To amend Rule 40D-8.041, F.A.C., to establish minimum flows and levels for the freshwater segment of the Alafia River pursuant to Section 373.042, Florida Statutes (F.S.).

 

WATER MANAGEMENT DISTRICTS

Southwest Florida Water Management District

RULE NO.: RULE TITLE:

40D-8.041 Minimum Flows

PURPOSE AND EFFECT: To amend Rule 40D-8.041, F.A.C., to establish minimum flows and levels for the freshwater segment of the Alafia River pursuant to Section 373.042, Florida Statutes (F.S.).

SUMMARY: The District has identified seasonal low, medium and high flow periods for the Alafia River. Short-term minimum flow compliance standards were developed for each of these periods using a “building block” approach. Two standards are flow-based and applied continuously regardless of season. The first is a Minimum Low Flow threshold of 59 cubic feet per second (cfs) at the Lithia Gage. The second is a Minimum High Flow threshold of 375 cfs at the Lithia Gage. The Minimum Low Flow for the river during the low flow period (April 20 through June 24) is based on fish passage depth and wetted perimeter inflection points. For the high flow period of the year (which runs from June 25 to October 27), a Minimum High Flow of 374 cfs is established. For the medium flow period (October 28 to April 19) it was determined that inundation of woody habitat would define the Minimum Flow. Using these limiting factors, the Minimum Medium Flow is the flow minus 19 percent at the Lithia Gage site, with the exception that the flows cannot go below 59 cfs at the Lithia Gage site and that minimum flows above 374 cfs need to be limited to an 8 percent reduction of the flows over 374 cfs. Five and ten year means and medians are proposed as long-term compliance standards.

SUMMARY OF STATEMENT OF ESTIMATED REGULATORY COSTS: No Statement of Estimated Regulatory Cost was prepared.

Any person who wishes to provide information regarding a statement of estimated regulatory costs, or provide a proposal for a lower cost regulatory alternative must do so in writing within 21 days of this notice.

SPECIFIC AUTHORITY: 373.044, 373.113, 373.171 FS.

LAW IMPLEMENTED: 373.036, 373.0361, 373.0395, 373.042, 373.0421 FS.

IF REQUESTED WITHIN 21 DAYS OF THE DATE OF THIS NOTICE, A HEARING WILL BE SCHEDULED AND ANNOUNCED IN THE FAW.

THE PERSON TO BE CONTACTED REGARDING THE PROPOSED RULE IS: Karen A. Lloyd, Assistant General Counsel, Office of General Counsel, 2379 Broad Street, Brooksville, FL 34604-6899, [phone], extension 4651

 

THE FULL TEXT OF THE PROPOSED RULE IS:

 

40D-8.041 Minimum Flows.

(1) Minimum Flows for the Lower Hillsborough River.

(1) through (2) renumbered (a) through (b) No change.

(2)(3) No change.

(3) Minimum Flows for Alafia River .

(a) The Minimum Flows are to ensure that the minimum hydrologic requirements of the water resources or ecology of the natural systems associated with the river are met.

(b) Minimum Flows for the Alafia River at the USGS Alafia River at Lithia Gage USGS # 02301500 (“Lithia Gage”) are set forth in Table 8-8 below. The long-term compliance standards set forth in Table 8-9 are established based on the application of the Minimum Flows to the lowest anticipated natural flow conditions. Minimum Flows for the Alafia River are both seasonal and flow dependent. Two standards are flow-based and applied continuously regardless of season. The first is a Minimum Low Flow threshold of 59 cfs at the Lithia Gage. The second is a Minimum High Flow threshold of 375 cfs at the Lithia Gage. The Minimum High Flow is based on changes in the number of days of inundation of floodplain features. There are also three seasonally dependent or Block specific Minimum Flows. The Block 1 and Block 2 Minimum Flows are based on potential changes in habitat availability for fish species and macroinvertebrate diversity. The Block 3 Minimum Flow is based on changes in the number of days of connection with floodplain features.

 

Table 8-8 Minimum Flow for Alafia River at USGS Alafia River at Lithia Gage
Period	Effective Dates	Where Flow on Previous Day Equals:	Minimum Flow Is
Annually	January 1 to December 31	59 cfs 59 cfs and 374 cfs 374 cfs	59 cfs Seasonally dependent – see Blocks below   Previous day flow minus 8%
Block 1	April 20 to June 25	57 cfs 57 cfs and 66 cfs 66 cfs and 374 cfs 374 cfs	59 cfs 67 cfs previous day flow minus 10% previous day flow minus 8%
Block 2	October 27 to April 19	59 cfs 59 cfs and 69 cfs 69 cfs and 374 cfs 374 cfs	59 cfs 67 cfs previous day flow minus 15% previous day flow minus 8%
Block 3	June 26 to October 26	59 cfs 59 cfs and 64 cfs 64 cfs and 374 cfs 374 cfs	59 cfs 67 cfs previous day flow minus 13% previous day flow minus 8%

 

(c) Compliance – The Minimum Flows are met when the flows in Table 8-9 are achieved.

 

Table 8-9 Compliance Standards for Alafia River at Lithia Gage
Minimum Flow	Hydrologic Statistic	Flow (cfs)
Annual Flow	10-Year Mean 10-Year Median 5-Year Mean 5-Year Median	192 101 163 86
Block 1	10-Year Mean 10-Year Median 5-Year Mean 5-Year Median	85 35 53 27
Block 2	10-Year Mean 10-Year Median 5-Year Mean 5-Year Median	137 82 110 66
Block 3	10-Year Mean 10-Year Median 5-Year Mean 5-Year Median	318 179 276 163

 

Specific Authority 373.044, 373.113, 373.171 FS. Law Implemented 373.036, 373.0361, 373.0395, 373.042, 373.0421 FS. History–Readopted 10-5-74, Amended 12-31-74, Formerly 16J-0.15, 40D-1.601, F.A.C., Amended 10-1-84, 8-7-00, _________.

 

NAME OF PERSON ORIGINATING PROPOSED RULE: Marty Kelly, Manager, Ecologic Evaluation, Resource Conservation and Development, 2379 Broad Street, Brooksville, FL 34604-6899, [phone], extension 4235

NAME OF SUPERVISOR OR PERSON WHO APPROVED THE PROPOSED RULE: Governing Board of the Southwest Florida Water Management District

DATE PROPOSED RULE APPROVED BY AGENCY HEAD: November 20, 2005

DATE NOTICE OF PROPOSED RULE DEVELOPMENT PUBLISHED IN FAW: October 30, 2005