Alafia River Minimum Flows and Levels - Southwest Florida Water ...
Alafia River Minimum Flows and Levels - Southwest Florida Water ... Alafia River Minimum Flows and Levels - Southwest Florida Water ...
5.6.2 Prescribed Flow Reduction for Lithia Springs Major – Recreational Use Assessment Results Based on Department of Health "bathing load" criteria, a flow of 218,000 gallons per day, or ~0.3 cfs, is necessary to support use of the Lithia Springs Major as a "bathing place" for the maximum number of individuals (436) that should be in the pool at any one time. Surveys conducted by District staff for several days in July 2003, indicate that an average of 16% of the park visitors who entered the park actually swam in the spring pool, although on one day, the percentage of park visitors utilizing the pool was 30%. Assuming that 16% of the 2,570 individuals visiting the park on the single busiest day between June 2001 and June 2003 entered the pool, the minimum necessary spring flow needed to support this use in accordance with state standards would be 205,500 gallons per day, or ~0.3 cfs. Assuming that 30% of the park visitors chose to swim on that day, a minimum discharge of 385,500 million gallons of water per day, or ~0.5 cfs would be required. The minimum flow necessary to support the traditional and long-standing recreational use of the spring as a bathing place is therefore apparently less than 1 cfs. This information was identified as a possible limiting factor for consideration in the development of minimum flows and levels for Lithia Spring Major. Based on this limiting factor, a prescribed flow reduction that permits consumptive-use of spring flows in excess of 1 cfs was identified for consideration in the establishment of a minimum flow for Lithia Springs Major. Use of this prescribed flow reduction for development of a short-term compliance standard for Lithia Springs Major was not considered appropriate for several reasons. First, although a flow of 1 cfs from the spring may be sufficient for meeting Department of Health requirements for public bathing places, allowing withdrawal of all flows in excess of 1 cfs would likely result in adverse impacts to recreational values. Flows as low as 1 cfs are uncommon at the site (see Figure 2-28), and would be associated with increased incursions of colored river water into the typical clear spring run and pool, which would lead to decreased availability of the pool for swimming and diminished aesthetic values. Second, although the extent of aquatic habitat in the Lithia Springs Major run is not great in comparison to habitat available in the Alafia River system, PHABSIM results indicated that percent-of-flow reductions in excess of 15% may be expected to result in more than a 15% loss of habitats in the spring run. Allowing spring flow to be reduced to 1 cfs, a flow that represents a 97% decrease from the mean annual daily flow for the spring, would therefore be expected to significantly impact spring run habitat. For these reasons, we do not recommend use of the prescribed flow reduction based on use of the pool as a bathing place for development of a prescribed flow reduction or short-term compliance standard. 5-20
5.6.3 Short-Term Compliance Standard for Lithia Springs Major PHABSIM and recreational use assessment results were inconclusive with regard to identification of prescribed flow reduction and short-term compliance standard for flows from Lithia Springs Major. Results from PHABSIM analyses indicate that up to a 5% reduction in flow would be protective of habitat in the spring run. Interpretation of results was, however, confounded by influence of the Alafia River on flows and levels in the spring run. A recreational use assessment indicated that even with substantial reductions in flow, the spring pool could still meet State criteria for public bathing places. The analyses did not, however, address potential recreational use impacts associated with the effect of significantly reduced flow on water chemistry/quality in the run and pool. For these reasons, results from the PHABSIM and recreational use assessment were judged to be insufficient for developing a prescribed flow reduction and short-term compliance standard for Lithia Springs Major. Minimum flow requirements for the estuarine portion of the Alafia River are currently being evaluated by the District. Because compliance with minimum flows and levels for the estuary may be contingent on flow or discharge from Lithia Springs Major, we recommend that establishment of a minimum flow for the springs be deferred until analyses for the estuarine segment of the Alafia River are completed. The report for the estuarine portion of the Alafia River will include recommendations for minimum flows for Lithia Springs Major. 5.7 Prescribed Flow Reduction and Short-Term Compliance Standard for Buckhorn Springs Main Potential changes in habitat availability in Buckhorn Creek associated with variation in Buckhorn Springs Main flow were used to develop a prescribed flow reduction for the spring. The prescribed flow reduction was used to develop a short-term compliance standard, which constitutes a proposed minimum flow for Buckhorn Springs Main. 5.7.1 Prescribed Flow Reduction for Buckhorn Springs Main - PHABSIM Results PHABSIM analyses were used to model potential changes in habitat availability for several fish species and macroinvertebrate diversity in Buckhorn Creek, downstream from Buckhorn Springs Main. Two different flow records were used 5-21
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5.6.3 Short-Term Compliance St<strong>and</strong>ard for Lithia Springs Major<br />
PHABSIM <strong>and</strong> recreational use assessment results were inconclusive with<br />
regard to identification of prescribed flow reduction <strong>and</strong> short-term compliance<br />
st<strong>and</strong>ard for flows from Lithia Springs Major. Results from PHABSIM analyses<br />
indicate that up to a 5% reduction in flow would be protective of habitat in the<br />
spring run. Interpretation of results was, however, confounded by influence of<br />
the <strong>Alafia</strong> <strong>River</strong> on flows <strong>and</strong> levels in the spring run. A recreational use<br />
assessment indicated that even with substantial reductions in flow, the spring<br />
pool could still meet State criteria for public bathing places. The analyses did<br />
not, however, address potential recreational use impacts associated with the<br />
effect of significantly reduced flow on water chemistry/quality in the run <strong>and</strong> pool.<br />
For these reasons, results from the PHABSIM <strong>and</strong> recreational use assessment<br />
were judged to be insufficient for developing a prescribed flow reduction <strong>and</strong><br />
short-term compliance st<strong>and</strong>ard for Lithia Springs Major.<br />
<strong>Minimum</strong> flow requirements for the estuarine portion of the <strong>Alafia</strong> <strong>River</strong> are<br />
currently being evaluated by the District. Because compliance with minimum<br />
flows <strong>and</strong> levels for the estuary may be contingent on flow or discharge from<br />
Lithia Springs Major, we recommend that establishment of a minimum flow for<br />
the springs be deferred until analyses for the estuarine segment of the <strong>Alafia</strong><br />
<strong>River</strong> are completed. The report for the estuarine portion of the <strong>Alafia</strong> <strong>River</strong> will<br />
include recommendations for minimum flows for Lithia Springs Major.<br />
5.7 Prescribed Flow Reduction <strong>and</strong> Short-Term Compliance<br />
St<strong>and</strong>ard for Buckhorn Springs Main<br />
Potential changes in habitat availability in Buckhorn Creek associated with<br />
variation in Buckhorn Springs Main flow were used to develop a prescribed flow<br />
reduction for the spring. The prescribed flow reduction was used to develop a<br />
short-term compliance st<strong>and</strong>ard, which constitutes a proposed minimum flow for<br />
Buckhorn Springs Main.<br />
5.7.1 Prescribed Flow Reduction for Buckhorn Springs Main -<br />
PHABSIM Results<br />
PHABSIM analyses were used to model potential changes in habitat availability<br />
for several fish species <strong>and</strong> macroinvertebrate diversity in Buckhorn Creek,<br />
downstream from Buckhorn Springs Main. Two different flow records were used<br />
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