All homes on Pete’s Mountain are limited by the Oregon Water Resources Department (OWRD) to irrigation use on no more than one-half acre, regardless of whether the resident is using a private well or a community well.  

Understanding the Half-Acre Rule

For Oregon homeowners planning landscaping projects or growing food gardens, understanding the state’s exempt water use rules can save you from unnecessary permitting while keeping you legally compliant. The most important restriction to know about is the half-acre limit for residential irrigation.

The Half-Acre Rule Explained

Under Oregon Administrative Rule 690-340-0010 and Oregon Revised Statute 537.545, homeowners can irrigate lawns and non-commercial gardens without a water permit, but only up to a total of half an acre (0.5 acres or about 21,780 square feet). This exemption applies specifically to “watering any lawn or noncommercial garden not exceeding 1/2 acre in area.”

What Counts Toward Your Half-Acre

The key word in the regulation is “total.” Your half-acre limit includes:

• All lawn areas – front yard, backyard, side yards, and any grass areas
• All garden spaces – vegetable gardens, flower beds, fruit trees, berry patches, and ornamental plantings
• Combined irrigation from any groundwater source – whether you use one well or multiple wells, the total irrigated area cannot exceed half an acre

This means if you have a quarter-acre lawn, you can only irrigate up to another quarter-acre of garden space to stay within the exemption.

Why Water Companies Implement Excess Use Policies

Many community water systems, like Pete’s Mountain Water Company, implement strict excess water use policies that align with Oregon’s half-acre irrigation exemption. These policies exist because community wells have physical limitations that directly impact all members.

For example, Pete’s Mountain Water Company operates two wells approximately 1,000 feet deep serving 88 members. During dry summer months, irrigation demand causes water levels to drop significantly. The water level during pump operation must remain at least 10 feet above the pump to prevent expensive damage. The conditions of their well permits allow irrigation of no more than ½-acre of lawn and garden per member, and the board is responsible to impose irrigation limitations when required to protect their resources and investment.

This illustrates why the state’s half-acre exemption exists – it protects both individual water sources and shared community systems from overuse that could damage equipment or deplete the water supply for everyone.

What Qualifies as “Non-Commercial”

The exemption only covers “non-commercial” gardens, meaning:

• Allowed: Home vegetable gardens for family consumption
• Allowed: Flower gardens and ornamental landscaping for personal enjoyment
• Allowed: Small fruit trees and berry bushes for household use
• Not allowed: Gardens where you sell produce, even at farmers markets or roadside stands
• Not allowed: Any irrigation for commercial marijuana or unregistered hemp cultivation

Measuring Your Property

To determine if you’re within the half-acre limit:

1. Calculate total irrigated area: Measure all areas where you apply water – lawns, gardens, flower beds, and any other landscaping
2. Use proper measurements: Half an acre equals 21,780 square feet, or roughly a square area 147 feet on each side
3. Include all water sources: Even if you use multiple wells or a combination of well water and municipal water, the total irrigated area counts toward your limit

What Happens If You Exceed Half an Acre

If your total irrigated area exceeds half an acre, you cannot rely on the exempt use provision. Instead, you must:

• Apply for a water use permit through the Oregon Water Resources Department
• Pay application fees and go through the formal review process
• Potentially face restrictions during times of water shortage
• Comply with additional reporting and monitoring requirements

Planning Your Landscape Within the Rules

To maximize your half-acre exemption:

• Prioritize high-value areas: Focus irrigation on vegetable gardens and essential lawn areas
• Consider drought-tolerant landscaping: Use native plants and xeriscaping for areas beyond your half-acre limit
• Design efficient layouts: Concentrate irrigated areas to minimize water waste and maximize growing space
• Plan for expansion: If you want to expand your garden later, consider applying for a permit from the start

Getting Compliance Confirmation

Because property boundaries and irrigation areas can be complex to measure, consider:

• Consulting with your local watermaster before installing irrigation systems
• Having a surveyor help calculate your total irrigated area if you’re close to the limit
• Keeping records of your irrigation layout and measurements for future reference

The half-acre exemption provides significant flexibility for most residential properties while maintaining Oregon’s commitment to responsible water use. By understanding and respecting this limit, homeowners can enjoy beautiful lawns and productive gardens while staying compliant with state water law.

Understanding these specific restrictions helps ensure your home irrigation projects remain legally exempt and protects Oregon’s water resources for everyone. When in doubt, contact your local watermaster for guidance specific to your property and water situation.

Additional Resources

For the complete text of Oregon’s water use authorization rules, including detailed exempt use definitions and requirements, visit the Oregon Administrative Rules, Division 690-340 maintained by the Oregon Secretary of State.