98% of Phoenix's water supply relies heavily on surface water sources, the (Salt, Verde, and Colorado rivers combined). Only 2% groundwater in the current supply.

• 52% comes from the Salt and Verde rivers
• 38% comes from the Colorado River
• 8% is reclaimed water

• Only 2% comes from groundwater.

What is Surface Water : Water that collects on the surface of the earth, such as in rivers, lakes, reservoirs, and streams. Examples in Arizona: Colorado River, Salt River, Verde River, Lake Mead, Lake Powell.

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What is Ground Water :  Water located beneath the earth's surface in soil pore spaces and fractures in rock formations. Examples in Arizona: The Central Arizona Groundwater Basin, Prescott Basin, and other regional aquifers.

Surface Water :

Colorado River Basin: A major source supplying water to multiple states, including Arizona. Key reservoirs include Lake Mead and Lake Powell.

‍Salt and Verde Rivers: Crucial for municipal and agricultural use within Arizona.

‍Other Rivers and Lakes: Serve regional needs and recreational purposes.

‍Groundwater :

Central Arizona Groundwater Basin: The most significant groundwater source for Phoenix and surrounding metropolitan areas.

‍Basins in Northern Arizona: Include the Prescott and Flagstaff basins, supplying water to their respective regions.

‍Recharge Areas: Primarily mountainous regions where precipitation infiltrates the ground to replenish aquifers.

Usage Statistics:

Surface Water:

Agricultural Use: Approximately 60-70% of Arizona's surface water is allocated for agriculture.

‍Municipal Use: Urban areas, including Phoenix, rely on surface water for a significant portion of their supply.

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‍Groundwater:

Municipal Use: Phoenix Metropolitan Area depends heavily on groundwater, especially during droughts.

‍Agricultural Use: Supplementary use in regions where surface water is scarce.

‍Residential Use: Individual wells for households in rural and suburban areas.

Contaminants:

Agricultural Runoff: Pesticides, fertilizers, and sediment.

‍Industrial Discharges: Heavy metals, chemicals, and thermal pollution.

‍Urban Runoff: Pathogens, oils, and urban pollutants.

‍Treatment Challenges:

Pathogen Control: Requires effective disinfection processes to eliminate bacteria and viruses.

‍Chemical Removal: Necessitates advanced treatment for contaminants like nitrates, heavy metals, and organic pollutants.

‍Groundwater Quality Contaminants:

Natural Contaminants: Arsenic, fluoride, and selenium from geological formations.

‍Anthropogenic Contaminants: Nitrates from fertilizers, heavy metals from industrial activities, and volatile organic compounds (VOCs) from improper disposal.

‍Protection Measures:

Wellhead Protection: Securing areas around wells to prevent contamination.

‍Regulation and Monitoring: Regular testing and adherence to safety standards to ensure water quality.​

Surface Water in Phoenix:

Primary Source: Reliant on the Salt and Verde Rivers, along with Colorado River allocations.

‍Infrastructure: Includes major reservoirs like the Salt River Project (SRP) and Verde River facilities.

‍Challenges: Managing allocations amidst prolonged droughts and increasing demand.

‍Groundwater in Phoenix:

Primary Source: The Central Arizona Groundwater Basin is crucial, especially during surface water shortages.

‍Sustainability Efforts: Initiatives to reduce reliance on groundwater, such as water recycling and conservation measures.

‍Issues: Over drafting leading to declining water tables and potential land subsidence.​