Pursuant to the Wells Project License Order adopting the Aquatic Settlement Agreement and the 401 Certification, Douglas PUD is required to maintain compliance with the state Water Quality Standard (WQS) for surface water criteria through continued implementation of a monitoring program for water temperature and total dissolved gas (TDG) above and below the Project area.
Douglas PUD has monitored surface waters upstream and downstream of Wells Dam for TDG concentration since 1998.
TDG is monitored as a part of Douglas PUD’s Gas Abatement Plan and the data Quality Assurance Project Plan, which are required by the Wells Project 401 Certification and the FERC License. Douglas PUD implements a host of structural
and operational constraints and protocols to meet TDG standards that vary throughout the year to protect aquatic life and improve downstream travel for juvenile salmonids. Higher tolerances for TDG between April and August facilitate downstream fish passage and survival through Douglas PUD’s Fish Bypass System and the rest of the Columbia River
hydrosystem.
Additionally, Douglas PUD maintains compliance with the state WQS for water temperature by monitoring water temperatures at various Wells Project locations and transmitting these data on a daily basis to a web-accessible database. Since 2001, Douglas PUD has carried out an extensive water temperature monitoring program to better understand the temperature dynamics throughout the Wells Project Area (See TDG and temperature monitoring page here) Modeling conducted prior to the relicensing of the Wells Project in 2012 showed that the presence of Wells Dam did not increase water temperature in the Columbia River above water quality criteria (Chapter 173-201A WAC; West Consultants Inc., 2008). Wells Dam is a ‘run of the river’ project that has a minimal effect on water temperatures. This is apparent in the Columbia River water temperature modeling work carried out by the U.S. Environmental Protection Agency, which shows that the dam actually cools the water during parts of the year when salmon are vulnerable to warm water (US EPA, 2021). Douglas PUD will continue to work with regulatory agencies to ensure water temperatures throughout Wells Reservoir to promote a healthy aquatic ecosystem consistent with our license requirements.
References:
U.S. Environmental Protection Agency (US EPA). 2021 Columbia and Lower Snake Rivers Temperature Total Maximum Daily Load. Seattle, WA
West Consultants, Inc. 2008. Development of a Water Temperature Model Relating Project Operations to Compliance with the Washington State and EPA Water Quality Standards (Water Temperature Study). Wells Hydroelectric Project, FERC No. 2149. Initial Study Report required by FERC. Prepared for Public Utility District No. 1 of Douglas County, East Wenatchee, WA. Appendix B – Pages 1992-2047