Watersheds

All the Water in the World

 

It is all Connected

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.

watershed

What is a Watershed

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.

watershed

North American River Basins

North American river basins...

Find your Hydrologic Unit Code (HUC)

The United States is divided and sub-divided into successively smaller hydrologic units which are classified into four levels: regions, sub-regions, accounting units, and cataloging units. The hydrologic units are arranged or nested within each other, from the largest geographic area (regions) to the smallest geographic area (cataloging units). Each hydrologic unit is identified by a unique hydrologic unit code (HUC) consisting of two to eight digits based on the four levels of classification in the hydrologic unit system.

The second level of classification divides the 21 regions into 221 subregions. A subregion includes the area drained by a river system, a reach of a river and its tributaries in that reach, a closed basin(s), or a group of streams forming a coastal drainage area.The first level of classification divides the Nation into 21 major geographic areas, or regions. These geographic areas contain either the drainage area of a major river, such as the Missouri region, or the combined drainage areas of a series of rivers, such as the Texas-Gulf region, which includes a number of rivers draining into the Gulf of Mexico. Eighteen of the regions occupy the land area of the conterminous United States. Alaska constitues region 19, the Hawaii Islands are region 20, and Puerto Rico and other outlying Caribbean areas are region 21. [The regions are shown in figure 1.]

The third level of classification subdivides many of the subregions into accounting units. These 378 hydrologic accounting units are nested within, or can be equivalent to the subregions.

The fourth level of classification is the cataloging unit, the smallest element in the hierarchy of hydrologic units. A cataloging unit is a geographic area representing part of all of a surface drainage basin, a combination of drainage basins, or a distinct hydrologic feature. These units subdivide the subregions and accounting units into smaller areas. There are 2264 Cataloging Units in the Nation. Cataloging Units sometimes are called "watersheds".

 

EPA Tracking

EPA...

USGS Monitoring

USGS Streamcat...

Storm Drains

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.

Dead Zones

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.

Aligned Watershed Organizations