G.B. Sonny Hall, PhD Technical Program Manager Veronika Thiebach Senior Assistant General Counsel St. Johns River Water Management District 1
SJRWMD MFLs Method MFLs Method Premises Case studies Lake Hiawassee : MFLs implementation with water budget modeling Volusia Blue Spring: Development of minimum flow regime 2
SJRWMD MFLs method was developed with a top down approach Identifies an acceptable departure from a natural hydrologic regime Not all hydrologic changes result in significant ecological changes Threshold beyond which unacceptable ecological effects occur (MFLs hydrologic conditions) 3
Multiple MFLs required to protect aquatic & wetland systems Collectively, MFLs define a new minimum hydrologic regime Each MFL is focused on protection criteria Maintaining essential characteristics of natural flooding & drying regime protects water resource structure & functions 4
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MFLs represented as hydrologic statistics Magnitude (flow or water level) Duration (how long, days) Event Return Interval (how often event recurs, years) Timing / seasonality (wet and dry seasons) Rate-of-change (how fast magnitude changes) 6
MFLs represented as hydrologic statistics MFLs Stage (ft NGVD) Flow (cfs) Duration (days) Return Interval (years) Minimum frequent high 1.9 4,600 30 2 Minimum average 0.8 2,050 180 1.5 Minimum frequent low 0.3 1,100 120 5 7
MFLs Method Premise 4 SJRWMD MFLs method primarily ecologically based Field data collection identifies important water resource features to be protected Protect most sensitive portions of system - Umbrella criteria Consider how MFLs protect other important water resource values 8
MFLs Method Premise 4 Section 62-40.473, Florida Administrative Code Consider seasonal fluctuations, nonconsumptive uses, and environmental values including: Recreation in and on the water Fish and wildlife habitats and the passage of fish Estuarine resources Transfer of detrital material Maintenance of freshwater storage and supply Aesthetic and scenic attributes Filtration and absorption of nutrients and pollutants Sediment loads Water quality Navigation 9
Utilize water budget models for a cumulative and a priori consumptive use approach Calibrate model using existing hydrologic records Use model to generate long -term water level record (existing conditions) Runoff Include new water uses in Seepage model to generate a new long-term water level record Compare results to determine if cumulative uses protect all MFLs? Simulated 56 year POR based on 2004 conditions Long-term rainfall Water Budget Model ET Increased seepage due to groundwater withdrawal Surface water withdrawal 10
Statistical analysis of model output provides a framework to summarize hydrologic characteristics of a water body Rely on a type of statistical analysis referred to as frequency analysis Frequency analysis estimates probability of hydrologic event occurring in any given year Weibull plotting position formula: m = rank of the event n = numbers of year of data 11
SJRWMD MFLs Method MFLs Method Premises Case studies Lake Hiawassee : MFLs implementation with water budget modeling Volusia Blue Spring: Development of minimum flow regime 12
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Lake Hiawassee: Recommended MFLs Recommended Minimum Level Elevation (ft NGVD) 1929 Datum Duration Return Interval Minimum frequent high level Minimum frequent low level 76.4 30 days 3 years 72.9 120 days 3 years 15
MFLs Stage (ft NGVD) Duration (days) Return Interval (years) Minimum frequent high 76.4 30 3 Minimum Frequent High Level Provides seasonal flooding to inundate majority of floodplain 76.4 ft NGVD - calculated as average of the mean elevations of wet prairie communities on Transects 1 5 30-day continuous flooding duration - Saturation or inundation to protect seasonally flooded wetlands from permanent encroachment by upland vegetation 3-year return interval (33 events in 100-years) - prevent permanent downhill shift of uplands species into wet prairie 16
MFLs Stage (ft NGVD) Duration (days) Return Interval (years) Minimum frequent low 72.9 120 3 Minimum Frequent Low Level Low water event - protects structure / functions of seasonally flooded wetlands 72.9 ft NGVD average of the minimum elevations of shallow marsh on Transects 1-5 120-day continuously dewatered regeneration & growth of seasonally flooded wetland plants during dry seasons with moderate droughts 3-year return interval (33 events in 100-years) dewatering floodplain / upper littoral zone maintains composition of emergent plant species & increases plant diversity 17
Minimum Level Case Study Lake Hiawassee Elevation (ft NGVD) Duration (days) Return Interval (years) Minimum Frequent High 76.4 30 3 Simulated 56 year POR based on 2004 conditions Frequent High Target maximum ground elevation continuously flooded for 30 days annually A 365-day hydrograph would have 336 (365-30+1 = 336) different values for a 30-day high Maximum stage in these 336 values saved Repeat for each year in POR Sort & rank saved values Calculate annual probabilities & plot 18
Minimum Level Case Study Lake Hiawassee Elevation (ft NGVD) Duration (days) Return Interval (years) Minimum Frequent High 76.4 30 3 Frequent High Target maximum ground elevation continuously flooded for 30 days annually A 365-day hydrograph would have 336 (365-30+1 = 336) different values for a 30-day high Maximum stage in these 336 values saved Repeat for each year in POR Sort & rank saved values Calculate annual probabilities & plot 19
Minimum Level Case Study Lake Hiawassee Elevation (ft NGVD) Duration (days) Return Interval (years) Minimum Frequent High 76.4 30 3 Frequent High Target maximum ground elevation continuously flooded for 30 days annually A 365-day hydrograph would have 336 (365-30+1 = 336) different values for a 30-day high Maximum stage in these 336 values saved Repeat for each year in POR Sort & rank saved values Calculate annual probabilities & plot 20
Minimum Level Case Study Lake Hiawassee Elevation (ft NGVD) Duration (days) Return Interval (years) Minimum Frequent Low 72.9 120 3 Frequent Low Target minimum ground elevation continuously dewatered for 120 days annually A 365-day hydrograph would have 246 (365-120+1 = 246) different values for a 120 days Minimum stage in these 246 values saved Repeat for each year in POR Sort & rank saved values Calculate annual probabilities & plot 21
Minimum Level Case Study Lake Hiawassee Elevation (ft NGVD) Duration (days) Return Interval (years) Minimum Frequent Low 72.9 120 3 Frequent Low Target minimum ground elevation continuously dewatered for 120 days annually A 365-day hydrograph would have 246 (365-120+1 = 246) different values for a 120 days Minimum stage in these 246 values saved Repeat for each year in POR Sort & rank saved values Calculate annual probabilities & plot 22
Recommended MFLs Based on field topography, vegetation, soils, and scientific literature Protected under 2004 land-use / groundwater use conditions Allow an additional 0.7 ft of Floridan aquifer decline 23
SJRWMD MFLs Method MFLs Method Premises Case studies Lake Hiawassee : MFLs implementation with water budget modeling Volusia Blue Spring: Development of minimum flow regime 24
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First magnitude spring (157 cfs or 101 mgd) Outstanding Florida Water Water quality characteristic of its source, the Floridan aquifer High clarity, no oxygen, high dissolved solids, stable temperature Internationally famous as a winter, warm-water refuge for the endangered West Indian manatee 28
Only large naturally occurring manatee warm -water refuge on Florida s east coast USFWS designated the spring and run as critical manatee habitat Manatees seek warm-water refuge when St. Johns River water temperature drops below 68º F Manatee use of Blue Spring as a winter, warmwater refuge has increased significantly since 1978 29
Model predicts 536 manatees by 2024 95 th upper confidence limit of maximum daily manatee growth of 6.84% 30
1995 1999 Initiated Blue Spring studies Developed recommended minimum average annual flow of 134 cfs and supporting documentation 2000 Conducted independent scientific peer review, data analyses, and interagency discussions Formed the Blue Spring Minimum Flow Interagency Working Group (MFIWG) 31
Blue Spring MFIWG members: USFWS FFWCC FDEP Save the Manatee Club, Inc. SJRWMD 32
2001 2006 Held MFIWG meetings to direct and review studies Developed recommendations for the Blue Spring minimum flow regime Completed additional interagency discussions, analyses, and independent scientific peer review Completed reports to document process, incorporate additional analyses and peer review comments 33
1999 Published Notice of Proposed Rule Development 2000 2002 Published Notice of Proposed Rule Received agency and public comment Published Notice of Change Conducted further analyses and re-evaluations 2003 Published Notice of Proposed Rule Development 2004 Held public workshops (3-23-04 and 4-20-04) Received agency and public comment Conducted further analyses and re-evaluations 2005 2006 Published Notice of Proposed Rule Development Held public workshop (12-6-05) Received agency and public comment Published Notice of Proposed Rule Rule effective: December 3, 2006 34
Based on 3 part approach: 1. Calculated MFLs needed to protect Blue Spring as a warm water refuge for increasing numbers of manatees using the spring. 2. Evaluated water resource values in Rule 62-40.473, F.A.C. 3. Considered and then determined values would be protected under the calculated MFLs 35
Defines minimum long-term average flow in five-year increments until 2024 Set minimum long-term average flow of 133 cfs from date of rule adoption to March 31, 2009 Increases minimum longterm average flow during each of four subsequent fiveyear intervals as follows: 36
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Requested authorization to develop a comprehensive Minimum Flow Regime Action Plan Would direct implementation of a multifaceted approach to ensure the increasing minimum flows required by the proposed rule are met in future Would be developed in cooperation with Blue Spring Minimum Flow Interagency Working Group and peer reviewers 38
Monitoring and Periodic Review Hydrologic and meteorological monitoring Manatee monitoring Hydrodynamic and groundwater modeling Updates Water resource values assessment Water Supply Planning/Alternative Water Supply Development 39
Formalized commitment of SJRWMD, FWC, and DEP to implementation of Action Plan and Achievement of the Plan s objectives Commits each party to strive for the funding needed to implement the Action Plan Has been executed by each party 40
Monitoring and Periodic Evaluation Completed Phase I of ecological monitoring (WSI. 2010. Water Resource Value Monitoring for Blue Spring and Blue Spring Run, Volusia County, Florida) Water Supply Planning and Alternative Water Supply Development Developing a Prevention Strategy for Volusia County to ensure Blue Spring flows do not fall below established MFR, as required by statute 41
Permitting and Enforcement Limit duration of consumptive use permits (CUPs) based on specific consideration of the phased Blue Spring MFR Structure groundwater allocations based on specific consideration of phased Blue Spring MFR Reporting and Periodic Review Developing consolidated report summarizing actions and data collected under each section of Blue Spring Action Plan 42