Montana DEQ is proposing new draft assessment methods for dissolved oxygen and ammonia for the state’s rivers and streams. Assessment methods are used to assess the aquatic life beneficial use for all state surface waters and inform water quality protection and restoration efforts. Both dissolved oxygen (DO) and ammonia are directly correlated with aquatic life, especially our sensitive wild trout and the macroinvertebrates they depend on for food. Low concentrations of DO negatively affect aquatic life, and can lead to death. Similarly, high concentrations of ammonia, which can be present in areas of low DO, can be toxic to aquatic life.
Despite the importance of assessing and managing ammonia and DO to maintain healthy fisheries in Montana, DEQ’s proposals have gaping scientific flaws that would undermine meaningful water pollution permitting by making assessment of pollution violations or harm unreliable, undermining preventative management, and failing to accurately assess stress, disease, and death of salmonids from ammonia toxicity or harmful levels of DO.
Below are the top scientific and legal issues we’ve identified with DEQ’s Draft Ammonia and DO Assessment Methods. DEQ is accepting public comment on the draft assessment methods through October 6, 2024 – comment now here.
Top Issues with the Draft Ammonia Assessment Method:
- The Draft Ammonia Assessment Method is misleading and incorrect.
- DEQ falsely assures that ammonia is easily treated and that ammonia is the only form of nitrogen that can be directly toxic to aquatic life at the levels found in Montana’s surface waters. The truth is that nitrate is directly toxic to aquatic life, and levels found in many Montana surface and shallow ground waters already are at or beyond thresholds that harm aquatic life. Nitrite is generally low in surface and subsurface waters, but nitrate is escalating in many waters due to sectors of human development.
- Fish such as salmonids and their and macroinvertebrate (bug) food are especially sensitive to nitrate toxicity, with increased egg mortality of salmonid fish and adverse impacts on early instar caddisfly larvae, and unfortunately many Montana surface waters are already contaminated by nitrate levels known to be toxic to sensitive aquatic life such as salmonids. Ammonia released in sewage and other pollution sources commonly is oxidized to the chemical form nitrate by nitrifying bacteria.
- Ammonia is not easily treated by adding oxygen unless nitrifying bacteria are also present, and so too there is limited natural treatment by groundwater in many Montana river valleys due to lack of organic soils (i.e., we have cobble and clay soils near rivers) and varying levels of oxygen and temperature in groundwater (i.e., shallow groundwater can be both oxygen rich and too cold for effective dinitrification). Many Montana waterways, including a stretch of the Yellowstone River, Canyon Ferry Reservoir, and Prickly Pear Creek are impaired, due in part to exceedances of ammonia. Ammonia data on Montana’s waterways are scarce, but various reports suggest that toxic ammonia levels in Montana’s streams are more common than indicated by DEQ, and coincide with contamination from untreated or poorly treated sewage discharges, livestock wastes, and certain mining activities.
- The Draft Ammonia Assessment Method is non-protective of aquatic life.
- DEQ is proposing an application period for the chronic ammonia criteria from March 15 – August 31 for warmwater fish species. This period is inadequate to protect spawning and early life history stages of 13 fish species known to live in Montana’s surface waters.
- Class A waters are to be maintained for high-quality purposes such as drinking water and salmonids, yet the new assessment methods offer poor protection from toxic ammonia. The draft ammonia assessment method describes what appears to be a reactive approach by the agency toward protecting many waters. Rather than measuring NH4+N, pH, and temperature in Class-A waterbodies, these waters are only to be assessed if modeling (which often fails to accurately capture river conditions), or if monitoring upstream vs. downstream from selected anthropogenic sources, indicates that the sources have increased ammonia concentrations. Models often fall far short of accurately depicting reality. The most accurate way to capture meaningful data and assess ammonia cycling and impacts is through representative monitoring at site-specific conditions; the draft assessment methods do not require representative monitoring.
- DEQ proposes applying less protective acute toxicity criteria to salmonid waters, unless salmonids are “present” (detected). However, there is no description of how DEQ assesses whether salmonids are present. Further, this approach creates a likelihood that early life stages of aquatic life can be easily missed if they are not already known to be present, in effect reducing potentially available habitat. This narrowed approach of less protective criteria for a smaller sweep of waters defeats the goal of consistent, strong protection of sensitive valuable species and their habitat.
- The data quantity and quality of the data collection proposed in the Draft Ammonia Assessment Method is inadequate to protect sensitive aquatic life from adverse effects of ammonia.
- DEQ’s proposed sampling frequencies are grossly insufficient to assess compliance with ammonia criteria. The agency did not carefully consider the number of samples needed for accurate assessment of compliance. The decision was not based on science but, rather, solely on the costs of collecting data. The proposed extremely sparse sampling will fail to reliably assess toxic ammonia levels, and therefore will fail to protect sensitive aquatic life such as salmonids and their food resources from stress, disease, and death due to ammonia toxicity.
- The inadequate sampling frequency is also unacceptable given the reality that sampling and analysis for ammonia is inexpensive in comparison to many other chemical environmental contaminants. For example, EPA reported that testing of dioxins, furans, PCBs, and congeners in water samples ranged from $790-$9,450 per sample. Compare those expensive tests to the average cost of commercial laboratories in Montana charging $25 or less per ammonia water sample.
- Sensitive aquatic life such as trout species and the macroinvertebrate taxa they depend upon for food are the foundation of Montana’s lucrative recreational fishing/tourism industry, estimated at a value of ~$350 million per year and supporting 6,280 jobs (American Fisheries Society 2023). Surely these extremely valuable sensitive species merit more protection than sampling only ~8 to 11 times for toxic ammonia over an entire decade?
- The Draft Assessment Method for Ammonia also proposes inappropriately using data collected prior to the addition of a known new pollution source. DEQ states that data collected up to a decade ago are to be considered current, and that if a known significant change in sources has occurred (such as an increase in sewage or a new sewage source), then best professional judgment can be used to decide which data collected during the decade is used for compliance assessment. This increases the likelihood of subjective and/or inaccurate, rather than science-based, data selection and is likely to result in non-protective decision-making about stream health and/or the need for restoration or improved pollution controls on polluting activities.
Other incorrect or questionable aspects of sampling included in the Draft Assessment Method for Ammonia:
- DEQ states that samples are to be preserved “as soon as possible” but within an hour. Considerable change in ammonia concentration can occur during the hour after collection. Samples should be preserved immediately using standardized practices.
- The inadequate sampling frequency proposed by DEQ will fail to capture average conditions reliably, and will also fail to capture sporadic, toxic, more extreme conditions based on limited sampling and the lax timing of sampling.
- DEQ states that “the number and locations of sites should represent the entire assessment unit or reach” (such as a stream or reservoir), but also states that only one site, even over an entire large assessment unit (e.g. a major river segment) will be acceptable for monitoring if it is in an area deemed by best professional judgment as “most at risk.” There should be much more clear requirements for designating assessment units and determining representative monitoring for stream reaches, especially for waterbodies affected by multiple pollution sources.
Top Issues with the Draft Dissolved Oxygen Assessment Method:
- The Draft DO Assessment Method is non-protective of aquatic life.
- Similar to the Ammonia Assessment Method, the DO Assessment Method proposes the use of data collected prior to the addition of a known new pollution source, and the data requirements are inadequate to protect sensitive aquatic life from adverse DO conditions based on their unscientific thresholds and sampling requirements.
- Sampling methods proposed and lax data requirements are inadequate for protecting sensitive aquatic life from adverse effects of DO.
- Non-protective sampling of assessment units: as with the ammonia method, DEQ states the minimum number of sites described as acceptable can be as few as only one per assessment unit. Analyses based on only least-impacted areas or a minor pollution source would be expected to underestimate DO sags and DO-related stress, diseases, and death of sensitive aquatic life. Because aquatic life move throughout a river, it is critical that sampling be representative of the segment based on statistical methodology, not convenience.
- DEQ has limited data collection and monitoring by requiring 16 days of data in a 30-day period (“30-day mean”) or 5 days of data in a 7-day period (“7-day mean”). It is misleading for DEQ to consider it acceptable to take only ~50-70% of the data needed for a 30-day mean or 7-day mean as it can skew results entirely, and it weakens the analysis to such an extent that low DO stress to sensitive fish can be entirely missed. Weather patterns and pollution events that can give rise to harmful DO conditions do not only occur during 50-70% of a sampling period.
- Furthermore, DEQ acknowledges that DO minima are worse during the warmest months, but then excuses assessors from having to measure during those months (pp. 6-7). The warmest period should be monitored for DO conditions as the first step in protecting adult fish of all species from DO-related health impairment.
- The temporal targets proposed for sampling can easily miss the most critical times for monitoring DO. The target for protection of early life stages, which are most sensitive to DO stress, should be the warmest part of the early life stage period for the fish species of interest, regardless of whether that period overlaps with DEQ’s defined growing season (March 15 – August 31). DEQ states that discrete samples collected between 4-8am will be considered representative of the lowest daily DO concentrations, but that will underestimate the severity of DO minima because the algae and aquatic plants will have had light for oxygen-producing photosynthesis for 1 to 2.5 hours. The minimum amount of oxygen present for sensitive aquatic life usually occurs just before dawn, not well after the sun rises.