Stormwater Pollution

STORMWATER POLLUTION IN MEDINA?

Did you know that rainwater picks up chemicals, metals and other toxic substances when it runs off our roofs, streets and lawns? This runoff water, known as stormwater can carry pollutants to Lake Washington and eventually become concentrated enough to harm water quality & aquatic ecosystems. There are several sources of pollutants which many residents may not be aware of. For example, draining chemical-laden pool/hot tub water into the street will make its way to Lake Washington where it can kill off fish and seriously threaten water quality.

One of the City’s major sources of stormwater pollution is fertilizers. Fertilizers are made of nutrients, such as nitrogen and phosphorus. (As of April 15, 2011 fertilizers containing phosphorus is prohibited per ESHB 1489) When it rains, these nutrients are carried by stormwater into the nearest stream or body of water. Too many nutrients can cause algae to grow, which uses up the oxygen in the water. Low levels of oxygen in water can hurt aquatic wildlife and even lead to fish kills. Fish kills can be caused by algal blooms, harmful bacteria, viruses, pesticides and herbicides in the water. When large numbers of fish die in water, they decompose, which further decreases the amount of dissolved oxygen available in the water for fish to breathe.

Algal blooms are caused when excessive amounts of nutrients enter slow-moving bodies of water. Nutrients, such as nitrogen and phosphorous, act as fertilizers that help algae grow in water. Algae uses dissolved oxygen to fuel night-time growth, when sunlight is unavailable for photosynthesis. When dissolved oxygen levels fall beneath certain levels, fish and other aquatic creatures can no longer survive.

You may not see the effects of fertilizers in stormwater right where you live, but their detrimental effects are very apparent in the Medina Park Ponds and numerous bays along Lake Washington.

Vehicles are also another source of many pollutants in stormwater. Oil, antifreeze, and other fluids often leak from cars onto parking lots or are spilled during maintenance. Normal automobile use also creates copper and other heavy metal dust, which settles onto surfaces wherever vehicle exhaust exists.

Another source of pollution that might not be apparent is bacterial contamination. Bacteria may come from pet, wildlife, or human waste. When waste is left outside, it is easily transported to nearby waterways by stormwater. Human waste may enter streams and rivers through sewer overflows, leaks in the sanitary sewer system, or failing septic systems. Pet waste is primarily from dogs, although cats may contribute some as well.

Fishing, boating, and swimming are all more dangerous in bacteria-contaminated waters. Bacteria can cause diseases and dangerous infections in animals and people that come in contact with the water.

Litter is also a stormwater pollutant. Litter thrown on the ground can end up in the storm drains, ditches and streams. Stormwater runoff carries large quantities of street litter to streams, rivers, and lakes.  Street litter is often made of plastics. Plastics take hundreds of years to biodegrade and can be harmful to birds and animals, which can become entangled in it or mistake it for food.

So, what can be done to help?

There are simple things you can do to help reduce stormwater pollution. Store chemicals away from rainwater and dispose of them properly. Maintain vehicles so they don’t leak. Wash your car at a car wash or on grass or gravel so water can sink in, instead of running off into storm drains (which do not treat water before releasing it to streams). Pick up after your pet, and dispose of pet waste in the toilet or trash. If you have a septic system, follow proper maintenance procedures. If you suspect a sanitary sewer overflow or leak, contact your local sewer authority immediately. Limit fertilizer use or consider organic alternatives. Pick up trash around your yard, street, parks, etc. Not only does this help animals and the environment, you’re doing your community a favor too!