Well abandonment in the Treasure Valley: what homeowners & developers need to know

Hydro is the Treasure Valley’s well-abandonment specialist. If you’re selling property, redeveloping land, or decommissioning an old domestic or irrigation well, here’s a clear, local guide to doing it right—and why it matters.

Why proper abandonment matters (for you and for the valley)

• Protect our aquifers. Idaho’s Well Construction Standards exist to prevent old wells from acting like open straws that let contaminants or poor-quality water move between aquifers. The rules explicitly require decommissioned wells to not accept fluids or allow water to move between zones.

• It’s the law. Idaho’s Well Construction Standards Rules (IDAPA 37.03.09) apply to both construction and decommissioning (abandonment) of existing wells. Only licensed well drillers (or those with a Director-approved waiver) may abandon a well.

• Local groundwater is under pressure. Most homes in the Treasure Valley rely on groundwater; growth and land-use change have raised concerns about long-term sustainability and shallow-aquifer declines in some neighborhoods.

When a well must be decommissioned

The IDWR Director can require decommissioning if a well:

• fails to meet minimum construction standards,

• is unusable,

• poses a threat to health/safety,

• violates groundwater quality rules, or

• lacks a valid authorization for use.

Property owners are also responsible for maintaining and properly decommissioning wells to prevent waste and contamination.

Paperwork & timing (what IDWR requires)

Before any fieldwork, IDWR must authorize the abandonment:

1. File “Authorization to Abandon (Decommission) a Well” (Form 238-4-2) with your IDWR regional office at least 72 hours before work begins.

2. There’s no IDWR fee for the authorization.

3. Abandonment must follow IDAPA 37.03.09 and be performed by a licensed Idaho well driller (unless IDWR grants a waiver).

After the work, the driller files the abandonment report / driller’s report with IDWR (typically within 30 days of completion).

How abandonment is done in the Treasure Valley

Every well is site-specific, but here’s the standard approach we use locally to meet IDWR rules and protect your aquifer.

1) Locate, verify, plan

We pull Well ID records, confirm construction details (casing, screens, seal depths), and design the decommissioning method to match IDWR standards for your well type and geology.

2) Perforate-and-pressure-grout (common local method)

For cased wells that don’t have a continuous seal to surface, IDWR may require perforating the casing every five feet (at least four equally spaced perforations per circumference) from bottom up to near surface, then pressure-pumping approved grout to fill voids outside the casing and the annular space. This prevents vertical movement and aquifer commingling.

In parts of Boise/Meridian designated as a West Ada Area of Drilling Concern (ADC), additional protections apply, and IDWR has emphasized perforation and pressure-grout standards to safeguard the aquifer.

3) Alternative, if applicable

If the casing can be removed safely, IDWR allows filling the borehole with approved seal material as the casing is pulled. For fully sealed cased wells or uncased wells, the well is filled from bottom up with approved materials.

4) Approved sealing materials

IDWR recognizes bentonite (chips/pellets/grout) and neat cement/cement grout as approved seal materials; we choose mixes that suit the formation and groundwater conditions.

5) Surface completion & documentation

We finish to grade per rule, complete the abandonment report, and provide you with a record for real-estate, development, or lender files.

Surface-seal depths (the “38-/18-foot” rule of thumb)

For most wells deeper than 38 feet, surface seals must extend to at least 38 feet below land surface. For wells <38 feet, seals generally must extend to 18 feet or five feet into the confining formation, whichever is greater—details depend on the geology (unconsolidated vs. consolidated, artesian conditions).

Why this is especially important here

The Treasure Valley’s aquifer system includes shallow, intermediate, and deep zones; changes in irrigation and urbanization have reduced incidental recharge in some places, contributing to shallow-well declines. Decommissioning old or unused wells correctly helps prevent cross-flow and protects the quality of deeper municipal supplies.

Local agencies and stakeholders continue to study and manage our water system—USGS and IDWR released a Treasure Valley groundwater-flow model in 2023 to inform sustainable planning.

What Hydro handles for you

• Turnkey compliance with IDWR (authorization filing, proof of licensure, abandonment report).

• Method selection (perforate-and-pressure-grout vs. pull-and-seal) tailored to your well type and local geology.

• ADC experience in West Ada and throughout the Treasure Valley.

• Clean, safe, documented closures that protect your property and the valley’s water.

Quick FAQ

Q: Do I really need to decommission my old well if it’s not in use?

A: Yes—unused wells are a contamination risk and can be subject to decommissioning under IDWR rules.

Q: Can I do it myself?

A: No. Idaho law requires a licensed driller (unless IDWR issues a waiver).

Q: How soon can work start?

A: IDWR must authorize the abandonment at least 72 hours in advance. We file for you.

Q: Which method will Hydro use on my well?

A: We evaluate your construction and geology, then follow IDWR-approved methods—often perforate-and-pressure-grout for older cased wells without a continuous surface seal.

Ready to decommission a well?

Hydro closes wells the right way—compliantly, cleanly, and with the documentation you’ll need. If you have a domestic, irrigation, monitoring, or industrial well anywhere in the Treasure Valley, we’re here to help.

-Jenae Sexton, owner of Hydro Drilling