Inland Water and Where it Goes

What does it mean to live on the Continental Divide? What role do watersheds play on the water we drink locally and the ocean’s health around the world? The Continental Divide is the largest division of watersheds in the United States. On the eastern slope of the Continental Divide, the South Platte River and the Arkansas River are part of an extensive network of waterways that drain into the Gulf of Mexico. Likewise, the Colorado River, the largest watershed in the American Southwest, connects the western slope of the Continental Divide to the Gulf of California.

A watershed is an area of land that contains streams and rivers that all drain into a single body of water, such as a lake or the ocean. Watersheds can be big or small, but they all have high points like ridges and mountains that capture water, store it, and eventually release it downhill. Many of our actions impact watersheds, and as the rivers and streams flow downstream through communities, the ocean becomes the final resting place for much of the pollution and contaminants that these rivers and streams are carrying. 


A dead zone is an area where nutrient levels are so high that the oxygen has been largely or entirely depleted. Marine life living in this zone either flee if mobile or die. One of the largest dead zones on the planet is the Gulf of Mexico where the mouth of the Mississippi—one of Colorado’s drainage point—ends.

The Gulf of Mexico supplies:

  • 72% of US shrimp
  • 66% of harvested oysters
  • 16% of commercial fishing 

The impacts of dead zones can be devastating, both economically and environmentally. In Louisiana for example, the dead zone amounts to about 235,000 tons (470 million pounds) of seafood lost every year. Each year the size of dead zones shifts and grows. In 2015 it was nearly 6,500 square miles, roughly the size of Connecticut and Rhode Island combined. The dead zone ranges anywhere from 4,500-8,500 square miles of ocean.

Hypoxic zones can occur naturally, but they are greatly enhanced by human activity. Excess nutrients are the primary cause of dead zones. Nutrients lead to an overgrowth of algae, which eventually decomposes in rivers or the ocean, and oxygen is required to decompose the excess algae, depleting the surrounding water of the oxygen needed to support life. Marine life then either flee if able or are left to suffocate. 

There over 550 dead zones worldwide, and the second largest resides in the northern Gulf of Mexico. In the United States, dead zones are also prominent on along the East Coast and in the Great Lakes. 

Storm drains flow directly to our rivers and streams unfiltered. Water is NOT diverted to a treatment facility. Storm drain water flows straight to a river or stream and eventually to the ocean. When it rains, anything dumped on the ground, roads, sidewalks, and driveways is washed into storm drains and water bodies. This includes pet feces, cigarette butts, trash, plastic bags and oil. Over 200 million gallons of used motor oil are improperly disposed of each year in America alone. That amount of oil is equal to about 19 Exxon Valdez oil spills.

The accumulation of pollutants leads to diminished water quality. Cigarette butts are the most littered item in America, and have been found in the stomachs of fish, birds, whales, and other marine creatures that mistake them for food. They contain thousands of chemicals that are carcinogenic to humans and the chemicals leach into water harming aquatic and marine life. Filters contain plastic, which breaks down but never disappears.

Dog waste is considered to be toxic by the EPA. The droppings Fido leaves behind contain disease-causing bacteria that can make people and wildlife sick. Dog waste can carry E.coli, fecal coliform, salmonellosis and other diseases. When it rains, dog waste is carried into storm drains and impacts creek and human health.

Washing your car can also have negative effects on our watersheds. If you wash your car in your driveway or a parking lot, the soapy water that washes off your car travels down the driveway and street and into the storm drain.

Dirty car wash water contains toxic pollutants from the car and the soap. Contrary to popular belief, this dirty wash water does not get cleaned at a wastewater treatment plant before it enters into the nearest stream, lake or sound. These contaminants can harm fish and wildlife, pollute streams, lakes and rivers, and even seep into our groundwater, an important source of drinking water.