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In mid-August, City staff discovered an error in the new flow meter for the City’s Centennial Well. Due to this error, the City was incorrectly reporting flows from Centennial well. Centennial Well withdrawals determine the requisite amount of mitigation to the Snoqualmie River, therefore the error in the flows from the Centennial Well led to under mitigation to the Snoqulamie River.
The City estimates the difference in rise in the South Fork of the Snoqualmie River from the under mitigation to be approximately 1/16 of an inch, which is well within the range of variation in the river due to climate. The City had sufficient mitigation water to provide the requisite mitigation water. The under mitigation was solely the result of a mechanical error.
Upon discovery of the error, City staff immediately notified the WA State Department of Ecology (DOE) and worked with DOE staff to provide compensatory mitigation to the river as quickly as possible. Due to City staff’s quick action, compensatory mitigation was completed within five calendar days of the City’s discovery of the issue.
As required by the Centennial Well water permit, the City submitted its official report on the error to DOE on August 22, 2019, and simultaneously notified the Tulalip and Snoqualmie Tribes. Included within that report are safeguards the City is taking to prevent this error from occurring in the future. The City is committed to complying with its water right and will work with DOE should further action relating to this error be required.
Event Report for Metering Error
The City has implemented the following safeguards to prevent recurrence of this or similar issues:
1. The City will use contractors experienced in work of this type and magnitude in the future, rather than using internal staff.
2. During the repair or replacement of any critical flow meters, the City will have a second instrument on-site to confirm accuracy prior to placing the new or replaced meter into service.
3. The City will only perform work of this type at times of the year that mitigation has not historically been required, whenever possible.
4. The City will include a section on metering in an update to the Operations & Maintenance Plan. This will include discussion of Ecology’s metering rule, how it applies to this system, and how the City will comply with the requirements of the rule.
5. The City will include a section strictly focused on mitigation water in the Emergency Response Plan required to be developed in accordance with the Water Infrastructure Act of 2018.
6. Finally, the City will formalize a request to Ecology to permanently convert the Cascade Golf Course water right from an irrigation water right to a mitigation water right. Upon successful conversion, the City will acquire all rights to, and construct the necessary infrastructure to make the Cascade Golf Course water right a viable mitigation source.