To amend Rule 40D-8.041, F.A.C. to establish a minimum flow for the Weeki Wachee River System pursuant to Section 373.042, Florida Statutes. For purposes of this rule, the Weeki Wachee System includes the watercourse from the Weeki Wachee Spring to ...

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 a minimum flow for the Weeki Wachee River System pursuant to Section 373.042, Florida Statutes. For purposes of this rule, the Weeki Wachee System includes the watercourse from the Weeki Wachee Spring to the Gulf of Mexico including Twin Dees Spring, Mud River (including Salt Spring) from Mud Spring to the confluence with the Weeki Wachee River and Jenkins Springs and associated spring run.
SUMMARY: Establishment of a minimum flow for the Weeki Wachee River System and identification of five and ten year mean and median annual averages for use in periodic evaluation of maintenance of the minimum flow.
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, 373.042, 373.0421 FS.
IF REQUESTED WITHIN 21 DAYS OF THE DATE OF THIS NOTICE, A HEARING WILL BE SCHEDULED AND ANNOUNCED IN FAW.
THE PERSON TO BE CONTACTED REGARDING THE PROPOSED RULE IS: Charlotte Edwards, Sr. Administrative Assistant, 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) through (10) No change.

(11) Minimum Flows for Weeki Wachee River System located within Hernando County, Florida.

(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 Weeki Wachee River System are met. The Minimum Flow for the Weeki Wachee River System is intended to maintain 90% of the natural flow of the Weeki Wachee River System. For purposes of this rule, the Weeki Wachee River System includes the watercourse from the Weeki Wachee Spring to the Gulf of Mexico including Twin Dees Spring, Mud River (including Salt Spring) from Mud Spring to the confluence with the Weeki Wachee River and Jenkins Springs and associated spring run.

(b) The Minimum Flow for the Weeki Wachee River System is 90% of its natural flow. This Minimum Flow is inclusive of spring flow, the freshwater and the estuarine portion of the Weeki Wachee River.

(c) The Minimum Flow applies upstream of the USGS Gage No. 02310525 at Weeki Wachee River near Brooksville (“Brooksville Gage”) to the Weeki Wachee Spring vent and downstream of the Brooksville Gage to the Gulf of Mexico. The Minimum Flow shall be met continuously and is evaluated on a daily basis.

(d) Because climatic variation can influence river flow regimes, five and ten year mean and median standards have been developed and are set forth in Table 8-18 (“Means and Medians”) as a tool to assess whether compliance with the Minimum Flow maintains 90% of the natural flow of the Weeki Wachee River System. The Means and Medians are hydrologic statistics that represent flows expected to occur during long-term periods when the Minimum Flows are being met. The Means and Medians are generated from flow records that are representative of a period devoid of significant anthropogenic impacts. The District will periodically evaluate the Means and Medians. These are evaluated as the mean and medians of annual means and medians, evaluated from January 1 through December 31 of each year. The evaluation is for both the flow at the Brooksville Gage and at the USGS Weeki Wachee Well No. 283201082315601. The flow at the Brooksville Gage is evaluated directly against Table 8-18. The well data is converted to flow with the relation Q (cfs) = 47.487 + 12.38 (well level) (ft) and then evaluated against Table 8-18. The Means and Medians were developed using the Minimum Flow and the presumed historic flow records. Therefore, it is expected that the Means and Medians will be met if compliance with the Minimum Flow is maintained. However, since future structural alterations could potentially affect surface water or groundwater flow characteristics within the watershed and additional information pertaining to Minimum Flows development may become available, the District is committed to periodic review and revision of the Minimum Flows, as necessary.

Table 8-18 Five and Ten Year Means and Medians for the Weeki Wachee River System
Critierion	Flow (cfs)
Minimum 10 Year Moving Average (Based On Annual Average Flows)	141
Minimum 10 Year Moving Average (Based On Annual Median Flows)	131
Minimum 5 Year Moving Average (Based On Annual Average Flows)	136
Minimum 5 Year Moving Average (Based On Annual Median Flows)	128

 

(e) Water Use Permits issued after [effective date of rule] that authorize surface water withdrawals from, or ground water withdrawals that impact Mud Spring, Salt Spring or Jenkins Spring, shall gauge the flow of the applicable spring and report the flow to the District as provided in the Water Use Permit.

Specific Authority 373.044, 373.113, 373.171 FS. Law Implemented 373.036, 373.0361, 373.042, 373.0421 FS. History–Readopted 10-5-74, Amended 12-31-74, Formerly 16J-0.15, 40D-1.601, Amended 10-1-84, 8-7-00, 2-6-06, 4-6-06, 1-1-07, 11-25-07, 2-18-08, 3-2-08, 5-12-08, ________.

NAME OF PERSON ORIGINATING PROPOSED RULE: Michael G. Heyl, Chief Environmental Scientist, Resource Projects Department, 7601 Highway 301 N, Tampa, Florida 33637, [phone], extension 2211
NAME OF AGENCY HEAD WHO APPROVED THE PROPOSED RULE: Southwest Florida Water Management District Governing Board
DATE PROPOSED RULE APPROVED BY AGENCY HEAD: December 16, 2008
DATE NOTICE OF PROPOSED RULE DEVELOPMENT PUBLISHED IN FAW: December 31, 2008