Connecting Streets to Lakes: The Hidden Path to Water Pollution

It’s a sunny, calm day at Como Lake. Painted turtles bask on a log as a green heron sits on a low branch nearby. Subtle flashes of fins from bluegill sunfish and minnows are visible through the lake’s surface alongside an abundance of native aquatic plants. The colorful asters and coneflowers blooming along the shoreline hum with busy bumblebees and fluttering butterflies. Paddleboarders and kayakers dot the lake, soaking up the September sunshine. Como Lake is a treasured destination, but would you guess that trash, oil and pet waste on a street over a mile away flow to Como Lake without any treatment?

Illicit Discharge

Protecting our lakes, rivers and wetlands is critical. Did you know rainwater and snowmelt from paved surfaces like streets, sidewalks, parking lots, and rooftops flow to storm sewer systems that drain to nearby waterbodies without treatment? Anything on paved surfaces – like trash, dirt, and motor oil – is carried by rainwater or snowmelt to a storm drain and can pollute our lakes, rivers, and wetlands. This type of pollution in our storm sewer systems is called an illicit discharge. Only water belongs in storm drains. Illicit discharges reduce water quality and can harm animals in and near the water.

Sources

The sources of an illicit discharge can be residential, commercial, industrial, municipal, or historic land use – like the site of a former dump or factory with lingering chemicals.

Common types of illicit discharges are trash, sediment, soil, pet waste, leaves and grass clippings, sanitary sewer back-ups, concrete washouts, chemical spills or dumping, incorrect fertilizer application, road salt spills, and others.

These pollutants can cause problems in our lakes, rivers, and wetlands, such as increased algal growth, harmful levels of bacteria like E. coli, habitats covered by sediment, dangerous chemicals in the water, and blockages of the storm sewer.

Solutions to Detect and Eliminate

With some types of illicit discharges, you may see oily or discolored black, brown, or gray water or an iridescent rainbow sheen. Or there could be debris flowing into a storm sewer. What can you do if you spot or suspect an illicit discharge? Try to contain the discharge if you have the right resources and can do so safely. Report the case to the relevant city if it’s stationary and does not create an immediate danger. Call local law enforcement if the illicit discharge poses a serious or immediate safety hazard or is active. When reporting an illicit discharge, provide documentation if you have it, share your observations and any actions you took, and note the date, time, and precise location.

CRWD staff can track illicit discharges through the storm sewer system to find their sources and the responsible party. To resolve an illicit discharge, CRWD coordinates with municipal and state partners, and offers technical support and problem-solving to eliminate illicit discharges.

Prevention

Now you know what to do if you spot an illicit discharge, but how can you help prevent one? Picking up pet waste, containing trash and recycling bins, cleaning up litter, stabilizing loose soil, washing vehicles in a car wash or on the lawn instead of a driveway, sweeping up grass clippings, and raking leaves away from the curb and boulevard are all ways to prevent illicit discharges.

You can protect our lakes, rivers and wetlands by volunteering to keep a storm drain near you clear of leaves and litter. Volunteering for fifteen minutes twice a month makes a big difference in water quality. Learn more and sign up at Adopt a Drain MN.

 

Clean Streets Lead to Clean Waters

Large industrial containers sit on a muddy ground with pools of murky water and patches of green vegetation.
Leaking containers at an industrial site released dye into the environment.
A parking lot storm drain with debris on the grate, and a patch of dried, white spill leading to the drain from across the parking lot..
Improperly stored sand and salt flow to a storm drain and directly to the Mississippi River.
Muddy water with erosion from a construction site flows along a curb to a storm drain during a rainstorm. The drain is covered with leaves and debris.
Bare soils at construction sites erode easily, releasing sediment into the storm sewer.
A sloped concrete wall along a paved roadway with cloudy, gray water pooling along the wall's base.
Not all illicit discharge is obvious, here a green clay tennis court overflows into an alley.
A stream with muddy water draining from a large hose running down the stream bank from a blue truck in a construction site. Trees and vegetation are on both sides of the stream with an old stone tunnel in the background.
Improper management of sediment laden water can have serious environmental impacts. A contractor was pumping sediment directly into an adjacent stream and severely damaged the aquatic ecosystem.
Dark brown motor oil pools in water flowing along a street curb.
Negligent waste management practices at car repair garage resulted in an engine oil spill onto the curb and stormsewer leading to a nearby lake.
A long, twisted fabric tube of a silt log from a construction site lays along a street curb with muddy water flowing past it.
Improper water management at a construction site released a large amount of sediment into the storm sewer.
A drainage grate in a parking lot with a large plume of chalky, gray clay from water that flowed to the drain. A pile of brown leaves is on the side of the drain, also covered in gray clay. A car is parked in the background.
Clay slurry from a utility installation was not properly contained and flowed to a storm sewer that drains to the Mississippi River.

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