Spring in Colorado comes with melting snow, precipitation and rushing stormwater. But impermeable surfaces like driveways, sidewalks and streets prevent the runoff from soaking into the ground. Instead, runoff water picks up residual amounts of chemicals, oils, fecal matter and other pollutants as it flows into the sewer system or directly into creeks and lakes. In the City of Boulder, it mostly goes to Boulder Creek.
Even though the quality of the water in Boulder Creek is good overall, according to city reports, there are elevated levels of Escherichia coli (E.Coli), which means there is fecal matter, from human sources, pets or wildlife, making its way into the creek. Water samples have also contained neonicotinoids, a type of insecticide, commonly used in agriculture, urban yards and for the prevention of termites and fleas.
Neonicotinoids are systemic, according to Aimée Code, pesticide program director of the Xerces Society, an invertebrate conservation group that has collaborated with the City of Boulder on research on declining bee populations. Even at extremely low levels, these chemicals are absorbed and circulated through a plant’s tissues, often killing the insects that feed on them, like bees.
“It is just easy for it to spread,” Code says. “As an insecticide, it was designed to be water soluble because then it would be uptaken by the plant, mov[ing] through plants and mak[ing] the plant poisonous for pests.”
Boulder banned the use of neonicotinoids in 2015, but the fact that residues keep showing up in water samples collected by the City shows that homeowners, landscapers and other people managing private property are still using these chemicals, according to Rella Abernathy, Boulder’s pest management coordinator. In some cases, the samples collected by the City showed the levels of neonicotinoids to be seven times higher than the safe benchmark set by the EPA.
Abernathy says she keeps hearing from residents about products they use which contain neonicotinoids, but acknowledges most of them are unaware they are using a harmful ingredient. With spring here, people want to make their gardens “healthy,” she says, but with that comes the need to educate the community. By trying to take care of lawns and gardens with the excess and sometimes unnecessary use of fertilizers and pesticides, chemical pollutants are bound to make their way into Boulder’s waterways.
“They use an all-in-one product that contains fertilizers and fungicide to take care of their plans, and they don’t know that’s a problem,” Abernathy says.
Once these chemicals make it into the creek, it has a cascading effect, according to Code, potentially killing or contaminating aquatic insects that are foundational to the larger ecosystem. Also, nearby plants can absorb creek water.
Meghan Wilson, Boulder’s communication manager, says neonicotinoids are linked to the decline of bees and can harm the ecosystem even at low levels. “Neonicotinoids are highly soluble and easily move from sites where they were applied into waterways, where they can kill or harm aquatic invertebrates, such as mayflies, caddisflies and dragonflies,” she says. “This indirectly affects fish, amphibians, birds and mammals that feed on these insects.”
The first step to avoiding contamination, according to Code, is to take a step back and rethink if your garden needs pesticides.
“Less than 2 percent of our yard insects are a pest. Often those insecticides aren’t making our yard more healthy. They can knock down beneficial insects,” Code says. “We should be excited to see larva eating our plants because that means we’re going to have caterpillars.”
If you do need pesticides or fertilizers, make sure you are using organic mulch or pest control methods that don’t contain neonicotinoids. Read the label and look out for imidacloprid, acetamiprid, dinotefuran, clothianidin and thiamethoxam, Code says.
Also, be careful with over-watering your lawn since excessive runoff wastes both water and chemicals you may have added to your yard. Do not fertilize if the forecast calls for rain in the next day or two. Use compost whenever possible instead of fertilizer and also compost the yard waste so it won’t go into the streets. Basically, anything that goes on the ground has the potential to end up in Boulder County Creek.
What we use in our yards, Code says, is going to move into streams and rivers. And there is no cleanup process, no water treatment along the way. “I think we need to be more aware, to be good stewards of the land, [to recognize that] what we’re using on our yards can be of harm.”