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Interagency Program Quarterly Highlights, July – September 1998

Delta Flow Measurement
July to September 1998

Richard N. Oltmann

1. Sacramento River upstream of Point Sacramento

2. San Joaquin River upstream of Point Sacramento

3. Montezuma Slough at eastern end

4. Middle Slough

5. New York Slough

6. Sherman Lake at Sacramento River

7. Sherman Lake at Broad Slough
(west side of Sherman Lake)

8. Mayberry Slough

9. Mayberry Cut

Neomysis/Zooplankton Study

Jim Orsi

Summer Townet Survey

Stephen Foss

Fall Delta Smelt Abundance

Zach Hymanson

Juvenile Salmon Monitoring Program

Erin Sauls

Central Valley Salmonid Team

Randall Brown

  • Mooching, a way of catching ocean salmon by basically dangling the bait, can result in high mortality of sub-legal sized salmon. The high mortality, due to the bait being swallowed, can be reduced by using a different type of hook.
  • During high flow years, the Yolo Bypass appears to provide good juvenile chinook salmon habitat.
  • Radio tag studies conducted on behalf of the East Bay Municipal Utility District can be used to provide information on salmon movement at flow splits. Two limitations are short battery life and the relatively large sized salmon used in the studies.

Splittail Investigations - Summer 1998

Randall Baxter

Mitten Crabs

Randall Brown

Rock Slough Fish Monitoring Program

Jerry Morinaka

Old River Fish Screen Facility (Los Vaqueros) Monitoring Program

Jerry Morinaka

Mallard Slough Monitoring Program

Lee Mecum

Agricultural/Municipal Diversion Effects Project Work Team

Zachary Hymanson

The Contaminant Effects PWT Makes Designated Action Recommendations to CALFED

Chris Foe

  • X2 Workshop Notes

Stephen Monismith, Stanford University

Introduction

  1. Refine our knowledge of X2 and its hydrodynamic and biological implications.
  2. Provide stakeholders with a consensus statement about the value (or lack thereof) of X2 and the relevance and biological significance of the relationships of abundance to X2.
  3. Clarify points of misunderstanding or technical disagreement.
  4. Build on the Estuarine Ecology Team's discussion of probable mechanisms underlying the X2 relationships.

Presentations

Wim Kimmerer: X2 review: Introduction and review of X2 and the Schubel workshops

  • It is a tidally averaged variable.
  • It is an open-water concept, not necessarily applicable to marshes.
  • It was selected to be an index of estuarine conditions.
  • It is correlated with a number of variables and effects, including changing physical/chemical processes, habitat, and abundance of organisms at all trophic levels (but not all organisms).
  • To date, there has not been much success at separating the effects of inflows from those of outflow, i.e., entrainment effects are weakened when X2 is downstream in Suisun Bay rather than in the delta.

Bruce Herbold: X2 standard development

  • Freshwater flows are difficult to connect to fish behavior, at least in the Western Delta and Suisun Bay, because tidal motions are generally (much) stronger. However, residual flow patterns that may lead to entrainment in the pumps are directly related to freshwater flows.
  • The number of days X2 was at or downstream of Chipps Island within a given water year type has generally decreased over the last 50 years. 3
  • Careful attention was given by the EPA as to how monitoring and compliance with an X2 standard should be done, i.e., the conversion of a standard requiring a sequence of monitoring stations to one using data from existing sites, as well as permitting several options for compliance (equivalent flow etc.).
  • Year type, although often convenient, compresses real hydrological variability, e.g., '97 was classified as a "wet" year, yet the rain essentially stopped in January.
  • X2 doesn't limit exports directly and so may not protect against entrainment, something the State Board is considering in its deliberations.

Jon Burau: Physical conditions in the low salinity zone - why flow has little direct effect during low flow

  • Contrary to a widely-held view, the Western Delta is not a river; transport there is the combined result of advection (residual currents) and dispersion mostly due to tides. The relative importance of residual flows and dispersion of course depend on flow rate.
  • The density gradient that results from the longitudinal salinity gradient is important to hydrodynamics and thus to transport. The exact nature of the linkage depends on the interaction of turbulent mixing by the tides with the stratification that develops (see Monismith et al 1996 4 ). X2 is significant because it sets the strength of this gradient and the upstream limit of gravitational circulation.
  • On a more direct level, ADCP data from Suisun Bay reveal a mean flow picture that is different from that hypothesized to maintain the ETM (Estuarine Turbidity Maximum), a better term for describing what has been known as the Entrapment Zone (this distinction was also made during the Schubel workshops). However, Jon (and Wim) prefer to refer to it as the LSZ (low-salinity zone), since: (1) the turbidity maximum isn't always found there; and (2) there is no agreement as to the location, significance, and nature of the ETM 5 . A revised picture emphasizes the importance of local topographic features like the rapid shoaling of the main channel near Benicia as well as the connection of channels to shallow high turbidity regions like Grizzly Bay.

Wim Kimmerer: Fish-X2: Update and analysis of time trends 6

  1. The use of log transforms in formulating these relationships;
  1. The formulation of statistical relations based only on the range of flow rates than can be controlled by operation of the water projects;

Bill Bennett: Causes of the X2-Fish Abundance relationships: How does freshwater flow regulate fish populations

  • Monitoring the population (catch/unit effort, abundance)
  • Identifying likely mechanisms (density dependence, stock-recruitment, environmental factors)
  • Developing life history tables (e.g., what life stage contributes most to mortality)
  • Using observation/experimentation to develop and test hypotheses
  • For Crangon franciscorum, starry flounder, and Pacific herring their reproductive strategies require them to transit the Golden Gate, suggesting outflow and gravitational circulation (which has been hypothesized to depend on the longitudinal density gradient and hence outflow) should be important factors. Passage across Potato Patch Shoal may be problematic 9 . However, for C. franciscorum, "many believe" that habitat space may be limiting rather than recruitment rate.
  • For X2/delta fish, there appear to be two pathways for effects: habitat/trophic effects (access/extent of shallow water, food, exotics, toxics); and hydrodynamic (retention, transport, entrainment).
  • For short-lived X2/delta fish effects on early life history are more likely to drive population dynamics.
  1. It has been shown that Sacramento splittail has higher year class success when the Yolo Bypass is flooded, something that coincidentally is more likely in wet years when X2 is relatively farther downstream on average.
  2. Gravitational circulation (the strength of which depends on X2, and on position relative to X2) has been hypothesized to transport organisms upstream against the mean flow driven by outflow, and so allow them to remain in the ETM. Recent data taken by Bill and Wim show that larval fish and zooplankton can use vertical migration to selectively use the vertically variable tidal currents to accomplish the same end 10 .
  1. "X2 is a useful indicator of population abundance for many species. Indeed, that so many constituents of [the] estuarine food web are associated with X2 is a unique and fortunate finding (i.e., this is why Jassby et al were published in Ecol. Applications.)"
  2. The "actual mechanisms vary and currently we don't know all [of the] mechanisms or how they interrelate."

BJ Miller: Policy implications of the X2 standard.

  1. X2 affects water supplies. Most of the CALFED alternatives produce little water but cost lots of money, so potential reductions in supply due to X2 regulations are of concern.
  2. While water users understand the importance of X2 to environmental protection and improvement, given point 1, water users have agreed that X2 needs critical re-examination.
  • Crangon--the relationship still looks pretty good
  • longfin smelt--used to be good, not so good anymore, much lower abundance for lower X2
  • delta smelt--never had one, don't have one now
  • splittail--still looks good
  • striped bass 38 mm--never had one, don't have one now
  • striped bass year 3--never had one, don't have one now
  • striped bass MWT--used to be good, not so good anymore, much lower abundance for lower X2
  • striped bass survival--still a relationship, but no data past 1993.
  • More workshops such as this one, including "outside experts" to help resolve the various biostatistics/fisheries issues that have been at the core of many of the X2/flow debates of recent years
  • Determining for which species an "X2-like" relationship is valid (or not), as well as understanding the mechanisms that underlie that relationship (if one exists)
  • Evaluating actions that could increase abundance of target species, in particular looking at both water project operational requirements and ecosystem improvements like requirements for flooded vegetation.

Panel Discussion

  1. X2 could serve as an example of "adaptive management" in the sense that CALFED uses the phrase to mean adjusting regulations in response to observed changes in the system (or the lack thereof). Among other things, this requires that we continue to track X2-fish relations (WK 16 ), and perhaps most importantly, that we recognize that X2 is an index of a variety of mechanisms affecting a variety of species (BH), something that may be taken to be the main point made in Jassby et al (1995). However, using an index like X2 will not necessarily be as efficient for single species like delta smelt or winter run salmon for which more specific actions like particular detailed regulations on pumping might be more efficient (BH).
  2. The challenge of using X2 to help manage the flow is complicated due to continuing changes in the estuary like variations in contaminant distributions, or invasions by introduced species, particularly, P. amurensis. Taking this to one limiting view, one can argue - because of food web changes apparently driven by P. amurensis, X2 is no longer a good index for management of the Bay-Delta system (TM). In the parlance of "adaptive management" one would argue that the adaptive action should be not to continue setting flow standards using X2! Alternatively, one could argue that while X2 is currently the best indicator (predictor) of ecosystem health, CALFED is free to consider other indicators (Gary Bobker), in which case we still need to understand the implications of the change from a pelagic/planktonic food web to one dominated by the benthos.
  3. The viability of adaptive management seems to be predicated on having hypothesized (or understood) mechanisms by which the management actions might accomplish stated goals, e.g. increasing the abundance of delta smelt. One set of hypotheses for X2 has been developed by the IEP Estuarine Ecology Team, and it may prove useful to test it experimentally for some specific organisms like Crangon (which may not be important overall) for which the X2-abundance (or flow-abundance) relations are strong, or to look at an intercomparison of longfin and delta smelt (BH). This may require a substantial financial investment as well as a more substantial involvement of university researchers (BH, BB).

Summary and Comments

  1. Is it possible to devise an experimental test of the success of X2? Yes, if one is willing to wait sufficiently long to see the results, and if one designs limited, focused experiments on hypothesized connections between X2 and abundance, e.g., X2 downstream means intensified gravitational circulation through the Golden Gate, which equates to better recruitment of things like Crangon (or Dungeness crab) into the Bay. This approach means a continued focus by the IEP on "studies" (research) in addition to monitoring, and most likely an enhanced role for university researchers. It also means continuous, careful, biostatistical analysis of the data. We should not be debating log vs. linear plots. Perhaps one should say that we need consensus by a group of statisticians; it shouldn't really matter what BJ Miller or I think about the statistical significance of X2-striped bass relationships.
  2. Is X2 any better as a standard than X1 or X3? From a statistical standpoint, there is no real difference given the self-similarity of the salinity distributions observed in Northern SF Bay. From a physics standpoint there is not much difference although if you were choosing between X2 and X6 or X0.5 there are real differences in flow structure. From a biological standpoint, Bill and Wim's X2 studies may show that X2 (like Ball and Arthur's earlier EZ work) is a good reference position for looking at the spatial structure of ETM (LSZ) populations. However, this all begs the question of why all the action at or around X2 given Jon's observations that show convincingly that the ETM (LSZ) does not function in the way hypothesized by Ball and Arthur (which, by the way, was a very useful hypothesis for guiding subsequent work).
  3. Is X2 more or less useful than outflow for use as a standard or conceptual tool for understanding the estuary? Since X2 and flow are tightly linked at timescales of a fortnight or more, X2 has only proven to be more useful as a standard in the sense that it could be promulgated, and thus was useful in breaking the logjam that had developed over flow regulation. Conceptually, on the other hand, it is different since it determines the strength of the density gradient that drives gravitational circulation, it measures where one finds habitat at a given salinity, and it thus determines where that habitat is positioned relative to the pumps. Jon provided a useful view of the difference--X2 is good for describing things related to the salt field in Suisun Bay and the western delta whereas flow is good for describing things where the currents it drives are comparable to those driven by the tides, e.g. somewhat upstream of Suisun Bay at low flows and possibly down in San Pablo Bay at high flows. Other variables, like contaminant levels, the presence of exotic species, or even, one might argue, the operation of the Montezuma Slough tide gates might be found to be important at times and for particular species.
  4. What needs to be done next? In terms of actions, there seems to be some interest in focusing some attention on species like Crangon or longfin smelt that exhibit a robust X2-abundance relation, and for which hypotheses exist as to possible mechanisms behind those relations. This might involve some workshop activity summarizing what is known, etc., but more likely requires designing new experiments and/or monitoring. From the standpoint of data analysis, careful examination of X2-abundance relations should be an ongoing activity, carried out by people who are skilled at the necessary biostatistics. I doubt that the X2-Q-time relationship needs re-evaluation, but it would not hurt, especially given the additional data that would be available for the high flows we have seen in the past few years 17 .

Acknowledgments

  • A Summary of the Current State of the X2 Relationships

Wim Kimmerer
Romberg Tiburon Center

A Brief History of X2

X2 and the Low Salinity Zone


Figure 1. Relationship of X2 to net delta outflow (DWR Dayflow model output). The model is a time-series model containing the log of monthly mean outflow and X2 in the previous month.

Table 1. Variables Related to Freshwater Flow into the San Francisco Bay-Delta Estuary and River System. *

Flow Variables

Sacramento River, San Joaquin River, tributary flow

Cause

Delta inflow and outflow

Cause

Inundation of flood plains and flood-control bypasses

Cause

Physical/chemical variables

Nutrient and organic carbon supply rate

Data

Sectionally-averaged seaward residual circulation

Cause

Residence time

Inferred

Distance up estuary to 2 psu salinity "X 2"

Data

Distance up estuary to any salinity

Inferred

Steepness of longitudinal density gradient

Data

Stratification seaward of LSZ

Inferred

Gravitational circulation seaward of LSZ

Inferred

Habitat Variables

Area of inundated river-margin habitat

Inferred

Temperature (weak effect)

Data

Dilution or mobilization of river-borne contaminants

Suspected

Area or volume encompassed by two salinity values

Inferred

Location of low-salinity zone and associated species

Data

Biological Variables

Abundance or survival of numerous species

Data

Transport of young anadromous fish into bay

Suspected

Entrainment of young into bay

Suspected

Proportional entrainment in export pumps

Inferred

* The table indicates whether the relationship is known from a clear causative link, known from data analysis, inferred from other information, or suspected.

An Update of the Fish-X2
Relationships

Figure 2. The fish-X2 relationships. Open symbols and solid lines, data before 1988; closed symbols and dashed lines, data from 1988 on; solid lines only include all the data. A, chlorophyll, monthly means; B, Eurytemora affinis abundance, survey means, with post-1988 data for March-June only; C, Mysid abundance (Neomysis mercedis until 1992, then also Acanthomysis spp.), survey means for May and later and for temperature over 18°C; D, Crangon franciscorum; E, Longfin smelt; F, Delta smelt; G, Pacific herring; H, Starry flounder; I, Sacramento splittail; J, American shad; K, striped bass survival index (ratio of summer young-of-the-year abundance index to egg abundance estimate); L, striped bass midwater trawl index. Data from IEP monitoring, provided as annual abundance indices except raw data were used for A-C. Curved lines in A and F are locally-weighted regressions drawn to capture the general trend in the data without fitting a chosen model; the curved line in C is a second-order polynomial regression. To account for zeros in the data, abundance indices for starry flounder were incremented by 10, and those for splittail by 1, before log-transformation.

Table 2. Summary of parameters of fish-X2 relationships. Slopes are given with estimated 95% confidence limits.

Taxonomic

Averaging

Pre-1988

All Data

Post-1988

Group

Variable

Period

N

Slope

N

Slope

N

Slope

Remarks

Phytoplankton

Chlorophyll

Month

114

--

46

--

No relationship

Eurytemora

Abundance
(0.5-6 psu)

Survey

257

-0.006
0.0035

37

-0.022
0.011

Calanoid
Copepods

Abundance
(>6 psu)

Survey

223

-0.013
0.004

109

-0.029
0.012

Mysids

Abundance

Survey

158

Nonlinear

74

-0.024
0.018

C. franciscorum

Abundance index

Mar-May

8

-0.025
0.019

18

-0.025
0.012

Longfin smelt

Abundance index

Jan-Jun

19

-0.062
0.016

29

-0.059
0.017

Delta smelt

Abundance index

Feb-Jun

No relationship

Pacific herring

Abundance index

Jan-Apr

7

-0.035
0.039

16

-0.026
0.022

1983 omitted; see text

Starry flounder

Abundance index

Mar-Jun

8

-0.031
0.029

18

-0.031
0.021

Sacramento splittail

Abundance index

Feb-May

19

-0.038
0.017

29

-0.028
0.013

American shad

Abundance index

Feb-May

19

-0.025
0.011

29

-0.015
0.010

Slope declined: increased abundance at high X2

Striped bass

Survival index

Apr-Jun

18

-0.022
0.012

25

-0.027
0.012

Striped bass

Abundance index

Jul-Nov

19

-0.037
0.015

29

-0.035
0.018

Some technical details

Interpretation of relationships

Use of log-transformed data

Figure 3. Longfin smelt. Comparison of relationships to X2 of raw (A) and log-transformed (B) data. Squares are pre-1988 and circles are post-1987 data. The darker line is calculated from a linear regression on log-transformed data, while the lighter line is from a generalized linear model with log link function, fit to the raw data.

Using all or part of
the data set

Figure 4. Results of a simulation illustrating the smoothing out of a postulated step function in response of a bay species (Crangon franciscorum used as an example) by temporal variability in X2 during the averaging period.

Table 3. Statistics for Piece-wise Regressions Around the Controllable Range (68 km) for Annual Indices Except for delta smelt (no significant relationship) and Striped Bass Midwater Trawl Index (only one x2 value <68 km).

Taxonomic group

Response Variable

Difference in Slopes*

C. franciscorum

Abundance index

-0.017 + 0.021

Longfin smelt

Abundance index

-0.002 + 0.03

Pacific herring

Abundance index

-0.077 + 0.02

Starry flounder

Abundance index

-0.020 + 0.016

Sacramento splittail

Abundance index

0.021 + 0.028

American shad

Abundance index

0.050 + 0.043

Striped bass

Survival index

-0.024 + 0.009

*Difference in slopes is the slope of the controllable range minus the slope of the remaining range, given with 95% confidence limits.

The "Adult Fish" test

Investigating the Mechanisms

Conclusions

Recommendations

  1. The flow-X2 relationship should be recalculated using all available data. This calculation should be updated on an annual basis.
  2. The fish-X2 relationships should continue to be updated annually, new ones should be identified, and any revisions to the overall trends should be announced.
  3. A major effort should be undertaken to determine the mechanisms underlying the X2 relationships.

References

Armor C, Herrgesell PL. 1985. Distribution and abundance of fishes in the San Francisco Bay Estuary between 1980 and 1982. Hydrobiologia 29: 211-227.

Bennett WA, Moyle PB. 1996. Where have all the fishes gone? Interactive factors producing fish declines in the Sacramento-San Joaquin Estuary. In: Hollibaugh JT, editor. San Francisco Bay: The Ecosystem. San Francisco: American Association for the Advancement of Science. p 519-542.

Bennett and Howard. 1997. IEP Newsletter. 10(4):7.

Burau JR. 1998. chapter in Kimmerer 1998.

Estuarine Ecology Team. 1997. An examination of the likely mechanisms underlying the "fish-X2" relationships. Interagency Ecological Program for the San Francisco Bay-Delta. Technical Report 52.

Hatfield SE. 1985. Seasonal and interannual variation in distribution and population abundance of the shrimp Crangon franciscorum in San Francisco Bay. Hydrobiologia 129:199-210.

Jassby AD, Powell TM. 1994. Hydrodynamic influences on interannual chlorophyll variability in an estuary: upper San Francisco Bay-Delta (California, USA). Estuar. Coast. Shelf Sci. 39:595-618.

Jassby AD, Kimmerer WJ, Monismith SG, Armor C, Cloern JE, Powell TM, Schubel JR, Vendlinski TJ. 1995. Isohaline position as a habitat indicator for estuarine populations. Ecological Applications 5:272-289.

Kimmerer WJ. 1997. IEP Newsletter. 10(4):11.

Kimmerer WJ, Orsi JJ. 1996. Causes of long-term declines in zooplankton in the San Francisco Bay Estuary since 1987. In: Hollibaugh JT, editor. San Francisco Bay: The Ecosystem. San Francisco: American Association for the Advancement of Science. p 403-424.

Kimmerer WJ, Schubel JR. 1994. Managing freshwater flows into San Francisco Bay using a salinity standard: results of a workshop. In: Dyer KR, Orth RJ, editors. Changes in fluxes in estuaries. Fredensborg, Denmark: Olsen and Olsen. p 411-416.

Kimmerer WJ, editor. 1998. 1994 Entrapment Zone Report. Interagency Ecological Program for the San Francisco Bay-Delta. Technical Report 56.

Odlin RF, Orsi JJ. 1997. Acanthomysis bowmani, A new species, and A. aspera Ii, mysidacea newly reported from the Sacramento-San Joaquin Estuary, California. Proc. Biol. Soc. Wash. 110: 439-446.

Schubel JR. 1993. Managing freshwater discharge to the San Francisco Bay-Delta Estuary: the scientific basis for an estuarine standard. San Francisco: San Francisco Estuary Project, U.S. Environmental Protection Agency.

Sommer TS, Baxter R, Herbold B. 1997. Resilience of splittail in the Sacramento-San Joaquin Estuary. Trans. Am. Fish Soc. 126:961-976.

Stevens DE. 1977. Striped bass (Morone saxatilis) year class strength in relation to river flow in the Sacramento-San Joaquin Estuary, California. Trans. Am. Fish. Soc. 106:34-42.

Turner JL, Chadwick HK. 1972. Distribution and abundance of young-of-the-year striped bass, Morone saxatilis, in relation to river flow in the Sacramento-San Joaquin Estuary. Trans. Am. Fish. Soc. 101: 442-452.

Unger. 1994. IEP Newsletter. p 7. (autumn).

Venables WN, Ripley BN. 1994. Modern applied statistics with S-plus. Springer-Verlag.

  • Relative Efficiency of the Midwater and Kodiak Trawl at Capturing Juvenile Chinook Salmon in the Sacramento River

Jeff McLain, U.S. Fish and Wildlife Service

Introduction

  • Does the Kodiak trawl catch larger salmon?
  • Does the Kodiak trawl catch more salmon?
  • Do the results of the Kodiak trawl show a higher density of salmon than the midwater trawl?
  • Is the Kodiak trawl worth the additional effort?

Methods

Figure 1. Schematic drawing of midwater (a) and Kodiak trawl (b) nets used in study at Sacramento.

Results

Table 1. Mean and range per tow of water sampled (m3), chinook catch, fork length (mm), and chinook density in the Kodiak and midwater trawl as well as the probability level and sample size.

Kodiak

Midwater

Mean

Range

Mean

Range

n

Test

p

Significant?

Salmon Catch

55.7

18 -103

21.3

4 - 62

34

Mann-Whitney

0.000

Yes

Fork Length

70.9

38 -112

68.9

32 - 100

34

T-test

0.000

Yes

Water Sampled (m3)

12,314

10,557 - 18,190

5,438

4,628 - 6,311

726

Mann-Whitney

0.000

Yes

Salmon Density (m3)

0.0047

0.0014 - 0.0088

0.0039

0.0008 - 0.0098

33*

T-test

0.13

No

* One tow deleted from cubic water sampled and density calculations because of a faulty flow meter reading.

Figure 2. Plot of salmon catch per tow in the Kodiak/midwater trawl experiment conducted between April 1 and April 4, 1998, at Sacramento.

Figure 3. Density plot of mean fork length per tow in the Kodiak/midwater trawl comparison experiment between
April 1 and April 4, 1998, at Sacramento.

Discussion

References

Garner J. 1978. Pelagic and semi-pelagic trawling gear. Farnham, England: Fishing News Books. 59 p.

McNeely RL. 1964. Development of the Cobb pelagic trawl, a progress report. Seattle, Washington: Research Bureau of Commercial Fisheries. p 240-247.

Noel HS. 1980. Pair trawling with small boats. New York: Food and Agriculture Organization of the Unites Nations. 77 p.

Thompson DB. 1978. Pair trawling and pair seining: the technology of two boat fishing. Farnham England: Fishing News Books. 167 p.

Sainsbury JC. 1996. Commercial fishing methods, an introduction to vessels and gear. Cambridge, Massachusetts: Fishing News Books. 359 p.

United States Fish and Wildlife Service. 1993. Abundance and survival of juvenile chinook salmon in the Sacramento-San Joaquin Estuary. Annual progress report.

  • Simulated Effects of Delta Outflow on the Bay -1998 Compared to Other Years

Noah Knowles (Climate Research Division, SIO-UCSD), Daniel R. Cayan (Climate Research Division, SIO-UCSD, USGS), David H. Peterson (USGS), R.J. Uncles (Plymouth Marine Laboratory)

Introduction

Figure 1. Delta outflow estimates for water years 1983, 1997, and 1998.

Data and Model

Results

Figure 2. Isohaline movement for WY 1998, including predicted salinity for July-September.

Figure 3. Evolution of X2 for three water years, including Water Year 1998 forecast.

Conclusions

References

[DWR] California Department of Water Resorces (US). 1998 June. California Water Supply Outlook. Sacramento (CA): DWR.

DWR. 1998. Sheila Greene, pers. comm. Delta outflow estimates are available from the California Data Exchange Center as station "DTO."

Knowles N, Cayan D, Peterson, DH, Uncles RJ. 1995. Modeling and predicting intertidal variations of the salinity field in the Bay-Delta. IEP Newsletter. (autumn).

Knowles N, Cayan D, Ingram L, Peterson DH, Uncles RJ. 1997. Diagnosing the flood of 1997 in San Francisco Bay with observations and model results. IEP Newsletter. 10(3):28-31.

Uncles RJ, Peterson DH. 1996. The long-term salinity field in San Francisco Bay. Continental Shelf Research. 16:2005-2039.

  • Effects of Delta Outflow and Local Streamflow on Salinity in South San Francisco Bay: 1995-1998

Larry Schemel (USGS)

Figure 1. Map showing the San Francisco Bay estuarine system and selected features and locations in South San Francisco Bay.

Figure 2. Daily mean values for salinity at the Dumbarton Bridge and the combined flow from local streams to South San Francisco Bay. Values for salinity were computed from measurements recorded at 15-minute intervals (1 m deep). Flow data are available from: URL http://waterdata.usgs.gov/nwis-w/CA. Information on the 1998 flood was obtained on 6/29/98 from: URL http://water.wr.usgs.gov/flood'98/11164500.html.

Figure 3. Salinity at the Bay Bridge and daily mean values for delta outflow. Salinity values (2 m deep) are available from: URL http://sfbay.wr.usgs.gov/access/wqdata/index.html. Delta outflow values computed by the DAYFLOW program for 1995-1997 water years were obtained on 2/18/98 from: URL: http://www.cd-eso.water.ca.gov/~dfriend/dayflow/doc.html. Delta outflow index values for 1998 are available from URL http://wwwoco.water.ca.gov/cmplmon/reports/hydro.html.

  • Progress in Modeling Salinity Impacts of Suisun Marsh Levee Breaches

Chris Enright, Kate Le, Kamyar Guivetchi, DWR

Introduction

Background:
The February 1998
Suisun Marsh Flood

Approach for Modeling the
Impact of Suisun Marsh
Levee Breaches

  • Run 1: Simulate the February 1998 Suisun Marsh flood as eleven breaches, each 100 feet wide, by 10 feet below MLLW.
  • Run 2: Simulate expanded breaches comprising between 10% and 40% of the exterior levee perimeter (similar to Frank's Tract).

Preliminary Findings

  • Salinity is increased in western Suisun Bay, but reduced in eastern Suisun Bay and the delta (Figures 1A, 2A, 3A).
  • The tidal range is reduced up to one-half foot along the axis of the estuary and the average water level is reduced in the delta (these plots are not shown here).
  • Increasing levee breach width allows increased salinity intrusion in the Bay and West Delta. The north and South Delta still experience salinity reduction (Figures 1B, 2B, 3B). Therefore, the salinity response is dependent on the configuration of the hydraulic connection between Suisun Bay and inundated areas.
  • The tidal range is reduced up to two-thirds foot along the axis of the estuary (plots not shown).
  • Marginal reductions of salinity are observed west of Sherman Island (plots not shown)
  • Significant increases in salinity are observed in the Delta (Figures 1C, 2C, 3C).
  • Marginal (though larger than Run 3) reductions of salinity are observed west of Sherman Island (plots not shown).

Figure 1. Jersey Point--1992. Historical Simulation of Mean Tidal Day Salinity.

Figure 2. Rio Vista--1992. Historical Simulation of Mean Tidal Day Salinity.

Possible Mechanisms

Figure 3. Old River at Rock Slough--1992. Historical Simulation of Mean Tidal Day Salinity.

Modeling Analysis In Progress

  • UC Davis Fish Treadmill Investigations Update

Ted Frink and Shawn Mayr, DWR
Christina Swanson, Paciencia S. Young, and Joseph J. Cech, Jr., Department of Wildlife, Fish, and Conservation Biology, UC Davis
Bob Fujimura, DFG
M. Levent Kavvas, Department of Civil and Environmental Engineering, UC Davis

  • Swimming Performance, Behavior, and Physiology of Delta Fishes in Complex Flows Near a Fish Screen: Biological Studies Using the Fish Treadmill

Christina Swanson, Paciencia S. Young, and
Joseph J. Cech, Jr., Department of Wildlife, Fish, and Conservation Biology, University of California, Davis

The Fish Treadmill

Objectives and Experimental Design

Measurements

Figure 1. Top view of the fish treadmill swimming channel as seen through one of the video cameras. The outer rotating screen is at top, the inner fixed screen simulating the fish screen is at bottom. Arrows indicate the directions of the approach, sweeping, and resultant flow vectors.

Potential Applications of Results

Table 1. Experimental Variables and Protocol Used in the Fish Treadmill Experiments

Flow (ft/s )

Approach

Sweeping

(10 flow treatments, one control and nine experimental)

0 (control)

0 (control)

0.2 (6 cm/s)

0

0.33 (10 cm/s)

0

0.5 (15 cm/s)

0

0.2

1.0 (31 cm/s)

0.33

1.0

0.5

1.0

0.2

2.0 (62 cm/s)

0.33

2.0

0.5

2.0

Temperature

12°C: winter and spring

19°C: summer and fall

Time of Day/
Light Level

Day, light level: 200-300 lux
Night, light level: 0-1 lux

Fish Size

small: <6.0 cm SL

medium: 6.0-8.0 cm SL

Number of Fish per Experiment

20

(All fish used only one time in the fish treadmill experiments)

Experiment
Duration

2 hours

Post-Experimental

48 hours

(Some fish sampled for stress responses during the post-experimental period)

Replicates per Treatment

3 replicates

Table 2. Measurements Made During Each Fish Treadmill Experiment

Measurement Type

Definition

Method

Performance

Impingement
Screen Contact
Survival
Injury

prolonged (>5 mim) contact with screen
temporary contact with screen
-----------------
damage to skin, scales, fins, eyes

measured visually throughout experiment
measured visually throughout experiment
measured at 0 and 48 h post-experimental
measured 48 h post-experimental

Behavior

Swimming velocity
over the ground
through the water
Orientation (rheotaxis)
Distance from screen
Schooling


cm/s, velocity past screen
cm/s, swimming velocity
orientation relative to resultant current
distance (cm) from inner fish screen
distribution of fish in swimming channel


measured using computer-assisted motion analysis of video tapes
measured using computer-assisted motion analysis of video tapes
measured using computer-assisted motion analysis of video tapes
measured using computer-assisted motion analysis of video tapes
measured visually throughout experiment

Physiological Responses

Plasma cortisol concentration
Plasma pH
Plasma lactate concentration
Plasma glucose concentration
Plasma chloride ion concentration (or osmolality)
Hematocrit

measured from pooled blood samples collected from randomly selected fish at selected times post-experimental

References

Bates K. 1988. Screen criteria for juvenile salmon. Washington: Habitat Management Division, Washington State Department of Fisheries. 11 p.

Clay CH. 1995. Design of fishways and other fish facilities. Boca Raton, FL: Lewis Publishers.

Gadomski DM, Hall-Griswold JA. 1992. Predation by northern squawfish on live and dead juvenile chinook salmon. Trans. Am. Fish. Soc. 121:680-685.

Hayes D. 1997. Fish treadmill investigations. IEP Newsletter. 10(1):16-18.

Kano RM. 1982. Responses of juvenile chinook salmon, Oncorhynchus tshawytscha, and American shad, Alosa sapidissima, to long term exposure to two-vector velocity flows. Sacramento: Interagency Ecological Study Program for the Sacramento-San Joaquin Estuary. Technical Report 4. FF/BIO-4ATR/82-4. 20 p.

Margraf FJ, Chase DM, Strawn K. 1985. Intake screens for sampling fish populations: the size selectivity problem. N. Am. J. Fish. Management 5:210-213.

Schreck CB. 1991 Approach to facility and design modifications: stress monitoring of migratory salmonids. In: Colt J, White RJ, editors. Fish Bioengineering Symposium. Bethesda, MD: American Fisheries Society Symposium 10. p.347-351.

Strange RJ, Cech JJ, Jr. 1992. Reduced swimming performance of striped bass after confinement stress. Trans. Am. Fish. Soc.121:206-210.

Swanson C, Young PS, Cech JJ, Jr. 1998. Swimming performance of delta smelt: Maximum performance, and behavioral and kinematic limitations of swimming at submaximal velocities. J. Exp. Biol. 201:333-345.

Wedemeyer GA, Barton BA, McLeay DJ. 1990. Stress and acclimation. In: Schreck CB, Moyle PB, editors. Methods for Fish Biology. Bethesda, MD: American Fisheries Society. p 451-489.

Young PS, Cech JJ, Jr. 1997. Calculations for required screen mesh size and vertical bar interval based on delta smelt morphometrics. IEP Newsletter. 10(1):19-20.

  • Salmon Stock Origin as Determined by Otolith Geochemistry

B. Lynn Ingram, Department of Geology and Geophysics, University of California, Berkeley

Peter K. Weber, Department of Geography, University of California, Berkeley

Ian D. Hutcheon, Lawrence Livermore National Laboratory

Introduction

Background

Water and Salmon Sampling

Figure 1. Map of Central and Northern California showing drainage area for San Francisco Estuary, major salmon spawning rivers, and reservoirs. Collection sites of river and hatchery waters and juvenile salmon are also shown.

Water Analysis for Trace Elements

Figure 2. Strontium, Oct. 1997 - Jan. 1998

Figure 3. Barium, Oct. 1997 - Jan. 1998

Figure 4. Manganese, Oct. 1997 - Jan. 1998

Figure 5. Magnesium, Oct. 1997 - Jan. 1998

Otolith Analysis for Trace Elements

Strontium Isotopic Analyses: Waters

Strontium Isotopic Analyses: Otoliths

( x )

Figure 6. 87Sr/86Sr ratios of otoliths of juvenile salmon plotted against 87Sr/86Sr ratios of river and hatchery waters from five salmon hatcheries in the Sacramento-San Joaquin drainage.

References

[DFG] California Department of Fish and Game (US). 1987. Estimates of fish entrainment losses associated with the State Water Project and federal Central Valley Project Facilities in the South Delta: Exhibit 17. California State Water Resources Control Board, 1987 Water Quality/Water Rights Proceeding. Sacramento: Department of Fish and Game. 31 p.

Fisher FW. 1994. Past and present status of Central Valley chinook salmon. Conservation Biology 8:870-873.

Gauldie RW, Coote G, Mulligan KP, West IF, Merret NR. 1991. Otoliths of deep water fishes: Structure, chemistry, and chemically coded life histories. Comp. Biochem. Physiol. 100(A):1-31.

Gilbert GK. 1917. Hydraulic mining debris in the Sierra Nevada. US Geological Survey Professional Paper. p 105-148.

Kennedy BP, Folt CL, Blum JD, Chamberlain CP. 1997. Natural isotope markers in salmon. Nature 387:766.

Koch PL, Halliday AN, Walter LM, Stearley RF, Huston TJ, Smith GR. 1992. Strontium (Sr) isotopic composition of hydroxyapatite from recent and fossil salmon: The record of lifetime migration and diagenesis. Earth Planet Sci. Lett. 108:277-287.

Kope RG, Botsford LW. 1994. The winter-run chinook salmon: Ready to reclaim the Sacramento River? Tideline 14:1-5.

Nichols FH, Cloern JE, Luoma SN, Peterson DH. 1986. The modification of an estuary. Science 231:567-573.

[USFWS] US Fish and Wildlife Service (US). 1987. The needs of chinook salmon, Oncorhynchus tshawytscha, in the Sacramento-San Joaquin Estuary: Exhibit 31. California State Water Resources Control Board, 1987 Water Quality/Water Rights Proceedings on the San Francisco Bay/Sacramento-San Joaquin Delta, California. Sacramento: US Fish and Wildlife Service. 179 p.

  • CALFED Comprehensive Monitoring, Assessment, and Research Program

Leo Winternitz and Collette Zemitis, DWR

The Comprehensive Monitoring, Assessment, and Research Program

CMARP Goals

  1. Provide information to management on a continuing basis necessary to evaluate the effectiveness of program actions and to support ongoing adaptive management actions.
  2. Describe conditions in the Bay-Delta and its watershed on appropriate temporal and spatial scales.
  3. Evaluate trends in the measures of environmental conditions.
  4. Identify the major factors that may explain the observed trends.
  5. Analyze data and report results to stakeholders and agencies on a timely basis.
  1. Build an understanding of physical, chemical, and biological processes in the Bay-Delta and its watershed that are relevant to CALFED program actions.
  2. Provide information useful in evaluating the effectiveness of existing monitoring protocols and the appropriateness of environmental attributes.
  3. Test causal relationships among environmental variables identified in conceptual models.
  4. Reduce areas of scientific uncertainty regarding management actions.
  5. Incorporate relevant new information from all areas of research.
  6. Revise conceptual models as our understanding increases.

CMARP Tasks

Task 1: Identify Goals and Objectives

Task 2: Develop a Conceptual Framework

Task 3: Monitoring Program Design

  1. Inventory Existing Monitoring Programs
  2. Develop Monitoring Elements (There are 6 elements and 13 sub-elements).
  3. Develop a Process for Data Management
  4. Develop a Process for Data Analysis and Monitoring
  5. Develop and implement Category III Monitoring Institutional Process

Task 4: Design a CALFED Focused Research Program

Task 5: Develop an Institutional Structure for Monitoring, Assessment and Research

CMARP Work Teams

Bay-Delta Shallow Water Habitats and Watersheds Sub-Work Team

River Resident Fish Work Team

Bay-Delta Salmon Work Team

Category III Monitoring Institutional Process Work Team

Data Management Work Team

Data Analysis and Reporting Work Team

Institutional Structure Development Work Team

CMARP Status

References

Brown RL. 1998. CALFED Comprehensive Monitoring, Assessment, and Research Program. IEP Newsletter. 11(3):31.

CMARP Steering Committee for CALFED. 1998 April. CMARP Stage 1 Report: A Proposal for the Development of a Comprehensive Monitoring Assessment and Research Program. URL: http://www.iep.water.ca.gov/cmarp/reports/cmarp.txt.

  • Results from a Review of the IEP Project Work Teams

Zach Hymanson (DWR) and Chuck Armor (DFG)

    Project Work Teams are established by the Management Team to implement one or more IESP [Interagency Ecological Study Program] elements. The teams are small, typically 3 to 6 people, working level groups consisting of members from agencies having a specific interest in the products of the team. Project Work Teams are intended to be "issue specific" groups which are established in response to specific information needs and their dissolution is planned for as part of their initiation... The interagency Project Work Teams will be actively and closely involved in element planning and the preparation and review of element products. The Project Work Teams are the source of proposed element work plans and budgets. Typically, individual IESP staff people will be assigned to more than one Project Work Team. Each Project Work Team will have a representative on the Management Team.

( x )

Figure 1. 1997 Organization of the Interagency Ecological Program for the Sacramento-San Joaquin Estuary.

( x )

Figure 2. Questionnaire for PWT chairpersons and members.

  • Suisun Bay Team. This team will no longer be considered a formal Project Work Team. This team was formed to oversee the entrapment zone studies completed between 1994 and 1996. The 1994 report is in final production and the 1995-96 report is in progress. Team members continue to meet as necessary to discuss/review the 1995-96 results.
  • Delta Agriculture/Municipal Diversion Evaluation Team. This team will continue its work as one of the Project Work Teams under the newly formed Fish Facilities Coordination Branch of IEP (see Figure 3). Team membership will largely remain the same, although the team's scope and mission may change somewhat.
  • Suisun Marsh Ecological Workgroup (SEW). The State Water Resources Control Board recommended DWR convene a technical workgroup, SEW, to develop recommended numerical salinity standards for the Suisun Marsh as a means to implement the Suisun Marsh narrative objective. A majority of the workgroup members are not involved in the IEP. The Management Team concluded it is not appropriate to consider this workgroup an IEP Project Work Team, given this workgroup's charge and composition. However, the IEP recognizes the importance of the SEW's work. A Management Team member will continue to serve as a liaison between IEP and SEW, and existing PWTs and individuals within IEP will continue to assist this workgroup as requested.
  • Addition of new Project Work Teams. The Management Team reviewed and approved the formation of three new PWTs: 1) the Water Quality PWT; 2) the Hydrodynamics PWT; and 3) the Shallow-water Habitat PWT. Each of these new PWTs is briefly described below.

Table 1. Summary of responses to PWT Questionnaire and Management Team Review

Project
Work Team

Is the PWT
aware of the
IEP mission and
objectives?

Does the PWT have
a mission statement
& objectives?

Does the PWT hold
regular meetings?

Does the PWT produce
meeting notes? Are
notes posted on the
IEP Home Page?

Is PWT membership
listed on the IEP
Home Page?

Are PWT members
satisfied with the group?
Is the team relevant?

Does the PWT have a
MT Representative?

Is continuance as an
IEP PWT recommended?

Comments

Central Valley Salmonid

Y

Y

Y

Y/N

Y

Y/Y

N

Y

1. Better communication between parent team and Management team is needed.
2. Management Team needs more information about satellite teams.

Estuarine Monitoring

N

Y

Y

Y/N

N

N/Y

Y

Y

1. Team members need dedicated time for participation.
2. PWT should produce a triennial report of monitoring programs.
3. PWT should become involved in CMARP conceptual modeling effort.
4. PWT should consider implications of an adaptive management strategy on monitoring programs.
5. Formation of a separate water quality PWT is recommended.

Estuarine Ecology

Y

Y

Y

Y/Y

Y

Y/Y

Y

Y

1. Need to increase fish biologist representation.
2. Need to improve project recommendation process.

Real Time Monitoring

N

Y

Y

N/N

N

Y/Y

Y

Y

1. Need to increase stakeholder involvement.
2. Completion of programmatic review may alter real-time monitoring program.

Contaminant Effects

N

Y

Y

N/N

N

Y/Y

Y

Y

1. Need additional ecologists/fishery biologists.
2. Contracting process is difficult.
3. Need to complete long-range plan.

Yolo Bypass

Y

Y

Y

Y/N

N

Y/Y

Y

Y

1. This is a single purpose team that will dissolve upon completion of Yolo Bypass studies.

Resident Fishes

N

Y

Y

Y/Y

Y

Y/Y

Y

Y

1. Improve Management Team feedback for project planning.

Delta Hydrodynamics Modeling

N

N

N

Y/N

N

Y/Y

Y

Y

1. Team could do more for IEP.
2. Team needs a Management Team representative.
3. Team should continue to increase interactions among biologists and hydrodynamisists.

Particle Transport Modeling

N

Y

N

Y/Y

Y

Y/Y

Y

Y

1. Team needs to develop long-term goals.
2. PWT should work more closely with Resident Fishes PWT.
3. Team should continue to increase interactions among biologists and hydrodynamisists.

Suisun Bay

N

N

N

N/N

N

Y/Y

N

N

1. Team is in final stages of completing its work.
2. A formal PWT is no longer needed.

Suisun Marsh Ecological Workgroup

N

Y

Y

Y/N

N

Y/Y

N

N

1. Team needs MT liaison.
2. Group will continue irrespective of IEP involvement.

Delta Ag/Muni Diversion Evaluation

N

Y

N

Y/N

N

Y/Y

Y

Y

1. PWT objectives need to be updated.
2. Membership change is needed.
3. Future of team to be determined based on fish facilities re-organization.

Hydrodynamics

n/a

Y

n/a

n/a

n/a

n/a

n/a

n/a

1. PWT is newly formed.
2. PWT will serve as "parent" to Delta Hydrodynamics and Particle Tracking teams.

Shallow-water Habitat

n/a

Y

n/a

n/a

n/a

n/a

n/a

n/a

1. PWT is newly formed.

Water Quality

n/a

Y

n/a

n/a

n/a

n/a

n/a

n/a

1. PWT is newly formed.
2. Will allow more focus on water quality monitoring and special studies.

( x )

Figure 3. Interagency Ecological Program.

References

Herrgesell PL, Kjelson MA, Arthur J, Winternitz L, Coulston P. 1993. A Review of the Interagency Ecological Study Program and Recommendations for its Revision. A report prepared for the Coordinators of the Interagency Ecological Study Program.

  • Steelhead Satellite Project Work Team

Dennis McEwan, CDFG

Mission Statement

Objectives

  1. Encourage, facilitate, and assist development of research on life history, distribution, population dynamics, abundance, and ecology of Central Valley steelhead.
  2. Encourage, facilitate, and assist development of monitoring and research to evaluate the effects of water development/management and other stressors on Central Valley steelhead.
  3. Provide technical review on steelhead research, monitoring, and restoration proposals.
  4. Encourage information exchange and standardized methods of data collection and reporting among agencies and individuals.
  5. Promote dissemination of project updates, research results, and current literature among scientists, resource managers, restoration specialists, and constituent organizations.
  • Life stage assessment protocol. A protocol to assess steelhead life stage is currently in development and should be available soon. It is our intent that all Central Valley monitoring projects begin using this protocol. This will allow us to document the occurrence of steelhead smolts, and to gain a better understanding of temporal and spatial aspects of smoltification.
  • Differentiation of natural and hatchery steelhead. With the initiation of a statewide mass-marking program for all hatchery steelhead, we now have a means to determine gross origin of both juvenile and adult steelhead. The team is working on standardizing collection of this information.
  • CALFED Monitoring and Research needs. We are currently developing a conceptual model for Central Valley steelhead and an assessment of existing monitoring and research projects for the Comprehensive Monitoring, Assessment, and Research Program (CMARP) of CALFED (see article on CMARP in this issue). This document will identify future needs for additional monitoring and research. A draft should be available by mid-October.
  • Visitor Statistics of the IEP World Wide Web Site

Willie Chang, PhD, DWR
willie@water.ca.gov

  1. The pages visited (the most/least).
  2. The names of the computers visiting (the most/least).
  3. The countries of the computers visiting (the most/least).
  4. The access frequencies of each year, month, day, and hour (peaks/lows).
  5. The access detail (date, time, host name, page).

( x )

Figure 1. Summary of web page access for 1998.

( x )

Figure 2. Monthly, daily, and hourly web page access for 1998.

( x )

Figure 3. Percentage of web page access for 1998, by country (continued in Figure 4).

( x )

Figure 4. Percentage of web page access for 1998, by country (continued form Figure 3.)

  • Annual Interagency Program Workshop

Zach Hymanson, DWR

  • Delta Outflow

Kate Le, DWR

( x )

1. This report was published in 1993 by the EPA San Francisco Estuary Project. See also: Jassby AD, and others. 1995. Isohaline position as a habitat indicator for estuarine populations. Ecological Applications. 5:273-289.

2. See http://calfed.ca.gov/historical/delta_accord.html

3. The statistical certainty of this conclusion was not given. That is, it is conceivable that this result may arise simply because the few years in a given decade that fell in a given water year type were slightly drier in the later decades than in the earlier decades.

4. Monismith SG, Burau J, Stacey M. 1996. Stratification dynamics and gravitational circulation in northern San Francisco Bay. In: Hollibaugh JT, editor. San Francisco Bay: The Ecosystem. Pacific Division: American Association for the Advancement of Science. p 123-153.

5. Wim Kimmerer, personal communication after the workshop.

6. Also see a separate report of Wim's analysis and discussion in this issue.

7. Charlesworth B. 1984. Evolution in age-structured populations. Cambridge UK: Cambridge University Press.

8. Estuarine Ecology Team. 1992 Jan. An assessment of the likely mechanisms underlying the fish-X2 relationships. Interagency Ecological Program Technical Report 52.

9. Consider that little is known about flows in the Central Bay or in the adjacent coastal ocean. Limited data suggest that exchange rates do increase with outflow, something that would be consistent with increases in density stratification that occur for large outflows. The physical basis for this is that both topographic and frictional controls on exchange are reduced by increased stratification.

10. Such behavior was documented in the St. Lawrence ETM by Laprise and Dodson in 1989 in an article in Mar. Ecol. Prog. Ser. 55:101-11.

11. 1995. Ecological Applications. 5:680-692.

12. Wim took a counter view, both in his presentation and in his article found in this issue.

13. These phrases were taken from my notes and from BJ's comments to me concerning a first draft of this report.

14. That is, the question that Wim discussed of restricting attention to controllable flows.

15. In reviewing a draft of my notes, BJ preferred that this be stated as follows: The statistical analyses of the abundance-inflow relationships produced essentially the same correlations as those for the abundance-X2 relationships and that, from statistical analysis, one could not tell which was better, X2 or inflow.

16. In this section I use the initials of the panelists in my attempt to attribute various comments and ideas to their originators.

17. Wim counters my view by stating, "The existing X2 time series is based on our interpolation and the `Jassby equation' is used to fill in the gaps including years since 1992." There are several potential problems with this: 1) the relationship could have changed; 2) the interpolation could be done differently; 3) the conversion from conductance to salinity could be different. I don't think the difference would be much, but the basis for this seems a bit thin given all that has been layered on top of it. At the time, who knew?