Willow Creek Reservoir Water Quality Research and Evaluation Studies

A.    Background

The overall goal of this project is to improve water quality conditions in Willow Creek Reservoir for the benefit of the community of Heppner, Oregon, and surrounding area. The reservoir is characterized by several water quality concerns, including dense cyanobacteria (or blue-green algae) blooms, low dissolved oxygen concentrations, and high nutrient concentrations. Cyanobacteria blooms are known to produce toxins, thereby threatening the aquatic ecosystem and potentially exposing humans and animals to risk of death or chronic illness such as neurodegeneration and liver damage. Each summer, Willow Creek Reservoir post’s health advisories warning users of the potential hazards associated with recreational activities on the lake. Furthermore, fish kills, foul odors and other nuisances are common in Willow Creek Reservoir affecting the community’s ambiance, limiting tourism and recreation on the lake.

This analysis draws upon prior research, readily available data, and new research and data to develop and implement an evaluation program for the restoration of Willow Creek Reservoir and its upper basin. Research results will provide public benefit through enhanced water quality in Willow Creek Reservoir producing public recreation opportunities and natural resource benefits.

B.    Program Description/Objective

The primary objective is to advance the scientific understanding of reservoir ecology through the following research pillars:

1.   Empirical Data Acquisition and Limnological Analysis: To maintain the integrity of high-resolution, longitudinal datasets, the research involves systematic environmental monitoring and experimental observation. This includes the monthly collection of water samples and the recording of in-situ physicochemical measurements to analyze long-term nutrient cycling patterns and ecosystem shifts. Rather than routine maintenance, site visits are designed to manage the reservoir aeration unit as a controlled experimental variable. This allows researchers to study the mechanical suppression of thermal stratification and quantify its subsequent impact on internal loading and overall water quality.

2.   Hydrodynamic Modeling and Predictive Analysis: The project will develop a comprehensive whole-lake hydrodynamic model. This model is a specialized research tool designed for the University to synthesize complex environmental data, simulate various "what-if" scenarios, and forecast the reservoir’s future water quality trajectory. While the insights derived from this model will inform the Portland District’s future best management practices and dam operations, the model itself serves as a transferable scientific tool. Findings derived from this model will be presented in formats accessible to stakeholders and the scientific community to aid in the regional understanding of water quality trajectories.

3.   Mitigation Strategy Evaluation: Researchers will evaluate the effectiveness of current systems and model alternative options including but not limited to the installed aeration system and water quality outlet operations. This investigative work is performed to identify the most cost-effective and ecologically sound strategies for protecting the public interest and restoring the reservoir’s health.

4.   Knowledge Dissemination: The partnership will facilitate the dissemination of research results through both public and technical forums to ensure that data serves the community as a transparent resource. While the University will provide monthly trip reports and a comprehensive annual report that integrates current findings with historical data to produce a clear, accessible record of reservoir health that will be made available to local stakeholders and the public. These efforts are designed to move beyond internal reporting, instead providing the transparency necessary to safeguard public health, drinking water resources, and recreational safety. Ultimately, this collaborative flow of information ensures that the research directly informs community-led restoration efforts and remains a matter of public record.

D.    Public Benefit

Willow Creek Reservoir (WCR) is considered a eutrophic water body and is characterized by severe cyanobacteria blooms (CyanoHABs) during the summer months. These blooms frequently trigger Oregon Health Authority (OHA) public health advisories, which negatively impact annual tourism and recreation. Furthermore, CyanoHABs contribute to fish kills and contribute to the overall deterioration of water quality and the aesthetic value. In response to these conditions, Willow Creek area community leaders have requested that U.S. Army Corps of Engineers (USACE) implement lake restoration efforts to improve water quality. The research and data collected through this project will support the development of a comprehensive restoration plan aimed at improving environmental conditions for public benefit. Additionally, this project will provide essential monitoring and reporting of water temperature and pH levels required to meet public health standards.