Surface Water
Rivers, lakes, streams, ponds, wetlands and oceans are all examples of surface water. Continually replenished by precipitation or rain runoff, surface water is a body of water easily seen as it flows downhill to where it collects.
If you were to take all of the water on Earth and measure it in terms of miles, it would equal approximately 326 million cubic miles. Put another way, if those same 326 million cubic miles were poured onto the United States, you would have to swim about 90 miles straight down before touching land!
About 4% of its land mass in the United States is covered by surface water. In fact, the Great Lakes, located in the northeastern part of the U.S., cover 98,000 square miles and contain about one-fifth of the Earth's freshwater supply. However, in other parts of the United States such as the western states, which include large areas of desert, supplies of freshwater are limited.
In order to ensure that surface water bodies and groundwater remain healthy, the federal government passed the Clean Water Act of 1972. This law requires the federal government to regulate the quality of the nation's water supply through two major strategies. First, the federal government is required to provide financial assistance to build sewage treatment facilities to clean wastewater before it's released into a local water body. Second, all industries and cities must obtain a permit through the National Pollution Discharge Elimination System before wastewater is released into a waterway.
The Clean Water Act was amended in 1987 and 1995. The 1987 amendments focus on four main areas: water toxins such as heavy metals and organic chemicals, sources of non-point pollution, increased responsibilities and requirements for state government, and reducing federal financial assistance for the building of local sewage treatment facilities. The Act's 1995 amendments focus on making its standards and regulatory requirements and wetlands permitting process more flexible. The amendments provide relief to businesses, states, local governments and individual landowners from what many of them viewed as excessive, impractical and costly regulations.
In California, under the Porter-Cologne Water Quality Control Act, the State Water Resources Control Board has ultimate authority over state water rights and water control policy. The Porter-Cologne Water Control Act also established nine Regional Water Quality Control Boards to supervise water quality on a day-to-day basis both locally and regionally for surface water and groundwater. This law works in conjunction with the Clean Water Act to grant National Pollutant Discharge Elimination System permits for certain point-source pollution discharges.
At both the federal and state level, laws such as the Clean Water Act and the Porter-Cologne Water Quality Control Act help to ensure that surface water bodies and groundwater sources remain healthy to meet a variety of uses. Often uses such as agriculture, fishing, industry, transportation, drinking and recreation are in direct competition with one another because each one may be dependent on the same source of water. Therefore, the protection, restoration and improvement of surface water bodies and groundwater sources are important to everyone.
Because of this uneven distribution of freshwater supplies, it is extremely important that sources such as rivers and lakes remain healthy. Freshwater bodies rely on a never-ending aquatic life cycle to maintain their health. Typically, a healthy aquatic life cycle includes these components:

- Oxygen: A gas upon which most life depends. Water contains dissolved oxygen. The amount of oxygen has a direct relationship between the size and number of animals found in a body of water.
- Phytoplankton: Microscopic free-floating green plants. These small plants form the beginning of an aquatic food chain. Additionally, phytoplankton take in sunlight, convert the sunlight into food and release oxygen into the water to be used by another life. This process is called photosynthesis.
- Zooplankton: Microscopic free-floating animals. These small animals eat phytoplankton and, in turn, are eaten by larger animals along the aquatic food chain.
- Fish: A vertebrate (animal with a spine) that lives in water. Healthy bodies of water have different kinds and sizes of fish.
- Bottom Life: Animals that live on the bottom of a healthy body of water. Bottom life includes worms, snails, crayfish, mussels, clams and insect larvae.
- Sediment: Mud, Sand, or Gravel which has settled to the bottom of a body of water. A healthy body of water has sediment that is free of chemical pollution that settle to the bottom and are harmful to fish and bottom life.