Waterkeeper Calls On DEQ To Use Existing Data And List Big Hole River As Impaired In Integrated Report

BOZEMAN, MT - Last week, Upper Missouri Waterkeeper submitted a letter to the Montana Department of Environmental Quality (DEQ) in response to its call for public comment on the 2022-2024 Draft Water Quality Integrated Report and data and surface water assessment requests.

The Integrated Report is the state’s mechanism, required by the federal Clean Water Act to be published biannually, for gathering all science on water quality, identifying waterways that are unhealthy and failing to attain their designated uses at law, and where impairment is found, triggering necessary clean-up and restoration plans. Impairment determinations are based on assessment of local conditions against water quality standards. Integrated Reports over the last dozen years have consistently identified nutrient pollution as the cause of nearly 20% of all waterway impairments on all assessed waters. 

Relevant to the draft 2022-24 Integrated Report, Montana recently removed the water quality goalposts for nutrient pollution control by repealing numeric nutrient standards, contrary to a well-supported body of science demonstrating how application of numeric nutrient criteria protect local water quality in countless Montana streams and rivers across the state. 

Waterkeeper’s comments identified the agency’s express refusal to analyze and make impairment decisions concerning nutrient pollution and harmful dissolved oxygen concentrations, two pollutant parameters directly linked to protection of aquatic life and Montana’s world-class trout fisheries. The letter also served as a resubmission of its Petition for Nutrient Impairment Designation on the Big Hole River, and included all nutrient and water quality data, photo/video evidence of algal blooms, and a macroinvertebrate study to support the request.

“DEQ has a mandatory duty under federal law to identify unhealthy waters based on available data,” said Guy Alsentzer, Executive Director of Upper Missouri Waterkeeper. “Instead of using existing, undisputed science to identify problems and initiate restoration planning for degraded waterways, the agency is pretending very real nutrient pollution problems don’t exist. There is zero discretion to delay use of best-available science; doing so isn’t just bad policy, it’s unlawful.”

Waterkeeper originally petitioned the department to declare the Big Hole River as impaired in February 2025 based on five years of sampling data, but the department denied the request and refused to assess numeric nutrient data demonstrating sections of the river are failing to support designated uses based on Senate Bill 358 from the 2021 Legislative Session. EPA, however, struck down Senate Bill 358’s attempt to eliminate numeric nutrient criteria in a series of disapproval letters sent to DEQ in May 2022. 

Because an Integrated Report is a primary mechanism for identifying unhealthy waterways, Waterkeeper is again formally requesting the Department fulfill its mandatory duty under the Clean Water Act to identify impaired waters, such as the Big Hole River (and other qualifying waterbody segments), based on all available data, including evidence of widespread algal blooms fueled by excessive nitrogen, phosphorus, high temperatures, and low dissolved oxygen concentrations. 

In October 2025, the EPA approved the State’s repeal of numeric nutrient criteria in part based on the premise that DEQ would instead use response-variable data, such as dissolved oxygen, pH, temperature, and ammonia. However, those assessment methods have not been finalized in rule or submitted to EPA for approval, and in practice, DEQ is not using the data it already has in front of it - including substantial scientific evidence regarding harmful nutrient and dissolved oxygen conditions submitted by Waterkeeper - in the combined 2022-24 Integrated Report. 

In its comments, Waterkeeper raised three key issues:

1. Montana's mandatory duty to assess the evidence presented and identify the Big Hole and other qualifying waters as impaired by nutrients;

2. The Department’s rationale for declining to assess available nutrient evidence or list waters that evidence demonstrates are nutrient impaired is not legally or technically valid;

3. DEQ’s speculative, future nutrient translator(s) or similar narrative nutrient assessment methodologies does not free the State from its duty to evaluate available evidence and make a determination of attainment or nonattainment.

“When the State fails to assess available science and make impaired waters decisions, the consequences are very real in Southwest Montana, a place where clean rivers are the backbone of our recreation, agriculture, and tourism economies and critical to the health and survival of our world-class wildlife,” concluded Alsentzer. “As a practical matter, delaying analysis of available science can be devastating for river conservation and shovel-ready projects. Once impairments are identified, it regularly takes DEQ years - and in the case of the Missouri mainstem, decades - to develop pollution clean up and restoration plans. Delay on the back of more delay means deserving waterways won’t receive the protections and restoration plans Congress intended in enacting the Clean Water Act over fifty years ago.”