Before the Illinois Pollution Control Board

Before the Illinois Pollution Control Board

Before the Illinois Pollution Control Board

In the matter of:

Proposed Amendments to

Dissolved Oxygen Standard

35 Ill. Adm. Code 302.206

)

R04-25

)

(Rulemaking – Water)

)

Comments on the Proposed Rule; First notice

Thomas J. Murphy, Ph. D.

September 17, 2007

Conclusion

The Board’s proposed rule is based on the premise that water that is 24% saturated

(3.5 mg oxygen/l at 0°C) will permit the full complement of indigenous aquatic organisms to

thrive. Nonsense! The IEPA and the DNR have presented evidence that more than 4 mg/L

of dissolved oxygen is necessary for many indigenous aquatic organisms. On the other hand,

no evidence has been presented in these proceedings to demonstrate that 3.5 mg/L oxygen at

cold temperatures is protective of indigenous aquatic life.

The Board is putting all of the

oxygen sensitive aquatic organisms in the general use waters at risk when the temperatures

get cold with

no evidence from studies at cold temperatures

to support this rule.

The Opinion and Order of the Board related to this rulemaking states (OOB p. 48),

“When setting water quality standards, the Board places

significant weight

on adopting a

standard that

fully protects aquatic life

, . . .”. By ignoring the temperature effects on the

availability of dissolved oxygen to organisms, the Board has clearly

not

met its goal with

these proposed rules.

Discussion

This rulemaking has been a long and arduous process. The stakeholders and the state

agencies have put considerable time and effort into updating the dissolved oxygen standards

for general use waters in Illinois, which have been in place for 35 years. A successful

outcome of these deliberations is critical to the future of all of the indigenous aquatic

organisms that expect to be able to thrive in the natural waters of the state.

The new evidence that been incorporated into these proposed rules give additional–

and necessary, protection in those months of the year when early-life stages of aquatic

organisms tend to be present. Unfortunately, the proposed rule does not address in any way

the fact that the availability to an organism of a given amount of dissolved oxygen in water

(in mg/L) decreases as the water temperature gets colder. The evidence presented in this

Opinion and Order of the Board (OOB) related to this rulemaking by the IEPA and DNR

indicate that the proposed rules–that cover both warm and cold times of the year, put

indigenous aquatic organisms at significant risk during the cold months.

Electronic Filing, Received, Clerk's Office, September 17, 2007

* * * * * PC# 112 * * * * *

An assumption related to oxygen uptake by organisms in these draft rules imply that if

there is any oxygen present in the water, then organisms can take it up. This is demonstrated

in the first line of the Introduction (OOB p. 1) where it is stated: “Dissolved oxygen …

occurs between water molecules as microscopic bubbles of oxygen that fish “breathe”

through their gills.” This statement is

not

correct. The oxygen is

dissolved

in the water. (A

glass of freshly drawn Guinness stout has millions of microscopic bubbles of gas suspended

in it. They are a separate phase–a gas (the stout is cloudy), and they slowly rise to the

surface, leaving the clear–though colored, liquid

solution

of stout in the glass.) Being in

solution in the water phase, oxygen can partition across membranes (gills), between phases

(air/water),

etc

. Transport is always from the region with higher concentration to the one of

lower concentration. For instance, a can of cold pop placed in a warm room always warms

up. The heat goes from the higher temperature room to the colder can. The cold can

never

loses heat to the warmer room.

Because transport is always from the higher concentration to the lower, an organism

can

only

obtain oxygen from water if the percent saturation in the water is higher than that in

the organism. And the situation, of course, is even more complicated. The complication is

that oxygen is only utilized in the mitochondria of the cells, a separate enclosed region

within cells. To get oxygen into the mitochondria where it is used to release energy for the

cells, the percent oxygen must be higher in the cells than in the mitochondria; to get oxygen

into the cells, the percent oxygen in the blood must be higher than that in the cells; and

finally, to get oxygen into the blood, the percent oxygen must be higher in the water than in

the blood. Thus the percent saturation of the oxygen in the water has to be sufficiently

higher than that in the mitochondria to drive the three transport processes to get sufficient

oxygen to the mitochondria.

In addition, the amount and the

rate

of oxygen transferred is

not

proportional to the

percent saturation of the water (or to its concentration in mg/L), rather they are proportional

to the

difference

in percent saturation across the membrane (you lose heat much more

rapidly when outside on a cold winter day, than on a cool fall day). For example, if an

organism has a blood oxygen saturation of 30%, it can gain no oxygen if the water oxygen

saturation is also 30%; if the water oxygen saturation is 35% the difference is 5% and some

oxygen will be transferred

. Now, if the water oxygen saturation is 50%, the difference in

saturation across the membrane is 20% and four times as much oxygen–and at four times the

rate, will be transferred than when the saturation was 35%

. An important implication of this

is that a fish with a blood oxygen saturation of 30% has to move at least four times as much

water over its gills if the water is 35% saturated than if the water is 50% saturated. Besides

experiencing a slower oxygen uptake, the fish has to expend considerable more energy to

acquire oxygen at low percent saturations and is exposed to four times the amount of the

other chemicals also in the water. Of course, if an organism finds itself in an environment

with an oxygen saturation less than its blood saturation, it will lose oxygen to the water.

In this rulemaking procedure, the IAWA and its supporters claim that the oxygen

standards should be based only on the mass concentration of DO (mg/L), and this

Opinion

and Order of the Board

has adopted that method. However, in previous testimony (PC #83,

Electronic Filing, Received, Clerk's Office, September 17, 2007

* * * * * PC# 112 * * * * *

PC #105) I have discussed that, based on the science of gas partitioning, that the availability

of oxygen to an aquatic organism is solely dependant on the

percent saturation

of the oxygen

in the water, which should serve as the rule-making criteria. The difference in these two

methods is that the one based on mass does not factor in the temperature dependence of

oxygen solubility. However that saturation is represented (3.5 mg/L DO at 25°C (43% sat.) is

much more available to an organism than 3.5 mg/L at 0°C (24% sat.)).

The Board needs to understand that a standard of 24% saturation–which is being

proposed (represented as 3.5 mg/L of DO at 0°C), is equivalent in oxygen availability to an

organism of 2 mg/L of DO at 25°C. Does the Board feel confident in proposing a 2 mg/L

standard for the March-July or August-February time periods? If not, why then is 3.5 mg/L

being proposed for a standard to be in effect in February and March?

The scientific problems with the proposed rules are only at low temperatures, and

independent of the units in the standard. The proposed rules are easily modified to prevent

irreparable harm–as documented by the IEPA and DNR (OOB pp. 50-59), that could befall

many organisms in the general use waters of Illinois, should these rules be adopted.

The proposed rules–ignoring the temperature dependence of the oxygen solubility, do

not create problems for waters that are warm, because these are the temperatures at which the

large majority of the studies have been performed, and where the errors are small due to the

limited temperature range.

On the other hand, there are

major differences

in the two methods at low temperatures

(see the example above for 3.5 mg oxygen/L) because the partitioning is driven by the

difference in percent saturation. To an organism, 3.5 mg/L of oxygen at 25°C is much less

available than 3.5 mg/L at 0°C (43%

24% saturation). As discussed by the Illinois DNR

in these rule making proceedings, (OOB pp. 50-59; 64-68), the DNR and IEPA:

•

Identified many organisms, including small-mouth bass, that require higher DO

saturations than 24%, which is 3.5 mg/L at 0°C.

•

Identified native mussels that have an 82% mortality rate at DO concentrations less

than 5 mg/L;

•

Identified 374 stream reaches that have a meaningful number of oxygen sensitive

organisms (OOB pp. 56-7); The Illinois Chapter of the American Fisheries Society

states that it has reviewed the record and believes that the DNR/IEPA procedures for

“earmarking ‘Category I’ stream segments are sound and scientifically based.” (PC

100 at 1; OOB p 62);

•

Reported sub-lethal effects on mayflies when the DO is in the 25-35% sat. range;

•

Identified 31 stream-fish species that require DO minima higher than the NCD’s

warmwater criteria;

•

Found that many stream macro invertebrates-the forage for many of the fish, are more

sensitive to low DO than are the fish.

(Because of the thin hypolimnion that forms when the central basin of Lake Erie

stratifies in the spring, this region of the lake goes anoxic before the lake overturns in the

Electronic Filing, Received, Clerk's Office, September 17, 2007

* * * * * PC# 112 * * * * *

fall, killing all the aerobic organisms present. In the terms of Earthday 1970, Lake Erie was

a “dead lake”. This annual phenomenon in Lake Erie has been intensively studied for the

past 40 years or so. When the dissolved oxygen concentration falls below 2 mg/L at 10°C the

waters are lethal to all the aerobic organisms in the lake, and the lake is said to be hypoxic.

Water with 2 mg/l of oxygen at 10°C is 18% saturated and it is

not

able to sustain aerobic

aquatic life.)

The Board’s proposed rule is based on the premise that water that is 24% saturated

(3.5 mg oxygen/l at 0°C) will permit the full complement of indigenous aquatic organisms to

thrive.

Nonsense

! The IEPA and the DNR have presented evidence that more than 4 mg/L

of dissolved oxygen is necessary for many indigenous aquatic organisms. On the other hand,

no evidence has been presented in these proceedings to demonstrate that 3.5 mg/L oxygen at

cold temperatures is protective of indigenous aquatic life.

The Board is putting all of the

oxygen sensitive aquatic organisms in the general use waters at risk when the temperatures

get cold with

no evidence from studies at cold temperatures

to support this rule.

The Opinion and Order of the Board related to this rulemaking states (OOP p. 48),

“When setting water quality standards, the Board places

significant weight

on adopting a

standard that

fully protects aquatic life

, . . .”. By ignoring the temperature effects on the

availability of dissolved oxygen to organisms, the Board has clearly

not

met its goal with

these proposed rules.

Proposal

The clear advance in these proposed rules is the recognition that early life stages

require higher levels of dissolved oxygen than adults do in order to properly develop. The

problem is that the proposed revisions to these Standards, in mg/L, each cover six month

periods that include both warm and cold months. As previously discussed, while these

concentrations of DO may be sufficient at warm temperatures, they are not protective at cold

temperatures with percent saturations of less than 25%. All that needs to be done is to choose

a standard (in mg/L, lbs/yd

, or whatever) that corresponds to a percent saturation of 33% or

greater – 5 mg/L at 0°C, or 4 mg/L at 5-10°C, as suggested by the IEPA and DNR evidence.

Since oxygen is much more soluble in water at cold temperatures, this modification should

cause minimal problems, as is demonstrated by the monitoring data presented in these

proceedings.

I am not suggesting that the DO standard be written in terms of percent saturation,

only that the standards as adopted be

based

on the science of gas partitioning in organisms,

and reflect the temperature dependence of oxygen solubility. I am suggesting that a standard

of 3.5 mg/L of oxygen at 0°C–equivalent in the availability of oxygen to fish of 2 mg/L at

25°C, is not a standard that, “

fully protects aquatic life,”

and should

not

be adopted.

It should be noted that all continuous DO measurements and most discrete

measurements (for BOD determinations, for instance) use electronic sensors that respond to

the percent saturation of oxygen in the water being tested rather than the 119 year old

Winkler chemical method

that yields DO in mass units.

Electronic Filing, Received, Clerk's Office, September 17, 2007

* * * * * PC# 112 * * * * *

Implementation Issues

On a different matter, I agree with the comments by Albert Ettinger of the

Environmental law and Policy Center (PC 101) and by Mr. Kollias of the Metropolitan

Water Reclamation District of Greater Chicago (PC 111) that implementation rules for these

proposed standards are critical to their effectiveness and need to be part of the proposed new

rules. Along with the practical issues discussed by Ettinger and Kollias, are measurement

uncertainties and their implications on the effectiveness of the proposed rules. USGS data on

continuous DO monitoring of several Illinois streams were presented early in the rule

making process and proved very useful in defining and understanding the issues. While it has

received little attention (see, however, April 25, 2005 Hearing Transcript, pp 88-9) the

USGS qualified their data with the statement that the reported DO concentrations had an

uncertainty of ±2 mg/L.

Assume that the proposed standard for Level 1 streams, other life stages, August

through February of 4 mg/L of DO is adopted. A monitoring value of 2.5 mg/L DO (17%

Sat. at 0°C) could be deemed to be in compliance since–within the precision of the

measurement, it is in accord with the standard. Likewise, a measured value of 5 mg/L would

raise no alarms or concerns as it is above the standard. However, the actual DO–within the

precision of the measurement, could be as low as 3 mg/L.

It needs to be understood that the

actual DO concentration in a body of water has a 50% chance of being below the standard

when a measurement indicates that the DO is at the standard value

(assuming that the data

are normally distributed).

Measurement uncertainties can be reduced, but not eliminated. They are an issue with

all actual determinations. The risk to the indigenous population of organisms of the actual

value of DO being up to 2 mg/L less that the measured value need to be taken into account

when setting standards. Such uncertainties are usually dealt with by including a margin of

error–some additional protection, to the regulations to protect those organisms at risk due to

these errors inherent in the measurement process. When the DO concentrations in these

proposed standards are determined by the Board, the risks due to the measurement

uncertainty could be taken into account by adding one or more mg/L to each of the proposed

standards, depending on a valid determination of the measurement uncertainty for

monitoring data.

References

1. Hawley, Nathan

et al

., EOS

, 313 (2006).

2. Winkler, Lajos, Chem. Ber., 21

, 2843 (1888).

Electronic Filing, Received, Clerk's Office, September 17, 2007

* * * * * PC# 112 * * * * *