metals or other contaminants.

Future applications may change as new, improved formulas are developed.   We do use conventional dry fertilizers on other areas not over the lid, and we leave grass clippings and mulch leaves to let the decomposing organic matter add nutrients to the soil.

Do you use pesticides in this park?
We occasionally need to use a very small amount of glyphosate, the active ingredient in Roundup®, to kill grass and weeds in the path or around trees to make it easier to mulch and keep the tree wells free of weeds. This is used very sparingly because of our limited maintenance hours, and we post signs  when an application is made. Pesticides are never allowed on top of or within 20 feet of the reservoir lid. We may experiment with products that are non-toxic when applied, such as corn gluten, a natural fertilizer and a pre-emergent weed killer that prevents germination of annual weed seeds, and we will hand-pull weeds in the grass if necessary.

Why is there standing water in the grass area?
Because the soil is comparatively shallow over the lid, and because construction activities tend to compact the soil, there have been some drainage issues that we are trying to correct by aerating the soil, feeding the turf grass, and topdressing with sand for drainage. The look of the grass should improve as time goes on and the turf becomes better established.

You can help prevent turf damage by keeping your dog on a leash and by making sure you scoop pet waste. If you notice a broken sprinkler head, a washout, or a very wet area, please call us, because it may indicate a problem with the irrigation system that we did not know about.

Thanks for your stewardship of Cal Anderson Park!