Denali Water Solutions, LLC Clean Water Act Settlement Summary

On November 12, 2024, the U.S. Environmental Protection Agency (EPA) announced a settlement with Denali Water Solutions, LLC (Denali), a national sewage sludge application company, for violations of the Clean Water Act at land application sites in Arizona and California. This is the first judicial settlement involving biosolids violations exclusively and sets a standard for the industry. Under the settlement agreement, Denali will pay a $610,000 civil penalty and is subject to a specific “Soil Sampling and Agronomic Rate Calculation Protocol” if they resume operations in Arizona or California in the next five years.  

• Overview Denali Water Solutions, LLC
• Summary of Violations
• Overview of Environmental and Health Impacts
• Overview of Consent Decree
• Comment Period
• Contact Information

Overview of Denali Water Solutions, LLC

Denali is a limited liability company headquartered in Russellville, Arkansas that operates nationwide. Denali accepts, hauls, and land applies biosolids generated by municipal wastewater treatment systems. Sewage sludge is a byproduct of the wastewater treatment process. To be classified as biosolids and land applied, sewage sludge must be treated to ensure that it meets EPA’s pollutant and pathogen requirements.  

Summary of Violations 

Denali violated Section 405(e) of the Clean Water Act, which prohibits the disposal of sewage sludge from a publicly owned treat works or POTW, except in accordance with the biosolids regulations. Denali land applied biosolids from POTWs to hundreds of land application sites in California and Arizona, in violation of the biosolids regulations.

Denali’s violations include: 

• Land applying to fallow fields, arable land that has been left unplanted;  
• Land applying above the agronomic rate, the maximum application rate of nitrogen that a crop can absorb in order to minimize excess nutrients passing below the root zone of a crop or vegetation on the land to the ground water; and 
• Failing to obtain or use reasonable site-specific information to determine the amount of biosolids that could be applied at each application site without exceeding the agronomic rate. Information Denali failed to gather included the anticipated crop to be planted, the actual crop that was planted, and actual crop yield data from the farms. Denali failed to conduct soil sampling at the land application sites to determine how much nitrogen was present prior to Denali’s land application, failed to use mineralization and volatilization percentages supported by research, sampling and empirical data, and failed to conduct soil sampling after land application to determine residual nitrogen remaining in the soil.

Overview of Environmental and Health Impacts

Overview of Consent Decree

The settlement requires Denali to pay a $610,000 civil penalty and to implement a “Soil Sampling and Agronomic Rate Calculation Protocol” (Protocol) if it does business in Arizona or California in the next five years. The Protocol, which is the first of its kind and is intended to set an industry standard, contains specific requirements to ensure that biosolids are applied at or below the agronomic rate for each land application site, and requires Denali to determine:   

• nitrogen need, using accurate crop information and realistic, localized yield data;  
• nitrogen levels in the biosolids through sampling; and  
• quantities of any other sources of nitrogen available to the crop, specifically:  
  • nitrogen in soil, via soil sampling;  
  • nitrogen in irrigation water, via water sampling; and  
  • expected available nitrogen gain/loss, via locally appropriate mineralization and volatilization rates.

Comment Period

The proposed consent decree was lodged in the U.S. District Court for the District of Arizona on November 7, 2024. The consent decree is subject to a 30-day comment period. Information on how to provide comments and a copy of the proposed consent decree are available on the Justice Department’s Propose Consent Decree webpage. 

Contact Information

For more information, contact:

Biosolids Center of Excellence,  
Region 7 (Midwest) - Kansas City, KS 
U.S. Environmental Protection Agency 
R7_Biosolids_Center@EPA.gov

Kasey Barton, Senior Attorney 
Office of Regional Counsel,  
Region 7 (Midwest) - Kansas City, KS 
U.S. Environmental Protection Agency  
Kasey.barton@epa.gov 

Seth Draper, Environmental Scientist
Biosolids Center of Excellence Coordinator
Enforcement and Compliance Assurance Division,
Region 7 (Midwest) - Kansas City, KS
U.S. Environmental Protection Agency
Draper.Seth@epa.gov 

Megan G. Knight, Attorney-Advisor
Water Enforcement Division
Office of Enforcement and Compliance Assurance
U.S. Environmental Protection Agency
Washington, D.C. 20460
Knight.megan@epa.gov

Zarina Patel, Engineer
Water Enforcement Division
Office of Enforcement and Compliance Assurance
U.S. Environmental Protection Agency
Washington, DC. 20460
Patel.zarina@epa.gov