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CHARLOTTE COUNTY v. SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
C. District Methodology for Calculating and Applying the Minimum Level 435. In the proposed SWUCA Rules published on December 2, 1994, the District included a map of the Upper Floridan's 1991 average potentiometric surface and indicated that the map would serve as a delineation of the minimum level for the UFAS within the SWUCA. The rules provide that until the potentiometric surface throughout the area met the indicated levels for a five-year period, no new permits would be issued within the SWUCA. 436. During Phase I of these proceedings, evidence was presented that under the methodology in the December 2 version of the rules, withdrawals or seasonal fluctuations that caused even minor shifts of localized potentiometric contour lines would have effectively precluded the issuance of new permits within the entire SWUCA. 437. Following the completion of Phase I, the District decided to propose a new methodology for calculating and applying the minimum level for the SWUCA. On April 14, 1995, the District published notice that it was withdrawing the methodology published in the December 2 version of the rules. In its place, the April 14 Modifications set forth a proposed new procedure for deriving and applying the minimum level. Although the new method was still based on the 1991 potentiometric surface, the new approach calculated an annual average potentiometric surface for the SWUCA as a whole. In addition, annual average potentiometric surface levels were also calculated for the separate areas previously designated as the ETB WUCA and the HR WUCA. Under the April 14 Modifications, the minimum level on average would have to be achieved in the ETB area, the HR area, and the entire SWUCA over a five-year period before the District would consider issuing permits for any new quantities in the SWUCA. In adopting the new methodology, the District sought to provide more flexibility within the regulatory scheme so that new permits would not necessarily be precluded as a result of seasonal or localized lowering of the potentiometric surface in one small area. 438. As noted in the Preliminary Statement, certain Petitioners sought entry of a summary final order finding that the District's actions in withdrawing the original proposal and publishing a new methodology were improper or invalid. After extensive argument and briefing by the parties, the motions for summary final order were denied for the reasons set forth in the Order Denying SFO entered on September 8, 1995. The parties to this proceeding were afforded a reasonable opportunity to conduct discovery with respect to the new methodology and a reasonable opportunity to present evidence challenging the proposal. 439. The new computer-assisted methodology calculated minimum levels for each of the three identified areas based on an average of the USGS potentiometric surface maps for May and September 1991. The following District calculations of average annual potentiometric surface areas for 1991 were specified in the April 14 Modifications as the minimum levels for the UFAS in the SWUCA: 46.8 feet for the SWUCA as a whole; 17.4 feet for Eastern Tampa Bay; and 78.3 feet for the Highlands Ridge. 440. The more persuasive evidence established that the District's methodology in calculating the minimum levels -- including the use of an annual average, the selection of a 1,000-square-meter cell for the computer gridding, and the determination to calculate the levels to one tenth of one foot (.1') -- was scientifically and statistically sound. 441. The USGS potentiometric surface maps depict the hydraulic head distribution within a geographic region. Since 1975, the USGS has prepared maps for the District for the months of May and September each year. The May map represents the end of the dry season, when heavy pumping reduces the potentiometric surface to what is usually its lowest point for the year, while the September map generally reflects the highest potentiometric surface following recovery of the aquifer from seasonal pumping and rainfall. 442. To prepare the maps, the USGS measures water levels in about 600 wells throughout the District over a two-week period. Trained USGS hydrologists or technicians take all of the measurements used to derive the maps, and data points include both production and monitoring wells. In addition, the USGS continuously operates recorded wells throughout the District. All of the District's regional groundwater monitoring wells are available to the USGS, but the District exercises no control over the measurements or the mapping process. 443. Measurements are logged into a computerized database, which is then evaluated with respect to prior water levels of the wells to see whether anomalies appear in the data. Maps prepared over the past 25-to-30 years provide historical data for determining irregularities, and about two percent of the readings are discarded as aberrations. 444. Because the USGS seeks to ensure that map contour lines accurately depict general groundwater flow conditions without rigorously adhering to any particular measurement, hydrologic judgment is involved in preparing the maps. The data collection procedures and map preparation are subject to review at the local USGS office, its sub-district office, and state office in Tallahassee. The USGS requires review outside of the originating office to guard against local bias in measurement interpretations. 445. The USGS maps contain the standard qualification that they are accurate to plus-or-minus one-half of a contour line, which is a random variation that may occur at any one point depicted on a map when compared with an actual measured value at that point. 446. The data points used in preparing the USGS maps can change from cycle to cycle, i.e., the same information is not used in the maps' preparation each year. The addition or deletion of data points can influence the location of contour lines on the USGS maps. Some parties have argued that the District's proposed regulatory strategy is scientifically flawed because the lack of continuity in data points means that a change in a contour line would not necessarily reflect a change in the underlying resource. The more persuasive evidence, however, was that any differences that may occur would be minor and would be averaged-out over the area(s) in question. 447. The evidence established that the USGS maps represent the best available information on potentiometric surface levels and the condition of the Upper Floridan Aquifer System. Moreover, the evidence established that it is reasonable for the District to use the USGS potentiometric surface maps as a basis for its regulation of groundwater use. 2. Conversion of USGS Maps to District Surface Grid 448. To derive the potentiometric surface averages for the ETB, HR and entire SWUCA contained in the proposed rules, the District began with the 1991 May and September USGS potentiometric surface maps. It then constructed a 1000-square-meter grid that was superimposed over the SWUCA area on both maps, using ARCINFO computer software that calculated an average of May and September values for each grid cell. Rather than using actual well measurements, the contour lines are established by estimating a value for each cell through a linear interpolation process.75 The District verified the results by comparing actual data point values depicted on the USGS maps for May and September 1991 with the model-predicted values at the same location. The evidence established that the District's methodology was scientifically sound. 449. The District's computerized averaging of the May and September potentiometric surfaces is intended to approximate the average annual levels for the area. The District makes no independent inquiry into the accuracy of the contour lines depicted on the May and September USGS maps. The USGS does not prepare average annual potentiometric surface contour maps, and several parties challenged the District's reasoning and methodology in proposing to regulate groundwater withdrawals on the basis of averages. 450. The more persuasive evidence established that the averaging of May and September potentiometric surface maps to indicate overall aquifer conditions is a reasonable method generally accepted in the scientific community. The averaged data can be used to determine changes in the resource over time. The suggestion by some Petitioners that the average maps are "manufactured data" inappropriate for regulatory purposes is rejected. 451. A District study comparing the accuracy of the annual figures obtained by averaging the May and September USGS maps with a mathematical average derived from continuously monitored well data confirmed that the averages reasonably approximate a rigorously derived mathematical average based upon continuous well data. There was no bias in the uncertainty towards over or under estimation of the condition of potentiometric surface conditions. Any inaccuracies introduced by averaging May and September levels are random and reduced or minimized by averaging the data from a large number of wells. Because digitalization of the contour lines would be consistently applied using the same approach, it is not critical whether the calculated average surface corresponds to actual data for a specific point at any time. 452. There is no question that for monitoring saltwater intrusion and guarding against serious damage to the resource, it is useful to consider the worst aquifer condition or lowest potentiometric levels which generally occur during heavy groundwater pumping in May. However, the District's decision to regulate withdrawals on the basis of averaged conditions, as opposed to best or worst condition, has not been proven arbitrary, capricious or otherwise invalid. The annual average condition is useful for purposes of detecting long-term trends.76 453. Proposed Rule 40D-8.628, F.A.C., would regulate new groundwater withdrawals on the basis of a five-year rolling average. Average potentiometric levels for each of the designated regions for five consecutive years would be averaged to determine the value that would then be compared with the minimum levels, i.e., 1991 average annual surface levels set forth in the rule. A potentiometric surface level falling below the 1991 baseline in any one year would not necessarily trigger the rule's restrictions if the five-year rolling average remains above the baseline. 454. By averaging several years together, a better indication of the aquifer's long-term health can be obtained, because drought events and other short-term or extreme fluctuations can be averaged-out. In addition, the methodology can potentially mediate the effects caused by anomalous sub-regional conditions. 455. The USGS maps which form the basis for the District's calculations show only contour elevations rounded to the nearest foot. Some parties have objected to the District's rounding of averages in Rule 40D-8.628 to one tenth of one foot (.1'). The more persuasive evidence established that it is scientifically and statistically acceptable and not "overly sensitive" to calculate the averages to 0.1 foot. 456. Contrary to the suggestion of some Petitioners, the interpolations inherent in the methodology for deriving the numeric levels do not vitiate the District's decision to calculate and apply the minimum levels to an accuracy of 0.1-foot. Imprecision intrinsic to the process of preparing the USGS maps and calculating the annual average potentiometric surfaces is irrelevant when considered over a large area, as long as the methodology contains no inherent bias and is consistently applied over time. The procedure proposed by the District would produce a reasonable and consistent method of calculating and applying the minimum levels. Using anything larger than 0.1-foot could allow the condition of the resource to fluctuate too widely. D. Achievement of Minimum Levels in the SWUCA, ETB and HR WUCAs Before New Withdrawals Considered 457. The SWUCA Rules would require the five-year average potentiometric level to be above the 1991 average potentiometric level in each of three areas -- the ETB WUCA, the HR WUCA and the entire SWUCA -- before the District would consider applications for the withdrawal of new or additional quantities of groundwater within the SWUCA.77 The levels set forth in proposed Rule 40D-8.628 were derived by calculating averages of the potentiometric surface for each of the areas involved utilizing the methodology described above and applying it to the appropriate segments of the District's 1,000-square-meter surface grid. The same grid segments could be used each year. 458. Although separate measurements and comparisons would be made for each of the three areas, they would still be regulated as a unit. Rule 40D-8.628 would not be considered met and no permits for new quantities would be issued if the aquifer level of any one of the three areas remained below the established minimum level. 459. Calculating the minimum aquifer level over a broad area may not provide sufficient detailed information regarding the condition of the resource, thereby potentially masking water resource problems. In other words, if a basin-wide average is used, the regulatory program may fail to detect serious problems in ETB or the HR. Moreover, using an average for the entire area would not necessarily protect the positive seaward gradient within the aquifer, thereby preserving discharge of freshwater through the system. 460. Using sub-areas in different positions along the groundwater flow path is desirable because what happens in one zone can affect the available water within the other. The precise boundaries of the sub-areas are not necessarily important, but zones that are perpendicular to groundwater flow lines are useful in monitoring and maintaining the seaward gradient. It is essential that the use of monitoring areas remain constant over time. 461. The District's selection of Eastern Tampa Bay and the Highlands Ridge as separate areas for calculating minimum levels was premised upon its determination that the detrimental effects of historical over-pumping had been previously manifest in the two areas. In addition, the areas' boundaries were well-known to the regulated public. Under the proposed rules, the ETB and HR sub-areas will essentially serve as monitoring areas for purposes of determining whether the appropriate gradient is being maintained throughout the aquifer system. 462. In sum, the more persuasive evidence establishes that the District's determination to use an area-wide average, together with separate averages for the ETB and HR areas, is a reasonable and logical decision that represents a significant improvement over the proposed methodology published in December, 1994. 463. Several Petitioners have objected to the District's selection and methodology for applying the minimum aquifer level in the SWUCA on the grounds that it unduly penalizes inland counties.78 In this regard, Petitioners point out that if the ETB WRAPs estimated "safe yield" quantities -- 150 MGD for ETB and 550 MGD for the remainder of the SWUCA -- are compared with actual pumping figures for the years subsequent to 1991, it appears that the ETB has exceeded its safe yield pumping levels by a significant amount, while the remainder of the SWUCA has been pumping at levels below or very near its safe yield.79 As expected, the five-year average potentiometric levels confirm that the ETB is below the minimum level proposed in Rule 40D-8.628, while the SWUCA as a whole and the Highlands Ridge are at or close to the proposed minimum levels for those areas. Petitioners contend the proposed rules would unfairly preclude the issuance of new permits in Polk, Highlands, DeSoto and Hardee Counties when only ETB has failed to meet its "safe yield" pumping limits. This argument ignores the interrelationship of withdrawals throughout the Southern Basin and misapprehends the purpose of the "safe yield" determinations in the ETB WRAP. The safe yield determinations were not intended to be allocations to the respective areas. 464. The District's scientists do not believe that over the five-year rolling-average period, aquifer levels will rise in the HR or the overall SWUCA while falling in the ETB sub-area, because of the high degree of interconnectivity within the system. Since 1981, there has been only one year (1989-1990) when the average potentiometric surface in both the HR sub-area and the entire SWUCA increased, while the ETB sub-area average decreased. In all other years since 1981, the three averages have moved in concert, except 1991-1992 when the SWUCA and ETB averages decreased and the HR average did not change. 465. While an anomalous climatic event or short-term change in pumping patterns in one portion of the Southern Basin could cause a divergent fluctuation to occur in the short-term, it is unlikely that the deviation would be sustained over a five-year period. Using five-year averages allows the District to factor-out short-term pumping changes and base its permitting decisions on the comprehensive health of the SWUCA's water resources. 466. Even if the ETB were the only area that did not meet its minimum level, it would not be advisable to allow new withdrawals along the Highlands Ridge because under the regional flow pattern, withdrawals from the HR would deplete the availability of the resource along the coast. The HR is a primary source of groundwater flow for the ETB and intervening areas, and increasing pumping along the HR could reduce the amount of groundwater available for the rest of the SWUCA. Thus, even though the ETB area currently shoulders the brunt of saltwater intrusion, the concentration of regulatory restrictions only within the ETB is not an acceptable approach to the control of saltwater intrusion since the potentiometric surface in the ETB is influenced by withdrawals from the entire groundwater flow path from the HR to the coast. In other words, if upstream users are allowed to continue to withdraw additional amounts of water, more problems may be created for downstream users. 467. Because of the interconnectedness of the UFAS in the Southern Basin, changes in groundwater pumping propagate and impact the potentiometric surface of the entire Basin, even though the impact of a particular withdrawal may be noticeable only on a localized level. While inland counties in the SWUCA may show little direct evidence of saltwater intrusion and lake levels have been relatively stable -- some even showing recent improvement from historical lows -- the permitting of groundwater withdrawals from inland counties must be considered in light of overall permitting in the SWUCA and the impact of all areas' pumping on saltwater intrusion. 468. While Petitioners complain that saltwater intrusion and declining lake levels are local problems that should be controlled by regulating uses within the affected local areas, the greater weight of the evidence supports the District's conclusion that there is a regional component to saltwater intrusion and declining lake levels. 469. The District has not directly factored -- in recharge characteristics and aquifer transmissivities as parts of its regional analysis. The District concluded that trying to factor those issues into the analysis would further complicate an already complex matter. This decision has not been shown to be arbitrary or capricious. 470. The evidence established that the District has considered the historical trends of water use throughout the District, as well as the limitations on some of the data, in reaching its conclusion that as a general rule, the potentiometric surfaces in each of the three identified areas are interrelated and tend to move in concert. No persuasive evidence has been presented to refute the District's conclusion. 471. It should be noted that the minimum levels set forth in proposed Rule 40D-8.628 are based upon an assessment of the current condition of the UFAS, the hydrogeology of the SWUCA, and the projected impacts of future pumping under the current permitted withdrawal distribution. The minimum levels established for the three areas were not intended to create allocations of groundwater to the respective areas. 472. Some Petitioners contend that, rather than (or in addition to) maintenance of an average potentiometric surface, an appropriate regulatory program should require adherence to "safe yield" by county or some other geographic sub-area. Such "safe yield" determinations based on political boundaries are not mandated by Chapter 373, and there is no hydrologic basis for such determinations. While it is sometimes necessary to utilize surface features or political boundaries to implement a regulatory program (particularly for groundwater,) any such use should be rationally related to the hydrogeology and not totally random. 473. DeSoto and Hardee Counties have objected to their inclusion in the SWUCA. They note that the point in DeSoto County closest to the Gulf of Mexico is approximately 15-20 miles from the coast, while that distance for Hardee County is about 40-45 miles. Moreover, there are no natural lakes in Hardee County and only one natural lake in DeSoto County. Thus, the counties contend that the major concerns addressed in the SWUCA Management Plan and Rules are largely irrelevant to them. 474. DeSoto and Hardee Counties rely principally on groundwater for public supply, agricultural and industrial uses. They are concerned that the SWUCA Rules will preclude the issuance of new water use permits in their counties, thereby negatively affecting growth and economic development. They point out that general groundwater use in DeSoto and Hardee County has declined since 1975, particularly from 1989 through 1994. While the counties' concerns are relevant issues to consider in developing an equitable allocation of water supplies, they do not provide a basis for ignoring the need to regulate the groundwater resources of the Southern Basin under a regional approach. 475. In sum, the District's methodology for calculating and applying the minimum aquifer level in each of the three areas based on five-year averages is a reasonable approach in view of the persuasive evidence that the SWUCA is a well-confined, highly transmissive basin in which all groundwater users share an interdependent responsibility for the condition of the aquifer system.
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