Fresh Water Flows

Fresh water flows from the clouds to the oceans. It percolates through sands, gravels, and soils. It flows down creeks and rivers and out to seas and lakes. It grows our food and quenches our thirst. It sustains our lives. 

Fresh Water Facts

Earth's Water Reserves

1. Only 2.5% of water on earth is fresh water

  • Only 1.2% of that 2.5% of fresh water is surface water
  • 30.1% is groundwater
  • The remaining fresh water is locked away in polar ice caps

2. Unlocked freshwater will be consumed, evaporate or flow to a river, eventually reaching a lake or ocean

3. The direction of the flow of water depends on its origination

  • Water follows a series of divides, watersheds and tributaries
  • Water carries oils, waste and other pollutants as it flows

4. The U.S. continental divide along the Rocky Mountains separates the flow of water between the East and West sides of America.

  • Ridges and hills divide watersheds from one another
  • Water flowing in its specified watershed will flow into tributaries
  • Tributaries connect with larger streams or rivers that flow into a confluence
  • Confluences feed into lakes, river basins or river deltas.
  • River deltas feed into oceans

Watersheds are “an area of land that drains all the streams and rainfall to a common outlet such as the outflow of a reservoir, mouth of a bay, or any point along a stream channel.”

Tributaries are “small streams that feed into larger streams or rivers. The larger, or parent, river is called the mainstem. The point where a tributary meets the mainstem is called the confluence.”

Fresh water watershed
Image: Hawaii Association of Watershed Partnerships

Fresh Water Pollutants

The flow of water not only pushes water in the direction of flow, but also pushes everything that water carries like sands, sediments, rocks, plastic pollution, agricultural/farm animal & human sewage, micropollutants (hormones, pharmaceuticals), fertilizer pollution and oil pollution. These particulates reduce water quality and often turbidity.

Turbidity refers to the relative clarity of water and is often related to cloudiness or haziness.

Pollutant Impacts

  1. Fish and other aquatic wildlife feed on micro-plastics or absorb oil droplets found in waterways.
    1. This bioaccumulates in their bodies and is transferred to humans when ingesting contaminated fish.
  2. Water contamination can also impact our drinking water, as experienced in Flint, Michigan and cities across every state in the U.S.
  3. Nutrients like fertilizers, sewage, or poorly treated wastewater impact chlorophyll content causing eutrophication and dead zones.

Eutrophication is excess nutrients (nitrogen and phosphorus) entering waterways leading to algal blooms, depleting oxygen in aquatic systems, killing aquatic life.

Anthropogenic Changes

Channelized Waterways

U.S. cities have channelized waterways in order to control water flow. Channelizing waterways turns river bedrock into concrete, destroying ecosystems.

Channelization increases the flow of water making it more difficult for aquatic life to survive. It also changes flood patterns, altering nutrient deposits in soils.

Household Consumption

On average an individual in the US uses 68 gallons of filtered water per day to shower, brush their teeth, run the dishwasher and washing machine, and use the toilet.

Conversely, some individuals in Africa survive on no more than 5 gallons of water per day. This water is often contaminated with water-borne diseases.

Industry Consumption

Agriculture requires significant water demands, particularly in drought-prone areas. Irrigation techniques and timing of irrigation directly relate to quantity of consumption.

Freshwater is also used in extraction processes. When fracking for natural gas, water is mixed with chemicals, many carcinogenic, and pumped underground, where the water is left.

Rain Garden in Bay View Michigan

Improving Water Systems

Household Consumption

Turn off faucets at home to reduce consumption.

Water plants in the early morning or evening.

Switch to phosphate-free detergents

Reduce fertilizer and herbicide usage in yards or gardens.

Install Sustainable Systems

Greywater systems filter soap-soiled water for re-use in gardens.

Rainwater catchment systems are useful for gardens too.

Rain gardens help reduce stormwater run-off and prevent contaminants from polluting rivers and lakes.


Desalination converts saltwater to freshwater through reverse osmosis.

It is an expensive investment and requires high energy inputs.

San Diego recently invested $1 billion into a desalination system to feed 7% of the city’s freshwater consumption.

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