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Blue Spring, Volusia County: Minimum Flow Regime

Blue Spring, Volusia County: Minimum Flow Regime
Frequently asked questions

• Why has the St. Johns River Water Management District (District) set a minimum flow regime for Blue Spring?
• What is the long-term average flow of Blue Spring?
• Does Blue Spring’s flow vary throughout the year?
• What is the current flow of Blue Spring according to the most recent data available?
• What is the approved Blue Spring minimum flow regime?
• Why is the approved flow regime a phased approach?
• How many manatees use Blue Spring throughout the year?
• How are manatees counted at Blue Spring during each manatee season?
• What is the projected growth rate of the manatee population that uses Blue Spring as a winter, warm-water refuge?
• How will the approved minimum flow regime protect manatees?
• Is the Blue Spring minimum flow regime designed to protect only manatees?
• How will the District use the approved flow regime at Blue Spring?
• How will the approved Blue Spring minimum flow regime impact the development of water supplies to meet future water supply needs?
• How will the District ensure that the increasing minimum flow regime will be met over time?
• Will visitors to Blue Spring notice a change in water levels as a result of the minimum flow regime?
• Will the District continue to collect information on Blue Spring?
• Does adoption of the minimum flow regime mean the spring flow will automatically be reduced?
• Did the District rely on expertise outside the agency to help develop and review the rule?

Why has the St. Johns River Water Management District (District) set a minimum flow regime for Blue Spring?

State law (Paragraph 373.042(2), Florida Statutes (F.S.), mandates that the District adopt minimum flows and levels (MFLs) for all first magnitude springs. First magnitude springs are those springs with a long-term average flow of at least 100 cubic feet per second (cfs) or 65 million gallons per day (mgd).

Additionally, Blue Spring was named as a water course to be prioritized for the establishment of MFLs in a 1995 Settlement Agreement between the District and the organizations Concerned Citizens of Putnam County For Responsive Government, Inc., and Citizens For Water, Inc.

The adoption of a minimum flow regime for Blue Spring will protect the spring from a reduction in flows that could threaten its water resource values and functions, including its use as a reliable winter warm-water refuge by manatees.

What is the long-term average flow of Blue Spring?

The long-term average flow of Blue Spring is 157 cfs (101 mgd). This average flow was calculated from 654 instantaneous manual flow measurements collected and compiled by the U. S. Geological Survey (USGS) and the District over a 75-year period of record (POR).

Does Blue Spring’s flow vary throughout the year?

Yes. Blue Spring’s flow is primarily driven by climatic conditions. Alternating cycles of drought and abundant rainfall affect flows throughout the year and also from year to year. The measured flow has ranged from a minimum of 87 cfs in November 2001 to a maximum of 218 cfs in February 1983.

What is the current flow of Blue Spring according to the most recent data available?

Currently, the USGS and District personnel take instantaneous manual flow measurements at monthly or bi-monthly intervals. The average flow for calendar year 2005 was 175 cfs (113 mgd). During 2005, Blue Spring flow varied from 156 cfs (101 mgd)* on May 16, 2005, to 200 cfs (129 mgd) on Jan. 4, 2005. The average flow for any calendar year may be above or below the long-term average flow of 157 cfs or 101 mgd.

* Due to rounding, the mgd value is the same for 156 cfs and 157 cfs.

What is the approved Blue Spring minimum flow regime?

The District has approved a Blue Spring minimum flow regime. The minimum flow regime was developed through a three-part approach. First, the District calculated a minimum flow that will protect the use of Blue Spring as a refuge to accommodate expansion of the West Indian manatee population. Second, the District evaluated the water resource values in Rule 62-40.473, F.A.C., relevant to Blue Spring. Third, the District considered whether these values would be protected under the minimum flow regime for Blue Spring, and determined they also would be protected.

The minimum flow regime defines the minimum long-term average flow in five-year increments until 2024. The minimum flow will increase over time. The first increment would allow a temporary reduction in the long-term average flow from 157 cfs (101 mgd) to 133 cfs (86 mgd) for the period of time from the date of rule adoption to March 31, 2009. This 15 percent decrease in flow represents the maximum allowable reduction in the Blue Spring long-term average flow for a period of up to five years. This minimum long-term average flow would be raised during each of four subsequent five-year intervals to the following:

• 137 cfs (from April 1, 2009, through March 31, 2014)
• 142 cfs (from April 1, 2014, through March 31, 2019)
• 148 cfs (from April 1, 2019, through March 31, 2024)
• 157 cfs (after March 31, 2024)

Why is the approved flow regime a phased approach?

The phased approach was developed to accommodate the increasing number of manatees using Blue Spring Run as a winter warm-water refuge. The model used to estimate future manatee use of Blue Spring is based on the projected increase in the manatee population that will use Blue Spring.

By law the District is required to calculate minimum flows and levels using the best information available. After careful consideration of existing scientific information, the District used the best available information to calculate minimum flows for Blue Spring and these calculations show that a long-term average flow of 157 cfs will be needed by the manatee population by 2024.

How many manatees use Blue Spring throughout the year?

Manatees frequent Blue Spring Run at any time of the year. However, the most intensive use occurs during the colder months of each year, when manatees seek warm-water refuge. Manatees seek refuge in the warmer waters of the Blue Spring Run when the temperature of the river drops below 68°F (20°C). Manatees typically begin congregating in the spring run in November and leave in March, which is referred to as the “manatee season.” Manatees typically leave the run each day to feed in the St. Johns River. No food resources are available to the manatees in Blue Spring Run.

Manatee use of Blue Spring Run as a winter warm-water refuge has increased dramatically since 1978, when routine manatee counts were begun. Based on counts performed for daily surveys, the maximum number of manatees observed on a single day during the manatee season has increased nearly seven-fold, from 28 in 1978 to 182 during the 2005 manatee season.

How are manatees counted at Blue Spring during each manatee season?

Since 1978, Blue Spring State Park biologists have tracked individual manatees’ occurrence within the spring run. Daily surveys are performed during the manatee seasons from the confluence of the spring run with the St. Johns River to the spring boil. Surveys are usually conducted in the morning, when the manatees are in greatest attendance. The field observation sheet for recording manatee data divides the spring run into 22 zones, based on landmarks located along the bank. The biologists record the locations of individual manatees within the 22 spring run zones on the field datasheets as they paddle a canoe upstream. River and spring run water temperatures and the location of the dark water intrusion are also recorded. This information is then entered into computer files for future data analysis.

What is the projected growth rate of the manatee population that uses Blue Spring as a winter, warm-water refuge?

Based on 28 years of observed manatee season maximum daily counts, the manatee population using Blue Spring as a winter, warm-water refuge grew at a rate of 6.6 percent per season. However, the District’s model used to project maximum daily manatee growth rate in future manatee seasons uses a 7.02 percent growth rate. The use of this higher growth rate recognizes the potential increase in the number of manatees using Blue Spring as a winter, warm-water refuge that may result from the future closure of artificial warm-water refuges (e.g., electrical energy power plants) in the St. Johns River and along Florida’s east coast. Using this higher growth rate, the manatee season maximum daily count is projected to increase from 158 manatees in the 2006 season, to 558 manatees by the 2024 season.

How will the approved minimum flow regime protect manatees?

The minimum flow regime is designed to protect Blue Spring as a winter, warm-water refuge critical to the survival of a growing manatee population. The regime will provide adequate warm water from the spring in winter months, including during catastrophic cold-weather conditions. Catastrophic conditions are defined as the simultaneous occurrence of the lowest St. Johns River water level, the coldest river water temperature, and the lowest spring flow that would be expected to occur only once every 50 years, lasting for three or more consecutive days. The time period of 50 years is based on the long life span of the manatee and the three-day duration is based on laboratory studies of manatee tolerance to cold water.

Is the Blue Spring minimum flow regime designed to protect only manatees?

No. While the adequate protection of manatee habitat was the controlling factor in establishing the Blue Spring minimum flow regime, the minimum flow regime also will protect other water resource values.

Rule 62-40.473(1), F.A.C., directs water management districts to consider the following water resource values:

• 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 other pollutants
• Sediment loads
• Water quality
• Navigation

These values were evaluated in a report entitled, Human Use and Ecological Evaluation of the Recommended Minimum Flow Regime for Blue Spring and Blue Spring Run, Volusia County. Based on this report, the District concluded that these ecological and human use values would be protected by the Blue Spring minimum flow regime.

How will the District use the approved flow regime at Blue Spring?

Once a Blue Spring minimum flow regime is adopted by rule, applicants seeking an environmental resource permit (ERP) or a consumptive use permit (CUP) would be required to provide reasonable assurance that the Blue Spring minimum flow regime would continue to be achieved by a proposed water withdrawal or the construction or operation of a proposed surface water management system. In addition, the District will include the Blue Spring minimum flow regime in the regional water supply planning process as a constraint in developing sustainable water supply options to meet existing and future water supply needs.

The establishment of a minimum flow regime for Blue Spring will limit the continued availability of groundwater to meet the increasing regional water supply demands. However, future water supply development in the area is also limited by other factors. For example, the District’s water supply plan indicates that wetland drawdown limits and MFLs established for nearby lakes in the Deland Ridge area are likely to be more constraining to additional groundwater use over the near term, than the Blue Spring minimum flow regime. However, eventually the Blue Spring minimum flow regime is expected to become the greatest limitation on groundwater use in the area.

How will the approved Blue Spring minimum flow regime impact the development of water supplies to meet future water supply needs?

The minimum flow regime will actually constrain or limit regional groundwater pumping for future water supply development. In fact, over the next 20 years this minimum flow regime will create the greatest limitation on groundwater development. As a result, the primary impact of the minimum flow regime is to create the need for water users to develop alternative water supply projects to supplement groundwater in meeting existing and future water supply needs.

How will the District ensure that the increasing minimum flow regime will be met over time?

The District intends to use all available regulatory and water supply planning tools necessary to ensure that the increasing minimum flow regime will be met. The District has already limited the duration of water allocations in recently issued consumptive use permits as needed to ensure that the increasing flow requirements will be met. The District intends to continue this practice in any future agency permitting actions concerning the use of groundwater that affects Blue Spring. In addition, the District has already included conditions on consumptive use permits recently issued, that require the permit holder to plan and develop alternative water supply sources to meet future water supply needs when the allocation expires. These permit conditions serve to put water users on notice that they cannot expect to renew certain groundwater allocations and that they will need to shift to the alternative water supplies currently being planned and developed. The District intends to continue to impose similar permit conditions on future agency permitting actions. The District regularly uses administrative and judicial remedies to enforce conditions of permits and intends to do the same for these permits. The District is strongly supportive of and is assisting water suppliers in the timely development of the alternative water supply projects that will be needed to reduce groundwater withdrawals in time to meet the increasing minimum flow requirement.

Will visitors to Blue Spring notice a change in water levels as a result of the minimum flow regime?

No, the change will not be perceptible to the eye. The water level in the spring run is almost totally determined by the level of the St. Johns River, not the magnitude of flow in the spring. The variability (range) of Blue Spring Run surface water levels is relatively small as compared to the water level variability of the adjacent St. Johns River. Even a large spring flow of 212 cfs (137mgd) results in only 1.5 inches (0.13 feet) of rise in the surface water level of the run from the mouth of the spring run to the spring boil. By contrast, the water level of the St. Johns River in winter ranges over 6 feet.

Will the District continue to collect information on Blue Spring?

Yes. The District will continue to work in coordination and partnership with other agencies to enhance existing data collection. This additional information and the District’s work in other areas (e.g. refinement and improvement of groundwater and hydrodynamic models) will be used by the District to determine whether rule amendments are warranted in the future.

Does adoption of the minimum flow regime mean the spring flow will automatically be reduced?

No, there is no automatic reduction in springflow. The actual reduction in springflow that may occur between now and the return to existing flow in the final phase of the rule is projected to be very gradual and remain significantly greater than the minimum flow regime most of the time. Based on projections of future water use, the maximum reduction in springflow is expected to be limited to about 4 percent of the 1995 flow condition, far less than allowed by the initial phases of the minimum flow regime rule. This is due to the gradual increase in water use and the presence of other MFLs adopted for nearby lakes that are expected to restrict water use more than the initial phase of the Blue Spring minimum flow regime. If, in fact, some small reduction in flow does occur, it will be temporary because the long-term historic average flow will need to be met in the final phase of the rule.

Did the District rely on expertise outside the agency to help develop and review the rule?

Yes. The District convened a working group to assist in the formulation of the minimum flow regime. The group included representatives from the following organizations:

• Florida Fish and Wildlife Conservation Commission (FWC)
• Florida Department of Environmental Protection (DEP)
• Blue Spring State Park, DEP
• St. Johns River Water Management District
• NewFields Companies, LLC

In addition, representatives from the U.S. Fish and Wildlife Service and Save the Manatee Club, Inc., participated in the working group, primarily by reviewing and commenting on draft recommendations.

Further, the District used seven additional outside experts to provide independent scientific peer review on the proposed rule. The area of expertise of these individuals included:

• Manatee physiology, ecology, and biology
• Geostatistical modeling and ISATIS software application
• Water resource values assessment
• Hydrology and hydraulics
• Freshwater snails
• Hydroecology
• Environmental fluids dynamic code modeling