Managing stormwater is a major challenge for urban and suburban areas, and it plays a big role in contributing to water pollution. While storm sewers help prevent flooding, they also carry pollutants from streets, lawns, and parking lots directly into local rivers and streams. By being mindful of how our everyday actions affect stormwater, we can reduce water pollution, protect clean water, and keep our rivers healthy.
Storm Sewers Move Stormwater to Rivers
Ideally, water is able to seep into the ground when it rains. From there, water travels through the ground into rivers. Rivers are nature’s drainage system and eventually bring local stormwater into the ocean. However, urbanization disrupts this natural process. Now, roads, parking lots, and buildings cover the ground, preventing water from soaking in and flowing to rivers.
To prevent stormwater from flooding our roads and homes, we install storm sewers to carry the water away. Stormwater sewer systems efficiently transport rainfall from storm drains to rivers. This is great for stormwater management but can have consequences for river health and water quality. As stormwater moves quickly over hard surfaces and into storm stewers, it picks up everything along the way and carries it straight into our rivers and streams. All that dirt, grime, and litter on the streets and ground? Rainfall will sweep it all up. While we enjoy the free cleaning rain provides, all that filth is just moved into local waterways.
Let’s take a closer look at some of the pollutants on the landscape that end up in rivers and streams:
Chloride from Road Salt
Rising chloride levels in local waterways are causing problems for fish, insects, amphibians, and aquatic plants. Chloride comes from road salt that is spread on the road to melt snow and ice in the winter. The melted snow flows off the roads into storm drains and rivers, taking toxic chloride with it. Leftover salt residue can continue to pollute our rivers well into the summer, months after we have stopped applying salt for the year.
Excess Nutrients
Nutrients are another critical pollutant that is easily washed into rivers. Nutrients in the right amount are important, allowing people, animals, and plants to grow up healthy and strong—but too much can become harmful and even toxic. In rivers, excessive nutrients, or eutrophication, can cause widespread algae blooms. These blooms hurt aquatic life, and some species like cyanobacteria release toxins into the water that can sicken and kill animals and people.
These nutrients come from several sources. Much of it comes from our wastewater in urban areas. Wastewater treatment plants are able to remove most of the nutrients in waste, but some still ends up in rivers. Nutrients can also wash off from land application of fertilizers. In rural areas, farms are the biggest source of nutrients from fertilizers. In urban areas, golf courses and residential lawns account for the most fertilizer use.
Soil Erosion and Debris
Even something as simple as bare ground can have an impact on water quality. Stormwater often washes loose soil into storm sewers, which then clouds rivers with mud. Similarly, litter and debris laying on roadsides gets washed into rivers too.
There is no way to avoid the fact that what we do on land, even small bits of land like our yards, can have cumulative impacts on our rivers. That’s why it’s so important to be mindful that what we do on the landscape can either help or hurt our river health.
Stormwater Solutions for Clean Water
Fortunately, simple changes can help us start to reduce pollutants like chlorides, excess nutrients, soil, and litter.
For chlorides, we need to use road salt to keep us safe in the winter, but we can be smarter and more efficient with how we use it. For example, better weather forecasting, routine equipment calibration, and proper application can drastically reduce the amount of salt we need while still maintaining—or even improving—safety on roads and walkways.
We can also reduce our nutrient impacts by using regenerative agriculture techniques that require less fertilizer. Homeowners can also reduce nutrient runoff by making sure they apply only as much fertilizer as plants need and when no rain is in the forecast for a few days. If you want to make a big difference, you can even convert some or all of your yard into native landscaping. Not only do wildflowers and other native plants look nicer than grass, they don’t require fertilizer and have deep roots that soak up stormwater.
Picking up litter and throwing it away keeps it out of rivers and stops it from ultimately washing to the ocean. You can also wash your car at a commercial facility, where they recapture wash water and clean it at treatment plants. It may cost a little more than doing it in your driveway, but it prevents soap, grease, dirt and other harmful chemicals from flowing down storm drains into rivers. If you see a pile up of leaves or other debris around a storm drain, take a minute to clear it away. Blockages lead to localized flooding and other issues.
Small Changes for a Big Impact on Clean Water
The health of our rivers has something to do with all of us. Over-applying fertilizer in your yard one time doesn’t destroy the river, and picking up one piece of litter doesn’t save it. But, when all of us degrade the water in small ways, it adds up fast. On the other hand, when all of us chip in to keep our water clean, it also adds up for a big impact and a healthy river!
Written by Alex Handel, Environmental Scientist at The Conservation Foundation
