When groundwater has been used

Groundwater from the Columbia South Shore Well Field is used as a secondary source for customers served by the Bull Run supply and also provides supplemental supply during the high-demand summer season. This page lists all the times we have used groundwater.

Common reasons we use groundwater:

  • Maintenance operation: The groundwater supply is a complex system composed of pumps, chemical feed systems, electronic controls, and other appurtenances; it must be operated regularly to identify maintenance needs and issues. By doing this maintenance operation, the bureau will ensure the reliability of the system when needed, either in an emergency or as part of seasonal supply.
  • Supply augmentation: During long, dry summers, the Water Bureau can blend groundwater with Bull Run water to make sure there’s enough for all during Portland’s dry season.
  • Turbidity in Bull Run: If Bull Run water is unavailable for any other reason, such as a storm, flood, fire or natural disaster, groundwater can temporarily become Portland’s sole source of drinking water. Turbidity is a measure of the cloudiness of water caused by suspended particles. When turbidity is too high in the Bull Run, we cannot serve that water to our customers.

This table shows all instances that we used groundwater for drinking water and the reason we used it.

Start dateDays usedTotal volume pumped (billion gallons)Range of daily production (million gallons per day)Reason for use
August 24, 2023833.218 to 78Supply Augmentation
November 22, 20222.035 to 30Augmentation due to Bull Run treatment equipment issue
November 5, 2022171.350 to 85Turbidity in Bull Run supply
October 13, 2022220.9 12 to 56Supply Augmentation
August 2, 2022230.30 to 40Maintenance Operation (Groundwater was used approximately 10 hours/day M-F for the 23 day duration at an approximate rate of 40 MGD)
February 8, 20224.2468 to 84In response to potential staffing shortages
November 15, 20213.1426 to 76Activation due to storm damage to Bull Run Corrosion Treatment facility.
August 3, 2021251.332 to 56Supply Augmentation
August 4, 2020230.40 to 54

Maintenance Operation (Groundwater was used approximately 10 hours/day M-F for the 23 day duration at an approximate rate of 54 MGD)

July 10, 2019491.835 to 40Supply Augmentation
June 20, 20181204.618 to 45Supply Augmentation
March 12, 2018100.1617 to 18Maintenance Operation
September 7, 201710.0110.4 to 36Delay in material delivery
February 13, 2017302.3933 to 83Activation during Cryptosporidium detection investigation in Bull Run and annual maintenance operation
July 25, 2016170.282.8 to 18.4Maintenance Operation
July 16, 20151125.321 to 68.5Supply Augmentation
June 11, 2015190.499 to 51Augmentation During Conduit Maintenance and Maintenance Operation
July 1, 201490.120 to 27.8Augmentation During Conduit Repair and Maintenance Operation
July 30, 201370.030 to 5Maintenance Operation
August 6, 2012180.030 to 5Maintenance Operation
February 23, 201250.2223.6 to 56.4Turbidity (Not a full Bull Run shutdown)
January 21, 2012110.8218 to 83.6Turbidity
August 9, 201160.030 to 22.3Maintenance Operation
January 16, 2011171.38.5 to 88.7Turbidity in Bull Run supply
August 9, 201060.034.1 to 5.4Maintenance Operation
September 28, 2009311.136Supply Augmentation
August 5, 200970.034 to 5Maintenance Operation
November 13, 200890.6527.4 to 96Turbidity in Bull Run supply
August 18, 200860.0034.7 to 6.4Maintenance Operation
September 28, 2007130.4318.3 to 36.4Supply augmentation
June 25, 2007601.447.7 to 87.1Supply augmentation
November 7, 2006141.127.8 to 92.2Turbidity in Bull Run supply
August 14, 2006783.584.5 to 72Supply augmentation
July 27, 2004291.0136.5Supply augmentation
January 29, 200440.0418.4Turbidity (Not a full Bull Run shutdown)
July 22, 2003633.720.8 to 72.6Supply augmentation
October 8, 2001120.446.9 to 45.8Supply augmentation
August 9, 2000411.710 to 36Supply augmentation
November 25, 1999191.519 to 89Flood and turbidity in Bull Run supply
December 28, 199850.3529 to 93.6Turbidity (rain on snow event)
September 4, 1996270.713 to 31Supply augmentation
February 7, 199680.54.9 to 86.6Flood and turbidity in Bull Run supply
November 28, 1995270.75.1 to 29.8Landslide in Bull Run watershed (Damage to conduits, not a turbidity event)
August 2, 1994732.52 to 36Supply augmentation
August 17, 1992451.517 to 30Supply augmentation
August 7, 1990 230.224.7 to 14Supply augmentation
September 4, 1987885.328 to 86Supply augmentation
February 25, 1986221.221 to 84

Turbidity in Bull Run supply

July 20, 1985190.3821Supply augmentation