Managed recharge occurs when surface water or treated wastewater is intentionally added to an aquifer or the zone of saturation below the water table either through injection wells or by applying water to the land surface (land application), allowing the water to infiltrate down.
Recharge through Injection Wells: An IDWR Responsibility
Injection wells are regulated by the Idaho Department of Water Resources (IDWR). Injection wells can directly or indirectly cause negative impacts to ground water resources. A permit is required. Learn more.
Monitoring of Ground Water: Recharge through Land Application: A DEQ Responsibility
Recharge by land application has the potential to impact the quality of ground and surface water. A monitoring program is necessary to determine if recharge activities are degrading ground water quality and/or adversely impacting beneficial uses.
When surface waters are land applied with the intent to recharge an underlying aquifer, no permit is required. However, DEQ is authorized by Idaho's "Wastewater Rules" (IDAPA 58.01.16.600) to require and approve a program to monitor ground water quality when surface waters are land applied. The monitoring plan must demonstrate that the soil and geology at a recharge site provide the level of treatment that will not allow movement of contaminants into the underlying ground water and that the soils and vegetative cover are capable of removing contaminants from the recharge water. The frequency and data submittal will depend on the following:
- Nature and volume of recharge water,
- Frequency and duration of application, and
- Characteristics of the site’s soil and underlying geologic material.
Section 600 of the Wastewater Rules further defines that the basis for evaluating and approving a monitoring program is determined by the following items:
- Type of recharge water for land application will not adversely affect a beneficial use of waters of the state.
- Nature of the soil and underlying geologic materials at the site provides reasonable assurance that the level of treatment is adequate to prevent pollutants in recharge water from reaching ground water.
- Soils and vegetative cover have the ability to remove pollutants in the recharge water.
An approved monitoring plan must also include water quality sampling, frequency, and reporting appropriate for the recharge site and existing water quality.
When treated wastewater, including Class A effluent, is land applied with the intent to recharge an underlying aquifer, a permit is required under Idaho's "Recycled Water Rules" (IDAPA 58.01.17). DEQ administers this permitting program.