Number range CHAPTER **G. Fred Lee & Associates**

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

27298 E. El Macero Dr.

El Macero, California 95618-1005

Tel. (530) 753-9630 • Fax (530) 753-9956

e-mail: gfredlee@aol.com

web site: http://www.gfredlee.com

April 14, 2003

Anthony Britten,

Chemical Review Manager

Carbaryl,

In response to the US EPA OPP April 4, 2003 request for comments on the
risk management for carbaryl, I wish to bring to the attention of the US
EPA OPP an experience I had with carbaryl toxicity as part of a study
that was conducted in the late 1990s in the Orange County, California,
Upper Newport Bay/San Diego Creek watershed.

As part of a US EPA-sponsored 319(h) project devoted to assessing the
occurrence and magnitude of aquatic life toxicity and its causes in the
Upper Newport Bay watershed, we found a high level of aquatic life
toxicity to *Ceriodaphnia dubia*. While normally we found high levels of
toxicity in various tributaries of San Diego Creek, which were due to
diazinon and/or chlorpyrifos, this time the toxicity was not associated
with either of these pesticides. Through a combination of chemical
measurements, TIE studies and work with the Orange County Agricultural
Commissioner, the high level of aquatic life toxicity that was found in
the sample of stormwater runoff from an agricultural area was determined
to be due to carbaryl. From records of pesticide application, it was
found that the day before the rainfall event carbaryl had been applied
to strawberry fields in this watershed. Presented below is an excerpt
from our several-hundred-page report covering our 319(h) study, which
presents the information we obtained in this situation. The complete
report,

Number range CHAPTERLee, G. F., Taylor, S., and County of Orange Public
Facilities and Resources Department, "Upper Newport Bay Water Quality
Enhancement Project, Final Report," Agreement Nos. 8-023-258-0 and
8-174-250-0, submitted to State Water Resources Control Board, Santa Ana
Regional Water Quality Control Board and Orange County Public Facilities
and Resources Department to meet the requirements of the US EPA 319(h)
Project, G. Fred Lee & Associates, El Macero, CA and RBF Consulting,
Irvine, CA, May (2001).

is available from me on request.

This situation is yet another example of the inadequate approach that is
used by the US EPA OPP in evaluating the potential environmental hazards
of pesticides, where the registration of pesticides for agricultural and
urban use does not include an evaluation of whether stormwater runoff
from an area which has received the pesticide application in accord with
the label could lead to aquatic life toxicity in the receiving waters
for the runoff. While often regulatory agencies will attempt to average
the concentrations of pesticides to assess their impacts on water
quality, a single runoff event, such as the one that we encountered
because we happened to be sampling at the time, could have a significant
adverse impact on the aquatic-life-related beneficial uses of the
tributary streams and Upper Newport Bay. While we monitored various
waterbodies in the Upper Newport Bay watershed over a period of about
four years, for aquatic life toxicity and a variety of pesticides and
frequently found small amounts of carbaryl in our samples associated
with stormwater runoff events, if we had not sampled this particular
runoff event we would never have seen the very high levels of aquatic
life toxicity that was found during it, and as a result might not know
that there was a major toxic pulse that occurred due to stormwater
runoff from an area where carbaryl had been applied on an agricultural
field.

As discussed in our writings on our website, The US EPA OPP needs to
significantly change its evaluation of the hazards associated with the
registration of pesticides, so that consideration is given as to whether
stormwater runoff events from areas where the pesticides are applied in
accordance with the registration label cause aquatic life toxicity.

If there are questions about these comments, please contact me.

G. Fred Lee, PhD, PE, DEE

Copies to: M. Lee, California Dept. of Pesticide Registration

Santa Ana Regional Water Quality Control Board

Central Valley Regional Water Quality Control Board

**Results of Aquatic Toxicity Testing Conducted During 1999-2000**

**within the Upper Newport Bay Watershed**

Prepared by

**G. Fred Lee, PhD, DEE**

G. Fred Lee & Associates

El Macero, CA

and

**Scott Taylor, PE**

**Frances Palmer**

RBF Consulting

Irvine, CA

Submitted to

**State Water Resources Control Board,**

**Santa Ana Regional Water Quality Control Board and**

**Orange County Public Facilities and Resources Department**

To Meet the Requirements of the

United States Environmental Protection Agency 319(h) Project

**May 2001**

# Executive Summary

## Background

In the late 1980s/early 1990s, it was found that the concentrations of
heavy metals in Upper Newport Bay tributaries and within the Bay
occurred in stormwater runoff above US EPA water quality criteria for
the protection of aquatic life from toxicity. It was also found at that
time that toxicity to *Ceriodaphnia dubia* (a freshwater zooplankton -
water flea) was present in stormwater runoff to the Bay. The cause of
this toxicity was not identified.

In the mid-1990s, an Evaluation Monitoring program was developed to
assess receiving water quality impacts from urban stormwater runoff.
While there were a number of water quality problems \-- use impairments
\-- in the Bay and its tributaries that were well documented at the time
of the initiation of the Evaluation Monitoring program, the area in
which there was inadequate information was that of aquatic life toxicity
and whether the heavy metals that were present in stormwater runoff from
the Bay=s watershed at concentrations above US EPA water quality
criteria were in toxic available forms.

A limited-scope toxicity monitoring program was initiated, focusing on
collecting samples of stormwater runoff from Upper Newport Bay at San
Diego Creek at Campus Drive in order to assess whether the previously
reported toxicity was present in this runoff. It was found that
stormwater runoff to Upper Newport Bay was toxic to *Ceriodaphnia* as it
entered the Bay. It was also found that this toxicity was due, at least
in part, to two organophosphate (OP) pesticides, diazinon and
chlorpyrifos. Further, there was some evidence, through toxicity
investigation evaluations (TIEs), that the heavy metals that were
present above US EPA worst-case-based water quality criteria were not
responsible for this toxicity. These findings led to the development of
a US EPA 205(j) grant to investigate in a more comprehensive manner the
occurrence of toxicity and its cause in the Upper Newport Bay Watershed.

The 205(j) project was a 2-year effort, in which over 160 toxicity tests
were conducted in the Upper Newport Bay Watershed and within the Bay,
focusing on *Ceriodaphnia* and *Mysidopsis* toxicity during stormwater
runoff events and under non-runoff conditions. All stormwater runoff
within the Upper Newport Bay Watershed in the 205(j) studies was found
to be toxic to *Ceriodaphnia* and *Mysidopsis*. Further, through
forensic TIE studies, it was found that one of the principal sources of
toxicity during wet weather and under dry weather flow conditions were
two nurseries located on one of the primary tributaries to San Diego
Creek, a primary tributary of Upper Newport Bay. The cause of the
toxicity was found to be diazinon and chlorpyrifos, where typically 3 to
5 TUa of *Ceriodaphnia* acute toxicity were present in stormwater
runoff. Typically, this runoff killed all *Ceriodaphnia* in the test
system within one or two days. Another 5 to 8 TUa of *Ceriodaphnia*
acute toxicity were present in stormwater runoff samples that were due
to unknown causes. Further, as part of the ongoing Evaluation Monitoring
program, it was found that a residential subdivision in Yorba Linda had
high levels of unknown-caused toxicity.

Through review of the California Department of Pesticide Regulation
(DPR) Pesticide Usage Reports, it was found that over 100,000 lb (ai) of
diazinon and chlorpyrifos were used each year in Orange County for
residential structural purposes. It was also found through the use of US
EPA gas chromatographic analytical procedures that only occasionally
could other OP pesticides and carbamate pesticides analyzed in these
procedures be responsible for some of the unknown-caused toxicity.
Further, additional TIE work was done in the 205(j) project to
investigate whether some of this unknown-caused toxicity was due to
heavy metals. It was found that the toxicity associated with discharges
from the nurseries, which at times contained 10 to as much as 20 TUa of
unknown-caused toxicity, was not due to heavy metals. A comprehensive
report covering the 205(j) studies was issued by Lee and Taylor (1999).

As part of developing the Clean Water Act 303(d) list of impaired
waterbodies in the Upper Newport Bay Watershed, the Santa Ana Regional
Water Quality Control Board (SARWQCB) listed Upper Newport Bay and its
tributaries as impaired, based on excessive concentrations of heavy
metals and aquatic life toxicity. This listing led to establishing total
maximum daily loads (TMDLs) to control the toxicity and excessive heavy
metals.

A US EPA 319(h) grant was obtained to determine the occurrence of
toxicity throughout the Upper Newport Bay Watershed and, to the extent
that funds available would allow, identify primary sources of toxicity.
Also, additional work was to be done in the 319(h) project on
identifying the constituents responsible for the unknown-caused
toxicity. As originally envisioned, the results of this 319(h) study
would serve as the basis by which the SARWQCB would establish the TMDL
and its allocation among sources. This report presents the results of
the 319(h) project.

## 319(h) Project Results

Beginning in September 1999 through May 2000, two dry weather (September
29, 1999 and May 31, 2000) and three stormwater runoff events (January
25, 2000, February 12, and 21, 2000) were sampled at up to10 locations
in the Orange County, CA, Upper Newport Bay Watershed. A total of about
375 toxicity tests and associated selected chemical measurements were
made on these samples. The 10 locations were selected to obtain
stormwater runoff from several limited land use activities (residential,
agriculture, open space and commercial nurseries) in the watershed
upstream of the sampling locations. All stormwater runoff samples were
highly toxic to *Ceriodaphnia dubia* and *Mysidopsis bahia*. In general,
no toxicity was found to fathead minnow larvae or the alga
*Selenastrum*.

### Toxicity Due to Pesticides

Stormwater runoff from all of the sampled watersheds showed high levels
of aquatic life toxicity. About a third to one-half of the toxicity
could possibly be accounted for based on the diazinon, chlorpyrifos and
-- for an ag-dominated watershed -- carbaryl concentrations found. The
cause of other toxicity is unknown, although many of the samples show
enhanced toxicity in the presence of PBO, indicating that some of the
toxicity could be due to pyrethroid pesticides. Even after extensive TIE
studies, it was not possible to identify the cause of the unknown-caused
toxicity or confirm that the toxicity was due at least in part to
pyrethroid pesticides.

The total mass of the OP pesticides diazinon and chlorpyrifos during a
stormwater runoff event was determined based on the analytical results
from the single grab sample taken during the runoff event and the total
estimated flow during the runoff event. It was found that the rate of
export of diazinon and chlorpyrifos ranged from about 0.01 × 10^-5^ to 3
× 10^-5^ lb/acre. Urban residential areas tend to show higher export
rates for diazinon and chlorpyrifos than agricultural and open space
areas. This pattern is expected based on how these two OP pesticides are
used in the Upper Newport Bay Watershed. The total amount of diazinon
and chlorpyrifos that is needed to cause the toxicity found in
stormwater runoff as it enters Upper Newport Bay is about 2 lb per
storm, with an average of about 10 storms per year (20 lb/yr), out of
the approximately 30,000 lb/yr that are applied to the Upper Newport Bay
Watershed.

The *Mysidopsis* toxicity could largely be accounted for based on
chlorpyrifos concentrations. There are significant questions about
whether the *Ceriodaphnia* and *Mysidopsis* toxicity found in stormwater
runoff is causing significant adverse impacts on the beneficial uses of
the Upper Newport Bay tributaries and the Bay. This conclusion is based
on the duration of exposure that aquatic life can receive during a
stormwater runoff event and the highly restricted toxicity of
chlorpyrifos to aquatic life.

The elimination of the over-the-counter sales and many residential uses
of chlorpyrifos will likely greatly reduce if not eliminate the
*Mysidopsis* toxicity in stormwater runoff in the Upper Newport Bay
Watershed. The phase-out of the use of the over 100,000 lb/yr (ai) of
chlorpyrifos on residential property within Orange County within the
next year may mean that 100,000 lb of some other pesticide(s) will be
used in Orange County. Continued monitoring of *Mysidopsis* toxicity in
stormwater runoff to Upper Newport Bay should be conducted to determine
if the remaining registered uses of chlorpyrifos cause aquatic life
toxicity in the Bay.

The current US EPA Office of Pesticide Programs (OPP) and the CA
Department of Pesticide Regulations approaches for evaluating
pesticides' environmental impacts do not adequately screen pesticides
registered for residential and agricultural uses to prevent stormwater
runoff aquatic life toxicity. Every pesticide approved for a potential
use should be evaluated with respect to the potential to be transported
from the point of application to surface waters, where they could be
adverse to the aquatic life-related and other beneficial uses of the
waterbody. The "pesticide roulette" that will take place next year
associated with the phase-out of chlorpyrifos could lead to even greater
environmental harm than the current, if any, adverse impacts of the
chlorpyrifos, diazinon and carbaryl found in stormwater runoff in the
Upper Newport Bay Watershed and the Bay.

The finding of high levels of carbaryl-caused aquatic life toxicity
following its application on agricultural land followed by a stormwater
runoff event points to a potentially significant problem with protecting
aquatic ecosystems from the adverse impacts of pesticide use. Such
situations, where there could be high levels of aquatic life toxicity in
waterbodies that occur under restricted conditions such as those
associated with stormwater runoff closely following the application of a
pesticide, could be significantly adverse to an aquatic ecosystem
without being measured in typical routine monitoring of pesticide
concentrations in surface waters.

This situation points to the need for US EPA OPP and CA DPR to
incorporate the fate/transport of pesticides from the point of
application to surface waters associated with stormwater runoff events
and deliberate and fugitive water releases, into their evaluation of the
environmental impacts of pesticides. Particular attention should be
given in registering pesticides to evaluate whether short-term episodic
events associated with stormwater runoff could be significantly adverse
to aquatic ecosystems without being detected by normal monitoring
systems. There is an urgent need for the federal and state pesticide and
water quality regulatory agencies and the public to develop an effective
pre-screening of pesticides for potential environmental impacts prior to
use under conditions where the pesticide could be present in stormwater
runoff from the area where the pesticide is applied. This pre-screening
should be followed by actual monitoring of stormwater runoff following
application of pesticides to determine under the variety of field
conditions where pesticides are being used, whether there is sufficient
transport associated with a runoff event to be adverse to aquatic
ecosystems. This follow up monitoring should be part of the pesticide
registration process.

Based on the results of this 319(h) and the previously conducted 205(j)
projects, it is clear that in order to properly regulate aquatic life
toxicity in urban and agricultural stormwater runoff there is need to
determine what the stormwater runoff-associated *Ceriodaphnia* and
*Mysidopsis* toxic pulses mean to the impairment of the beneficial uses
of fresh and marine waterbodies. In the Upper Newport Bay and its
watershed (and, for that matter, in many other areas), there are
appropriate questions about the magnitude, if any, of the impairment of
the beneficial uses of the waterbodies in which this toxicity is found.
There is an urgent need for studies to determine whether these toxic
pulses are adverse to higher trophic level organisms, such as edible
fish that are of primary interest to the public. This will require
detailed multi-year projects examining how organism assemblages are
impacted by toxic pulses of pesticides.

The current passive approach of finding a potential water quality
beneficial use impairment associated with the use of a pesticide and
then trying to regulate it, should be changed to a proactive approach in
which pesticide registration involves the requirement that the pesticide
manufacture/user must conduct appropriate studies to determine if, after
the pesticide application, there is release of the pesticide in
stormwater runoff/discharges to water courses. If the pesticide is
measured in the runoff or discharges using adequately sensitive
analytical methods, then the impact of the pesticide on the beneficial
uses should be determined. Consideration must be given in these studies
to additive and cumulative impacts of pesticides and other pollutants.

There is need to determine how pesticides used on residential
properties, agricultural lands and other areas for various purposes lead
to stormwater runoff aquatic life toxicity in the receiving waters for
the runoff. Such studies could provide the information needed to
appropriately use pesticides to control pests without adverse impacts on
the beneficial uses of the waterbodies receiving the runoff from the
area where the pesticides are applied. Further information on this topic
is available in the Discussion section of the 205(j) report (Lee and
Taylor, 1999).

##### 

##### Excerpts from report pertinent to Carbaryl

##### Toxicity of Samples Collected on February 12, 2000

Table 4-26 presents the summary data for the 7-day *Ceriodaphnia*
toxicity test for the samples collected on February 12, 2000. All
stations but station 8, Sand Canyon, showed a 100% kill of
*Ceriodaphnia* in one to three days. The Sand Canyon station showed 22%
kill over the 7-day period. This station had a much lower level of
toxicity to *Ceriodaphnia* than all other stations.

+-------------------------------+-------+-------+----------+---------+
| Table 4-26                    |       |       |          |         |
|                               |       |       |          |         |
| Summary of 7-day              |       |       |          |         |
| *Ceriodaphnia* Toxicity Test  |       |       |          |         |
| Conducted on Samples          |       |       |          |         |
| Collected\                    |       |       |          |         |
| from Upper Newport Bay        |       |       |          |         |
| Watershed on February 12,     |       |       |          |         |
| 2000^2^                       |       |       |          |         |
+-------------------------------+-------+-------+----------+---------+
| **Treatment **                | **Re  |       | **Mortal | **Final |
|                               | produ |       | ity^1^** | pH**    |
| ** **                         | ction |       |          |         |
|                               | ^1^** |       | (%)      | **at 24 |
|                               |       |       |          | hr **   |
|                               | *     |       |          |         |
|                               | * (ne |       |          |         |
|                               | onate |       |          |         |
|                               | s/adu |       |          |         |
|                               | lt)** |       |          |         |
+-------------------------------+-------+-------+----------+---------+
|                               |       |       |          |         |
+-------------------------------+-------+-------+----------+---------+
|                               | **x** | *     |          |         |
|                               |       | *se** |          |         |
+-------------------------------+-------+-------+----------+---------+
| Laboratory Control            | 26    | 1.0   | 5.3^P^   | 8.1     |
|                               | .2^P^ |       |          |         |
+-------------------------------+-------+-------+----------+---------+
| SD Creek @ Campus             | \*    | \*    | 100(1)   | 7.9     |
+-------------------------------+-------+-------+----------+---------+
| SD Creek @ Harvard            | \*    | \*    | 100(1)   | 7.9     |
+-------------------------------+-------+-------+----------+---------+
| Peters Canyon @ Barranca      | \*    | \*    | 100(1)   | 7.7     |
+-------------------------------+-------+-------+----------+---------+
| Hines Channel @ Irvine Blvd   | \*    | \*    | 100(1)   | 7.5     |
+-------------------------------+-------+-------+----------+---------+
| San Joaquin @ Sand Canyon     | \*    | \*    | 100(1)   | 8.3     |
+-------------------------------+-------+-------+----------+---------+
| S.A. Delhi/Mesa               | \*    | \*    | 100(3)   | 7.9     |
+-------------------------------+-------+-------+----------+---------+
| El Modena - Irvine Ch. @      | \*    | \*    | 100(1)   | 7.7     |
| Peters Canyon                 |       |       |          |         |
+-------------------------------+-------+-------+----------+---------+
| Sand Canyon - N.E. corner     | 1.1   | 0.9   | 22       | 7.6     |
| Irvine Blvd                   |       |       |          |         |
+-------------------------------+-------+-------+----------+---------+
| Costa Mesa Channel @ Highland | \*    | \*    | 100(2)   | 7.9     |
+-------------------------------+-------+-------+----------+---------+
| Central Irvine Channel @      | \*    | \*    | 100(1)   | 7.6     |
| upstream of Culver            |       |       |          |         |
+-------------------------------+-------+-------+----------+---------+
| P. The laboratory control met |       |       |          |         |
| all EPA criteria for test     |       |       |          |         |
| acceptability. 100% of the    |       |       |          |         |
| daphnids had a third brood.   |       |       |          |         |
|                               |       |       |          |         |
| 1\. Highlighted cells         |       |       |          |         |
| indicate a significant        |       |       |          |         |
| reduction in reproduction or  |       |       |          |         |
| increase in mortality         |       |       |          |         |
| relative to the               |       |       |          |         |
|                               |       |       |          |         |
| laboratory control water. The |       |       |          |         |
| mortality endpoint was        |       |       |          |         |
| analyzed using Fisher\'s      |       |       |          |         |
| Exact Test. The reproductive  |       |       |          |         |
|                               |       |       |          |         |
| endpoint was analyzed using   |       |       |          |         |
| Dunnett\'s Test (p\<.05).     |       |       |          |         |
|                               |       |       |          |         |
| 2\. This test was set up on   |       |       |          |         |
| 14 February 2000.             |       |       |          |         |
|                               |       |       |          |         |
| \(#\) indicates days to 100%  |       |       |          |         |
| mortality.                    |       |       |          |         |
|                               |       |       |          |         |
| \* Reproduction was not       |       |       |          |         |
| calculated due to significant |       |       |          |         |
| mortality.                    |       |       |          |         |
+-------------------------------+-------+-------+----------+---------+

Table 4-27 presents a summary of the *Ceriodaphnia* 96-hr PBO and
dilution TIE results for the samples collected on February 12, 2000. The
San Diego Creek at Campus Drive sample was toxic to *Ceriodaphnia*
through the 12.5% dilution, but not toxic at the 6.25% dilution. This
indicates that there are about 8 TUa of *Ceriodaphnia* toxicity in this
sample.

+-----------------------+---+---+----+---+-------------------+------+
| Table 4-27            |   |   |    |   |                   |      |
|                       |   |   |    |   |                   |      |
| Summary of            |   |   |    |   |                   |      |
| *Ceriodaphnia*        |   |   |    |   |                   |      |
| 96-hour PBO and       |   |   |    |   |                   |      |
| Dilution TIE          |   |   |    |   |                   |      |
| Conducted on Samples  |   |   |    |   |                   |      |
|                       |   |   |    |   |                   |      |
| Collected from Sites  |   |   |    |   |                   |      |
| 1 and 2 on February   |   |   |    |   |                   |      |
| 12, 2000^1,2,4^       |   |   |    |   |                   |      |
+-----------------------+---+---+----+---+-------------------+------+
| **Treatment**         | * |   |    |   | **Conclusions**   | **F  |
|                       | * |   |    |   |                   | inal |
| ** **                 | % |   |    |   | ** **             | pH** |
|                       | M |   |    |   |                   |      |
|                       | o |   |    |   |                   | **at |
|                       | r |   |    |   |                   | 24   |
|                       | t |   |    |   |                   | hr** |
|                       | a |   |    |   |                   |      |
|                       | l |   |    |   |                   |      |
|                       | i |   |    |   |                   |      |
|                       | t |   |    |   |                   |      |
|                       | y |   |    |   |                   |      |
|                       | f |   |    |   |                   |      |
|                       | o |   |    |   |                   |      |
|                       | r |   |    |   |                   |      |
|                       | e |   |    |   |                   |      |
|                       | a |   |    |   |                   |      |
|                       | c |   |    |   |                   |      |
|                       | h |   |    |   |                   |      |
|                       | d |   |    |   |                   |      |
|                       | a |   |    |   |                   |      |
|                       | y |   |    |   |                   |      |
|                       | o |   |    |   |                   |      |
|                       | f |   |    |   |                   |      |
|                       | t |   |    |   |                   |      |
|                       | h |   |    |   |                   |      |
|                       | e |   |    |   |                   |      |
|                       | t |   |    |   |                   |      |
|                       | e |   |    |   |                   |      |
|                       | s |   |    |   |                   |      |
|                       | t |   |    |   |                   |      |
|                       | ^ |   |    |   |                   |      |
|                       | 3 |   |    |   |                   |      |
|                       | ^ |   |    |   |                   |      |
|                       | * |   |    |   |                   |      |
|                       | * |   |    |   |                   |      |
+-----------------------+---+---+----+---+-------------------+------+
|                       | * | * | *  | * |                   |      |
|                       | * | * | *3 | * |                   |      |
|                       | 1 | 2 | ** | 4 |                   |      |
|                       | * | * |    | * |                   |      |
|                       | * | * |    | * |                   |      |
+-----------------------+---+---+----+---+-------------------+------+
| Laboratory Control    | 0 | 0 | 0  | 0 | Control met all   | 7.6  |
|                       |   |   |    |   | EPA criteria for  |      |
|                       |   |   |    |   | test              |      |
|                       |   |   |    |   | acceptability.    |      |
+-----------------------+---+---+----+---+-------------------+------+
| Laboratory Control +  | 0 | 0 | 0  | 0 | No artifactual    | 7.7  |
| PBO                   |   |   |    |   | toxicity present  |      |
|                       |   |   |    |   | in control        |      |
|                       |   |   |    |   | blanks.           |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Campus @   | 0 | 0 | 0  | 5 | No toxicity       | 8.3  |
| 1.56%                 |   |   |    |   | detected.         |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Campus @   | 0 | 0 | 0  | 0 | No toxicity       | 8.1  |
| 3.13%                 |   |   |    |   | detected.         |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Campus @   | 0 | 5 | 5  | 5 | No toxicity       | 7.4  |
| 6.25%                 |   |   |    |   | detected.         |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Campus @   | 9 | 1 | 1  | 1 | Toxicity          | 7.4  |
| 12.5%                 | 5 | 0 | 00 | 0 | detected.         |      |
|                       |   | 0 |    | 0 |                   |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Campus @   | 0 | 9 | 1  | 1 | Delay in          | 7.5  |
| 12.5% + 100 ppb PBO   |   | 5 | 00 | 0 | mortality may     |      |
|                       |   |   |    | 0 | suggest that the  |      |
|                       |   |   |    |   | toxicity was at   |      |
|                       |   |   |    |   | least in part due |      |
|                       |   |   |    |   | to a              |      |
|                       |   |   |    |   | metabolically     |      |
|                       |   |   |    |   | activated         |      |
|                       |   |   |    |   | pesticide.        |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Campus @   | 1 | 1 | 1  | 1 | Toxicity          | 7.5  |
| 25%                   | 0 | 0 | 00 | 0 | detected.         |      |
|                       | 0 | 0 |    | 0 |                   |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Campus @   | 9 | 1 | 1  | 1 | Toxicity          | 7.5  |
| 25% + 100 ppb PBO     | 0 | 0 | 00 | 0 | detected.         |      |
|                       |   | 0 |    | 0 |                   |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Harvard @  | 0 | 0 | 0  | 0 | No toxicity       | 7.7  |
| 1.56%                 |   |   |    |   | detected.         |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Harvard @  | 0 | 0 | 0  | 0 | No toxicity       | 7.7  |
| 3.13%                 |   |   |    |   | detected.         |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Harvard @  | 0 | 0 | 0  | 0 | No toxicity       | \-   |
| 6.25%                 |   |   |    |   | detected.         |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Harvard @  | 1 | 1 | 1  | 1 | Toxicity          | 8.1  |
| 12.5%                 | 0 | 0 | 00 | 0 | detected.         |      |
|                       | 0 | 0 |    | 0 |                   |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Harvard @  | 0 | 5 | 1  | 1 | Delay in          | \-   |
| 12.5% + 100 ppb PBO   |   | 2 | 00 | 0 | mortality may     |      |
|                       |   |   |    | 0 | suggest that the  |      |
|                       |   |   |    |   | toxicity was at   |      |
|                       |   |   |    |   | least in part due |      |
|                       |   |   |    |   | to a              |      |
|                       |   |   |    |   | metabolically     |      |
|                       |   |   |    |   | activated         |      |
|                       |   |   |    |   | pesticide.        |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Harvard @  | 1 | 1 | 1  | 1 | Toxicity          | 8.1  |
| 25%                   | 0 | 0 | 00 | 0 | detected.         |      |
|                       | 0 | 0 |    | 0 |                   |      |
+-----------------------+---+---+----+---+-------------------+------+
| SD Creek @ Harvard @  | 4 | 1 | 1  | 1 | Toxicity          | 8.1  |
| 25% + 100 ppb PBO     | 0 | 0 | 00 | 0 | detected.         |      |
|                       |   | 0 |    | 0 |                   |      |
+-----------------------+---+---+----+---+-------------------+------+
| 1\. Four replicates   |   |   |    |   |                   |      |
| with 18 mls of sample |   |   |    |   |                   |      |
| and 5 *Ceriodaphnia*  |   |   |    |   |                   |      |
| each.                 |   |   |    |   |                   |      |
|                       |   |   |    |   |                   |      |
| 2\. Daphnids were fed |   |   |    |   |                   |      |
| the standard EPA      |   |   |    |   |                   |      |
| amount of food for    |   |   |    |   |                   |      |
| only four hours a     |   |   |    |   |                   |      |
| day.                  |   |   |    |   |                   |      |
|                       |   |   |    |   |                   |      |
| 3\. Highlighted cells |   |   |    |   |                   |      |
| indicate areas of     |   |   |    |   |                   |      |
| significant interest. |   |   |    |   |                   |      |
| No statistical        |   |   |    |   |                   |      |
| analyses were done.   |   |   |    |   |                   |      |
|                       |   |   |    |   |                   |      |
| 4\. This test was set |   |   |    |   |                   |      |
| up on 17 February     |   |   |    |   |                   |      |
| 2000.                 |   |   |    |   |                   |      |
+-----------------------+---+---+----+---+-------------------+------+

Table 4-34 presents the summary of the pesticides found in the GC
analysis by APPL Laboratories of the samples collected for the February
12, 2000, stormwater runoff event. Diazinon and chlorpyrifos were also
analyzed by *Aqua*Science, using ELISA procedures; these values are
presented in Table 4-34 with an "A" following the concentration.

There were 460 ng/L of diazinon and 260 ng/L of chlorpyrifos found in
the San Diego Creek sample collected at Campus Drive. While several
other pesticides were detected in this sample, only carbaryl was present
at concentrations that could contribute to the *Ceriodaphnia* toxicity.
Carbaryl, also known as sevin, is a carbamate pesticide. According to C.
Foe (pers. comm., 1998) the LC~50~ for carbaryl to *Ceriodaphnia* is on
the order of 3,500 to 5,200 ng/L. For the purposes of this study's
calculations of expected *Ceriodaphnia* TUa, a carbaryl *Ceriodaphnia*
LC~50~ will be assumed to be 4,000 ng/L. The LC~50~ normalized sum of
the concentrations of diazinon, chlorpyrifos and carbaryl yielded an
estimated *Ceriodaphnia* TUa of about 5. Therefore, there were about 3
TUa of unknown-caused toxicity in the February 12, 2000, San Diego Creek
sample collected at Campus Drive.

The 12.5% dilution of the San Diego Creek sample collected on February
12, 2000, when treated with 100 µg/L of PBO, showed reduced toxicity
compared to the untreated 12.5% sample. These results indicate that part
of the toxicity could have been due to OP pesticides. This is in accord
with the results of the total toxicity compared to the estimated
toxicity due to diazinon and chlorpyrifos.

Table 4-27 also presents the results for the toxicity test performed on
San Diego Creek at Harvard Avenue collected on February 12, 2000. The
results of the total and dilution series toxicity test, with and without
PBO, are nearly identical to the results obtained for the San Diego
Creek sample taken on February 12, 2000, at Campus Drive.

Table 4-28 presents the *Ceriodaphnia* 96-hour PBO and dilution TIEs for
the Peters Canyon at Barranca Parkway and Hines Channel at Irvine
Boulevard samples collected on February 12, 2000. The Peters Canyon at
Barranca sample also had about 8 TUa of *Ceriodaphnia* toxicity. The
addition of 100 µg/L PBO to the 12.5% dilution of this sample showed an
increased toxicity where a 100% kill occurred within one day rather than
in two days as occurred in the 12.5% sample without PBO. This indicates
the potential for pyrethroid pesticides to be a cause of part of this
toxicity.

Essentially identical results were obtained for the Hines Channel sample
collected at Irvine Boulevard on February 12, 2000, as were found at the
Peters Canyon at Barranca sample. Both samples had about 8 TUa of
measured *Ceriodaphnia* toxicity. Based on the data presented in Table
4-34, the Peters Canyon sample had an estimated *Ceriodaphnia* toxicity
of 5 TUa and the Hines Channel sample had an estimated *Ceriodaphnia*
toxicity of 3 TUa. Therefore, there were about 3 TUa of unknown-caused
*Ceriodaphnia* toxicity in the Peters Canyon at Barranca and 5 TUa of
unknown-caused *Ceriodaphnia* toxicity in the Hines Channel at Irvine
Avenue samples collected on February 12, 2000. There was also some
evidence for PBO activation of *Ceriodaphnia* toxicity in both the
Peters Canyon and the Hines Channel samples collected on February 12,
2000.

+------------------------+----+----+---+---+----------------+-------+
| Table 4-28             |    |    |   |   |                |       |
|                        |    |    |   |   |                |       |
| Summary of             |    |    |   |   |                |       |
| *Ceriodaphnia* 96-hour |    |    |   |   |                |       |
| PBO and Dilution TIE   |    |    |   |   |                |       |
| Conducted on Samples   |    |    |   |   |                |       |
| Collected from Sites 3 |    |    |   |   |                |       |
| and 4 on February12,   |    |    |   |   |                |       |
| 2000^1,2,4^            |    |    |   |   |                |       |
+------------------------+----+----+---+---+----------------+-------+
| Treatment              | *  |    |   |   | *              | **    |
|                        | *% |    |   |   | *Conclusions** | Final |
| ** **                  | M  |    |   |   |                | pH**  |
|                        | or |    |   |   |                |       |
|                        | ta |    |   |   |                | **at  |
|                        | li |    |   |   |                | 24    |
|                        | ty |    |   |   |                | hr**  |
|                        | f  |    |   |   |                |       |
|                        | or |    |   |   |                |       |
|                        | ea |    |   |   |                |       |
|                        | ch |    |   |   |                |       |
|                        | d  |    |   |   |                |       |
|                        | ay |    |   |   |                |       |
|                        | of |    |   |   |                |       |
|                        | t  |    |   |   |                |       |
|                        | he |    |   |   |                |       |
|                        | t  |    |   |   |                |       |
|                        | es |    |   |   |                |       |
|                        | t^ |    |   |   |                |       |
|                        | 3^ |    |   |   |                |       |
|                        | ** |    |   |   |                |       |
+------------------------+----+----+---+---+----------------+-------+
|                        | *  | *  | * | * |                |       |
|                        | *1 | *2 | * | * |                |       |
|                        | ** | ** | 3 | 4 |                |       |
|                        |    |    | * | * |                |       |
|                        |    |    | * | * |                |       |
+------------------------+----+----+---+---+----------------+-------+
| Laboratory Control     | 0  | 0  | 5 | 5 | Control met    | 8.0   |
|                        |    |    |   |   | all EPA        |       |
|                        |    |    |   |   | criteria for   |       |
|                        |    |    |   |   | test           |       |
|                        |    |    |   |   | acceptability. |       |
+------------------------+----+----+---+---+----------------+-------+
| Laboratory Control +   | 0  | 0  | 0 | 0 | No artifactual | 7.9   |
| PBO                    |    |    |   |   | toxicity       |       |
|                        |    |    |   |   | present in     |       |
|                        |    |    |   |   | control        |       |
|                        |    |    |   |   | blanks.        |       |
+------------------------+----+----+---+---+----------------+-------+
| Peters Canyon @        | 0  | 0  | 0 | 0 | No toxicity    | 7.9   |
| Barranca @ 1.56%       |    |    |   |   | detected.      |       |
+------------------------+----+----+---+---+----------------+-------+
| Peters Canyon @        | 0  | 0  | 0 | 0 | No toxicity    | 7.9   |
| Barranca @ 3.13%       |    |    |   |   | detected.      |       |
+------------------------+----+----+---+---+----------------+-------+
| Peters Canyon @        | 0  | 0  | 5 | 1 | No toxicity    | 7.9   |
| Barranca @ 6.25%       |    |    |   | 5 | detected.      |       |
+------------------------+----+----+---+---+----------------+-------+
| Peters Canyon @        | 10 | 1  | 1 | 1 | Toxicity       | 7.9   |
| Barranca @ 12.5%       |    | 00 | 0 | 0 | detected.      |       |
|                        |    |    | 0 | 0 |                |       |
+------------------------+----+----+---+---+----------------+-------+
| Peters Canyon @        | 1  | 1  | 1 | 1 | Toxicity       | 7.8   |
| Barranca @ 12.5% + 100 | 00 | 00 | 0 | 0 | detected.      |       |
| ppb PBO                |    |    | 0 | 0 |                |       |
+------------------------+----+----+---+---+----------------+-------+
| Peters Canyon @        | 1  | 1  | 1 | 1 | Toxicity       | 7.8   |
| Barranca @ 25%         | 00 | 00 | 0 | 0 | detected.      |       |
|                        |    |    | 0 | 0 |                |       |
+------------------------+----+----+---+---+----------------+-------+
| Peters Canyon @        | 80 | 1  | 1 | 1 | Toxicity       | 7.8   |
| Barranca @ 25% + 100   |    | 00 | 0 | 0 | detected.      |       |
| ppb PBO                |    |    | 0 | 0 |                |       |
+------------------------+----+----+---+---+----------------+-------+
| Hines Channel @ Irvine | 0  | 0  | 0 | 0 | No toxicity    | 7.9   |
| Blvd @ 1.56%           |    |    |   |   | detected.      |       |
+------------------------+----+----+---+---+----------------+-------+
| Hines Channel @ Irvine | 0  | 0  | 0 | 0 | No toxicity    | 7.9   |
| Blvd @ 3.13%           |    |    |   |   | detected.      |       |
+------------------------+----+----+---+---+----------------+-------+
| Hines Channel @ Irvine | 0  | 0  | 0 | 2 | No significant | 7.9   |
| Blvd @ 6.25%           |    |    |   | 5 | toxicity       |       |
|                        |    |    |   |   | detected.      |       |
+------------------------+----+----+---+---+----------------+-------+
| Hines Channel @ Irvine | 0  | 1  | 1 | 1 | Toxicity       | 7.9   |
| Blvd @ 12.5%           |    | 00 | 0 | 0 | detected.      |       |
|                        |    |    | 0 | 0 |                |       |
+------------------------+----+----+---+---+----------------+-------+
| Hines Channel @ Irvine | 1  | 1  | 1 | 1 | Acceleration   | 7.8   |
| Blvd @ 12.5% + 100 ppb | 00 | 00 | 0 | 0 | of toxicity    |       |
| PBO                    |    |    | 0 | 0 | suggests that  |       |
|                        |    |    |   |   | the toxicity   |       |
|                        |    |    |   |   | is in part due |       |
|                        |    |    |   |   | to a           |       |
|                        |    |    |   |   | pyrethrin.     |       |
+------------------------+----+----+---+---+----------------+-------+
| Hines Channel @ Irvine | 1  | 1  | 1 | 1 | Toxicity       | 7.8   |
| Blvd @ 25%             | 00 | 00 | 0 | 0 | detected.      |       |
|                        |    |    | 0 | 0 |                |       |
+------------------------+----+----+---+---+----------------+-------+
| Hines Channel @ Irvine | 1  | 1  | 1 | 1 | Toxicity       | 7.9   |
| Blvd @ 25% + 100 ppb   | 00 | 00 | 0 | 0 | detected.      |       |
| PBO                    |    |    | 0 | 0 |                |       |
+------------------------+----+----+---+---+----------------+-------+
| 1\. Four replicates    |    |    |   |   |                |       |
| with 18 mls of sample  |    |    |   |   |                |       |
| and 5 *Ceriodaphnia*   |    |    |   |   |                |       |
| each.                  |    |    |   |   |                |       |
|                        |    |    |   |   |                |       |
| 2\. Daphnids were fed  |    |    |   |   |                |       |
| the standard EPA       |    |    |   |   |                |       |
| amount of food for     |    |    |   |   |                |       |
| only 4 hr/day.         |    |    |   |   |                |       |
|                        |    |    |   |   |                |       |
| 3\. Highlighted cells  |    |    |   |   |                |       |
| indicate areas of      |    |    |   |   |                |       |
| significant interest.  |    |    |   |   |                |       |
| No statistical         |    |    |   |   |                |       |
| analyses were done.    |    |    |   |   |                |       |
|                        |    |    |   |   |                |       |
| 4\. This test was set  |    |    |   |   |                |       |
| up on 17 February      |    |    |   |   |                |       |
| 2000.                  |    |    |   |   |                |       |
+------------------------+----+----+---+---+----------------+-------+

Table 4-29 shows that the San Joaquin Channel sample collected at
University Drive had about 32 TUa of *Ceriodaphnia* toxicity. Table 4-34
shows that the estimated TUa, based on diazinon, chlorpyrifos and
carbaryl for the San Joaquin Channel, was 29 TUa with about two-thirds
of it due to carbaryl, and one-third to chlorpyrifos. Therefore, the
measured and expected toxicity based on chlorpyrifos and carbaryl were
in good agreement for the sample collected at the San Joaquin Channel at
University Drive on February 12, 2000. Table 4-30 shows that the
addition of 100 µg/L of PBO to the 3.13% San Joaquin Channel sample
collected at University Drive on February 12, 2000, eliminated the
toxicity at least over a four-day period, indicating that some of the
toxicity was likely due to an OP pesticide. The San Joaquin Channel at
University Drive watershed is predominantly rural land with some
agriculture. It appears that agricultural activities in the San Joaquin
Channel watershed upstream of the sampling station at University Drive
used both chlorpyrifos and carbaryl during the previous fall/winter.

Tables 4-29 and 4-30 present the results of the *Ceriodaphnia* toxicity
testing with and without PBO for the Santa Ana Delhi Channel at Mesa
Drive collected on February 12, 2000. The toxicity test for this same
sample was set up again, with the data presented in Table 4-31. The
results of the two sets of tests on this sample are similar, thus
demonstrating the reproducibility of the toxicity testing. This sample
killed all *Ceriodaphnia* in three days. The addition of 100 µg/L of PBO
eliminated this toxicity, indicating that it was likely due to an OP
pesticide. Table 4-34 shows that the Santa Ana Delhi Channel sample
collected on February 12, 2000, had about 0.25 TUa of estimated
diazinon- and chlorpyrifos-caused toxicity.

Table 4-32 presents the results of the *Ceriodaphnia* 96-hour PBO and
dilution TIE conducted on the February 12, 2000, sample collected at
Peters Canyon Channel at Walnut Avenue (Station 7a). Table 4-32 shows
that this sample killed 100% of the *Ceriodaphnia* within one day down
through the 6.25% dilution. There was no toxicity in the 3.13% dilution.
Therefore, this sample had about 16 TUa of *Ceriodaphnia* toxicity.
Table 4-34 shows that the LC~50~ normalized sum of the diazinon,
chlorpyrifos and carbaryl toxicities was about 8.5 TUa. Therefore, there
were about 7.5 TUa of unknown-caused toxicity in the sample. The 6.25%
dilution of this sample that contained 100 µg/L of PBO showed an
increased toxicity to *Ceriodaphnia* during the first day compared to
the 6.25% sample without PBO. This indicates the possibility of
pyrethroid pesticides being present in the sample.

Table 4-32 presents the summary of the *Ceriodaphnia* 96-hour PBO
dilution TIE for samples collected on February 12, 2000, at Central
Irvine Channel at Monroe. The 12.5% dilution of this sample killed 100%
of the *Ceriodaphnia* within two days. The addition of 100 µg/L of PBO
to the 12.5% sample enhanced the toxicity so that a 100% kill was
achieved in one day. While no kill of *Ceriodaphnia* occurred in the
6.25% dilution sample in four days, 85% kill occurred in one day with
the addition of 100 µg/L of PBO. These results are strong indicators of
pyrethroid pesticide toxicity. The Central Irvine Channel at Monroe
sample collected on February 12, 2000, had a TUa of 8. The data in Table
4-34 show that the expected TUa for this sample, based on diazinon and
chlorpyrifos concentrations, is 4. Therefore, there were about 4 TUa of
unknown-caused toxicity in this sample.

<table style="width:100%;">
<colgroup>
<col style="width: 25%" />
<col style="width: 3%" />
<col style="width: 1%" />
<col style="width: 1%" />
<col style="width: 2%" />
<col style="width: 2%" />
<col style="width: 1%" />
<col style="width: 2%" />
<col style="width: 1%" />
<col style="width: 1%" />
<col style="width: 2%" />
<col style="width: 1%" />
<col style="width: 2%" />
<col style="width: 1%" />
<col style="width: 1%" />
<col style="width: 25%" />
<col style="width: 2%" />
<col style="width: 1%" />
<col style="width: 6%" />
<col style="width: 3%" />
<col style="width: 0%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="21"><p>Table 4-29</p>
<p>Summary of <em>Ceriodaphnia</em> 96-hr PBO and Dilution TIE Conducted
on Samples Collected from Sites 5 and 6 on February 12,
2000<sup>1,2,4</sup></p></td>
</tr>
<tr class="even">
<td colspan="2" rowspan="2"><p><strong>Treatment</strong></p>
<p><strong> </strong></p></td>
<td colspan="12"><strong>% Mortality for each day of the
test<sup>3</sup></strong></td>
<td colspan="4" rowspan="2"><p><strong>Conclusions</strong></p>
<p><strong> </strong></p></td>
<td colspan="3" rowspan="2"><p><strong>Final pH</strong></p>
<p><strong>at 24 hr</strong></p></td>
</tr>
<tr class="odd">
<td colspan="3"><strong>1</strong></td>
<td colspan="3"><strong>2</strong></td>
<td colspan="3"><strong>3</strong></td>
<td colspan="3"><strong>4</strong></td>
</tr>
<tr class="even">
<td colspan="2">Laboratory Control</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="4">Control met all EPA criteria for test
acceptability.</td>
<td colspan="3">7.7</td>
</tr>
<tr class="odd">
<td colspan="2">Laboratory Control + PBO</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">33</td>
<td colspan="3">33</td>
<td colspan="4">Mortality is not statistically significant from the
laboratory control</td>
<td colspan="3">8.3</td>
</tr>
<tr class="even">
<td colspan="2">San Joaquin @ University Drive @ 1.56%</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">5</td>
<td colspan="3">5</td>
<td colspan="4">No Toxicity detected.</td>
<td colspan="3">8.5</td>
</tr>
<tr class="odd">
<td colspan="2">San Joaquin @ University Drive @ 3.13%</td>
<td colspan="3">5</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="4">Toxicity detected.</td>
<td colspan="3">8.5</td>
</tr>
<tr class="even">
<td colspan="2">San Joaquin @ University Drive @ 6.25%</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="4">Toxicity detected.</td>
<td colspan="3">8.6</td>
</tr>
<tr class="odd">
<td colspan="2">San Joaquin @ University Drive @ 12.5%</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="4">Toxicity detected.</td>
<td colspan="3">8.6</td>
</tr>
<tr class="even">
<td colspan="2">San Joaquin @ University Drive @ 12.5% + 100 ppb
PBO</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="4">Toxicity detected.</td>
<td colspan="3">8.0</td>
</tr>
<tr class="odd">
<td colspan="2">San Joaquin @ University Drive @ 25%</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="4">Toxicity detected.</td>
<td colspan="3">8.2</td>
</tr>
<tr class="even">
<td colspan="2">San Joaquin @ University Drive @ 25% + 100 ppb PBO</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="4">Toxicity detected.</td>
<td colspan="3">8.1</td>
</tr>
<tr class="odd">
<td colspan="2">S.A. Delhi/Mesa @ 100%</td>
<td colspan="3">0</td>
<td colspan="3">79</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="4">Toxicity detected.</td>
<td colspan="3">8.2</td>
</tr>
<tr class="even">
<td colspan="2">S.A. Delhi/Mesa @ 100% + 100 ppb PBO</td>
<td colspan="3">0</td>
<td colspan="3">5</td>
<td colspan="3">5</td>
<td colspan="3">5</td>
<td colspan="4">Absence of mortality suggests that the toxicity was at
least in part due to a metabolically activated pesticide.</td>
<td colspan="3">8.2</td>
</tr>
<tr class="odd">
<td colspan="21"><p>1. Four replicates with 18 mls of sample and 5
<em>Ceriodaphnia</em> each.</p>
<p>2. Daphnids were fed the standard EPA amount of food for only four
hours a day.</p>
<p>3. Highlighted cells indicate areas of significant interest. No
statistical analyses were done.</p>
<p>4. This test was set up on 17 February 2000.</p></td>
</tr>
<tr class="even">
<td colspan="20"><p>Table 4-30</p>
<p>Summary of <em>Ceriodaphnia</em> 96-hr PBO and Dilution TIE Conducted
on Samples Collected from Sites 5 and 6 on February 12,
2000<sup>1,2,4</sup></p></td>
<td></td>
</tr>
<tr class="odd">
<td rowspan="2"><strong>Treatment</strong></td>
<td colspan="12"><strong>% Mortality for each day of the
test<sup>3</sup></strong></td>
<td colspan="4" rowspan="2"><strong>Conclusions </strong></td>
<td colspan="3" rowspan="2"><strong>Final pH<br />
at 24 hr</strong></td>
<td></td>
</tr>
<tr class="even">
<td colspan="3"><strong>1</strong></td>
<td colspan="3"><strong>2</strong></td>
<td colspan="3"><strong>3</strong></td>
<td colspan="3"><strong>4</strong></td>
<td></td>
</tr>
<tr class="odd">
<td>Laboratory Control</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="4">Control met all EPA criteria for test
acceptability.</td>
<td colspan="3">8.1</td>
<td></td>
</tr>
<tr class="even">
<td>Laboratory Control + PBO</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="4">No artifactual toxicity present in control blanks.</td>
<td colspan="3">8.0</td>
<td></td>
</tr>
<tr class="odd">
<td> </td>
<td colspan="3"> </td>
<td colspan="3"> </td>
<td colspan="3"> </td>
<td colspan="3"> </td>
<td colspan="4"> </td>
<td colspan="3"> </td>
<td></td>
</tr>
<tr class="even">
<td>San Joaquin @ University Drive @ 3.13%</td>
<td colspan="3">0</td>
<td colspan="3">18</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td colspan="4">Toxicity detected.</td>
<td colspan="3">-</td>
<td></td>
</tr>
<tr class="odd">
<td>San Joaquin @ University Drive @ 3.13% + 100 ppb PBO</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="4">Absence of mortality suggests that the toxicity was at
least in part due to a metabolically activated pesticide.</td>
<td colspan="3">8.1</td>
<td></td>
</tr>
<tr class="even">
<td>S.A. Delhi/Mesa @ 100%</td>
<td colspan="3">0</td>
<td colspan="3">10</td>
<td colspan="3">90</td>
<td colspan="3">100</td>
<td colspan="4">Toxicity detected.</td>
<td colspan="3">8.1</td>
<td></td>
</tr>
<tr class="odd">
<td>S.A. Delhi/Mesa @ 100% + 100 ppb PBO</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="4">Absence of mortality suggests that the toxicity was at
least in part due to a metabolically activated pesticide.</td>
<td colspan="3">7.9</td>
<td></td>
</tr>
<tr class="even">
<td colspan="20"><p>1. Four replicates with 18 mls of sample and 5
<em>Ceriodaphnia</em> each.</p>
<p>2. Daphnids were fed the standard EPA amount of food for only four
hours a day.</p>
<p>3. Highlighted cells indicate areas of significant interest. No
statistical analyses were done.</p>
<p>4. This test was set up on 29 February 2000.</p></td>
<td></td>
</tr>
<tr class="odd">
<td colspan="19"><p>Table 4-31</p>
<p>Summary of <em>Ceriodaphnia</em> 96-hr PBO and Dilution TIE Conducted
on Samples Collected from Sites 5 and 6 on February 12,
2000<sup>1,2,4</sup></p></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="3" rowspan="2"><p><strong>Treatment</strong></p>
<p><strong> </strong></p></td>
<td colspan="12"><strong>% Mortality for each day of the
test<sup>3</sup></strong></td>
<td rowspan="2"><p><strong>Conclusions</strong></p>
<p><strong> </strong></p></td>
<td colspan="3" rowspan="2"><strong>Final pH<br />
at 24 hr</strong></td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td colspan="3"><strong>1</strong></td>
<td colspan="3"><strong>2</strong></td>
<td colspan="3"><strong>3</strong></td>
<td colspan="3"><strong>4</strong></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="3">Laboratory Control</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td>Control met all EPA criteria for test acceptability.</td>
<td colspan="3">8.1</td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td colspan="3">Laboratory Control + PBO</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td>No artifactual toxicity present in control blanks.</td>
<td colspan="3">8.0</td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td colspan="3">San Joaquin @ University Drive @ 3.13%</td>
<td colspan="3">0</td>
<td colspan="3">18</td>
<td colspan="3">100</td>
<td colspan="3">100</td>
<td>Toxicity detected.</td>
<td colspan="3">-</td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td colspan="3">San Joaquin @ University Drive @ 3.13% + 100 ppb
PBO</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td colspan="3">0</td>
<td>Absence of mortality suggests that the toxicity was at least in part
due to a metabolically activated pesticide.</td>
<td colspan="3">8.1</td>
<td colspan="2"></td>
</tr>
</tbody>
</table>

Table 4-31 (continued)

+----------------------+----+---+---+---+------------------+-------+
| **Treatment**        | *  |   |   |   | **Conclusions**  | **    |
|                      | *% |   |   |   |                  | Final |
| ** **                | M  |   |   |   | ** **            | pH\   |
|                      | or |   |   |   |                  | at 24 |
|                      | ta |   |   |   |                  | hr**  |
|                      | li |   |   |   |                  |       |
|                      | ty |   |   |   |                  |       |
|                      | f  |   |   |   |                  |       |
|                      | or |   |   |   |                  |       |
|                      | ea |   |   |   |                  |       |
|                      | ch |   |   |   |                  |       |
|                      | d  |   |   |   |                  |       |
|                      | ay |   |   |   |                  |       |
|                      | of |   |   |   |                  |       |
|                      | t  |   |   |   |                  |       |
|                      | he |   |   |   |                  |       |
|                      | t  |   |   |   |                  |       |
|                      | es |   |   |   |                  |       |
|                      | t^ |   |   |   |                  |       |
|                      | 3^ |   |   |   |                  |       |
|                      | ** |   |   |   |                  |       |
+----------------------+----+---+---+---+------------------+-------+
|                      | *  | * | * | * |                  |       |
|                      | *1 | * | * | * |                  |       |
|                      | ** | 2 | 3 | 4 |                  |       |
|                      |    | * | * | * |                  |       |
|                      |    | * | * | * |                  |       |
+----------------------+----+---+---+---+------------------+-------+
| S.A. Delhi/Mesa @    | 0  | 1 | 9 | 1 | No toxicity      | 8.1   |
| 100%                 |    | 0 | 0 | 0 | detected.        |       |
|                      |    |   |   | 0 |                  |       |
+----------------------+----+---+---+---+------------------+-------+
| S.A. Delhi/Mesa @    | 0  | 0 | 0 | 0 | Absence of       | 7.9   |
| 100% + 100 ppb PBO   |    |   |   |   | mortality        |       |
|                      |    |   |   |   | suggests that    |       |
|                      |    |   |   |   | the toxicity was |       |
|                      |    |   |   |   | at least in part |       |
|                      |    |   |   |   | due to a         |       |
|                      |    |   |   |   | metabolically    |       |
|                      |    |   |   |   | activated        |       |
|                      |    |   |   |   | pesticide.       |       |
+----------------------+----+---+---+---+------------------+-------+
| 1\. Four replicates  |    |   |   |   |                  |       |
| with 18 mls of       |    |   |   |   |                  |       |
| sample and 5         |    |   |   |   |                  |       |
| *Ceriodaphnia* each. |    |   |   |   |                  |       |
|                      |    |   |   |   |                  |       |
| 2\. Daphnids were    |    |   |   |   |                  |       |
| fed the standard EPA |    |   |   |   |                  |       |
| amount of food for   |    |   |   |   |                  |       |
| only 4 hr/day.       |    |   |   |   |                  |       |
|                      |    |   |   |   |                  |       |
| 3\. Highlighted      |    |   |   |   |                  |       |
| cells indicate areas |    |   |   |   |                  |       |
| of significant       |    |   |   |   |                  |       |
| interest. No         |    |   |   |   |                  |       |
| statistical analyses |    |   |   |   |                  |       |
| were done.           |    |   |   |   |                  |       |
|                      |    |   |   |   |                  |       |
| 4\. This test was    |    |   |   |   |                  |       |
| set up on February   |    |   |   |   |                  |       |
| 29, 2000.            |    |   |   |   |                  |       |
+----------------------+----+---+---+---+------------------+-------+

+--------------------+---+---+---+---+------------------------+------+
| Table 4-32         |   |   |   |   |                        |      |
|                    |   |   |   |   |                        |      |
| Summary of         |   |   |   |   |                        |      |
| *Ceriodaphnia*     |   |   |   |   |                        |      |
| 96-hour PBO and    |   |   |   |   |                        |      |
| Dilution TIE       |   |   |   |   |                        |      |
| Conducted on       |   |   |   |   |                        |      |
| Samples Collected  |   |   |   |   |                        |      |
| from Sites 7 and   |   |   |   |   |                        |      |
| 10 on February 12, |   |   |   |   |                        |      |
| 2000^1,2,4^        |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| **Treatment**      | * |   |   |   | **Conclusions**        | **F  |
|                    | * |   |   |   |                        | inal |
| ** **              | % |   |   |   | ** **                  | pH** |
|                    | M |   |   |   |                        |      |
|                    | o |   |   |   |                        | **at |
|                    | r |   |   |   |                        | 24   |
|                    | t |   |   |   |                        | hr** |
|                    | a |   |   |   |                        |      |
|                    | l |   |   |   |                        |      |
|                    | i |   |   |   |                        |      |
|                    | t |   |   |   |                        |      |
|                    | y |   |   |   |                        |      |
|                    | f |   |   |   |                        |      |
|                    | o |   |   |   |                        |      |
|                    | r |   |   |   |                        |      |
|                    | e |   |   |   |                        |      |
|                    | a |   |   |   |                        |      |
|                    | c |   |   |   |                        |      |
|                    | h |   |   |   |                        |      |
|                    | d |   |   |   |                        |      |
|                    | a |   |   |   |                        |      |
|                    | y |   |   |   |                        |      |
|                    | o |   |   |   |                        |      |
|                    | f |   |   |   |                        |      |
|                    | t |   |   |   |                        |      |
|                    | h |   |   |   |                        |      |
|                    | e |   |   |   |                        |      |
|                    | t |   |   |   |                        |      |
|                    | e |   |   |   |                        |      |
|                    | s |   |   |   |                        |      |
|                    | t |   |   |   |                        |      |
|                    | ^ |   |   |   |                        |      |
|                    | 3 |   |   |   |                        |      |
|                    | ^ |   |   |   |                        |      |
|                    | * |   |   |   |                        |      |
|                    | * |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
|                    | * | * | * | * |                        |      |
|                    | * | * | * | * |                        |      |
|                    | 1 | 2 | 3 | 4 |                        |      |
|                    | * | * | * | * |                        |      |
|                    | * | * | * | * |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Laboratory Control | 0 | 0 | 5 | 5 | Control met all EPA    | 8.1  |
|                    |   |   |   |   | criteria for test      |      |
|                    |   |   |   |   | acceptability.         |      |
+--------------------+---+---+---+---+------------------------+------+
| Laboratory         | 0 | 0 | 0 | 0 | No artifactual         | 8.0  |
| Control + PBO      |   |   |   |   | toxicity present in    |      |
|                    |   |   |   |   | control blanks.        |      |
+--------------------+---+---+---+---+------------------------+------+
| Peters Canyon      | 0 | 0 | 0 | 0 | No Toxicity detected.  | 8.1  |
| Channel @ Walnut   |   |   |   |   |                        |      |
| Avenue @ 0.78%     |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Peters Canyon      | 0 | 0 | 0 | 0 | No Toxicity detected.  | 8.1  |
| Channel \@Walnut   |   |   |   |   |                        |      |
| Avenue @ 1.56%     |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Peters Canyon      | 0 | 0 | 0 | 0 | No Toxicity detected.  | 8.1  |
| Channel @ Walnut   |   |   |   |   |                        |      |
| Avenue @ 3.13%     |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Peters Canyon      | 0 | 1 | 1 | 1 | Toxicity detected.     | 8.1  |
| Channel @ Walnut   |   | 0 | 0 | 0 |                        |      |
| Avenue @ 6.25%     |   | 0 | 0 | 0 |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Peters Canyon      | 7 | 1 | 1 | 1 | Toxicity detected.     | 8.0  |
| Channel @ Walnut   | 5 | 0 | 0 | 0 |                        |      |
| Avenue @ 6.25% +   |   | 0 | 0 | 0 |                        |      |
| 100 ppb PBO        |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Peters Canyon      | 1 | 1 | 1 | 1 | Toxicity detected.     | 8.1  |
| Channel @ Walnut   | 0 | 0 | 0 | 0 |                        |      |
| Avenue @ 12.5%     | 0 | 0 | 0 | 0 |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Peters Canyon      | 8 | 1 | 1 | 1 | Toxicity detected.     | 8.0  |
| Channel @ Walnut   | 0 | 0 | 0 | 0 |                        |      |
| Avenue @ 12.5% +   |   | 0 | 0 | 0 |                        |      |
| 100 ppb PBO        |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Central Irvine     | 0 | 0 | 0 | 0 | No Toxicity detected.  | 8.2  |
| Channel @ Monroe @ |   |   |   |   |                        |      |
| 0.78%              |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Central Irvine     | 0 | 0 | 0 | 5 | No Toxicity detected.  | 8.2  |
| Channel @ Monroe @ |   |   |   |   |                        |      |
| 1.56%              |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Central Irvine     | 0 | 0 | 0 | 0 | No Toxicity detected.  | 8.1  |
| Channel @ Monroe @ |   |   |   |   |                        |      |
| 3.13%              |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+

Table 4-32 (continued)

+--------------------+---+---+---+---+------------------------+------+
| **Treatment**      | * |   |   |   | **Conclusions**        | **F  |
|                    | * |   |   |   |                        | inal |
| ** **              | % |   |   |   | ** **                  | pH** |
|                    | M |   |   |   |                        |      |
|                    | o |   |   |   |                        | **at |
|                    | r |   |   |   |                        | 24   |
|                    | t |   |   |   |                        | hr** |
|                    | a |   |   |   |                        |      |
|                    | l |   |   |   |                        |      |
|                    | i |   |   |   |                        |      |
|                    | t |   |   |   |                        |      |
|                    | y |   |   |   |                        |      |
|                    | f |   |   |   |                        |      |
|                    | o |   |   |   |                        |      |
|                    | r |   |   |   |                        |      |
|                    | e |   |   |   |                        |      |
|                    | a |   |   |   |                        |      |
|                    | c |   |   |   |                        |      |
|                    | h |   |   |   |                        |      |
|                    | d |   |   |   |                        |      |
|                    | a |   |   |   |                        |      |
|                    | y |   |   |   |                        |      |
|                    | o |   |   |   |                        |      |
|                    | f |   |   |   |                        |      |
|                    | t |   |   |   |                        |      |
|                    | h |   |   |   |                        |      |
|                    | e |   |   |   |                        |      |
|                    | t |   |   |   |                        |      |
|                    | e |   |   |   |                        |      |
|                    | s |   |   |   |                        |      |
|                    | t |   |   |   |                        |      |
|                    | ^ |   |   |   |                        |      |
|                    | 3 |   |   |   |                        |      |
|                    | ^ |   |   |   |                        |      |
|                    | * |   |   |   |                        |      |
|                    | * |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
|                    | * | * | * | * |                        |      |
|                    | * | * | * | * |                        |      |
|                    | 1 | 2 | 3 | 4 |                        |      |
|                    | * | * | * | * |                        |      |
|                    | * | * | * | * |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Central Irvine     | 0 | 0 | 0 | 5 | No Toxicity detected.  | 8.1  |
| Channel @ Monroe @ |   |   |   |   |                        |      |
| 6.25%              |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Central Irvine     | 8 | 1 | 1 | 1 | Toxicity suggests that | 8.0  |
| Channel @ Monroe @ | 5 | 0 | 0 | 0 | the toxicity is in     |      |
| 6.25% + 100 ppb    |   | 0 | 0 | 0 | part due to a          |      |
| PBO                |   |   |   |   | pyrethrin              |      |
+--------------------+---+---+---+---+------------------------+------+
| Central Irvine     | 0 | 1 | 1 | 1 | Toxicity detected.     | 8.0  |
| Channel @ Monroe @ |   | 0 | 0 | 0 |                        |      |
| 12.5%              |   | 0 | 0 | 0 |                        |      |
+--------------------+---+---+---+---+------------------------+------+
| Central Irvine     | 1 | 1 | 1 | 1 | Acceleration of        | 8.1  |
| Channel @ Monroe @ | 0 | 0 | 0 | 0 | toxicity suggests that |      |
| 12.5% + 100 ppb    | 0 | 0 | 0 | 0 | the toxicity is in     |      |
| PBO                |   |   |   |   | part due to a          |      |
|                    |   |   |   |   | pyrethrin.             |      |
+--------------------+---+---+---+---+------------------------+------+
| 1\. Four           |   |   |   |   |                        |      |
| replicates with 18 |   |   |   |   |                        |      |
| mls of sample and  |   |   |   |   |                        |      |
| 5 *Ceriodaphnia*   |   |   |   |   |                        |      |
| each 4 hr/day.     |   |   |   |   |                        |      |
|                    |   |   |   |   |                        |      |
| 3\. Highlighted    |   |   |   |   |                        |      |
| cells indicate     |   |   |   |   |                        |      |
| areas of           |   |   |   |   |                        |      |
| significant        |   |   |   |   |                        |      |
| interest. No       |   |   |   |   |                        |      |
| statistical        |   |   |   |   |                        |      |
| analyses were      |   |   |   |   |                        |      |
| done.              |   |   |   |   |                        |      |
|                    |   |   |   |   |                        |      |
| 4\. This test was  |   |   |   |   |                        |      |
| set up on February |   |   |   |   |                        |      |
| 17, 2000.          |   |   |   |   |                        |      |
+--------------------+---+---+---+---+------------------------+------+