CHARLOTTE COUNTY v. SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT

PREVIOUS SECTION

5. Stressed Lakes - BOR Sections 7.3.5.1 and 7.5.3. (NTB WUCA) and proposed BOR Section 4.2.B.3 (SWUCA)

a. NTB

757. Pinellas has challenged existing Sections 7.3.5.1 and 7.3.5.3 of the Basis of Review. These provisions are only applicable in the Northern Tampa Bay WUCA.

758. Section 7.3.5.1 creates a presumption relating to requested new withdrawals from stressed lakes in the NTB WUCA and provides as follows:

759. Under BOR Section 7.3.5.1, the District has conclusively determined that any new withdrawals from a stressed lake will cause unacceptable environmental impacts to the lake and, therefore, such new withdrawals will be denied. It is not clear how renewal permits from a stressed lake are handled.

760. BOR Section 7.3.5.3 authorizes the District to deny a WUP for any new groundwater withdrawal within the NTB WUCA which adversely impacts a stressed lake or causes a lake to become stressed. This provision is potentially very broad. On its face, it applies to any "new" WUP that has a measurable impact on a stressed lake or would cause a lake to become stressed irrespective of the other factors and/or withdrawals that may be impacting that lake. Only minimal evidence was presented as to how this provision is applied. It is not clear how or if this provision applies to renewal permits. Apparently, the District will allow impacts to be mitigated and/or will analyze renewal permits differently than applications for new uses in applying both of these stressed lake provisions. The conditions and factors that will be considered in making these determinations are not set forth in the rules. The District's rules do not provide any methodology or standards for an applicant to rebut the District's conclusion.

b. SWUCA

761. Under proposed BOR Section 4.2.B.3 of the SWUCA Rules, the presumptive guidelines for lakes would not be applied by the District in the SWUCA when adopted lake levels indicate that a lake is in a stressed condition. The proposal includes provisions, similar to the NTB WUCA provisions for stressed lakes, that would limit new withdrawals and reduce existing withdrawals.

762. Impacts to a stressed lake can be reduced by replacing surface water withdrawals from the lake with groundwater withdrawals that are located as remotely as practicable from the lake. Proposed BOR Section 4.2.B.3.d(2), authorizes replacement of a surface water withdrawal from a stressed lake with a groundwater withdrawal even when the groundwater withdrawal may have an unacceptable adverse impact as defined by the performance standards and even when the minimum groundwater levels in the area have not been met. The District claims that this provision is necessary so that it can substitute groundwater withdrawals for surface water withdrawals when it appears that the groundwater withdrawals will be less harmful. This provision is applicable only when a lake is "stressed due to regional causes."

763. ECOSWF has challenged this provision on the grounds that it allows for the continuation of a use that fails to meet the Conditions For Issuance and consequently does not satisfy the three-prong test. This issue is discussed in the Conclusions of Law.

6. Impacts on Streams - BOR Section 4.2.C.2.

a. Background

764. Section 4.2.C.1 of the Basis of Review sets forth the performance standards for streams. These standards relate to flow rates and provide that the flow rate of a stream should not deviate or be reduced from the normal rate and range of fluctuation to the extent that water quality, vegetation or animal populations in streams and estuaries are adversely impacted or to the extent that recreational use or aesthetic qualities of the water resource are adversely impacted. The performance standards further require that flow rates should not be reduced from the existing level of flow to the extent that salinity distributions in tidal streams and estuaries are significantly altered as a result of withdrawals.

765. In Section 4.2.C.2 of the BOR, the District has created a presumptive threshold between acceptable and unacceptable impacts to streams and other water courses within the District for purposes of evaluating WUP applications. This provision provides as follows:

766. Under this stream flow reduction presumption, if an applicant demonstrates that stream flow will not be cumulatively reduced by more than 10 percent, it is presumed that there will be no unacceptable environmental impacts from the withdrawal, the performance standards are deemed to be met and no further scientific information need be provided to the District by the applicant.

767. As a matter of policy and practice, the District interprets and applies the presumption set forth in BOR Section 4.2.C.2 in the inverse. In other words, if a withdrawal, combined with other withdrawals, does reduce the rate of daily flow by more than ten percent, it is presumed that the withdrawal will cause unacceptable environmental impacts. The inverse presumption is not specifically set forth in a rule.

768. If a proposed withdrawal, combined with other withdrawals, is projected to exceed the 10 percent threshold, the District staff recommends denial of a permit unless the applicant can demonstrate, to the satisfaction of the District, that the proposed diversion of the stream flow will not have an adverse impact.

769. The ten percent flow reduction presumption in BOR Section 4.2.C.2 was adopted as part of the 1989 rule revisions and sought to provide a basis for cumulative analysis of withdrawals. Prior to October 1, 1989, the District's water use permitting rules used a five percent or less presumption for stream flows. Under this approach, each withdrawal was evaluated individually to determine if that withdrawal would reduce the stream flow by more than five percent. This approach proved to be inadequate, mainly because of the inability to consider the cumulative impact of multiple withdrawals.

770. The District applies the stream flow presumption found in BOR Section 4.2.C.2 to all streams throughout the District regardless of type or location.

771. Although the District contends the stream flow presumption can be rebutted by site specific information, neither the District nor any third party or applicant has ever successfully rebutted the presumption.

b. Purpose of the Ten Percent Stream Flow Presumption

772. The intent of the 10 percent stream flow presumption is to provide a mechanism to tie cumulative water use to the "natural" flow of a stream and to protect the "natural" variability of flows within the stream. According to the District, the presumption is intended to provide both a method for calculating withdrawals (a percentage of daily flow at the time of withdrawal) and a numerical value for withdrawals of a stream.

773. District Environmental Scientist Sid Flannery provided the analysis for the 10 percent stream flow reduction presumption. His rationale is set forth in a 1989 memorandum he prepared for the Rules Revision Committee entitled: "Evaluation of Potential Impacts to Streams and Estuaries." That report recognized that:

774. There has not been a written update to Mr. Flannery's 1989 stream flow memorandum.

775. From a biological perspective, it is important to maintain the natural variations in flow when withdrawing freshwater from streams. The inundation of the floodplain, the maintenance of the morphometry of the stream channel, the ability of fish to swim through the river and the maintenance of aquatic biota are all dependent upon the naturally occurring flow regime. Streams are highly variable and there are interactions of abiotic parameters which are effected by the flow regime. The best way to protect those interactions is to protect the flow regime.

776. The evidence supports the District's view that tying withdrawals to a percent of flow can help ensure the natural cycles are maintained by automatically adjusting for wet and dry periods. This approach allows water use to increase as flow goes up and decrease when flow goes down.

777. The stream flow presumption in BOR Section 4.2.C.2a. represents an effort to tie cumulative water use to stream flow. This concept of linking withdrawals to a percentage of stream flow at the time of withdrawal emanated during negotiations in 1988 between the District and Dr. Thomas H. Fraser in connection with the renewal of a water use permit for withdrawals from the Peace River by General Development Utilities ("GDU") to provide public drinking water to residents located within existing and proposed developments. GDU was concerned with possible water quality problems at flows below a certain level and the ability of the existing water treatment plant to adequately treat such water. Dr. Fraser, former director of the Environmental Quality Laboratory, recommended that the District employ a percent flow at the time of withdrawal approach to stream flow management. The District implemented this approach when the GDU permit came up for renewal in 1988. Data collected since 1988 in connection with that permit has confirmed the usefulness of the approach.

778. Despite the desirability of tying stream withdrawals to a percentage of flow, problems arise in trying to develop and/or apply a single presumptive threshold for use with all streams in the District. Before discussing these problems, it is helpful to review the scientific analysis that the District relied upon in developing the 10 percent stream flow presumption.

c. Development of the Ten Percent Flow Guideline

779. After the adoption of the Florida Water Resources Act in 1972, the District began to examine the ecological requirements of natural systems, including rivers and estuaries. More particularly, the District has been accumulating information about estuaries since 1977, when the District contracted with the University of Miami to conduct a literature review of articles concerning the role of freshwater in estuaries. The District also sponsored a seminar in 1977 at which nationally recognized scientists presented papers regarding the management of freshwater flow into Florida's estuaries.

780. In 1981, the District began studies on the estuaries within its jurisdiction, looking specifically at their freshwater flow requirements. The studies included evaluations of the hydrology and salinity relationships of estuaries. Similar studies have been undertaken by the USGS and other entities. These studies all confirm that freshwater flows from streams correspond to salinity values in estuaries and that the timing and volume of freshwater flows are two of the most important factors controlling the physical, chemical and biological characteristics of estuaries.

781. In developing the presumption during the 1989 rule revisions process, the District reviewed the available data and conducted several studies from which it concluded that flow reductions on the order of ten percent corresponded to relatively small changes in the salinity structure of the tidal portion of an estuary. In some instances, the District says the impact of a ten percent reduction in streamflow upon the salinity structure was close to being undetectable.

782. Some of the studies relied upon by the District included biological assessments of the region's estuaries. These studies confirmed that the natural processes occurring in the estuaries should be managed so as to maintain the natural pattern of freshwater flows. The studies mapped shoreline vegetation communities and, by calculating the salinity movement with the ten percent flow reduction, determined that anticipated movement would be very small compared to the transitional areas of vegetation.

783. Based upon its review of the available data, the District concluded that, if withdrawals were limited to a maximum of ten percent of flow at all points in the drainage basin, the effects should be minimal in comparison with the natural variability within the rivers.

784. The District says that studies it has conducted or reviewed subsequent to 1989, support the conclusions reached in the 1989 rule development process, i.e., that withdrawals would generally be within the safe range if limited to ten percent of flow while a withdrawal or diversion of 20 to 30 percent would likely cause observable ecological changes.

d. Challenges to District's Scientific Analysis

785. Various parties have challenged the District's scientific analysis in developing the streamflow presumption. The issues raised include the following:

(i) Use of Salinity Gradient

786. As the prime scientific and technical basis for the 10 percent stream flow reduction presumption, the District focused upon the relationship between salinity distribution (i.e., location and movement of isohalines)¹⁰⁵ and freshwater flow.

787. Movement of isohalines back and forth under natural cycles can greatly influence the distribution of biological organisms in an estuary. Thus, tracking the location and movement of horizontal salinity gradients, as reflected by isohalines, is an important parameter for analyzing the effects of withdrawals from streams that furnish freshwater inflow to estuaries.

788. Most of the studies conducted and relied upon by the District to support its 10 percent presumption utilized specific conductance to measure salinity values at various locations in estuaries. Specific conductance measures the total electrical conductivity of the water and salinity is a major factor influencing conductivity. While conductivity is generally a useful method of tracking salinity levels, its value is limited at low salinities. Moreover, the salinity level by itself will not determine the impact upon flora and fauna. The ionic composition of low salinity waters can be significant in determining which species are living and moving throughout a tidal river.¹⁰⁶

789. Several parties contend that the District's focus on salinity and the movement of isohalines does not provide adequate information regarding the environmental impacts resulting from changes in stream flow. Many species differ in the degree to which they can tolerate abiotic factors, such as salinity and temperature. Because of possible variations in other abiotic factors, automatic conclusions should not be drawn as to the effect upon biota solely from salinity changes. Nonetheless, the more persuasive evidence established that salinity is a dominant factor affecting the ecology and biology of estuarine resources. Accordingly, while the limitations of the studies must be kept in mind in the development of a regulatory strategy, it is reasonable and scientifically sound to use salinity gradients as a key measurement for studying the effects of freshwater withdrawals on an estuarine system. The evidence revealed that isohaline positions have been utilized as an indicator by which to manage estuarine resources by regulators in other areas.

790. Charlotte claims that the studies relied upon by the District to support the 10 percent stream flow presumption utilized a variety of salinity levels to specify the distinction between fresh and saline waters. As a result, Charlotte argues

Charlotte's proposed finding of fact No. 25, p. 20.

791. The District's general goal in its studies has been to map the salinity distribution and measure the network and movement of various isohalines simultaneously in the river channels. In utilizing this approach, the District is not concerned with the exact location of a particular isohaline. Instead, the District uses the location of the different isohalines to track the movement of the salinity distribution. The movement of isohalines varies considerably from season to season. Since any particular location on a river may encounter different isohalines at different times of the year, choosing an isohaline that represents the precise transition to freshwater is irrelevant.

(ii) Use of Regression Analysis

792. Multiple linear regression analysis is an analytical technique utilized in many of the studies relied upon by the District to examine and predict the location of various salinity concentrations as a function of stream flow. This analysis studies the relationship of one key parameter with other specified variables.

793. The District has applied regression equations to the flow records for numerous rivers in the District to predict the change in position of various isohalines following a ten percent reduction to stream flow. When the analysis was based upon the median flow or typical flow for the period of record calculated using daily flow records, relatively small movements of the isohalines were predicted. The analysis was also run on low flow conditions (i.e., flow rates that were exceeded 85 percent of the time). While there were some variations, the movement of the isohalines was generally not significantly different than at median flows.

794. Charlotte claims it is not technically or scientifically sound to use a multiple linear regression analysis based upon stream flow and tidal information obtained from selected gauges in a stream to determine the impact of a variation in stream flow upon isohalines in the estuary. Charlotte correctly points out that a one-dimensional study does not address the horizontal and vertical variations of salinity in the estuary and that there are other factors which impact salinity distribution in an estuarine system including wind, temperature, precipitation, topography and size of the system as well as other hydrographic features. Nonetheless, the evidence establishes that, while utilizing only stream flow and tides to forecast movement of isohalines in an estuary will not give a completely accurate depiction of the distribution of salinity in an estuarine environment, it is a useful starting point.

795. Charlotte argues that the only scientifically appropriate manner of evaluating the impact of a stream withdrawal, no matter what the magnitude of that withdrawal may be, is to utilize a modeling technique.

796. Hydrodynamic models exist which can include the effects of other factors affecting movement of isohalines in addition to flow. However, such modeling is very expensive. For example, the USGS has done modeling work on Charlotte Harbor, which involved collecting data over a four-year period in order to calibrate a two-dimensional hydrodynamic model of the harbor to assess its characteristics and in-flow area. This modeling effort cost approximately $900,000. Similarly, the original budget to collect data and design and run a model for Sarasota Bay was $780,000.

797. The immense complexity makes it difficult to develop a model that can reasonably represent the dynamics of a river/estuarine system. For example, the USGS has been unsuccessful in its attempts to model the mouth of the Peace River and match the model to the field results. Because of the cost and complexity of multiple variable modeling, the USGS, like the District, has found regression analysis to be a cost effective way to reasonably estimate isohaline movement in response to withdrawals.

798. In sum, a large percent of the variation of salinity at a fixed station in an estuary can be explained by measuring flow without including other independent factors. Thus, the more persuasive evidence establishes that using regression analysis to locate the position of isohalines can be extremely useful in assessing potential impacts to Southwest Florida estuaries from stream withdrawals. However, an appropriate regulatory strategy should recognize that the impacts resulting from the withdrawal of water from a stream are not just a function of the percentage reduction in flow and/or movement of certain isohalines. Even if changes in the isohaline structure in an estuary as a result of a withdrawal are small, there is no scientific basis for conclusively determining that there will be no environmental impacts from a withdrawal in the estuary and/or the river. Each river has site-specific characteristics that determine which variables are of greatest importance to that particular riverine and estuarine system.

(iii) Requirements of Up-River Freshwater Portions of a Stream

799. A river typically includes more than one major ecological system. For example, a typical river could have an estuarine system, a main river channel system and a head water system. Each system plays a different role and has different needs. The variability of each should be considered in evaluating the health of the entire system. The challenged presumption makes no distinction between the various ecological systems.

800. The District's research in support of the presumption emphasized the downstream reaches of the rivers through studies of the estuaries. The District has conducted or evaluated only limited studies of the uppermost, non-tidal portions of rivers, yet the 10 percent stream flow presumption rule applies "to any point in a drainage system" from the mouth of the river up to its headwaters.

801. Most of the rivers in Southwest Florida are relatively short. Consequently, most water users and withdrawals tend to be in the downstream reaches. The District felt it could better evaluate the total basin yield by focusing on the downstream areas where most of the impacts are expected to occur. In this regard, the District notes the importance of estuaries from an ecological and economic perspective. Most of the species comprising the sport and commercial saltwater fisheries in southwest Florida rely upon estuaries for survival.¹⁰⁷ However, there are also valuable nursery areas for fish located upriver.

802. The District has reviewed and considered certain studies which analyzed the variability of salinity at a given point upstream in a river.¹⁰⁸ These studies concluded that limiting withdrawals to no more than a ten percent reduction helped to ensure that natural variations remained the dominant factor in water level fluctuations in the river.

803. The studies confirm the value of a regulatory scheme that focuses on preserving the natural flow regime. However, they do not establish that there is a specific numerical cutoff that is appropriate for all portions of every river and stream in the District.

804. Because the upper reaches of a river are generally narrower, salinity gradients can move greater distances. In many instances, the upstream biota are subject to only minimal tidal fluctuations and may not be accustomed to frequent and significant changes in salinity gradients. There are different interactions upstream between chemical constituents, the temperature of the water may be different, there are different biota and habitat, and the geometry and gradients are usually quite different. A withdrawal of water at an upstream location may have an impact upon the river system which is not detectable in the estuary through a change in isohaline location. Freshwater tributaries can be particularly sensitive to stream flow reductions. Protection of the natural system is not automatically accomplished by application of the 10 percent presumption in these areas.

805. The District emphasizes that its presumption protects the variability of the natural flow regime, which is a key factor in protecting freshwater stream ecology. However, there is no scientific basis for concluding that the 10 percent threshold is an appropriate indicator of the health of all components of a river system.

(iv) Site-Specific Differences

806. The dynamics of each river (i.e., the relationship between its volume and the velocity of flow) is unique and is dependent upon the gradient and peculiar configuration of each particular stream. The volume of water moving through a river system affects the habitat for fish, phytoplankton and vegetation on stream banks. The amount of energy moving down the river has erosional and depositional effects, thus impacting the water quality and ecological characteristics of the river.

807. Vegetation is different in the various basins in the District because of climatological differences. Thus, each river has unique ecological concerns. In fact, various segments of the same river can have different concerns.

808. Not only is there a wide range of variation in the volume of flows among the various rivers, there is a difference in volume of flows within the same river during different months of the year, and those variations are not constant among the various rivers. The consistency of flows within a particular river affects the temperature of the river, and the temperature of the river affects the growth of organisms. These site-specific factors are not addressed by applying a numerical percentage of withdrawal rate to all streams.

809. A 10 percent reduction in stream flow during periods of low flow can have a very different impact than a 10 percent reduction during periods of high flow. During the dry season, low salinity isohalines in southwest Florida are not typically found in the open-water bay regions of estuaries. Instead, they are located within the channels of the tidal areas up river. During low flow times, relatively small changes in flow can lead to significant movement up-river of the isohalines. The location and management of these low salinity transition zones is important because many transitional species and important fishery production areas in the low salinity zone, can be impacted by even slight increases in salinity conditions.

810. A numerical threshold, such as 10 percent, should not be utilized as an end-point to determining the environmental impacts of a withdrawal. There is some level of flow in every stream below which no withdrawals of water should occur. A numerical threshold could be very destructive to the natural system absent the establishment of some floor or cap on the flow of the river beyond which no further withdrawals should occur. The level of flow beyond which further withdrawals should not occur is different for every stream and is dependent upon the characteristics of that stream and its estuary.

811. Permit conditions are sometimes used by the District to tie the 10 percent withdrawal rate to certain flow conditions and to prohibit any diversion from the stream or river when the flow rates are less than a specified amount at various times during the year. However, the rules do not delineate the factors that will be considered in determining when and how such conditions will be imposed. Since the factors that are considered in reaching such a determination are not addressed in the rules, the imposition of such a limitation is totally discretionary on the part of the District.

812. In sum, determining the appropriate amount of water which can safely be withdrawn from a stream, necessarily requires site-specific information including the actual flows of the river (both historically and at the time of withdrawal), the location of the site of withdrawal, the distribution of salt over a wide range of tides¹⁰⁹ and flows, the geometry and morphology of the stream, the distribution and abundance of habitats, the vegetation and biotic communities in the area, the water quality and water chemistry of the stream, and how the particular stream is affected by groundwater and groundwater withdrawals.

v. Conclusion

813. On its face, the stream flow reduction presumption applies to all streams located within the sixteen-county jurisdictional area of the District. The actual impacts of the withdrawal of water from a stream will depend upon the physical, chemical and ecological characteristics of the particular stream, the amount of base flow of the particular stream and the water body which receives the flow.

814. While the evidence in this case clearly demonstrates the importance of regulating stream withdrawals in a manner that minimizes the alterations of salinity distributions in the receiving water body, there is no scientific basis for a uniform diversion of flow percentage that can be tolerated by every river and stream in the District.

815. There are no pristine rivers remaining in the District. The District rules currently provides no standards or basis for distinguishing between streams with different hydrologic and ecological conditions. The evidence established that a 10 percent stream flow presumption is probably not adequately protective for a number of sensitive rivers in the District including the Homosassa, Crystal, and Chassahowitzka.

816. The District claims flexibility is built into the rules through BOR Sections 4.0 and 4.2 which provide for the use of site-specific information in conjunction with applying the 10 percent presumption to a stream withdrawal.

817. Certainly, the unique circumstances of each case cannot be anticipated and written into the rules. Moreover, it is a practical impossibility to test in an experimentally controlled setting the effect of a ten percent reduction in daily flow on a river and/or estuary that has a high natural variability. However, the factors that will be considered in evaluating a permit application can and should be delineated. A guideline for managing withdrawals based on protecting the natural flow regime is desirable, but the limitations of such a guideline should be explicitly recognized and the manner in which it will be applied should be delineated as clearly as possible. The District's presumption as written is vague and grants unbridled discretion to the District in determining when it will be applied.

818. The District's presumption does not simply provide that withdrawals above a certain level will be given greater scrutiny. Instead, the District presumes no "unacceptable environmental impact" if a stream flow is not reduced by more than 10 percent and inversely presumes there is an "unacceptable environmental impact" if the reduction is more than 10 percent. The simple knowledge that 10 percent of a stream flow is being reduced does not reveal whether water quality, vegetation or animal populations are going to be adversely impacted.

819. The studies relied upon by the District do not establish a definitive cause and effect relationship between a change in flow and any specific effect upon the biota of an estuary or a river. The physical and ecological diversity of streams precludes the effective use of a single numerical threshold as a demarcation between acceptable or unacceptable environmental impacts for all stream withdrawals. The presumption as currently written can be used to impermissibly shift the burden of proof in a permitting proceeding. The District argues that, even if the ten percent guideline results in issuance of a permit because no site-specific information is available to indicate that the guideline should not be applied, the District can always require ecological monitoring or other specific permit conditions to ensure the integrity of the stream system. Such monitoring is certainly important and an appropriate permit condition in many cases. However, monitoring can not be a basis for shifting the burden of proof in a permit proceeding.

e. Method of calculating the 10 percent Presumptive Threshold

820. The manner in which the presumptive threshold of 10 percent is calculated is critical to its implementation, yet the rules provide little guidance or structure for making the calculation. Most problematic is the lack of any standards for determining the baseline from which the 10 percent is to be calculated.

821. Generally, the District imposes a condition on a WUP that requires the permittee to measure or gauge whether the ten percent presumption is exceeded by comparing post-withdrawal flow measurements with measured pre-withdrawal flow as close to the time of withdrawal as possible. The cumulative impacts are measured by adding up all the withdrawals from a particular river to insure the combined withdrawals do not reduce the rate of flow at any point in the river by more than 10 percent.¹¹⁰

822. The 10 percent reduction in the rate of daily flow is supposed to be measured "at the time of withdrawal."¹¹¹

823. This approach is qualified by the final sentence of the presumption which provides: "Estimated available yield will be determined based on historical flow records or best available data and existing permitted use." The role of permitted uses in conjunction with "historical flow records" for purposes of applying the 10 percent stream flow reduction presumption is vague and ambiguous.

824. In effect, there are no firm criteria for determining what the starting point is for measuring the 10 percent. It is not clear when or how historical flow records will be used, how the District will select the period of record to be analyzed or how previous physical alterations to a river will be considered. It also is not clear how the last sentence of the presumption can be reconciled with a calculation of 10 percent "at the time of withdrawal", which would seem to suggest that the District will measure the 10 percent reduction against a recent or simultaneously measured flow, not an historical flow.¹¹²

825. The District has historic flow records for most major streams and rivers within its jurisdictional area. However, the quality and quantity of those records varies greatly and they do not always predate withdrawals or groundwater impacts. Some rivers have had long-standing withdrawals and/or have been altered by man-made changes including impoundments and development. Nonetheless, the 10 percent stream flow reduction presumption is applicable uniformly to rivers with data of varying quality and extent. There is no delineation of the factors that will be considered in determining how or even if the presumption would apply to rivers, such as the Anclote and Peace Rivers, which have been impacted by previous groundwater and/or surface water withdrawals.

826. The District claims that the intent of the presumption is to tie cumulative water use to the "natural" flow of a stream so that the "natural" flow characteristics of the stream are preserved after the withdrawal. The presumption does not refer to "natural flow" let alone provide a definition of the term. The District has no consistent or reliable method of determining the "natural" conditions of a river. This determination will effectively determine how the presumption is applied, particularly when flow rates have been altered over time.

827. The presumption provides that the rate of daily flow should not be reduced by more than 10 percent "at any point in the drainage system." What is included within a "drainage system" will affect how and where flow should be measured. The rules provide little guidance in this regard.

828. A "drainage system" is not a term with a commonly accepted or understood meaning in the fields of aquatic or stream ecology and it is not defined by the District. Theoretically, it could include wetlands along the sides of the stream or at the headwaters and/or lakes within the drainage area. The concept of a "drainage system" could also include groundwater. It is not clear from the rules whether withdrawals from groundwater or lakes within the stream basin can and/or should be included in the analysis.

829. Evaluating the impacts of groundwater withdrawals on a river or stream is extremely complex. For example, groundwater withdrawals near a river or stream can sometimes actually supplement the stream or river flow. For example, if the withdrawn water is used nearby for irrigation, the run-off can increase the stream flow. To date, the 10 percent stream presumption in BOR 4.2.C.2 has generally been applied only to a withdrawal or combination of withdrawals directly from a river or stream and application of the presumption has not included an evaluation of the effect of any groundwater withdrawals. The evidence indicates that groundwater withdrawals have reduced the rate of flow in some streams and rivers. The District claims any measurable effects of groundwater withdrawals on stream flow can be considered as site specific information.

830. However, if the baseline for applying the presumption is at the time of withdrawal, it is not clear how historic reductions from groundwater withdrawals can be included.

831. The current presumption does not provide any standards or principals for how long-standing uses should be considered and/or how to measure flow when multiple withdrawals exist on a stream.

832. There were a number of stream or river withdrawals in existence before the District adopted the stream presumption in 1989, including municipal supply withdrawals from the Shell Creek, the Myakkahatchee Creek, the Hillsborough River, the Braden River, and the Little Manatee River. All of these withdrawals exceeded the ten percent presumption on at least some days. The District has allowed the renewal of a number of these existing surface water withdrawals without requiring compliance with the ten percent stream presumption.¹¹³ The District has no written guidelines, standards or criteria as to when a long- standing existing withdrawal from a river has to comply with the ten percent stream presumption. It is not clear what factors will be considered in reaching this determination. At least one District witness testified that if alternate sources of water were available, the District would be more likely to strictly apply the ten percent presumption. However, this policy is not set forth in the rules and there are no standards or guidelines for determining the availability of other sources of water.

833. There are two other aspects of the stream flow presumption that merit comment. The evidence indicates that the 10 percent presumption may not be sufficient or appropriate for streams which contain impoundments or other structures. The second sentence of the stream flow presumption apparently tries to account for this limitation by providing that "the effects of water retention in instream impoundments will be included in the determination of flow reductions." It is not clear what this provision means or how this provision is applied. The rules provide no guidance as to how to calculate the "effects" of water retention in instream impoundments. The evidence also indicates that, in applying the stream presumption, the District considers the diversion capacity of a withdrawal facility even though this consideration is not clear from the face of the rules.

f. Conclusion

834. Without question, the regulation of withdrawals from a stream involves many site-specific issues and the District's rules must be general enough to provide flexibility to address these matters. The District argues its staff should be allowed to exercise its discretion and judgment on a case-by-case basis with regard to the application of the presumption. However, there are no guidelines or criteria which guide staff as to when a withdrawal from a river must comply with the presumption or the inverse presumption. As currently written, the District's stream flow presumption is unacceptable. The ambiguity and vagueness of the terms "combined with other withdrawals," "rate of daily flow," "drainage system," and "at the time of withdrawal," coupled with the undefined measuring stick of "unacceptable environmental impact," render it virtually impossible to determine how the 10 percent figure is to be measured and provide no meaningful basis for the review of permitting decisions.

835. The District says it utilizes the 10 percent stream flow presumption simply as a means of facilitating the evaluation of permit applications and it is not used as a pass/fail cutoff. If site-specific information demonstrates that the 10 percent presumption is not appropriate, the District says such information will be used to evaluate compliance with the performance standards. The presumption shifts the burden of proof, which normally and properly rests with a permit applicant, to the District and/or a third-party challenger to produce evidence that the 10 percent threshold is not applicable if a withdrawal is under the threshold.

836. The desired goal of tying withdrawals to stream flow can be accomplished without the imposition of a uniform numerical value which purports to be determinative of the existence of unacceptable or acceptable environmental impacts upon all streams. By using the performance standards, the District can require an applicant's withdrawals, combined with other withdrawals, to mimic the natural flow of the river or stream from which the withdrawals are to be taken.

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