Water Environment Services

WES, in cooperation with other local jurisdictions, has developed a BMP Sizing Tool to assist developers in meeting flow duration matching requirements customized to Clackamas County conditions. The Tool sizes facilities so that post-development peak flow durations will match the pre-development peak flow durations ranging from 42% of the 2-year to the 10-year flows, as determined by HSPF continuous rainfall model simulation.

The BMP Sizing Tool automates some of the required calculations to support BMP sizing and design for a specific set of stormwater management facility types (See Section 9.0 of User's Guide).

Responses to frequent BMP Sizing Tool questions can be found in Appendix A of the User's Guide, including:

• Rain gardens, stormwater planters, vegetated swales, and infiltrators are referred to as LID facilities. The BMP Sizing Tool uses different methods for sizing LID facilities (Section 9.2) and detention ponds (Section 9.3).
• If there are multiple types of post-development surface covers on the site, each of the areas should be delineated separately and entered separately in the BMP Sizing Tool under the Discharge Management Areas tab. 
• Predevelopment surface conditions should reflect historical conditions (i.e., grass or forest). Even when the pre-development condition is impervious surface, it should be included in the BMP Sizing Tool as grass or forest.
• The BMP Sizing Tool sizes facilities to manage the 10-year peak flow (based on continuous simulation.) However, WES design standards require conveyance systems to be sized for the peak flow from a 25-year, 24-hour design storm.
• The BMP Sizing Tool is based on LID principles, including the concept of prioritizing small, distributed surface vegetated facilities. As a guideline, it is recommended that the area draining into a single BMP facility should not exceed approximately 10 acres.

Resources

• Install the BMP Sizing Tool
• User's Guide for the BMP Sizing Tool

The Watershed Health Education Program educates youth about the importance of protecting our watersheds. The program makes it possible for local teachers and their students to get out of the classroom and into the field, where they gain hands-on experience making assessments, restoring streamside habitats, and studying the factors that determine healthy rivers and streams. These students then share their knowledge with friends, family and the broader community through presentations and activities, making an even bigger impact on protecting public health and the environment. WES works with partners to educate K-12 students in our community, and some projects span multiple years. To learn more about this program and projects, please contact Gail Shaloum at gshaloum@clackamas.us.

Educational Opportunities

• Children’s Clean Water Festival
• Clackamas Water Education Team
• Clackamas River Water Providers
• Tualatin River Watershed Partners for Clean Water
• Lower Columbia Estuary Partnership
• Ecology in Classrooms & Outdoors
• John Inskeep Environmental Learning Center at Clackamas Community College

Report problems such as a sewer spill, illegal dumping into a storm drain or sewer odor from our facilities.

Your name and contact information will be considered to be submitted in confidence, and the county will not disclose your name or contact information except as required by law.

Thank you for helping us to protect public health and the environment!

Our staff inspects the industrial pretreatment processes of businesses to eliminate illegal discharge of harmful chemicals into the sewage treatment process and collects wastewater samples to ensure industrial compliance with federal and state environmental regulations and local sewer ordinances.

WES Source Control

In addition to the federal and state-mandated Industrial Pretreatment Program, our Industrial Permits Division also administers other programs. These other programs include:

• Septage receiving
• Extra-strength billing
• Restaurant fats, oils and grease (FOG) reduction
• Illicit discharge investigation
• Surface water sampling
• Temperature monitoring
• Mercury minimization activities

Industrial Pretreatment

• Local Discharge Limits

Permitted Industrial User Determination

Industries who meet the criteria to require permit coverage as a Permitted Industrial User.
If the answer is yes to any of the questions below, your business meets the criteria to apply for an receive an Industrial Wastewater Discharge Permit:

• Does discharge require pretreatment to comply with federal, state or local discharge limitations?
• Does the industry discharge more than 30 lbs. of BOD (Biochemical Oxygen Demand) or TSS (Total Suspended Solids) in any given day?
• Does discharge exceed 350mg/L of BOD or TSS per day?
• Does discharge exceed 10,000 gpd?
• Does discharge require more than 20mg/L of Cl2 (Clorine) at the treatment plant?
• Does discharge contain any hazardous substances?

If the answer is no to all of the above questions, the industry does not meet the criteria that requires permit coverage and is not a Permitted Industrial User. However, WES Rules and Regulations still apply to business operations and their wastewater discharge.
 

Significant Industrial User Determination

Industries who meet the qualifications as a Significant Industrial User.

First, if your industry does not meet the criteria to be a Permitted Industrial User, the questions below do not apply.
If the answer is yes to any of the questions below, your business meets the criteria to be classified as a Significant Industrial User:

• Is the Industry a Categorical Industry User?
• Does Process Wastewater discharge exceeds 25,000 gpd (gallons per day)?
• Does the Industry process waste makes up 5% or more of the average dry weather hydraulic or organic loading?
• Is there reasonable potential from the Industry’s discharge to adversely affect the plant operation?

If the answer is no to all of the above questions, the business may be a Permitted Industrial User. Please see Permitted Industrial User Determination.

Pollution Prevention Academy

WES’ Pollution Prevention Academy is a free, voluntary program designed for the staff of commercial and industrial customers located in WES’ wastewater and stormwater service areas. In 2026, the Pollution Prevention Academy covered 4 topics focused on compliance with local regulations and permits. 
 

Fats, Oil and Grease

• Preferred Pumper Program
• Best Management Practices for Fats, Oil and Grease
• Restaurant Inspection Checklist for Fats, Oil and Grease

Septage Receiving

• Septage Program Hauler Procedures
• Industrial User and Septage Fees

Local Discharge Limits are specific rules that businesses must follow when they send wastewater into the sewer system. These limits help keep the treatment plant running safely and smoothly, protect workers, and prevent harmful pollutants from reaching the Willamette River. They also help ensure that treated waste can be disposed of properly and that plant operations are not disrupted.

Local Discharge Limits are one of several tools used by WES’ Industrial Pretreatment Program to meet requirements set by the Oregon Department of Environmental Quality (DEQ).

Residual fats, oils, and grease (FOG) are by-products of cooking and cleaning that can cause major blockages in municipal sewer systems. 

Over 30% of sanitary sewer blockages are caused by FOG buildup. Proper FOG management keeps plumbing systems safe and can reduce maintenance costs. 

1. Dry Clean-Up 

Always remove food waste using dry methods before using water-based cleaning. Wet methods can wash FOG into drains, causing pipe buildup. 

Tips for dry clean-up: 

• Use rubber scrapers to remove grease from cookware, utensils, and serving ware.
• Use food-grade paper to soak up grease under fryer baskets.
• Wipe down work areas with paper towels, not cloth towels (which can transfer grease to drains).
• Never pour cooking oils, fats, or grease down the drain.
• Educate staff to keep drain screens in place to prevent utensils and debris from entering plumbing. 

2. Spill Prevention 

Preventing spills keeps kitchens safer and reduces FOG entering drains. 

Best practices: 

• Empty containers before they are full.
• Cover grease/interceptor barrels during transport.
• Provide ladles, containers, and tools for safe handling of grease. 

3. Equipment Maintenance 

Regular maintenance is key to FOG control. 

Grease traps and hoods: 

• Clean under-sink grease traps according to daily/weekly schedules.
• Contract professional cleaning for large hood filters; smaller hoods can be cleaned with hot water and minimal detergent.
• Ensure ventilation systems are balanced with proper make-up air. 

Fryer management: 

• Skim/filter fryer grease daily; change oil based on test kits, not guesswork.
• Dispose of used oil into rendering tanks instead of drains.
• Establish a fryer rotation system to extend oil life and reduce carbon buildup. 

Cleaning intervals: 

• Vary by establishment size and food type; high-volume fryers may require monthly cleaning.
• Fully clean grease traps by removing liquids and solids, scraping walls, and preventing sediment accumulation. 

4. Oil and Grease Collection / Recycling 

FOG can be a valuable resource if collected properly. 

Collection tips: 

• Use covered 25-gallon barrels for oil/grease.
• Keep barrels covered at all times to prevent stormwater contamination.
• Separate prerinse (hot water only) and wash/rinse steps to trap grease effectively.
• Dispose of grill-top scraps, hood debris, and fryer solids into rendering barrels. 

Food donations: 

• Edible food waste can be donated to food banks.
• Inedible scraps can be collected by livestock feeders. 

5. Grease Traps 

Proper sizing, construction, and placement are critical: 

• Ensure all FOG-bearing drains (mop sinks, prep sinks, dishwashers, prerinse sinks, floor drains) feed into grease traps.
• Do not connect toilets to grease traps.
• If needed, consider installing a second grease trap with flow-through venting. 

Tip: Consult local city/county authorities or EPA guidance for proper sizing and installation. 

6. Consumer Tip 

Beware of “miracle” FOG solutions: 

• Some products do not prevent downstream accumulation.
• Check vendor references and verify that the system works as claimed.
• Remember: “Out of sight” does not mean “out of mind.”