The Technical Guidance Committee (TGC) is responsible for maintaining the Technical Guidance Manual, reviewing best management practices for individual and subsurface sewage disposal, and providing recommendations on variances and commercially manufactured wastewater treatment components and systems. The TGC comprises six members: one DEQ representative (chair), three health district representatives, one State of Idaho-licensed professional engineer, and one licensed installer. TGC meetings occur quarterly unless, a special issue warrants a special meeting.
The Technical Guidance Manual provides guidance on the design, construction, alteration, repair, operation, and maintenance of standard individual and subsurface sewage systems, their components, and alternatives. The manual is updated periodically to adapt to the dynamic and complex nature of small wastewater disposal systems. Updates are cited below.
- Technical Guidance Manual for Individual and Subsurface Sewage Disposal Systems (Last updated: December 2025)
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DEQ awards $4,500,000 to Twenty Mile Creek Water Users Association in Boundary County, Idaho
BOISE – The Idaho Department of Environmental Quality (DEQ) today announced the award of a $4,500,000 low-interest drinking water construction loan to the Twenty Mile Creek Water Users Association in Boundary County, Idaho.
DEQ awards $89,505 to two Idaho water systems
BOISE — The Idaho Department of Environmental Quality (DEQ) awarded $89,505 to two water systems to help evaluate deficiencies and determine necessary upgrades.
DEQ awards $1,800,000 to the City of Lewiston
BOISE – The Idaho Department of Environmental Quality (DEQ) today awarded $1,800,000 in low-interest drinking water emerging contaminant construction loan funding to the City of Lewiston in Nez Perce County, Idaho.
DEQ seeks applications for fiscal year 2027 nonpoint source management grant program
BOISE – The Idaho Department of Environmental Quality (DEQ) is seeking grant applications for the fiscal year 2027 federal nonpoint source management § 319 funding cycle.
DEQ announces public comment period on draft fiscal year 2027 State Revolving Fund Intended Use Plan
Accepting comments from April 20, 2026, through May 18, 2026.
DEQ seeks comment on a proposed settlement action with PEG Development, LLC
Accepting comments from April 20, 2026, through May 20, 2026.
Current Year Manual Updates
| Date | Description |
|---|---|
| December 2025 | Section 2.2.4 Surface Water Separation Distances Section 4.25 Seepage Pits Section 5.12 Nitrogen reduction approvals Appendix C Uncommon Wastewater Flows Appendix E Pumpers Guidance Manual |
| August 2025 | Appendix C Uncommon Wastewater Flows Section 4.17.5 Pit Privy Abandonment Section 2.2.4.1 Surface Water Separation Reductions Section 5.2 Septic Tank Approvals |
| May 2025 | Section 3.3.2 Empirical Flows Section 4.8.4 ETPS Construction Appendix C Uncommon Wastewater Flows |
| February 2025 | Section 4.26 Steep Slope System Section 4.15 Individual Wastewater Incinerator |