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



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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 37
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.