Three Basin Rule: Sandy's Unique Discharge Limitations

Sandy faces unique restrictions on the amount of treated wastewater we are allowed to discharge - a significant bottleneck that vastly increases the complexity and cost of our wastewater improvement projects.

The Three Basin Rule

Because of our location, Sandy is subject to the Three Basin Rule - a state drinking water regulation originally adopted in the 1970s and last amended in the 1990s, which permanently caps the volume of effluent that can be discharged in the Clackamas, Santiam, and McKenzie River basins. 

DOES THE RULE ALLOW the Limit TO Be Increased?

Unfortunately, no.  The discharge limit set for Sandy in the 1990s is the same number today - despite the fact that our population has grown substantially since that time. This wastewater discharge restriction applies to Sandy in perpetuity, regardless of how much we grow or how well we treat our wastewater with improved technology. 

How Unique Is This Problem?

Only five small cities in Oregon are subject to the Three Basin Rule, and of these Sandy discharges into by far the smallest receiving stream (Tickle Creek), creating additional limitations on our system (our treatment plant's effluent can only make up a certain percentage of Tickle Creek's water volume, and the creek is gradually drying up over time).

CAN ANYTHING BE DONE TO UPDATE THE RULE?

Potentially.  Marion County, which experienced devastating wildfire damage in recent years, filed a petition in August 2024 to amend the Three Basin Rule to allow new discharges from fire-impacted rural communities (that previously used septic systems).  The City of Sandy submitted public comments supporting the petition, and encouraging DEQ to use this moment as an opportunity to comprehensively update the rule to reflect modern improved treatment technology.  Click here to read Sandy's comments on the petition.