Role of a Comprehensive Toxicity Assessment and Monitoring.pdf

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Role of a Comprehensive Toxicity Assessment and MonitoringProgram in the Management and Ecological Recovery

of a Wastewater Receiving Stream

Mark S. Greeley Jr. Lynn A. Kszos

Gail W. Morris John G. Smith Arthur J. Stewart

Received: 7 October 2009/ Accepted: 7 April 2011 / Published online: 15 May 2011

Springer Science+Business Media, LLC (outside the USA) 2011

Abstract National Pollution Discharge Elimination Per-

mit (NPDES)-driven effluent toxicity tests using Cerio-daphnia dubia and fathead minnows were conducted for

more than 20 years to assess and monitor the effects of

wastewaters at the United States (U.S.) Department of

Energy Y-12 National Security Complex (Y-12 Complex)

in Oak Ridge, Tennessee. Toxicity testing was also con-

ducted on water samples from East Fork Poplar Creek

(EFPC), the wastewater receiving stream, as part of a

comprehensive biological monitoring and assessment pro-

gram. In this paper, we evaluate the roles of this long-term

toxicity assessment and monitoring program in the man-

agement and ecological recovery of EFPC. Effluent toxicity

testing, associated toxicant evaluation studies, and ambient

toxicity monitoring were instrumental in identifying toxi-

cant sources at the Y-12 Complex, guiding modifications to

wastewater treatment procedures, and assessing the success

of various pollution-abatement actions. The elimination of

untreated wastewater discharges, the dechlorination of

remaining wastewater streams, and the implementation of

flow management at the stream headwaters were the pri-mary actions associated with significant reductions in the

toxicity of stream water in the upper reaches of EFPC from

the late 1980s through mid 1990s. Through time, as regu-

latory requirements changed and water quality improved,

emphasis shifted from comprehensive toxicity assessments

to more focused toxicity monitoring efforts. Ambient tox-

icity testing with C. dubia and fathead minnows was sup-

plemented with less-standardized but more sensitive

alternative laboratory toxicity tests and in situ bioassays.

The Y-12 Complex biological monitoring experience

demonstrates the value of toxicity studies to the manage-

ment of a wastewater receiving stream.

Keywords In situ bioassay Effluent toxicityLong-term

monitoring Ambient toxicity Biomonitoring

Introduction

When the United States (U.S.) Environmental Protection

Agency (USEPA) applied water quality-based limitations

for toxic pollutants to National Pollutant Discharge Elimi-

nation System (NPDES) permits in the 1980s, many indus-

trial facilities and municipalities around the U.S. found they

were unable to immediately meet strict chemical-based

water quality criteria. One such industrial facility was the

U.S. Department of Energy (DOE) Y-12 National Security

Complex (formerly known as the Y-12 Plant and hereafter

referred to as the Y-12 Complex) in Oak Ridge, Tennessee.

The Y-12 Complex, a nuclear weapons component produc-

tion facility constructed at the headwaters of East Fork

Poplar Creek (EFPC) during the early 1940s as part of the

U.S. Manhattan Project, was by the mid 1980s discharging

The submitted manuscript has been authored by a contractor of the

U.S. Government under contract DE-AC05-00OR22725. Accordingly,

the U.S. Government retains a nonexclusive, royalty-free license to

publish or reproduce the published form of this contribution, or allow

others to do so, for U.S. Government purposes.

M. S. Greeley Jr. (&) L. A. Kszos G. W. Morris

J. G. Smith A. J. Stewart

Environmental Sciences Division, Oak Ridge National

Laboratory, Oak Ridge, TN 37831, USA

e-mail: [email protected]

L. A. Kszos

Neutron Sciences Directorate, Oak Ridge National Laboratory,

Oak Ridge, TN 37831, USA

A. J. Stewart

Oak Ridge Associated Universities, Oak Ridge, TN 37830, USA

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Environmental Management (2011) 47:10331046

DOI 10.1007/s00267-011-9679-3


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both treated and untreated wastewaters to the stream from

over 200 outfalls (Stewart and others 2011). The NPDES

permit issued to the facility in May 1985 required the Y-12

Complex to establish a Toxicity Control and Monitoring

Program (TCMP) for the purpose of identifying and con-

trolling the release of toxicants to EFPC from permitted

discharges. This NPDES permit was also among the first in

the nation to require the biological monitoring of thereceiving stream, resulting in the establishment of a Bio-

logical Monitoring and Abatement Program (BMAP) to

ensure and evaluate the effectiveness of the Y-12 Complex

TCMP and associated water pollution control programs in

protectingthe classified uses of EFPC (Loar and others 2011;

Peterson2011; Peterson and others 2011; Stewart and others

2011).

Whole effluent toxicity testing was the primary inves-

tigative tool of the Y-12 Complex TCMP. Effluent toxicity

testing conducted for the TCMP was used extensively

beginning in 1985 to: (1) locate and prioritize sources of

toxicants to EFPC; (2) identify and evaluate toxicants ofconcern; (3) guide changes in wastewater treatment oper-

ations to facilitate reductions in toxicant loading to the

receiving stream; (4) ensure the efficacy of treatment

modifications; and (5) monitor the toxicity of remaining

wastewaters following toxicant reduction efforts.

Ambient toxicity testing was one of several compli-

mentary bioassessment approachesincluding bioaccu-

mulation monitoring, analyses of bioindicators in sentinel

fish species, and surveys of stream communities

employed in the multi-task BMAP to assess changes over

time in water quality and the ecological health of EFPC as

water pollution controls and associated remedial actions

were implemented at the Y-12 Complex. Testing of EFPC

waters for ambient toxicity was initiated in 1986 and con-

tinued to the 2005 renewal of the facilitys NPDES permit.

The diversity and long-term nature of the BMAP, com-

bined with the intensive toxicity assessments conducted for

the TCMP, provide a unique opportunity to examine the

relationship between specific water pollution controls and

remedial actions at a major industrial facility (Loar andothers

2011) and resultant changes in ambient toxicity (this paper),

water quality (Stewart and others 2011), pollutant bioaccu-

mulation (Southworth and others 2011), and the health of

aquatic organisms and communities (Hill and others2010;

Adams andHam 2011; Ryon 2011; Smith andothers 2011) in

a freshwater receiving stream. Elements of the aquatic tox-

icity testing program for the Y-12 Complex have been dis-

cussed previously (Stewart and others 1990; Stewart1996;

Loar andothers 1992; Kszos andothers 1992; Hinzman 1993;

Stewart 1996; Kszos andothers 1997; Hinzman 1998; Adams

and others2002; Kszos and Stewart2003).

Radiological and non-radiological contaminants of his-

torical concern in EFPC include elevated nutrients, chlorine

in process waters, polychlorinated biphenyls (PCBs), and

mercury, uranium, and various other metals from a variety

of industrial process at the Y-12 Complex (Loar and others

2011). Environmental contaminants originate from multiple

point sources within the Y-12 Complex, including waste-

water treatment facility outfalls and storm drains, and from

non-point sources such as groundwater inputs and runoff

from contaminated floodplain soils. Beginning in the 1980sand continuing to the present, the Y-12 Complex committed

to a series of remedial actions and pollution abatement

activities to reduce toxic wastewater discharges to EFPC.

Table1summarizes some of the major actions taken by the

Y-12 Complex which could have contributed in the ensuing

decades to significant improvements in the water quality of

EFPC. A more detailed description of these remedial

actions and pollution abatement activities can be found in

Loar and others (2011).

Figure1 demonstrates the functional relationships

between wastewater toxicity testing performed under the

TCMP and ambient toxicity testing performed for theBMAP in establishing effluent limitations for new waste-

water treatment facilities at the Y-12 Complex (adapted

from Kingrea1986; Loar and others 1992). From the ini-

tiation of these programs, the complimentary TCMP and

BMAP toxicity testing programs acted in tandem to both

guide and evaluate the success of the Y-12 Complexs

toxicity control and pollution reduction efforts.

The goals of the this paper are to: (1) reevaluate, from

the perspective of more than 20 years of toxicity moni-

toring experience in the EFPC watershed, the relationships

between specific water pollution controls and remedial

actions implemented by the Y-12 Complex and changes in

the measured toxicity of effluent streams and ambient

EFPC waters; (2) explore the relationships between effluent

and ambient toxicity and changes over time in the condi-

tions of stream communities; (3) examine the respective

contributions of effluent toxicity assessments, routine

ambient toxicity monitoring, and related special studies

and toxicant evaluations to facilitating and monitoring of

the ecological recovery of the receiving stream; and (4)

discuss implications of the Y-12 Complex TCMP and

BMAP toxicity assessment experience for the environ-

mental management of receiving waters.

Materials and Methods

Study Sites

For the purposes of orientation, the locations of the Y-12

Complex and the primary BMAP monitoring sites along

EFPC are shown in Fig.2 (for greater detail on BMAP

sampling locations see Loar and others 2011). EFPC

1034 Environmental Management (2011) 47:10331046

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originates within the Y-12 Complex in Oak Ridge, Tennes-see, where it receives wastewaterdischargesvia underground

outfalls before emerging aboveground just upstream of a

BMAP sampling location at EFPC kilometer 25 (EFK25).

For several years, EFPC flowed through a retention basin

(originally New Hope Pond, which was replaced in 1988 by

Lake Reality) located near the border of the Y-12 Complex

downstream of a BMAP sampling location at EFK24. The

Lake Reality retention basin was permanently bypassed in

1998 as part of the Y-12 Complex pollution control and

management strategy, allowing subsequent free flow ofstream water from upper EFPC within the Y-12 Complex to

lower EFPC downstream of the old retention basins. Upon

exiting the Y-12 Complex just downstream of EFK23, EFPC

flows through the City of Oak Ridge prior to merging with

Poplar Creek approximately 25 km from the stream origin.

The only additional significant wastewater discharge to

EFPC is the municipal Oak Ridge Wastewater Treatment

Facility located near EFK14 (Fig. 2), a facility which also

receives some wastewaters from the Y-12 Complex.

Table 1 Summary of selected pollution abatement and remedial actions at the Y-12 Complex from 1985 through 2000

Dates Activity

19861992 Source collection and elimination of untreated discharges

1986 Completion of a central pollution control facility

19861987 Relining of sanitary and storm sewers

1988 Replacement of original retention basin (New Hope Pond) with a new lined basin, Lake Reality

Late 1992 Dechlorination of major wastewater discharges (with minor discharges dechlorinatedduring 1993 1994)

19962000 Additional relining of sanitary and storm sewers

1996 Completion of central and east end mercury treatment systems

1996 Implementation of flow management (temporary)

Early 1997 Implementation of flow management (permanent)

1996 Lake Reality bypass (temporary)

1998 Lake Reality bypass (permanent)

2000 Bank stabilization project

Adapted from Loar and others (2011)

BAT EffluentLimitations

Modify EffluentLimitations

Develop ToxicityControl Plan and/or

Conduct TRE

Final EffluentLimitations

Is WastewaterToxic?(TCMP)

Are Classified UsesBeing Maintained?

(BMAP)

Is WastewaterToxic?(TCMP)

Yes

No

Yes

Yes

No

Yes

Fig. 1 Decision tree for

establishing effluent limitations

for wastewater treatment

facilities at the Y-12 Complex.

BAT = Best Available

Technology (modified from

Kingrea 1986, and presented

originally in Loar and others

1992)

Environmental Management (2011) 47:10331046 1035

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Initial ambient toxicity assessments conducted in 1986

with standard aquatic test organismsCeriodaphnia dubia

(C. dubia) and fathead minnows (Pimephales promelas)

evaluated water from 11 sites in lower EFPC downstream

of the retention basin near the boundary of the Y-12

Complex, and one site in upper EFPC immediately

upstream of the retention basin. Because of a need to iso-

late very specific point sources of potential toxicants, moresites along EFPC were eventually examined for ambient

toxicity than the five routinely monitored by other BMAP

tasks, and toxicity sampling locations were more specifi-

cally delineated (for instance, EFK25.1 for an ambient

toxicity site rather than the less-specific EFK25 designation

used by other BMAP tasks: see Table 2 for EFPC locations

monitored at least once for ambient toxicity). After the

initial toxicity assessments had demonstrated that ambient

toxicity was mainly restricted to upper EFPC, subsequent

ambient tests with C. dubia and fathead minnows focused

on a smaller subset of the originally tested locations within

lower EFPC and added additional testing sites in upperEFPC (Table2).

In situ bioassays, which place test organisms such as the

fingernail clam into the stream for exposure purposes (test

described elsewhere in this paper), lack the obvious con-

trols of laboratory toxicity tests. Thus, three reference

streams located off the Oak Ridge Reservation in nearby

valleys were used in the in situ clam tests to provide

comparisons with the conditions expected for EFPC if the

Y-12 Complex had not been constructed. Located in

watersheds with rural impacts but no industrial contami-

nation, these reference streamsHinds Creek (HCK20),

Cox Creek (CXK0.2) and Brushy Fork (BFK7)have

similar physical and chemical characteristics to EFPC but

are unaffected by Y-12 Complex discharges (Fig.2).

Toxicity Tests

Effluent Toxicity Testing

Requirements for effluent toxicity testing were included in

both the 1985 and subsequent 1995 NPDES permits issued

to the Y-12 Complex. During the period covered by the

1985 permit, cooling tower blowdown, storm drain dis-

charges, and treatment facility effluents were tested peri-

odically with chronic 3-brood C. dubia tests (initially by

the methods of Horning and Weber 1985; current test

method 1002.0 in USEPA2002a) and 7-day fathead min-

now larvae growth and survival tests (initially by the

methods of Horning and Weber1985; current test method1000.0 in USEPA 2002a). Following the 1995 renewal of

the NPDES permit (which remained in effect through

2005), acute 48-h effluent tests based solely on C. dubia

survival (current test method 2002.0 in USEPA 2002b)

replaced the previous chronic effluent testing as a permit

requirement.

By testing various dilutions of wastewater effluents, the

standardized chronic toxicity tests determined a no-effect-

concentration (NOEC) of effluent, with either survival and

Fig. 2 Locations of biological

monitoring sites on EFPC in

relation to the Y-12 Complex.

EFK= East Fork Poplar Creek

kilometer. Note that only core

BMAP monitoring sites are

shown on the map as point

references for more numerous

toxicity testing sites along

EFPC


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reproduction (C. dubia) or survival and growth (fathead

minnows) as test endpoints. Acute toxicity tests identified a

concentration (the Lethal Concentration50 or LC50) of

effluent which could be lethal to 50% of the test organisms

over a given test period (usually 48 h). In the case of both

the NOEC and the LC50, the lower the value the greater thetoxicity of the tested effluent. Additional details of sam-

pling protocols, test methods, and data analysis procedures

for the effluent toxicity tests can be found in Stewart and

others (1990) and Stewart (1996).

Toxicity Loading Analyses

To evaluate the relative contributions to EFPC of toxins

from the various Y-12 Complex waste streams, each

wastewaters NOEC was compared to its expected final

concentration in the receiving stream [the instream waste

concentration (IWC)]. If the NOEC was less than the IWC,the wastewater could be expected to be harmful upon

discharge to the receiving stream. To facilitate compari-

sons across wastewater streams, the expected ambient

toxicity from effluent discharges was characterized by

instream Toxic Units (iTUc if derived from chronic test

results; iTUa if derived from acute test results), with the

iTUc o r a defined as the wastewaters calculated instream

waste concentration (IWC) divided by the wastewaters

NOEC. Thus an instream TUc[ 1 (where the NOEC is

less than the IWC) indicates that discharges have the

potential to be harmful to stream organisms possessing

similar sensitivity to toxicants in the stream water as the

C. dubia and fathead minnow larvae test organisms.

Ambient Toxicity Testing with Standard Test Organisms

Because the toxicity of ambient receiving waters is gen-

erally much lower than the toxicity of effluents measured

directly at a wastewater discharge, ambient toxicity testing

was routinely performed with chronic 3-brood C. dubia

tests and 7-day fathead minnow (Pimephales promelas)

(initially by the methods of Horning and Weber 1985;

USEPA 2002a) with an emphasis on test organism

responses to full-strength stream water (Stewart 1996).

Ambient toxicity testing on EFPC waters began in 1986,

when significant remedial actions at the Y-12 Complex

were just underway, and continued at selected monitoringlocations through the 2005 renewal of the NPDES permit

(Table2).

Supplemental Ambient Tests

To supplement the standardized C. dubia and fathead

minnow toxicity tests, the ambient toxicity testing program

also employed less-standardized laboratory toxicity tests

and in situ bioassays with additional test organisms. Tests

Table 2 C. dubia and fathead minnow chronic toxicity tests conducted on ambient water samples from EFPC through 2005

Sitea 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Upper East Fork Poplar Creek

EFK25.1 7 10 10 12 12 11 4

OF 201 2 5 4 4 4 4 4 4 4 4 4 4

EFK24.6 9 12 10 10 9 12 12 11 12 2

EFK24.1 6 8 8 11 11 11 9 12 12 11 12 5 4 4 4 4 4 4 4 4

Lower East Fork Poplar Creek

EFK23.8 17 13 12 12 10 9 9 12 12 11 12 5 4

EFK22.8 3 4 3 3 3 4 4 4 4 4 4 1

EFK21.9 1 4 3 3 3 4 4 4 4 4 4 1

EFK20.5 3 4 3 3 3 4 4 4 4 4 4 1

EFK18.2 3 4 3 3 3 4 4 4 4 4 4 1

EFK16.1 2

EFK13.8 3 4 3 3 3 4 4 4 4 4 4 1

EFK10.0 3 4 3 3 3 4 4 4 4 4 4 1

EFK7.6 2

EFK5.1 2

EFK2.1 2

With the exception of EFK 25.1, fathead minnow testing ceased in 1996 after four tests at each of the four upstream sites and one test each at

downstream sitesa

EFK= East Fork Poplar Creek kilometer; OF 201(Outfall 201) is an instream NPDES monitoring site approximately 10 m downstream of

EFK25.1


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conducted with species other than C. dubia and fathead

minnows generally addressed specific toxicity-related

issues that could not be studied readily with the standard

toxicity tests, such as examining the potential for contin-

uing low-level ambient toxicity in upper EFPC after

C. dubia and fathead minnows had stopped responding in

routine ambient tests.

Alternative model organisms used in laboratory testsincluded the medaka (Oryzias latipes), a small aquarium

fish widely employed in basic research into early vertebrate

development and in studies of the effects of pollutants on

developmental processes. In these tests, newly-fertilized

medaka embryos were individually exposed in 7-ml glass

vials or plastic 24-well plates to water from various loca-

tions along EFPC by methods adapted from USEPA

guidelines for a fish developmental toxicity test (Benoit

and others1991). In this test, survival and the incidences of

developmental abnormalities were assessed daily and test

solutions were renewed every other day.

In situ bioassays conducted in EFPC and nearby streamsemployed native species such as the fingernail clam,

Sphaerium fabale (Smith and Beauchamp2000). In the in

situ fingernail clam test, clams were placed in individual

clear Plexiglas tubes anchored to the bottom of the stream,

and left in situ for up to 85 days. Further details of the

experimental procedures can be found in Smith and

Beauchamp (2000).

Statistical Analyses

Statistical procedures used to estimate a wastewaters

NOEC or LC50in C. dubiaand fathead minnow tests were

performed according to USEPA test guidelines (currently

USEPA 2002a, 2002b). Various alternative statistical

methods for evaluating the results of ambient tests using

these test organisms, including ANOVA, were also used as

described in Stewart (1996). Individual-based medaka test

results were statistically analyzed with Chi-square tests.

Clam bioassays were statistically evaluated by ANOVA

and associated tests as detailed in Smith and Beauchamp

(2000).

Results

Toxicity of Wastewater Discharges from the Y-12

Complex

From 1986 through 1992, 72 chronic toxicity tests with

C. dubia and fathead minnows were conducted to charac-

terize the toxicity of cooling tower blowdown discharges,

various untreated waste streams, and effluents from several

Y-12 Complex wastewater treatment systems. The relative

toxicities of wastewater streams before and after untreated

discharges to EFPC were eliminated in the early 1990s are

presented in Table 3. The average total toxicant loading to

upper EFPC from Y-12 Complex wastewaters before theseuntreated discharges were eliminated exceeded 4 iTUc, a

value far greater than the 1 iTUc threshold for expected

instream chronic toxicity. Following the elimination of

these untreated discharges, the average toxicity loading to

the stream was reduced substantially to a relatively low

0.24 iTUc.

Routine toxicity monitoring with C. dubia, and less

frequently with fathead minnows, continued on selected

effluents from Y-12 Complex wastewater treatment facili-

ties, storm drains and cooling towers through 2005 as

specified in the facilitys NPDES permit. Consideration of

the annual worst-case results of quarterly C. dubia tox-

icity tests performed from 1986 through 2005 on effluents

from the three main wastewater treatment facilities at the

Y-12 Complex (Fig.3) demonstrated that even these

treated wastewaters occasionally exceeded the threshold

for expected instream toxicity. For example, effluent from

Table 3 Comparison of toxicity loading analyses to East Fork Poplar Creek using results of chronicC. dubiaand fathead minnow toxicity tests

conducted from 1986 through 1992 on cooling tower blowdown and various treated and untreated waste streams at the Y-12 Complex before and

after the elimination of untreated waste discharges

Toxicity loading of wastewater discharges

Before elimination of untreated discharges After elimination of untreated discharges

Wastewater source Annual flow

(l/Year)

Instream chronic

toxic units (iTUc)a

Annual flow

(l/Year)

Instream chronic

toxic units (iTUc)a

Cooling towers 556 9 106

0.12 354 9 106

0.05

Untreated waste streams 113 9 106 3.82 0 0

Treated waste streams 138 9 106

0.23 447 9 106

0.19

Total 807 9 106

4.07 801 9 106

0.24

aInstream chronic toxic units (iTUc) = Instream waste concentration (IWC)/No-Observed-Effect-Concentration (NOEC)


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the Groundwater Treatment Facility alone contributed[4

iTUc of toxicants to the upper reaches of EFPC on twoseparate occasions during chronic tests conducted in 1993

and 1995.

Following the replacement of chronic toxicity testing

requirements with acute testing requirements in the 1995

renewal of the Y-12 Complex NPDES Permit, the mea-

sured toxicity of individual wastewaters in these routine

effluent tests never again exceeded an instream toxicity

threshold of iTU[1 (Fig. 3). The implications of this

change in test methods to the toxicity testing programs

ability to predict the effects of wastewater discharges on

the biotic communities in EFPC are discussed in the fol-

lowing section of this paper.

Ambient Toxicity of the Receiving Stream

Fathead Minnow and C. dubia Tests

Routine toxicity testing of ambient water samples from

EFPC was begun in 1986 as part of comprehensive BMAP

efforts to characterize stream conditions prior to the initi-

ation of extensive remedial actions and pollution abatement

activities planned by the Y-12 Complex in the EFPC

watershed (Table1). Early ambient toxicity tests (Table2)

initially focused on the waters of lower EFPC downstream

of the retention basin near the boundary of the Y-12

Complex (Fig.2). In these early ambient tests, no con-

clusive evidence was found of toxicity to eitherC. dubiaor

fathead minnows (Table4), although occasional reductions

in fathead minnow survival or growth (as shown in Table 4

for ambient samples from EFK22.8 and EFK18.2) spo-

radically occurred in some ambient water samples.

Other ambient tests conducted in the mid to late 1980s

specifically compared the toxicity of water from EFK24.1

in upper EFPC with the toxicity of water from EFK23.8 in

lower EFPC. Water from EFK23.8 sampled downstream of

the New Hope Pond retention basin had no adverse effect

on either C. dubia or fathead minnows in the two 1986

Fig. 3 Annual worst-case C. dubia toxicity test results for

effluents from the three main wastewater treatment facilities at the

Y-12 Complex. Resultsexpressed as instream Toxic Unitswere

derived from chronic 3-brood tests through 1995 and from acute 48-h

tests after 1995; tests were typically conducted quarterly

Table 4 Results of chronic Ceriodaphnia dubiaand fathead minnow

toxicity tests of ambient water samples collected daily from 10 sites in

lower EFPC in early 1986 prior to the initiation of major remedial

actions by the Y-12 Complex

Ceriodaphnia Fathead minnow

Sitea

Survival

(%)

Reproduction

(offspring per

female)

Survival

(%)

Growth

(mg/

larva)

EFK23.8 100 27.6 90.0 0.564

EFK22.8 100 28.9 92.5 0.382a

EFK21.9 100 30.3 95.0 0.515

EFK20.5 100 30.6 92.5 0.536

EFK18.2 100 29.8 92.5 0.425b

EFK16.1 90 37.0 87.5 0.481

EFK13.8 90 34.5 90.0 0.583

EFK10.0 100 23.3 90.0 0.468

EFK7.6 100 30.2 80.0 0.495

EFK5.1 90 28.6 85.0 0.479

EFK2.1 100 28.6 87.5 0.639Control 100 28.6 100.0 0.571

Adapted from technical report by Loar and others (1992)a

EFK= East Fork kilometerb Test endpoints that differed significantly from controls (ANOVA,

P\0.05)

Table 5 Comparison of chronic toxicity to C. dubia and fathead

minnows in tests of different ambient water samples collected in 1986

from upper EFPC (EFK 24.1) and lower EFPC (EFK 23.8) conducted

just prior to the initiation of major remedial actions by the Y-12

Complex

August 1986 September 1986

Sitea Survival

(%)

Reproduction/

growth

(mean, SD)

Survival

(%)

Reproduction/

growth

(mean, SD)

C. dubia

Control 100.0 13.2 (3.3) 100.0 20.4 (5.5)

EFK24.1 90.0 4.4 (4.5)b

80.0 11.7 (4.6)b

EFK23.8 100.0 14.8 (2.6) 100.0 18.0 (3.5)

Fathead minnows

Control 92.5 0.53 (0.05) 92.5 0.36 (0.07)

EFK24.1 90.0 0.41 (0.07) 92.5 0.26 (0.08)

EFK23.8 97.5 0.50 (0.06) 75.0 0.26 (0.07)

Adapted from technical report by Loar and others (1992)a

EFK= East Fork kilometerb Test endpoints that differed significantly from controls (ANOVA,

P\0.001)


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ambient toxicity tests shown in Table 5; in contrast, water

sampled from EFK24.1 upstream of the retention basin

significantly reducedC. dubiareproduction in both of these

early tests (ANOVA, P\ 0.001).

Table6 summarizes the results of a subsequent series of

ambient toxicity tests initiated in 1988 and 1990, respec-

tively, for two additional sites in upper EFPC at EFK24.6

and EFK25.1 within the Y-12 Complex. In tests conductedprior to 1992, the frequencies ofC. dubia test failures due

to reductions in either survival or reproduction were 60%

or greater for both sampling locations. By 1992, the fre-

quencies of test failures for both sites had decreased sig-

nificantlyto 0% for EFK 24.6 and to 30% for EFK

25.1following the elimination of untreated wastewater

streams in Y-12 Complex discharges. The annual fre-

quencies of test failures for both sites then fluctuated from

0 to 33% before testing was eventually discontinued at

EFK25.1 in 1996 and at EFK24.6 in 1997 (Table 2).

Routine ambient toxicity testing was also conducted

from 1994 through 2005 at a fourth site in upper EFPCa

newer instream NPDES monitoring station (Outfall 201)located just downstream of EFK25.1 (Table 2and Fig. 4).

Similar to the situation for the other testing sites in upper

EFPC, toxicity test failures (as indicated in Fig. 4 by

NOEC values\100%) involving water from Outfall 201

were relatively common prior to 1996, particularly in the

case of C. dubia tests. Following the implementation of

flow management in EFPC in 1996, there was only a single

subsequent test failure with either C. dubia or fathead

minnows at this ambient sampling site through 2005

(Fig.4).

Supplemental Ambient Tests with Alternative Test

Organisms

To supplement the standardized C. dubia and fathead

minnow tests, studies of ambient toxicity in EFPC were

also conducted with other native and non-native test

organisms. Results of laboratory tests of water samples

from EFPC using newly-fertilized embryos of the medaka,

a small non-native fish commonly employed as a model for

vertebrate development, are shown in Fig.5. In tests begun

in 1997, survival of medaka embryos and larvae through

2 days post-hatch was significantly reduced compared to

laboratory controls in water samples from various sites in

both lower and upper EFPC (Chi square tests of individual-

based results, P\ 0.01). Embryo survival in these tests

Table 6 Changes over time in the frequency of chronicC. dubiatests

demonstrating significant decreases in either survival or reproduction

in ambient water from two sites in upper EFPC

EFK24.6 EFK25.1

Timeperiod

n Frequency of testfailures (%)

n Frequency of testfailures (%)

Pre-1992 41 60 17 76

Elimination of untreated discharges completed

1992 9 0 10 30

Late 1992: dechlorination of major discharges begun

1993 12 8 12 17

1994 12 0 12 33

1995 11 27 11 9

Early 1996: initial implementation of flow management

1996 12 0 4a

0

1997 2

a

0

EFK= East Fork kilometera

Toxicity monitoring at site discontinued

Fig. 4 Results of chronic

C. dubia and fathead minnow

toxicity tests of ambient water

sampled from East Fork Poplar

Creek at Outfall 201, an

instream NPDES monitoring

site located just downstream of

EFK 25.1 within the Y-12

Complex (NOEC =

No-Observed-Effects-

Concentration)


1 3


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gradually increased over time for all tested locations in

EFPC, and by 2003 had approached the levels of laboratory

controls in water samples from monitoring sites in lower

EFPC (EFK13.8 and EFK18.2). However, significant

decreases in embryo survival (P\0.05) continued through

2005 in ambient water samples from tested sites in upper

EFPC (EFK24.6 and EFK25.1).

In addition to laboratory tests using alternative test

organisms such as the medaka, in situ bioassays with

species such as the native fingernail clam (Smith and

Beauchamp 2000) were conducted as early as 1988 at

various locations in EFPC and other streams in the OakRidge area. Results of clam bioassays conducted annually

from 1998 through 2005 at three locations in EFPC and

three nearby reference streams unaffected by industrial

discharges are shown in Fig. 6. Clam survival in these

bioassays was consistently high at all three reference

streams; similar to survival in the reference streams at

EFK13.8 in lower EFPC; and significantly reduced at

EFK23.4 and EFK24.4 (ANOVA, P\ 0.05). Clam growth

was also relatively high in the reference streamsalthough

more variable from year-to-year than the survival end-

pointbut was again significantly reduced (P\ 0.05) at

all three of the tested EFPC locations.

Discussion

The toxicity assessment and monitoring program described

in this paper is but one facet of the extensive water pollution

controls and biological monitoring efforts conducted at the

Y-12 Complex since the mid 1980s. The relationships

between toxicity testing and receiving-water impacts have

been previously examined in relatively short-term studies

(examples include Eagleson and others1990; Dickson and

others1992; Kosmala and others 1999). However, relativelyfew long-term studies have examined how toxicity assess-

ments, as implemented through NPDES permitting

requirements in the mid-1980s and continuing to the present,

have been used in conjunction with other approaches such as

bioaccumulation studies and biological surveys to success-

fully assess the effects of aquatic pollution and monitor the

ecological recovery of receiving waters following an

extensive and prolonged implementation of water pollution

controls.

0

25

50

75

100

1997

1998

2000

2001

2002

2003

2004

2005

EFK25.1

EFK24.6

EFK23.4

EFK18.2

EFK13.8

Control

MedakaSurviva

l(%)

YearSite

Fig. 5 Survival of medaka embryos during toxicity tests of ambient

water from EFPC. EFK= EFPC kilometer

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

1998

1999

2000

2001

2002

2003

2004

2005

EFK24.4EF

K23.4EFK

13.8BFK

7CXK0.2HC

K20

Lengthincre

ase(mm)

Year

Site

0

25

50

75

100

1998

1999

2000

2001

2002

2003

2004

2005

EFK24.4EF

K23.4EFK13.8B

FK7CXK0.2H

CK20

Survival(%)

Year

Site

Fig. 6 Growth and survival of fingernail clams during in situ

bioassays in EFPC and reference sites. Reference sites were Hinds

Creek (HCK20), Cox Creek (CXK0.2), and Brushy Fork (BFK7) (see

Smith and Beauchamp2000). Data are not presented for Cox Creek in

2002 due to loss of bioassay units from vandalism. Test durations

varied from 80 to 85 days


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Whole effluent toxicity testing isalong with chemical

analyses and biological surveysa significant component

of the USEPA integrative approach for controlling toxics in

surface waters (USEPA1991). Considered to be predictive

of the health of receiving waters (Eagleson and others

1990; Grothe and others 1996; DeVlaming and Norberg-

King 1999; Maltby and others 2000), effluent toxicity

testing requirements have been routinely included for manyyears in NPDES permits issued for industrial facilities and

municipalities under the U.S. Clean Water Act, and have

been specifically included in the Y-12 Complexs NPDES

permits since the mid 1980s. Since effluent toxicity limits

began to be applied to NPDES permits in the 1980s,

compliance of wastewater discharges with toxicity limits

has improved significantly at the Y-12 Complex and

nationwide as well (Ausley 2000).

Chronic effluent toxicity testing conducted for the Y-12

Complex TCMP using the standard aquatic test organisms

C. dubia and fathead minnows conclusively demonstrated

that wastewaters discharged from the facility were suffi-ciently toxic in the mid 1980swith a calculated total

iTUc[ 4 at expected instream waste concentrationsto

provide a likely explanation for both the observed ambient

toxicity of stream water from upper EFPC and measured

impairments of stream communities (Ryon 2011; Smith

and others 2011). Intensive toxicity testing of numerous

effluent streams throughout the Y-12 Complex over the

period 19861992 was instrumental in identifying two

untreated process wastewaters as the most significant

sources of toxicity to the receiving stream. Before redi-

rection to treatment facilities, these particular discharges

were estimated to be responsible for approximately 94% of

the total toxicity loading to the stream from Y-12 Complex

wastewaters, in only 14% of total discharges. By 1992

once these particular discharges had been rerouted to

wastewater treatment facilities, all other untreated dis-

charges eliminated, and the toxicity of remaining waste-

water discharges such as cooling tower and wastewater

treatment facility effluents significantly decreased through

chemical substitutions and process modificationsthe

average releases of toxicants to EFPC from the Y-12

Complex had been reduced nearly twenty-fold to a value

(total iTUc = 0.24) well below the chronic threshold for

expected instream toxicity. However, monitoring of the

chronic toxicity of various wastewater treatment facilities

continued to demonstrate the occasional presence of

detectable toxicants in these effluent streams through at

least 1996 that undoubtedly contributed to the continuing

impairment of stream communities in upper EFPC during

this period of time. Whether this episodic chronic toxicity

of wastewater effluents persisted after 1996 will never be

known, as the mandated change from chronic toxicity

testing of effluents to less sensitive acute toxicity testing in

the 1995 renewal of the NPDES permit for all practical

purposes negated the ability of the effluent testing program

to effectively monitor such intermittent releases of toxi-

cants to the stream that were not actually acutely lethal to

the test organisms.

In addition to routine monitoring of effluent toxicity,

special toxicant identification studies were also conducted

for the Y-12 TCMP whenever new sources of significanttoxicity were discovered during routine effluent or ambient

toxicity tests. Examples of such studies based on the ulti-

mate chemicals of concern included investigations focused

on nickel (Kszos and others 1992), chlorine (Stewart and

others1996), uranium (Taylor and others 1987), and lith-

ium (Kszos and others2003). Whenever sources of toxicity

were identified, environmental management strategies

(typically, best management practices) were invoked to

mitigate the problem (Taylor and others 1987). Specific

examples of remedial actions taken to reduce pollutants

identified through the ambient toxicity testing program

included: (1) installation of a post-treatment carbon filter atthe West End Treatment Facility to lower the effluents

toxic concentrations of nickel; (2) whole-stream dechlori-

nation in upper EFPC by use of sodium metabisulfite; (3)

the removal and containment of urea, used as a deicer, from

an open storage site that was found to be draining to EFPC;

and (4) rerouting from upper EFPC to the Oak Ridge

Wastewater Treatment Facility of sulfate-rich effluent from

a coal-fired boiler unit.

Ambient toxicity testing, although not as commonly

used as effluent toxicity testing, has been suggested to be

possibly a more accurate and relevant predictor of receiv-

ing-waters effects (Birge and others 1989; Stewart and

others 1990; Dickson and others 1992). Just as effluent

toxicity indicated the presence of toxicants in discharges

sampled at the pipes, ambient toxicity testing provided

direct evidence of the presence of toxicants in upper EFPC

downstream of the Y-12 Complex outfalls. Ambient tox-

icity testing initially focused on numerous sampling sites in

lower EFPC downstream of the retention basins and only a

single site in upper EFPC at EFK 24.1, located just

upstream of the basins. In these early ambient toxicity tests

conducted before the first retention basinNew Hope

Pondwas closed in late 1988 and replaced by Lake

Reality, the average reproduction ofC. dubiaover a total of

nine such tests was 44% lower in water samples from the

upstream EFK24.1 site than in water samples from the

downstream EFK23.8 site (complete results not shown).

These early tests led to several preliminary conclusions

regarding the ambient toxicity of EFPC waters: (1) ambient

toxicity, if present in the lower reaches of EFPC, was

unable to be conclusively detected through the use of

C. dubia and fathead minnow testing [the infrequent and

sporadic reductions in fathead minnow growth or survival


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occasionally observed in ambient tests of samples from

lower EFPC were attributed to pathogens in the water

samples (Kszos and others 1997)]; (2) the ambient waters

of upper EFPC were persistently toxic to C. dubia but not

to fathead minnows; and (3) passage through the retention

basin was apparently beneficial in reducing the ambient

toxicity of EFPC waters.

Once it became obvious from the results of these earlyambient tests that neither C. dubia nor fathead minnow

tests could reliably detect toxicity in the waters of lower

EFPC, the focus of further ambient toxicity investigations

quickly shifted to upper EFPC. Routine ambient toxicity

monitoring was conducted on at least a quarterly basis

beginning initially at EFK24.1 during 1986, then further

upstream at EFK24.6 in 1988, and at EFK25.1 in 1990. The

latter two sampling sites were eventually replaced for

routine ambient toxicity testing purposes by a new instream

NPDES monitoring location located just downstream of

EFK25.1 at Outfall 201.

By 1992, with the elimination of untreated dischargesand other measures taken to improve EFPC water quality,

water samples collected from upper EFPC at EFK24.1 had

become consistently non-toxic to bothC. dubiaand fathead

minnows (Adams and others 2002). However, ambient

toxicity to C.dubia continued to be detected well into the

1990s in water samples from sites further upstream within

the Y-12 Complex. Much of this remaining ambient tox-

icity in upper EFPC was attributed to the presence of total

residual chlorine (TRC) from discharges of cooling tower

blowdown and chlorinated process water (Stewart and

others1996). The dechlorination of major outfalls to EFPC

began in late 1992 and continued for the next several years

as additional discharges were subsequently treated. How-

ever, occasional failures of the dechlorination systems

contributed to fish kills in upper EFPC even after this time

(Etnier and others 1996) and probably also to the contin-

uing ambient toxicity observed at some EFPC locations

through the mid 1990s. With the implementation of flow

management in 1996, which significantly increased the

flow of EFPC at the stream headwaters to volumes similar

to those present before extensive water pollution controls

began in the mid 1980s, ambient toxicity to C. dubia and

fathead minnows largely disappeared from EFPC ambient

waters.

Similar to the toxicant identification studies conducted

for the TCMP, routine monitoring of ambient toxicity for

the BMAP was supplemented by special studies designed

to address specific toxicological concerns. For example,

several of the toxicant evaluations performed for the

TCMP also had associated BMAP special studies that

examined the potential effects of toxicants of concern on

ambient toxicity or specific EFPC biota. Special toxicity-

related studies conducted in support of both the ambient

and effluent toxicity testing programs included: (1) inves-

tigations of the production, export, and ecological effects

of bioparticles in the Lake Reality retention basin (Cice-

rone and others 1999); (2) a demonstration that in-stream

toxicological problems due to chlorine were modified

substantially by environmental conditions (e.g., sunlight

and algal biomass; Stewart and others1996); and (3) both

in situ and laboratory investigations into the acclimation ofminnows to TRC in EFPC (Lotts and Stewart 1995).

Other tests employing longer exposure durations or

more sensitive test organisms or life stages were also used

in the BMAP program to help monitor the later stages of

stream recovery after C. dubia and fathead minnows had

stopped responding in ambient tests. Among the alternative

tests used for this purpose were a 21-days medaka embryo

development test and an in situ fingernail clam bioassay of

8085-days duration (Smith and Beauchamp 2000). Both

test organisms were affected at locations whereor at

times whenneither C. dubia nor fathead minnow tests

detected ambient toxicity, for example at sites in lowerEFPC throughout the study period and at sites in upper

EFPC following the implementation of flow management.

Another special study involved the use of full life-cycle C.

dubia tests to determine specifically if longer exposure

durations with this standard test organism could reveal

toxicant effects not seen in the shorter 3-brood tests

(Stewart and Konetsky1998).

Results of the Y-12 Complex toxicity studies, consid-

ered together, suggest that effluent and ambient toxicity

testing with C. dubia and fathead minnows, alternative

laboratory toxicity tests with other organisms, and in situ

bioassays were all predictive to some degree of observed

biological impacts in EFPC. For instance, fish community

(Ryon 2011) and benthic invertebrate (Smith and others

2011) surveys conducted in the mid to late 1980s demon-

strated impairment of instream aquatic communities at a

time when C. dubia and fathead minnow effluent and

ambient toxicity tests indicated there should be toxic

effects on stream communities. In addition, observed

reductions in the measured toxicity toC. dubiaand fathead

minnows of both effluents and the ambient waters of upper

EFPC through the mid 1990s were accompanied by gradual

improvements in EFPC fish and benthic invertebrate

communities. Taken together, this evidence suggests a

certain degree of predictive and causal association between

effluent and ambient toxicity and the ecological condition

of EFPCbut with some caveats. For instance, neither

C. dubia nor fathead minnow ambient tests were suffi-

ciently sensitive even in the early stages of the BMAP in

the mid 1980s to detect toxicity in the waters of lower

EFPC, when the absence of pollution-sensitive fish and

benthic invertebrate species from these communities was

strongly suggestive of toxic impacts in the stream.


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12/15

Furthermore, C. dubia and fathead minnow ambient tests

were also incapable of detecting the apparent continuing

low-level toxicity of stream water from both lower and

upper EFPC following flow management as implied by the

results of alternative ambient tests with medaka and fin-

gernail clams and the continuingalthough also dimin-

ishingimpairments of stream communities during this

period. Based on the Y-12 Complex BMAP experience, therelative sensitivities of the various testing approaches to

assessing ambient toxicity in EFPC were as follows: in situ

tests (clam test/most sensitive)[ alternative laboratory

tests (in this case, the medaka test focused on fish devel-

opment)[ chronic C. dubia tests[ acute C. dubia tests

and chronic and acute fathead minnow tests (least

sensitive).

With the significant reductions in the toxicity of both

Y-12 Complex wastewaters and EFPC ambient waters that

have occurred over time, additional factors such as habitat

degradation and the continuing presence of excessive

nutrients in Y-12 Complex wastewater may be assumingincreasingly greater significance to the further recovery of

stream communities in EFPC. For example, excessive

nutrients in wastewater effluents, which stimulate periph-

yton production and thus foster an overabundance of

grazers in both fish and benthic invertebrate communities

(Hill and others2010; Ryon2011; Smith and others2011),

may now be exerting greater influence on the composition

of these communities in the upper reaches of EFPC than

any remaining low-level ambient toxicity, although this

hypothesis remains to be conclusively proven. This

example illustrates the potential difficulties of interpreting

monitoring results from a single line of evidence (for

instance, from only ambient toxicity test results), especially

in the later stages in the recovery of a receiving body of

water, and emphasizes the importance of taking a weight

of evidence or multi-criteria approach (La Point and

Waller 2000) to the implementation of a successful bio-

monitoring program.

Summary and Environmental Management

Implications

The Y-12 Complex case-study demonstrates the value of a

long-term and diverse toxicity assessment and monitoring

program to a large industrial facility seeking to reduce or

eliminate toxic impacts to receiving waters. Effluent tox-

icity testing conducted for the Y-12 Complex TCMP

helped identify sources of toxicants and facilitate signifi-

cant reductions in toxicity loading to the upper reaches of

EFPC in the late 1980s and early 1990s. Decreases in

effluent toxicity documented by the testing program in turn

led to measurable decreases in the ambient toxicity of

stream water and marked improvements in the biological

health of the stream (Ryon 2011; Smith and others2011).

Ambient toxicity testing conducted for the Y-12 Complex

BMAP was particularly useful in evaluating the effective-

ness of pollution abatement actions and, in conjunction

with other BMAP activities such as instream biological

surveys, in directly assessing and monitoring the ecological

recovery of the receiving stream.With some exceptions, such as the problematic switch

from chronic to acute testing of wastewater effluents in the

1995 renewal of the NPDES permit, the Y-12 Complex

toxicity assessment and monitoring program is a prime

example of the successful implementation of adaptive

environmental management principles. The program was

diverse, with multiple species used and a variety of sites

tested as appropriate, and generally very adaptable (except

when specifically mandated otherwise by regulatory deci-

sions), with test methods and scope evolving as the situa-

tion and information needs changed over time. As the

toxicity of effluents and the receiving stream decreased dueto the success of remedial actions or pollution abatement

measures, testing became more focused, sites were drop-

ped, and more sensitive tests and bioassays were developed

and applied as needed to further evaluate and monitor

wastewater toxicity and subsequent improvements in

stream water quality.

In summary, the Y-12 Complex TCMP and BMAP case-

studies show the utility of effluent and ambient toxicity

assessments as environmental management tools. Effluent

and ambient toxicity testing, special toxicological studies,

and toxicity identification studies have been particularly

useful to environmental managers and regulators in

evaluating causal and mechanistic relationships between

environmental contamination, pollution control and envi-

ronmental remediation activities, and subsequent effects on

the ecological condition of receiving waters. The Y-12

Complex example further illustrates the importance of

combining toxicity studies with other assessment tech-

niques such as chemical analyses, bioaccumulation

assessments, and instream biological surveys in an inte-

grated weight of evidence approach for successfully

assessing and monitoring the ecological health of a

receiving body of water.

Acknowledgments The authors acknowledge the many individuals

who made significant contributions to this project, including Kitty

McCracken, Belinda Konetsky, Linda Wicker, W. Kelley Roy, Peggy

Braden, G. Jayne Haynes, Richard D. Bailey, and numerous intern

students. Logan Elmore provided assistance with figures. The work

was funded by the Environmental Compliance Department of the

Y-12 National Security Complex, which is managed by BWXT Y-12,

LLC for the U.S. Department of Energy under contract number

DE-AC05-00OR22800. Oak Ridge National Laboratory is managed

by the University of Tennessee-Battelle LLC for the U.S. Department

of Energy under contract DE-AC05-00OR22725.


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