My Aquifer > For Private Well Owners > Useful well definitions.


Aquifer: A natural underground layer, often of sand or gravel, that contains potable water.

AST (Aboveground Storage Tanks): Sites with aboveground storage tanks.

Bored Well: Bored wells are excavated with earth augers. Bored wells are usually cased with concrete pipe. Bored wells are the modern equivalent of the older dug wells.

Borehole: The well shaft. Must be lined with a solid pipe that seals out contaminants and stabilizes the hole.

Casing: The lining in the borehole.

CERCLIS: This includes sites considered for listing under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA). CERCLA, more commonly known as "Superfund", is designed to clean up hazardous waste sites that are on the national priority list (NPL).

Consolidated Formation: Subsurface geologic formation in which the particles are firmly cemented together (such as slate, sandstone, or granite).

Dairy: Sites included in the primary contaminant source inventory represent those facilities regulated by Idaho State Department of Agriculture (ISDA) and may range from a few head to several thousand head of milking cows.

Deep Injection Well: Injection wells regulated under the Idaho Department of Water Resources generally for the disposal of stormwater runoff or agricultural field drainage.

Drilled Well Construction: Drilled wells use either percussion or rotary construction methods. Percussion drilling repeatedly drops a heavily weighted chisel bit to break up the formation at the bottom of the borehole. For rotary drilling, a cooling solution is circulated in the hole to protect the fast-moving drill stem as it moves downward.

Dug Wells: Wells that are relatively large in diameter, usually excavated by pick and shovel. They are often lined with brick, rock, concrete, or vitrified clay. These wells were common before World War II. Most were dug with a pick and shovel, and are much more shallow than drilled wells. You've probably seen photos of old-fashioned wells with crank-down baskets--those are examples of dug wells. The large opening makes it difficult to keep contaminants out of the well.

Driven Well Construction: Driven wells are built by driving a small diameter pipe, equipped with a drive point and screen, into the earth. This isn't a good method for deep wells that must be dug in hard soils. Shallow driven wells are often installed by homeowners or farmers - individual's who usually lack the equipment or expertise to construct the well with proper protection.

Enhanced Inventory: Enhanced inventory locations are potential contaminant source sites added by the water system. These can include new sites not captured during the primary contaminant inventory, or corrected locations for sites not properly located during the primary contaminant inventory. Enhanced inventory sites can also include miscellaneous sites added by the Idaho Department of Environmental Quality (DEQ) during the primary contaminant inventory.

Floodplain: This is a coverage of the 100-year floodplains.

Inorganic Contaminant (IOC): Examples include nitrates, fertilizers, metals, etc.

Inorganic Priority Area: Priority one areas where greater than 25% of the wells/springs show constituents higher than primary standards or other health standards.

Jetted Well Construction: Uses high-pressure water to dislodge soil and wash it away. In dense or partially consolidated formations, a chisel bit may be used with the jet to help break up the formation.

Landfill: Areas of open and closed municipal and non-municipal landfills.

LUST (Leaking Underground Storage Tank): Potential contaminant source sites associated with leaking underground storage tanks as regulated under RCRA.

Mines and Quarries: Mines and quarries permitted through the Idaho Department of Lands.

Nitrate Priority Area: Area where greater than 25% of wells/springs show nitrate values above 5mg/l.

NPDES (National Pollutant Discharge Elimination System): Sites with NPDES permits. The Clean Water Act requires that any discharge of a pollutant to waters of the United States from a point source must be authorized by an NPDES permit.

Organic Priority Areas: These are any areas where greater than 25 % of wells/springs show levels greater than 1% of the primary standard or other health standards.

Recharge Point: This includes active, proposed, and possible recharge sites on the Snake River Plain.

RICRIS: Site regulated under Resource Conservation Recovery Act (RCRA). RCRA is commonly associated with the cradle to grave management approach for generation, storage, and disposal of hazardous wastes.

SARA Tier II (Superfund Amendments and Reauthorization Act Tier II Facilities): These sites store certain types and amounts of hazardous materials and must be identified under the Community Right to Know Act.

Synthetic Organic Contaminants (SOC): Examples include petroleum products (gasoline and diesel fuels), pesticides, etc.

Toxic Release Inventory (TRI): The toxic release inventory list was developed as part of the Emergency Planning and Community Right to Know (Community Right to Know) Act passed in 1986. The Community Right to Know Act requires the reporting of any release of a chemical found on the TRI list.

Unconsolidated Formation: Subsurface geologic formation in which the particles are not firmly cemented together (such as sands, gravel, or saprolite (soft, disintegrated rock remaining in its original place).

UST (Underground Storage Tank): Potential contaminant source sites associated with underground storage tanks regulated as regulated under RCRA.

Volatile Organic Contaminants (VOC): Examples include petroleum products (gasoline and diesel fuels), solvents, degreasers, etc.

Wellheads: These are drinking water well locations regulated under the Safe Drinking Water Act. (The actual wellhead is the top of the well, the part you can see at the surface.)

Yield: The rate at which water flows into the well during pumping (for example, 100 gallons per minute).