Montana DEQ Proposes New Frameworks to Gauge Water Quality
The Montana Department of Environmental Quality (DEQ) is currently inviting feedback from the public regarding two proposed frameworks: a Draft Eutrophication Assessment Method for Lakes and Reservoirs and a Draft Harmful Algal Bloom Assessment Method. Once these assessment methods are finalized, they will serve as tools for DEQ water quality experts to evaluate whether a waterbody is suitable for purposes like recreation and aquatic life.
The Draft Eutrophication Assessment Method for Lakes and Reservoirs centers on specific scientific indicators, referred to as biological responses, which include metrics like water transparency and the extent of algae proliferation within a waterbody. The Draft Harmful Algal Bloom Assessment Method assess the toxicity and duration of harmful algal blooms. Eutrophication is the scientific term used to describe the way excessive nutrient levels in a waterbody stimulate the growth of plants and algae. This can affect aquatic life and recreation. These conditions can also result in harmful algal blooms. Harmful algal blooms, also commonly referred to as “HABs” or “blue-green algae,” are composed of cyanobacteria. When present in high amounts, these bacteria can discharge toxins into the water, potentially resulting in skin irritation, human illness, and death in livestock or pets that consume the water.
The Stakes of HABs
The DEQ’s proposed Draft Harmful Algal Bloom Assessment Method is designed to evaluate the toxicity and duration of these events. The assessment methods inform water quality protection and restoration efforts. To determine where restoration funding should be directed, the DEQ concentrates its water quality monitoring efforts on locations susceptible to pollution issues. Both assessment frameworks first investigate whether human-caused pollution is present before assessing the conditions of the water and its biological health. Following an assessment, officials create waterbody objectives derived from site-specific information regarding pollutants linked to HABs and eutrophication.
Scientific Methodology and Regulatory Context
The Draft Eutrophication Assessment Method for Lakes and Reservoirs relies on biological responses, including measures of algae growth and water clarity. Following an assessment, officials create waterbody objectives derived from site-specific information regarding pollutants linked to HABs and eutrophication.
This work is part of a package of eutrophication assessment methods the agency is developing. The DEQ previously sought public input earlier this year regarding the Draft Assessment Method for Eutrophication in Wadeable Streams and Medium Rivers. The agency is working on reviewing, considering, and responding to those comments. As a collective, these assessment methods will provide guidance for assessments of waterbodies across the state. To view the draft assessment methods, visit DEQ’s online public notice.
