|
||||||||||||||||
|
||||||||||||||||
|
||||||||||||||||
|
| ||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||
Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 37
Chapter 3
Review of Environmental Workgroup Reports
INTRODUCTION
The District divided its analysis of potential ecological effects of surface water
withdrawals among seven workgroups, each of which addressed a major ecosystem component:
wetlands (emphasizing vegetation), biogeochemistry, plankton, littoral zone—submerged aquatic
vegetation (or SAV), benthic macroinvertebrates, fish, and wetland wildlife. The last workgroup
originally was part of the wetlands workgroup but became a separate group when the analysis of
potential effects on wildlife began in earnest in late 2010. The analyses conducted by all these
workgroups were heavily dependent on the output from the hydrology and hydrodynamics
(H&H) workgroup. Each workgroup produced reports over the last two years describing their
approach, results, and conclusions related to their area of interest. The Committee based its
review on the most recent of these reports (produced during the summer of 2011), as well as on
presentations given to the Committee during its meetings. Although each workgroup used
different sampling and analytical methods appropriate for their ecosystem component, the
District established a common framework for the workgroups to facilitate synthesis of results
across workgroups into an integrated assessment. This chapter discusses the products of each
workgroup separately in the order listed above, but to facilitate an understanding of the design
elements of the overall study that were common among the workgroups, it first describes these
elements.
Because a wide variety of environmental conditions occur across the St. Johns River
basin, the District divided the river into nine segments (Figure 3-1), within which conditions are
relatively uniform conditions. Such factors as geomorphology, soils, hydrology, wetland types,
and water chemistry were used to delineate the segments. Workgroups focused their activities in
segments they considered relevant for their ecosystem component, and thus not all studies were
conducted in every segment. Information on the basis for selection of segments for analysis is
given in the sections on the individual workgroups.
The workgroups conducted their analyses using a common set of water withdrawal
scenarios (see Chapter 2 for details). A long-term record of water flows and levels at various
locations along the river for each withdrawal scenario was derived by the H&H workgroup, as
described in Chapter 2, and each of the ecological workgroups used information relevant to their
segments from this common hydrologic database. As noted earlier, some activities within the
drainage basin, such as the Upper Basin projects, produced model output with water flows and
levels greater than those in the baseline case. The workgroups prioritized withdrawal scenarios
by deviation from base conditions, and the scenario with the largest deviations generally was
37
OCR for page 38
38 Review of the St. Johns River Water Supply Impact Study: Final Report
FIGURE 3-1 The St. Johns River was divided into nine segments for the purposes of the ecological
analyses.
SOURCE: Kinser et al. (2011).
analyzed first. Analyses of other scenarios were continued down to the scenario(s) with minor to
negligible effects.
To help focus the studies on potential withdrawal effects, each workgroup, following a
recommendation from this Committee, developed a conceptual model during Phase 2 of the
WSIS. Most of these models were modified by the workgroups as their studies proceeded and
they gained information about their system components. The conceptual models—basically box
and arrow diagrams—were intended to show plausible cause-effect relationships between key
environmental drivers and changes in some ecosystem attribute relevant to the ecosystem
component of interest (e.g., phytoplankton, benthos, fish). In turn, the models also showed how
OCR for page 39
Review of Environmental Workgroup Reports 39
changes in an ecosystem attribute might be a driver for change in attributes of other ecosystem
components, and development of an understanding of the linkages among the workgroups was an
important reason for constructing the conceptual models. Where possible, each workgroup
included what the District called a “hydroecological model” in the conceptual model. The
former model was an equation (or set of equations) that the workgroup used to quantify the
effects of changes in the driver variables on the ecosystem attribute. In most cases, the
hydroecological model was an empirically derived relationship. In some cases, the workgroup
was unable to find or develop a quantitative model, and a more qualitative or subjective approach
was used to assess the effects. Examples of the District’s conceptual and hydroecological
models are included in discussions of the workgroup reports in subsequent sections of this
chapter, and Figure 3-2 is a flow diagram that illustrates the general approach the District used in
conducting its analyses.
The workgroups were given a mandate to characterize potential environmental effects of
water withdrawals using three criteria: persistence, strength, and diversity. Persistence was
defined in terms of recovery time relative to the return interval for conditions causing a given
effect; strength was defined in terms of both the intensity and scale (geographic area affected);
and diversity was defined in terms of the range of environmental attributes showing effects. In
some cases quantitative numeric values were used to define these criteria, but in most cases the
delineation was ordinal or categorical. Based on the three criteria, the District developed five
categories of effects ranging from negligible to extreme: (1) Negligible—no appreciable change
in any ecosystem component; (2) Minor—ephemeral and weak; no significant change in any
ecosystem component; (3) Moderate—ephemeral and weak; no significant change in natural
resource values; (4) Major—persistent and strong, but not diverse; significant change in natural
resource values; and (5) Extreme—persistent, strong, and diverse; significant change in natural
FIGURE 3-2 General flow pattern for the WSIS analysis.
SOURCE: Lowe (2011).
OCR for page 40
40 Review of the St. Johns River Water Supply Impact Study: Final Report
resource values. These categories were defined in an effort to obtain consistency among the
workgroups in their assessments of effects, but the non-quantitative, categorical nature of the
criteria inevitably led to some subjectivity and differences in interpretation among the groups.
The managers of the WSIS also provided guidelines to the workgroups in an effort to
obtain consistency relative to the assessment of uncertainty in the analyses. Five levels of
uncertainty, ranging from very low to very high (Table 3-1) were defined with reference to three
criteria: availability of a predictive model, supporting evidence, and understanding of the
mechanism for an effect.
Subsequent sections of this chapter describing the individual workgroup reports generally
follow a common outline. The conceptual model developed by the workgroup is presented first,
along with any hypotheses or key questions that drove their analyses. The geographic context of
the workgroup’s effort (i.e., the river segments they studied) is described next, along with the
basis for the workgroup’s decisions to focus on those segments. The methods used by the
workgroup are described next. Included in this discussion is a summary of the types of
data/information the workgroup used, the extent to which they relied on H&H data, field
sampling and experimental data (where relevant), analytical protocols to extract information
from the data, and a description of how the workgroup assessed uncertainty. Results obtained by
the workgroup and their conclusions with regard to the effects of water withdrawal on ecosystem
attributes relevant to their area of interest are summarized, along with a discussion of the levels
of uncertainty in their results and conclusions. The sections next provide a critical analysis of
the work, including the correctness of the approach, critical data gaps, uncertainties in the
conclusions, and the extent to which the workgroup responded to previous recommendations of
this Committee. Finally, where appropriate, the sections include a brief discussion of
recommendations for use of adaptive management concepts and follow-up assessment programs.
TABLE 3-1 Categories of uncertainty used in the WSIS and criteria on which they were based.
Uncertainty Criteria
Very low Very strong quantitative evidence—strong predictive model (PM), strong supporting
evidence (SE), good understanding of mechanism (UM)
Low Strong quantitative evidence—strong PM and either SE or UM
Medium Moderate quantitative evidence or strong qualitative evidence—PM or both SE and UM
High Weak quantitative evidence or moderate qualitative evidence—no PM but either SE or
UM
Very high Weak qualitative evidence—no PM, weak SE and UM—weak in all three areas
OCR for page 41
Review of Environmental Workgroup Reports 41
WETLANDS
The wetlands workgroup was tasked with assessing the potential effects of surface water
withdrawals on floodplain wetlands, specifically changes to vegetation communities that might
result from altered hydrology and/or changing salinity regimes. To accomplish this they used a
multistep process that included:
1. Developing a screening-level assessment to identify river segments that have the
highest likelihood of change and that became the focus of subsequent analyses;
2. Completing an assessment of existing MFL transect data on the distribution of
wetland plant community types across the elevational/hydrological gradient of the
floodplain, from river to upland, and determining how those might change;
3. Acquiring LiDAR data for areas of the watershed, where available (portions of river
segments 5, 6, 7 and 8), and compiling a digital elevation model (DEM); and
4. Conducting a GIS analysis to predict hydroperiod changes in wetlands on the
floodplain of river segment 8, where impacts to river stage were predicted to be
greatest, and salinity changes in segment 2, where changes in the salinity regime were
predicted to be highest.
The goals were to determine whether water withdrawals have the potential to (1) alter the species
composition of floodplain wetland communities, (2) alter the extent of wetlands or various
wetland communities found there, and/or (3) lead to a shift in the location of boundaries between
wetland types.
Conceptual Model
A conceptual model illustrating the effects of water withdrawals on wetland plant
communities was developed to investigate possible responses to alterations in wetland
hydroperiod and salinity (Figure 3-3). Decreases in water levels were predicted to lead to a
decline both in the duration of inundation of some wetlands (expressed by stage exceedence
curves, or stage-frequency relationships) and an increase in salinity in wetlands in the lower
stretches of the river that could lead to a shift in wetland plant community composition or
changing boundaries between freshwater and salt-tolerant wetland community types. Ecological
response models in the conceptual model indicate potential relationships between these variables,
and predicted changes in community boundaries and wetland extent are illustrated using a GIS-
based “Hydroperiod Tool” to model changes in floodplain inundation. Inputs to the conceptual
model include results of the H&H modeling, as well as information on soil characteristics from
the biogeochemistry workgroup, which was supposed to provide empirical data on soil accretion
rates on the floodplains. Changes in soil surface elevation have the potential to exacerbate or
ameliorate the effects of predicted changes in river stage. Outputs of the wetlands workgroup
were provided to the benthos, fish, littoral zone, plankton, and wetlands wildlife workgroups to
aid in their analyses.
OCR for page 42
42 Review of the St. Johns River Water Supply Impact Study: Final Report
FIGURE 3-3 Conceptual model of the wetlands workgroup.
SOURCE: Kinser et al. (2011).
The wetlands workgroup generated four hypotheses from the conceptual model and
identified specific hydrological criteria to test each:
H1: Changes in inundation depth and duration, relative to baseline, will lead to changes
in the extent of wetlands in the landscape. (This hypothesis would be accepted if the
average annual hydroperiod moves outside a range of 10 to 90 percent exceedence.)
H2: Changes in inundation depth and duration, relative to baseline, will change the extent
of wetland community types in the landscape. This would be accepted if average depth
and hydroperiod changes sufficiently to alter the relative areas of the hydrologic zones
associated with each community types, resulting in a shift in proportionality.
H3: Changes in the seasonal pattern of water depths will affect the structure of the
wetland communities. This would be accepted if hydrologic seasonality is altered
sufficiently to change community characteristics such as species composition,
reproduction, recruitment, or mortality.
H4: Changes in salinity levels will alter the extent of freshwater wetlands. This would be
accepted if the salinity level and duration exceeds freshwater species tolerances
(established, for example, through literature searches) causing community boundaries to
shift.
OCR for page 43
Review of Environmental Workgroup Reports 43
These hypotheses were tested over limited geographical areas. Hypotheses 1-3 were tested in
segments 7 and 8 and hypothesis 4 in segment 2.
Methods
Assessing the potential effects of modeled changes in river levels on floodplain wetlands
was done in two stages. In the first step a screening-level assessment of the nine segments
delineated along the St. Johns River (Figure 3-1) was conducted to identify the segments most
likely to experience altered hydrology, thus warranting a detailed analysis of the effects of
withdrawals. River segments with a low potential for change due water withdrawals were
eliminated from subsequent, more detailed analyses. The screening was based on the results of
the hydrologic models under various water withdrawal scenarios provided by the H&H
workgroup.
The second step used a combination of stage exceedence curves to relate the distribution
of plant communities along the elevational gradient of the floodplain and a GIS-based analysis to
display the spatial extent of wetlands in the targeted river reaches and how wetland community
composition, wetland area, and boundaries between wetland community types might be affected
by water withdrawals. This analysis was done using a combination of a DEM based on LiDAR
data, generation of exceedence curves using elevation and plant community information from
MFL transects, and a “Hydroperiod Tool.” The latter tool performed GIS-based analysis that
provided estimates of daily water depth over an area by subtracting the ground surface elevation
(DEM) from interpolated water surface elevations based on river stage. The latter feature
allowed the output from the H&H workgroup to be distributed over the floodplain and enabled
determination of changes in the spatial extent of wetlands (total area and area of each community
type).
An early issue identified by the wetlands workgroup was the need for a high resolution
DEM for use in the spatial analysis of wetland inundation. The coarse resolution of USGS
contour data (5-ft intervals) was not adequate for the workgroup’s needs, and so available
LiDAR data were used to derive a DEM with a contour accuracy of between 10 and 11.7 cm.
Interference of the LiDAR readings by dense wetland vegetation made a correction for ground
elevation necessary. This was accomplished using data from the four MFL transects in segment
8, which include detailed data on ground elevation, as well as the location of wetland plant
communities along the topographical/hydrological gradient.
The potential change in community boundaries in segments 7 and 8 was calculated using
a combination of historical surface water elevations (see below), the change in those elevations
caused by withdrawals (indicating dewatered areas), and a response function based on data
gleaned from literature (both primary sources and grey literature) that described vegetation
responses qualitatively. As part of this analysis, stage exceedence curves of the change in mean
daily water level were used to estimate whether wetland communities would shift downslope and
reestablish at lower elevations where hydrological exceedences match a previous elevation. The
distribution of communities along the elevation gradient of the floodplain (from river edge to
upland edge) thus was used to determine the minimum elevation for each community type, and
the lower boundary of each community then was moved downslope to the new, ecologically
appropriate elevation.
OCR for page 44
44 Review of the St. Johns River Water Supply Impact Study: Final Report
Historical records on surface water elevation were gathered from 11 stations along the
river for a 10-year period of record. Depth-to-groundwater data were obtained from groundwater
wells on the MFL transects. These data were used to calculate stage exceedence curves along
floodplain elevations.
A second driver of potential changes to wetlands from water withdrawals is changes in
salinity. This was evaluated by considering the upstream movement of isohalines in the lower
St. Johns in river segment 2. The Ortega River, a tributary to the St. Johns River, was used as a
model system. The Ortega River has an extended gradient of wetland communities spanning a
broad range of salinities. Vegetation ranges from freshwater hardwood swamps in the
headwaters to brackish marshes of Spartina bakeri near the confluence of the Ortega and the St.
Johns. Vegetation was sampled along the river corridor using nested plots to document species
composition. Measurements of soil conductivity and salinity, pore water salinity, and pH also
were made. Breakpoints were established between plant community types and regressed against
salinity data to quantify the relationship between the two. This relationship was transferred to
the St. Johns River so that the potential changes in plant communities could be predicted.
Results
The screening level assessment identified river segments most at risk for impacts based
on changes in average annual water levels and salinity using the Full1995NN scenario, which
shows maximum change from the base condition (Base1995NN). The highest likelihood of
stage effects was found for segments 7 and 8—average decreases in river levels of 4 and 5 cm,
respectively. Segment 2 showed the highest likelihood for salinity effects—a 0.12 PSU change
in salinity. The reaches of segment 8 deemed to be the most vulnerable to change, and for which
LiDAR data was available, were the focus of analysis for impacts resulting from water level
changes.
Floodplain hydrology is complex, and water movement depends on whether water levels
are above or below ground. William Wise (University of Florida) contributed background
information to the workgroup, documenting that floodplain soils in segment 8 typically are very
poorly drained with low hydraulic conductivities, resulting in slow lateral flow of soil water and
long residence times in this dimension. The movement of water in the soil (when soils are not
inundated) tends to be dominated by vertical flows due to the downward movement of
precipitation and upward movement of evapotranspiration. In general, during low-flow periods
when the river is below its banks, the low hydraulic conductivity of the soils means that the time
needed for the water table in the floodplain to equilibrate with the river level is long. Under
these conditions river flows have a relatively minor effect on wetland hydrology. During periods
of overbank flooding, however, the ponded depth of wetlands on the floodplain is the same as the
river stage.
Graphical analysis of river stage versus water level in the wetlands showed this pattern;
levels tend to be decoupled at low flows (when the water table is below ground) and converge
when water levels are above ground (during times of overbank flooding). This pattern held true
for most of the seven wells that the workgroup analyzed, but there were periods when
groundwater levels tracked river levels even at low stage, suggesting a weak link between river
stage and groundwater stage (e.g., Mulberry Mound well 1; Figure 66, middle left panel p. 71,
Kinser et al., 2011). Generally, however, the workgroup concluded that changes in surface
OCR for page 45
Review of Environmental Workgroup Reports 45
water-levels in the wetlands are likely to be the primary driver of ecological change and focused
their analysis on changes in hydroperiod.
The wetlands workgroup analyzed each withdrawal scenario in turn, starting with the
most pronounced decrease in water levels and consequent ecological effects under the
Full1995NN scenario. Water withdrawals were found to lead to the dewatering of portions of
the floodplain and subsequent movement of wetland boundaries along the hydrological gradient
from riverbank to upland. Shallow marshes were found to be one of the most affected
community types, and under this modeled “worst case” scenario, the total length of shallow
marsh on the County Line MFL transect in segment 8, for example, decreased by up to 69.4
percent, while the extent of wet prairies increased by 76 percent (see Table 3-2). Within segment
8, the workgroup estimated that 27.5 percent of the total wetland area would be dewatered; even
under the Full1995PN scenario (i.e., with the upper basin projects completed), 20.6 percent of
total wetland area would be dewatered. Thus, substantial changes to wetlands in this segment
are expected. (The subsequent analysis for segment 7 found smaller effects than for segment 8).
For segment 2, correlations between (1) river water salinity and soil salinity and (2) soil
salinity and vegetation communities were used to determine breakpoints in salinity tolerance
between community types. Based on modeled changes in river salinity, plant community
boundaries were predicted to shift upstream by about 1 km on the Ortega River. For the modeled
changes in salinity in the St. Johns River, this translates to a projected shift of saline and
freshwater community types of between ~55 and ~63 km under the Full1995NN scenario.
The above findings are reflected in the decision matrix for levels of effect that the
wetlands workgroup constructed (see Table 3-3). The environmental effects of withdrawals
were evaluated qualitatively based on three factors: strength [three levels related to intensity, as
well as spatial extent: low (1-25%), medium (25-75%) and high (> 75%)]; persistence [how
much recovery occurs between perturbations (full, partial, little, or none)]; and diversity
(percentage of species within a community and/or number of community types significantly
affected, rated low, medium and high using the same breakpoints as above). This approach is a
variation on the intensity-frequency-duration variables used to characterize ecological
disturbance. Each of the 27 possible combinations of effects was rated on a continuum ranging
from negligible to extreme. The largest effects were found for the Full1995NN scenario in
segment 8, which received ratings of 2, 3, 3, representing a “major” level of effects. Based on
the lack of water level changes described in the H&H report, the workgroup concluded that
segments 1-4 would have negligible effects.
TABLE 3-2 Community Statistics for County Line Transect. Change between Historical and Full1995NN
Scenarios.
SOURCE: Kinser et al., 2011.
OCR for page 46
46 Review of the St. Johns River Water Supply Impact Study: Final Report
TABLE 3-3 Summary of Withdrawal Effects on Wetlands Metrics for the Full1995NN Scenario.
River Upper and Boundaries Wetlands Boundaries Overall
Region lower between hydrologic between
wetland wetland seasonality freshwater
boundaries types and saltwater
communities
* 1,1,1 *1,1,1 *1,1,1
1 *
*1,1,1
*1,1,1 * 2,3,2 *1,1,1 *2,3,2
2 *
* 1,1,1 * 1,1,1 *1,1,1 * 1,1,1
3 *
* 1,1,1 *1,1,1 *1,1,1 * 1,1,1
4 *
* 1,1,1 ***1,3,1 *1,1,1 * 1,1,1
5 ***
* *1,1,1 ***1,3,1 *1,1,1 * 1,1,1
6 ***
* *1,1,1 ***2,3,2 *1,1,1 *1,1,1
7 ***
* *1,3,1 ** 2,3,3 *1,1,1 *1,1,1
8 **
Level of Effect Uncertainty
Negligible * Very Low
** Low
Minor
*** Medium
Moderate
**** High
Major
***** Very high
Extreme
Cross hatching indicates abbreviated analysis
SOURCE: Table 40 from Kinser et al. (2011).
The uncertainty associated with the workgroup’s predictions was assessed using best
professional judgment in two different ways. Ratings for the response variables that were
directly assessed in segments 2 and 8 were based solely on ecological effects; i.e., the workgroup
did not combine its ratings with the uncertainty associated with modeled output of the
withdrawal scenarios from the H&H workgroup. Conversely, an abbreviated uncertainty
analysis, based only on results of the H&H workgroup or arrived at deductively, was done for
response variables in river segments where little to no change in river hydrology was predicted.
In this case, a rating of “very low” uncertainty was assigned for the response variables in each
segment (1 asterisk). In total, a direct assessment of effects was made for two response variables
in segment 2 and for all four response variables in segment 8. With regard to the “overall effect
OCR for page 47
Review of Environmental Workgroup Reports 47
column,” the level of effect and uncertainty ratings were assigned using the most extreme rating
of any of the response variable ratings.
As in the other workgroups, uncertainty was based on the strength of the predictive
model, the strength of supporting evidence (e.g., literature and corroborating data), and the level
of understanding of the underlying mechanisms of change. Each variable could take one of three
states (low, medium, high), and the resulting uncertainties ranged from very low to very high.
The wetlands workgroup had the benefit of a sound understanding of the biological mechanisms
that lead to change and a rich data set for analysis and modeling in segment 8. Uncertainty was
reported as low in segments of the river where the H&H workgroup predict little hydrological
change, and a somewhat higher (moderate) where hydrological changes were predicted to be
sufficient to create an ecological response.
Critique
The wetlands workgroup produced a solid analysis of potential impacts of water
withdrawals to the St. Johns River. Their integration of a LiDAR-based DEM with floodplain
stage exceedence curves to assess the spatial extent of hydrological impacts is a novel approach,
and the workgroup is commended for the effort required to pull all these pieces together into an
integrated whole. The salinity analysis strategically made use of the Ortega River tributary as a
model system from which results could be translated to the larger St. Johns River. The
Committee is confident that the methods developed here will be adaptable to other river
segments and will be useful to analyze potential changes in river flow in the future.
One limitation of the workgroup’s results is the limited area to which their analyses were
applied. Only segment 8 (with an average 5-cm decrease in level) was initially included in the
full analysis, although segment 7 later was analyzed following a recommendation from this
Committee. LiDAR data also are available for portions of segments 5 and 6, and it would be
straightforward to expand the analysis to these segments (where an average 4-cm decrease in
levels is predicted).
The assignment of uncertainty to the workgroup’s results is not clearly presented in the
tables denoting level of effects. Some uncertainty assignments were made using the ecological
analysis of the wetlands workgroup, but most effects were given the lowest uncertainty rating
based on results of the H&H modeling. If this dual approach is to be used, it should be spelled
out more clearly in the legend of the table.
***
The work of the wetlands workgroup evolved substantially over the course of the study,
and their final report represents a rigorous scientific study of floodplain wetlands along the St.
Johns. The integration of field data on the distribution and composition of plant communities,
measurements of floodplain topography, remote sensing data (LiDAR) and application of the
Hydroperiod Tool was computationally challenging, but the result is a robust picture of the
spatial extent of dewatering and shifting boundaries between wetland types. The work is limited
by the geographical extent of the analysis, however. Acquisition and processing of LiDAR data
for segments 5 and 6 would enable the analysis to be expanded and would allow the District to
OCR for page 85
Review of Environmental Workgroup Reports 85
FIGURE 3-10 Conceptual model of the potential effects of water withdrawals on the estuarine fish
community of the St. Johns River showing key effects considered.
SOURCE: Miller et al. (2011).
freshwater inflows were estimated from USGS gauges at DeLand and Rodman Dam near Orange
Springs; these were summed to estimate total daily inflow into the St. Johns River upstream of
the FIMS sampling regions. This approach did not account for additional inflow from smaller
tributaries for which no data exist. The data screening and statistical approach used in
MacDonald et al. (2009) was modified by the workgroup based on the approach outlined in
Helsel and Hirsch (2002) and Helsel (2011).
Abundance was reported as trip abundance (based on individual monthly samples) and
annual abundance (summed monthly samples) by gear type. Trip abundance was calculated
based on periods of highest abundance of each pseudospecies as indicated by length–frequency
plots. The geographical center (km from mouth) of the trip abundance of each pseudospecies
was used to calculate distribution responses to changing inflow (called center-of-abundance) at
the same lagged time periods. Each monthly sampling trip was a single data point in the
regression with the center-of-abundance being calculated for all samples within each trip.
Pseudospecies were selected initially based on having > 100 individuals by gear type and
at least 5 percent frequency of occurrence in all samples, and mean daily flow data used were
lagged at 30-day intervals from 30 to 360 days. This produced 444 pseudospecies–lag
combinations for further processing. These non-transformed pseudospecies–lag combination
data were compared to inflow with a Spearmean’s rho statistic (Helsel, 2011) and the
combinations with rho > 0.4 and p < 0.05 were retained for further analysis. Because some of
the Spearman results of the pseudospecies–lag data had similar rho values for multiple lag
periods, the District further reduced the data combinations by processing only those with rho
values that were within ±3% of the highest rho. The District took those data and processed four
linear regressions with various levels of transformation: (1) no transformation, (2) dependent
variable transformed, (3) independent variable transformed, and (4) both variables transformed.
The District also calculated a predicted r2 value (pred r2) based on the PRESS statistic (Predicted
RESidual Sum of Squares statistic) for each regression, and the combinations with the best linear
OCR for page 86
86 Review of the St. Johns River Water Supply Impact Study: Final Report
r2 value (and best pred r2) were selected for further analysis. Finally, the District took these
equations and processed them relative to the output from various H&H withdrawal scenarios
related to the baseline. The final set of pseudospecies–lag period combinations included 20
pseudospecies for center-of-abundance (distribution), 21 pseudospecies for annual abundance,
and 40 for trip abundance (Miller et al., 2011).
Finally, like the other workgroups, the fish workgroup quantified the ecological
significance of their data (for each FIMS zone and fish assemblages) by developing three
metrics: strength, persistence, and diversity.
Results
Center-of-Abundance Responses. Twenty (20) pseudospecies (2 freshwater and 18
estuarine/marine) had significant median center-of-abundance regressions versus inflow. The r2
values ranged between 0.27 and 0.73 (mean = 0.42). All pseudospecies moved downstream with
increasing freshwater inflow, which expanded the freshwater area while reducing the saltwater
area. Application of the linear regressions for these 20 pseudospecies to the H&H model outputs
indicated that for the Full1995NN, Half1995NN, and Full1995PN scenarios, the center-of-
abundance moved upstream with reduced inflow compared to the Base1995NN; the changes
were small (2.9 km; 1.8 miles). In contrast, movement varied for the other scenarios, with all 20
pseudospecies moving downstream for the Half2030PS scenario; 13 moving downstream and 7
upstream under the Full2030PS scenario; and 13 moving upstream, 4 downstream, and 3 not
moving under the FwOR2030PS scenario. Maximum movements ranged from 1.2 km (0.8
miles) downstream for white shrimp ( 15 mm TL size class only) to 2.8 km (1.7 miles)
upstream for striped mullet (31-45 mm TL size class only).
Abundance Responses. Of the 61 pseudospecies that exhibited a strong change in
abundance versus freshwater inflow change, 13 were freshwater and 48 estuarine/marine. Size-
dependence and lag flow characteristics greatly influenced the abundance response of many
pseudospecies. The general pattern was that when freshwater inflow was reduced, a decrease in
the freshwater assemblage abundances (e.g., bluegill, channel catfish, white catfish, and redear
sunfish in selected size groups) was observed, along with an increase in estuarine/marine
assemblage abundances (e.g., white mullet, various gobies and flounders, Atlantic croaker, spot,
spotted seatrout, and blue crab for selected size groups). This pattern generally reversed when
freshwater inflow was increased. For example, the pooled freshwater assemblage members
increased under the Half2030PS and Full2030PS scenarios relative to the Base1995NN scenario,
but not in the more extreme FwOR2030PS. In contrast, the pooled estuarine assemblage
members changed less from scenario to scenario, probably due to their euryhaline nature. The
sciaenid and marine assemblages changed considerably, shifting mainly from very abundant
under the Full1995NN, Half1995NN, and Full1995PN scenarios to less abundant under the
Half2030PS and Full2030PS scenarios. The fish workgroup indicated that changes occurred
mainly due to the shifting interface between oligohaline and low mesohaline regions of the St.
Johns River.
Levels of Effect. Given the large number and variability in the pseudospecies
considered, it is difficult to make gross generalizations about the impacts of water withdrawals
OCR for page 87
Review of Environmental Workgroup Reports 87
on fish in the lower St. Johns River. Nonetheless, the fish workgroup produced a level-of-effects
table found below as Table 3-10. The table shows the effects of the Full1995NN scenario, which
was deemed to have the largest overall effect on fish assemblages. The top half of the table
(segments 1-3) reflects the estuarine fish analysis, and the bottom half of the table reflects the
results of the freshwater fish analysis. It should be noted that the entrainment/ impingement
analysis (first column in Table 3-10) is incomplete, such that those results and interpretations are
preliminary under all scenarios.
To determine the uncertainty rankings in Table 3-10, the fish workgroup (like the other
workgroups) assessed the strength of the statistical models used, supporting evidence from the
literature, and their understanding of the responsible mechanisms. Statistical model strength was
based on the calculated r2 and pred r2. Supporting evidence scores were based on the number of
studies that could provide support for withdrawal effects documented in this study. Finally,
causal mechanisms were thought to be well understood for almost all pseudospecies, except for a
few that the fish workgroup thought required higher uncertainty.
TABLE 3-10 Summary of Withdrawal Effects on Fishes for the Full1995NN Scenario.
SOURCE: Miller et al. (2011).
OCR for page 88
88 Review of the St. Johns River Water Supply Impact Study: Final Report
Critique
Overall, the fish workgroup is commended for modifying their approach to this complex
issue, in response to the Committee’s input over the course of two years. The fish workgroup is
the only one to have found a “major” response to water withdrawal, although this was for an
extreme scenario that is not plausible. Because the response surrounds the potential entrainment
or impingement of larval organisms at intake sites, it is imperative that this analysis be
completed soon and that precautions are taken when designing intake structures to avoid these
impacts. The workgroup should evaluate the times of year when entrainment/impingement is
important (such as during seasonal spawning peaks). If protective intake structures cannot be
constructed, the District may need to write conditions into its permits that require water suppliers
to reduce surface water extraction during those peak recruitment periods.
Throughout the text of Miller et al. (2011) responses of both pseudospecies and
assemblages are discussed in an equivalent manner, and that is not appropriate because an
assemblage is a collection of pseudospecies that represent what is collected in an area. The
Committee suggests that the fish workgroup consider using only one of these designations
(assemblage or pseudospecies) throughout the document for clarity, or provide a table indicating
which pseudospecies responses were used to delineate the overall assemblage responses. Also,
the detailed changes noted for each individual pseudospecies within a certain fish assemblage are
probably not as important as the total number of changes within the assemblage relative to the
modeled scenarios. That is, changes in the fish assemblages are more important in estimating the
impacts from proposed water withdrawals because those changes may influence food web
integrity and energy flow within the St. Johns River.
WETLANDS WILDLIFE
The wetlands wildlife workgroup assessed the potential effects of surface water
withdrawals on the 320 species of vertebrate wildlife that depend on the St. John’s River
floodplain habitat. Their stated goal was to identify any potential adverse impacts to floodplain
wildlife. The workgroup used a qualitative approach to evaluate impacts, in large part because
of the lack of quantitative data on species responses to changing hydrologic regimes for many of
the species found in the watershed. Information gleaned from the literature, in combination with
input from the work of the wetlands, benthos, and fish workgroups, was used to make best
professional judgments on the effects of withdrawals on wildlife with respect to salinity in river
segments 1 and 2, and with respect to altered hydroperiod in segments 7 and 8. To accomplish
this, species were assigned to one of four “wildlife hydrologic types,” groupings of species with
similar hydrologic requirements and so, it is assumed, similar responses to hydrologic change.
Conceptual Model
A conceptual model depicting the potential effects of water withdrawals on wetland
wildlife species was developed to investigate possible responses to alterations in hydroperiod and
salinity (Figure 3-11). Inputs include the results from the H&H workgroup on the predicted
changes in flow, water depth, and salinity for each scenario that was investigated. The
OCR for page 89
Review of Environmental Workgroup Reports 89
FIGURE 3-11 Conceptual model for the wetlands wildlife workgroup.
SOURCE: Curtis (2011).
workgroup predicted that changes in water depth would lead to changes in wildlife abundance as
mediated by the changes in wetland type and area (shown as an input from the wetlands
workgroup). The results of the fish and benthic invertebrate workgroups were integrated to
make qualitative estimates of changes in secondary productivity of the floodplain wetlands.
Benthos and fish, particularly crayfish, apple snails, and small marsh fish, serve as prey for many
wildlife species. Declines in the abundance and distribution of prey species could result in
declining wildlife populations.
Methods
To assess the potential effects of modeled changes in hydrologic parameters like river
stage on wetland wildlife, information and data were gathered from existing literature and on-
line sources. No new field data were collected for this analysis. Much of the literature is based
on previous Florida research projects, including some that detail the links between wildlife
habitat requirements and floodplain hydrology (e.g., hydroperiod and inundation frequency).
In order to increase the sensitivity of the model, each species was assigned a “hydrologic
type” that describes its hydrologic preferences. The terms that describe the hydrologic types
OCR for page 90
90 Review of the St. Johns River Water Supply Impact Study: Final Report
were drawn from the wetland plant indicator status terminology (Reed, 1988), and include
obligate (OBL), facultative wet (FACW), and facultative (FAC). The workgroup added a fourth
category, aquatic (AQ), for species that use open water habitats greater than 2 m deep. Each
species was assigned to a category based on the hydroperiod required to support that species
(including information on the time for metamorphosis (where applicable) and floodplain
recession rates), as established from the literature. The hydroperiods that correspond to the
wildlife hydrologic types range from a high of 310-365 days of inundation per year for AQ
species to many fewer days of inundation for FAC species; only AQ species are associated with
a specific water depth (> 2 m).
A hydrologic wildlife model was created by combining the eleven vegetation
communities that are typically found on the St. John’s River floodplain with four categories
describing the duration of floodplain inundation (permanently flooded to dry/intermittently
flooded) with the four wildlife hydrologic types. The result is a qualitative model that describes
the predicted distribution of species along the floodplain’s hydrologic gradient (permanently
flooded to dry). From this, an assessment of impacts was made.
Results
The screening level assessment of hydrologic change by river segment was used to
identify groups of estuarine species that may be affected by water withdrawals in river segments
1 and 2, and freshwater wildlife in segments 6, 7 and 8. A partial assessment was also made for
some categories of the freshwater species in segments 2 and 3. The overall effects for wildlife
were determined for four withdrawal scenarios: the Full1995PN for which a table showing the
levels of effects was developed (Table 3-11), and the Half2030PS, Full2030PN, and Full2030PS
scenarios. The latter three were judged to have similar effects, and so the results were combined
on a single table. Under the Full1995PN scenario, minor impacts were predicted for estuarine
species in segment 1, moderate impacts were predicted for estuarine species in segment 2, and
moderate impacts were predicted for freshwater species in segments 2, 7 and 8. These
predictions were made for both freshwater and saltwater aquatic (AQ) and obligate (OBL)
species. No assessments were made for facultative (FAC) or facultative wet (FACW) species.
Uncertainty was judged to be very high for all predictions.
To make these assessments on the level of impacts, the results from the H&H modeling
and the wetlands, benthic invertebrates, and fish workgroups were evaluated. Under the worst
case Full1995PN scenario, the loss of hardwood swamp and Bald-cypress that is expected due to
salinity increases would result in a loss of cover and nesting habitats for a number of species,
including species of salamanders, turtles, snakes, herons, eagles, and ospreys. However, the
ichthyofaunal distribution changes described for the fish pseudospecies (both reduced and
increased), and their actual relationship to local wildlife, were equivocal or indeterminate. The
workgroup concluded that despite the moderate level of effects predicted for the estuarine fish
community, the overall fish and estuarine invertebrate biomass may not be greatly altered for the
floodplain wildlife in this segment. Thus, moderate effects were predicted for segment 2 and
minor effects for segment 1. Freshwater species in segment 2 were also assigned a moderate
impact.
In the upper basin under the Full1995PN scenario, moderate effects were predicted for all
freshwater wildlife groups in segments 7 and 8. These segments were deemed to be the most
OCR for page 91
Review of Environmental Workgroup Reports 91
sensitive to freshwater wildlife due to predicted changes in floodplain hydroperiods (although
changes to wetland hydroperiods, which also may alter invertebrate and fish abundance, were
only assessed for segment 7). An assessment of the level of effects was also made for freshwater
species in segment 3 (moderate) and in segment 2 (moderate). Information on how the
designations were made for segment 3 was not provided.
Overall, the AQ and OBL wildlife groups were predicted to persist if water withdrawals
occur, partly due to compensation from the upper basin projects. Habitat shifts due to sea level
rise, on the other hand, may lead to a shift from freshwater to estuarine habitats in the lower
reaches of the river with consequent impacts to freshwater species there. One conclusion
reached by the workgroup is that the 50 percent exceedance curve for floodplain inundation
TABLE 3-11 Summary of Withdrawal Effects on Wildlife for the Full1995PN Scenario as well as the
FwOR1995NN, FwOR2030PS, Full1995NN, Half1995PN, Full2030PN,Half2030PS, and Full2030PS
Scenarios.
Level of Effect Uncertainty
Negligible * Very Low
** Low
Minor
*** Medium
Moderate
**** High
Major
***** Very high
Extreme
Cross hatching indicates abbreviated analysis
SOURCE: Curtis (2011).
OCR for page 92
92 Review of the St. Johns River Water Supply Impact Study: Final Report
appears to be an important threshold for obligate (OBL) species; most species in this group use
habitat that has a 50 percent or greater inundation rate.
Potential declines in the productivity of small fish were a major driver of the predicted
impacts to piscivorous wildlife in segments 7 and 8. Eight listed species were found to depend
on small marsh fish, including alligators, wood storks, and the least tern. The percent of fish in
the diets of these species ranges from about 2 to nearly 100 percent.
Critique
The wetlands wildlife workgroup conducted a qualitative review of the potential impacts
of withdrawals to floodplain wildlife species. The analysis was limited by the lack of
quantitative, species-specific information on the response of wildlife to altered hydrology and
salinity. Thus, the analysis is an integration of a very thorough literature review along with the
results of the H&H modeling effort and input from the wetlands, benthic invertebrate, and fish
workgroups. Effects due to salinity changes in the lower reaches of the river were predicted to
be much greater than impacts from lower water levels in the upper basin. The literature
synthesis was thorough and will be of benefit to future research and management efforts in the
St. Johns basin, particularly because it covers such a broad range of species. This report
represents a true integration of the literature analysis with the results of other ecological
workgroups, most notably the wetlands and fish workgroups, meeting the spirit of the approach
outlined in their conceptual model. Future studies might address these links. For example, a
study investigating whether the 50 percent exceedence of floodplain inundation represents a
threshold for the persistence of listed wildlife species in different habitat types would be a useful
undertaking.
The findings of the wildlife workgroup are obscured by the diverse ways in which species
were classified according to their hydrologic attributes. Four categories of wildlife “hydrologic
types” were introduced in the text and used in a hydrologic model showing the distribution of
those types along a gradient of flooding (permanently wet to dry). However, the effects of water
withdrawals were shown for only two of these categories. Establishing wildlife hydrologic types
is an appropriate way to deal with the diversity of habitat requirements for the species included
in the analysis, but the terms used to describe them were borrowed from wetland plant indicator
categories used to delineate jurisdictional wetlands, and they are not fully appropriate as applied
here. The plant categories describe the probability of finding a given species in a wetland
habitat; for example, an OBL plant species is expected to occur in wetlands >99 percent of the
time, but the OBL category is not linked with the duration of inundation. For the wildlife species
in this report, however, the categories describe generally how much water the species needs for
its annual habitat requirements without consideration of how flooding is associated with key life
history stages. This is particularly troublesome for amphibians, which are all obligate species in
the sense that they require standing water for reproduction. Finally, the ways in which the
impacts of withdrawals were assessed for species in river segments 3, 6, and 8 were not
presented. Because the wetlands workgroup did not directly analyze floodplain wetland changes
in these segments, the wildlife levels of effects ratings should be removed.
OCR for page 93
Review of Environmental Workgroup Reports 93
REFERENCES
Brady, N. C., and R. R. Weil. 2002. The Nature and Properties of Soils. Thirteenth Edition.
Upper Saddle River, New Jersey: Prentice Hall.
Bonvechio, T. F., and M. S. Allen. 2005. Relations between hydrological variables and year-
class strength of sportfish in eight Florida waterbodies. Hydrobiologia 532:193-207.
Clarke, K. R., and R. M. Warwick. 2001. Change in Marine Communities: An Approach to
Statistical Analysis and Interpretation. 2nd Edition. Plymouth, United Kingdom:
PRIMER-E.
Coveney, M. F., J. C. Hendrickson, E. R. Marzolf, R. S. Fulton, J. Di, C. P. Neubauer, D. R.
Dobberfuhl, G. B. Hall, H. W. Paerl, and E. J. Philips. 2011. Water Supply Impact
Study Plankton Working Group Draft Final Report: Assessment of Impacts from Water
Withdrawals. July 20, 2011.
Cowardin, L. M., V. Carter, F. C. Golet, and E. T. LaRow. 1979. Classification of wetlands and
deepwater habitats of the United States. Washington, D.C. and Jamestown, ND: U.S.
Department of the Interior, Fish and Wildlife Service.
Curtis, D. 2011. Water Supply Impact Study Floodplain Wildlife Working Group Draft Final
Report: Assessment of Impacts from Water Withdrawals. November 2, 2011.
DeAngelis, D. L., W. F. Loftus, J. Trexler, C., and R. E. Ulanowicz. 1997. Modeling fish
dynamics and effects of stress in a hydrologically pulsed ecosystem. Journal of Aquatic
Ecosystem Stress and Recovery 6:1-13.
Diaz, R. J., and R. Rosenberg. 1995. Marine benthic hypoxia: a review of its ecological effects
and the behavioural responses of benthic macrofauna. Oceanography and Marine
Biology: an Annual Review 33:245-303.
Dobberfuhl, D., E. Lowe, L. Battoe, R. Chamberlain, S. Hall, C. Jacoby, R. Mattson, L. Morris,
J. Slater, K. Moore, and R. Virnstein. 2011. Water Supply Impact Study Littoral Zone
Working Group Draft Final Report: Assessment of Impacts from Water Withdrawals.
2011.
Helsel, D. R. 2011. Comments on the statistical methods used in the FIMS report by McDonald
et al. (2009), and the subsequent review by Newfields. Final Report to the St. Johns
River Water Management District, Practical Stats, Highlands Ranch, Co.
Helsel, D. R., and R. M. Hirsch. 2002. Chapter A3 Statistical Methods in Water Resources.
Techniques of Water-Resource Investigations of the United States Geological Survey.
Book 4 Hydrologic Analysis and Interpretation. Reston, VA: USGS.
Hendrickson, J. 2011. APPENDIX 4. CE-QUAL-ICM Setup, Calibration and Withdrawal
Scenario Results. In: Water Supply Impact Study Plankton Working Group Draft Final
Report: Assessment of Impacts from Water Withdrawals. July 20, 2011.
Kadlec, R. H., and S. D. Wallace. 2008. Treatment Wetlands. CRC Press.
Keenan, L. W., E. F. Lowe, E. J. Dunne, A. M. K. Bochnak, J. Di, W. VanSickle, R. Freese, C.
P. Neubauer, I. Bujak, J. Hendrickson, K. R. Reddy, and A. Wright. 2011. Water Supply
Impact Study Biogeochemistry Working Group Draft Final Report: Assessment of
Impacts from Water Withdrawals. July 1, 2011
Kinser, P., S. Fox, L. Keenan, A. Ceric, F. Baird, P. Sucsy, W. Wise, and C. Montague. 2011.
Water Supply Impact Study Wetlands Working Group Draft Final Report: Assessment of
Impacts from Water Withdrawals. August 22, 2011.
OCR for page 94
94 Review of the St. Johns River Water Supply Impact Study: Final Report
Lowe, E. 2011. Water Supply Impact Study (WSIS) Environmental Analysis Synthesis.
Presentation to the NRC Committee. May 23, 2011.
MacDonald, T. C., J. Solomon, C. B. Guenther, R. B. Brodie, and R. H. McMichael, Jr. 2009.
Assessment of relationships between freshwater inflow and populations of fish and
selected macroinvertebrates in the lower St. Johns River, Florida. Report submitted to
the St. Johns River Water Management District. St. Petersburg, FL: Florida Fish and
Wildlife Research Institute, Fish and Wildlife Conservation Commission.
Mattson, R. 2011. Benthic Macroinvertebrate Workgroup. Presentation to the NRC Committee.
May 23, 2011.
Mattson, R., J. Mace, J. Slater, C. Jacoby, K. W. Cummins, R. W. Merritt, P. A. Montagna .
2011. Water Supply Impact Study Benthic Macroinvertebrate Working Group Draft
Final Report: Assessment of Impacts from Water Withdrawals. July 2011.
Miles, C. J. and P. L. Brezonik. 1981. Oxygen consumption by a photochemical ferrous-ferric
catalytic cycle. Environ. Sci. Technol. 15:1089-95.
Miller, S., et al. 2011. Water Supply Impact Study Fish Working Group Draft Final Report:
Assessment of Impacts from Water Withdrawals. August 2011.
Montagna, P. A., T. A. Palmer, and J. B. Pollack. 2011. Draft Final Report. St. Johns Estuary:
Estuarine Benthic Macroinvertebrates. Phase 2 Final Report. Report by the Harte
Research Institute for Gulf of Mexico Studies. Submitted to the St. Johns River Water
Management District, Palatka, FL.
NRC (National Research Council). 2009. Review of the St. Johns River Water Supply Impact
Study: Report 1. Washington, DC: The National Academies Press.
NRC. 2010. Review of the St. Johns River Water Supply Impact Study: Report 3. Washington,
DC: The National Academies Press.
Peebles, E. B., M. S. Flannery, R. E. Matheson, Jr., and J. P. Rast. 1991. Fish nursery utilization
of the Little Manatee River estuary: relationships to physicochemical gradients and the
distribution of food resources. Pp. 341-367 In: S. F. Treat and P. A. Clark (eds.) Proc.
Tampa Bay Area Sci. Inform. Symposium, Vol 2. Tampa Bay Regional Planning
Council, Tampa, FL.
Peterson, M. S. 1988. Comparative physiological ecology of centrarchids in hyposaline
environments. Canadian Journal of Fisheries and Aquatic Sciences 45(5):827-833.
Reed, Jr., P. B. 1988. National List of Plant Species That Occur in Wetlands: 1988 National
Summary. Washington, DC: U.S. Fish and Wildlife Service.
Ross, L. T. 1990. Methods for Aquatic Biology. Florida Dept. of Environmental Regulation
Technical Series Vol. 10, No. 1.
Soulen, H. 1998. The effects of habitat complexity and predation on the distribution of grass
shrimp (Decapoda:Palaemonetes) in the lower St. Johns River Basin, Florida. M.S.
Thesis. Georgia Southern University, Statesboro, GA. Appendix 3 In: F. Jordan, An
evaluation of relationships between submerged aquatic vegetation and fish community
structure in the St. Johns River. Final report September 2000. Report submitted to St.
Johns River Water Management District, Palatka, FL.
Strobel, C. J., and T. Heitmuller. 2001. National Coastal Assessment Field Operations Manual.
Environmental Monitoring and Assessment Program. EPA/620/R-01/003. Washington,
DC: EPA.
OCR for page 95
Review of Environmental Workgroup Reports 95
Xie, H., O. C. Zafiriou, W.-J. Cai, R. G. Zepp, and Y. Wang. 2004. Photooxidation and its
effects on the carboxyl content of dissolved organic matter in two coastal rivers in the
southeastern United States. Environ. Sci. Technol. 38:4113-4119.
