Publications Home || Browse by topic || Browse by program || Ecology website

Publication Summary

Our Ecology website has changed, which can cause broken links.
To report these, please contact us with the publication and broken link.


Evaluation of Groundwater Quality and Discharge Conditions at the Confluence of Deep Creek with the Spokane River

Publication number Date Published
19-03-010May 2019
VIEW NOW Evaluation of Groundwater Quality and Discharge Conditions at the Confluence of Deep Creek with the Spokane River (Number of pages: 52) (Publication Size: 2987KB)

Trouble viewing? Try these free options.
Author(s) Sinclair, K. and B. Gallagher
Description The Spokane River and Lake Spokane are on Washington’s 303D list of impaired waters for periodic violations of surface water quality standards – notably, dissolved oxygen. Reducing the nutrient inputs from point and non-point sources that fuel algal growth (e.g., nitrogen and phosphorus) is key to improving water quality conditions in the Spokane River.

In August 2016, the Washington State Department of Ecology undertook a study to better understand and characterize the dissolved nutrient load that potentially enters the Spokane River as direct groundwater discharge from the Deep and Coulee Creek watersheds. The study results indicate that upwelling groundwater discharges year round to lower Deep Creek and the Spokane River across a narrow discharge zone centered at the point where the Deep Creek channel enters the Spokane River.
The estimated lower- and upper-bound groundwater fluxes to the Spokane River/lower Deep Creek varied seasonally and ranged from approximately 0.14 to 4.6+ cubic feet per second during the 2016-2017 study period. The estimated lower- and upper-bound daily mass loads to the river for OP and DTP followed a similar pattern and ranged from approximately 0.03 to 1 kg/d. The estimated lower- and upper-bound daily mass loads for dissolved nitrate+nitrite-N and TPN ranged from approximately 0.5 to 17.5 and 0.4 to 13.6 kg/d, respectively.
The mission of the Department of Ecology is to protect, preserve, and enhance Washington’s environment. To help us meet that goal, please consider the environment before you print or request a copy.

ADA Accessibility
The Department of Ecology is committed to providing people with disabilities access to information and services by meeting or exceeding the requirements of the Americans with Disabilities Act (ADA), Section 504 and 508 of the Rehabilitation Act, and Washington State Policy #188.
Visit Ecology’s website for more information.
Contact EAP Publications Coordinator at 360-407-6764 or
Keywords Deep Creek, Spokane River TMDL, groundwater quality, groundwater monitoring, surface water/groundwater interaction, Spokane County, groundwater reporting, surface water, Spokane River, ground water monitoring, ground water sampling, groundwater, ground water, Surface waters
DATA Environmental Information Management (EIM) #KSIN0009


Quality Assurance Project Plan: Evaluation of Groundwater Conditions at the Terminus of Deep and Coulee Creeks (Spokane County)