St. Marks River Rise Rule Development Workshop December 20, 2018 - - PowerPoint PPT Presentation

Rule Development Workshop December 20, 2018

Minimum Flows for the

• St. Marks River Rise

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What is an MFL?

Limit at which further withdrawals will cause significant harm to the water resources or ecology of the area.

Purpose:

To protect water resources and associated

• ecology. Provides information to support

water supply planning and water use permitting evaluations.

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Statutory Requirements s.373.042, F.S.

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Priority Waterbodies

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• St. Marks River Rise Study Area

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NORTHWEST FLORIDA WATER MANAGEMENT DISTRICT

• St. Marks River Rise

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NORTHWEST FLORIDA WATER MANAGEMENT DISTRICT

237 cfs 689 cfs Spring Flow 452 cfs

NORTHWEST FLORIDA WATER MANAGEMENT DISTRICT

Enhanced Data Collection

• More than 60 sites
• Hydrology

– Aquifer levels – River stage and flow – Spring flow

• Water Quality

– Salinity – Temperature

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Enhanced Data Collection

• Elevation Data

– River channel – Floodplain

• Ecological Data

– Vegetation Communities – Instream Habitat

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Elevation Data

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Baseline Time Series

• No measurable impacts from withdrawals
• Baseline is period of record:

– (October 1, 1956 – November 27, 2017)

8 250 500 750 1000 1250 1500 1750 2000 1/1/1956 1/1/1961 1/1/1966 1/1/1971 1/1/1976 1/1/1981 1/1/1986 1/1/1991 1/1/1996 1/1/2001 1/1/2006 1/1/2011 1/1/2016 Flow (cfs) Date

• St. Marks Rise Spring Discharge

500 1,000 1,500 2,000 0% 25% 50% 75% 100% River Rise spring Discharge (cfs) Exceedance Frequency

Baseline Spring Flow (cfs)

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Florida Administrative Code (F.A.C.) Requirements

Chapter 62-40.473(1), F.A.C.

• 1. Natural seasonal fluctuations in water flows or levels,
• 2. Non-consumptive uses, and
• 3. Environmental values associated with coastal, estuarine,

riverine, spring, aquatic, and wetland ecology, including:

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• 1. Natural seasonal fluctuations in water flows or levels,
• 2. Non-consumptive uses, and
• 3. Environmental values associated with coastal, estuarine,

riverine, spring, aquatic, and wetland ecology, including:

(a) Recreation in and on the water (b) Fish and wildlife habitats and the passage of fish (c) Estuarine resources (d) Transfer of detrital material (e) Maintenance of freshwater storage and supply (f) Aesthetic and scenic attributes (g) Filtration and absorption of nutrients and other pollutants; (h) Sediment loads (i) Water quality (j) Navigation

“Water Resource Values” (WRVs)

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Water Resource Value Metrics

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• Recreation

– Safe Power Boat Passage (2 ft x 30 ft) – Safe Canoe/Kayak Passage (1.5 ft Depth)

• Fish and Wildlife Habitats

– Fish Passage (0.6 ft Depth) – Manatee Passage (3.8 ft x 3.8 ft) – Floodplain Wetland Inundation – Instream Woody Habitat Inundation

• Estuarine Resources

– Low Salinity Habitats (Volume, Surface Area, Shoreline Length)

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Hydrology Models

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• Models used to quantify

changes in spring flow and WRV metrics

– River hydraulic model – spring flow effects on river stage and flow – Estuarine Model – spring flow effects on salinity

• Significant harm threshold:

15% reduction in metric

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Results

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Spring Flow Range Limiting Metrics Allowable Flow Reduction (cfs) Low (<400 cfs) Dead Woody Debris Habitat 67 Medium (400 - 600 cfs) Live Roots Habitat 42 Hardwood Hammock 33 Cypress Hardwood Swamp 34 Boat Passage 40 Manatee Passage 50 High (>600 cfs) Ironwood Hammock 50 Ash Swamp 101

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Results

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NORTHWEST FLORIDA WATER MANAGEMENT DISTRICT

Minimum Flow

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• Most limiting metric protective of full range of flows
• Hardwood Hammock inundation: 33 cfs reduction when

spring flow is 447 cfs

• Applied to long-term average daily spring flow (452 cfs)

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Long-term Daily Average Minimum Spring Flow (cfs) Allowable Flow Reduction (cfs) Percent Allowable Flow Reduction (%) 419 33 7.3%

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Peer Review

• Independent experts in

Hydrology, Ecology, and Environmental Flows

• Scope of Peer Review

– Supporting Data and Information – Technical assumptions – Procedures and Analyses

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Peer Review Comments

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“…The Panel supports and endorses the District’s approach to determining the minimum flow and final selection of the minimum flow for the St. Marks River Rise and Spring Run.”

Key Revisions

• Improved riverine model and provided additional documentation
• Removed boat launching metric
• Reduced boat passage depth

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Evaluation of Need for Prevention

• r Recovery Strategy

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• St. Marks River Rise currently

meets the proposed minimum flow

– No recovery strategy needed

• Effects of projected withdrawals

through 2040 do not exceed available spring flow of 33 cfs

– No prevention strategy needed

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MFL Assessment

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• MFL status anticipated to be assessed every 5 years
• Difference between 30-year average flow and the baseline flow

compared to the available water of 33 cfs

• MFL anticipated to be reevaluated in 10 years

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Rulemaking Schedule

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November 1, 2018 Notice of Rule Development was published December 20, 2018 Rule Development public workshop followed by 14 day public comment period February 28, 2019 Anticipated Board review and approval of draft rule language April 1, 2019 Deadline to publish Notice of Proposed Rule End of May, Anticipated effective date of Proposed Rule beginning of June, 2019

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Thank You

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