Sedro-Woolley is known as the Gateway to the Cascades — and beneath that beautiful landscape lies some of the most varied geology in Skagit County. From river-bottom alluvium to upland hardpan and fractured bedrock, well construction here requires local experience.

At Access Well Drilling & Pumps, we combine regulatory knowledge, modern equipment, and hands-on valley experience to deliver reliable, code-compliant well systems for homeowners, farmers, and property developers throughout Sedro-Woolley.

1. Understanding the Skagit Instream Flow Rule

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Much of Sedro-Woolley falls under the Skagit Instream Flow Rule (WAC 173-503), which affects how new wells are permitted.

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Pre-2001 vs. New Wells:

Wells established before April 14, 2001 are generally considered exempt from the mitigation framework adopted after the rule. New wells may be subject to mitigation requirements depending on parcel location and basin boundaries.

Mitigation Program Areas:

Some properties rely on the Skagit River Basin Mitigation Program to demonstrate legal water availability for building permits. When applicable, property owners may need to:

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● Secure a Proof of Mitigated Water Supply

● Install an approved water meter

● Comply with usage limits outlined in the mitigation agreement

Requirements vary by parcel. We help property owners determine their specific status and guide them through the process.​

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2. Required Construction Procedures

72-Hour Notice (NOI Filing)

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Before drilling begins, Washington law requires a Notice of Intent (NOI) to be filed with the Department of Ecology at least 72 hours in advance. This filing is mandatory for all new well construction. We handle this process as part of our standard service.

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Setbacks & Health Department Standards​

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Skagit County and state regulations require minimum setbacks to protect water quality. Typical residential standards include:

• 100 feet from septic drainfields

• 50 feet from septic tanks

• 5 feet from property lines

• Additional distances from potential contamination sources
   

We ensure your well is sited to meet current county and state requirements.​​​

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3. Sedro-Woolley Geology: What’s Underground?

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Sedro-Woolley spans multiple geological zones.

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Valley Floor (River Bottom Areas)

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Near the Skagit River and its tributaries, we encounter sand, gravel, and layered silt deposits. These areas often produce good water yields but require:

• Proper casing installation

• Well screen design suited for fine sediment

• Thorough well development to prevent sand production
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Upland Benches (Cokedale & Northern Areas)

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In higher elevations and toward the foothills, glacial till (hardpan) is common. This dense clay-and-rock mixture:

• Requires heavier drilling equipment

• Can protect deeper aquifers

• Often produces stable long-term wells
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Bedrock & Fractured Formations

Closer to the Cascade foothills, we may encounter fractured bedrock. These wells rely on intersecting water-bearing fractures and require air-rotary drilling techniques.​​​​

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4. Common Sedro-Woolley Well Challenges

Lost Circulation in Gravel Zones

In coarse gravel formations, drilling fluid can dissipate into the formation. We use appropriate casing techniques to stabilize the borehole and maintain well integrity.

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Mineral Content

Iron and manganese are common in Sedro-Woolley groundwater and can cause staining and taste issues. We offer filtration systems designed specifically for local water chemistry.

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Water Usage Limits (Mitigation Wells Only)

For properties operating under mitigation agreements, water use is typically limited to an annualized average (commonly 318 gallons per day). Indoor and limited outdoor use allocations may apply depending on the specific mitigation terms.

These limits do not apply to all wells — only those subject to mitigation agreements.​​​

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5. Typical Depths & Yields in Sedro-Woolley

While each parcel is unique, common ranges include:

• Typical Depth: 80–250 feet

• Shallow River-Adjacent Wells: Sometimes under 50 feet, but more prone to seasonal fluctuation

• Average Yield: Often 10–25 gallons per minute (GPM)
   

Yield requirements for building permits typically reference a minimum daily water supply standard. We design wells to meet or exceed those requirements.