The purpose of this rulemaking is to establish minimum flows pursuant to Section 373.042, F.S., for the Little Manatee River, located in Hillsborough and Manatee Counties. The effect of the rule is to support the District’s ....

 

WATER MANAGEMENT DISTRICTS

Southwest Florida Water Management District

RULE NO.:RULE TITLE:

40D-8.041Minimum Flows

PURPOSE AND EFFECT: The purpose of this rulemaking is to establish minimum flows pursuant to Section 373.042, F.S., for the Little Manatee River, located in Hillsborough and Manatee Counties. The effect of the rule is to support the District’s water supply planning, water use permitting, and environmental resource permitting programs.

SUMMARY: Section 373.042, F.S., requires the District to establish minimum flows and levels for water bodies located within the District’s boundaries. This rulemaking is necessary to establish minimum flows for the Little Manatee River. The establishment and periodic evaluation of minimum flows is required by statute to ensure that the minimum hydrologic requirements of the water resources and ecology of the river and surrounding area are maintained. The minimum flows for the Little Manatee River are being developed using previously peer-reviewed, Governing Board adopted methods.

SUMMARY OF STATEMENT OF ESTIMATED REGULATORY COSTS AND LEGISLATIVE RATIFICATION:

The Agency has determined that this will not have an adverse impact on small business or likely increase directly or indirectly regulatory costs in excess of $200,000 in the aggregate within one year after the implementation of the rule. A SERC has not been prepared by the Agency.

The Agency has determined that the proposed rule is not expected to require legislative ratification based on the statement of estimated regulatory costs or if no SERC is required, the information expressly relied upon and described herein: The District conducted an economic review of the revisions to the rule and determined that the impact or regulatory cost, if any, of the revisions will not exceed any one of the economic analysis criteria in a SERC as set forth in Section 120.541(2)(a), F.S. The proposed minimum flows are unlikely to constitute an additional significant regulatory constraint on groundwater or surface water withdrawals in the area due to existing resource conditions and regulatory constraints in the area.

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.

RULEMAKING AUTHORITY: 373.044, 373.113, 373.171, F.S.

LAW IMPLEMENTED: 373.036, 373.042, 373.0421, F.S.

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

THE PERSON TO BE CONTACTED REGARDING THE PROPOSED RULE IS: Kym Holzwart, Lead Ecologist, at [phone], ext. 4295, or [e-mail].

 

THE FULL TEXT OF THE PROPOSED RULE IS:

 

40D-8.041 Minimum Flows.

(1) through (23) No change.

(24) Minimum Flows for the Upper Little Manatee River.

(a) For purposes of this rule, the Upper Little Manatee River in Hillsborough County, FL and Manatee County, FL includes the watercourse from its headwaters to the Environmental Protection Commission of Hillsborough County Water Quality Monitoring Station No. 1616 located at 82.40557 W, 27.66662 N, and tributaries to the watercourse.

(b) Minimum Flows for the Upper Little Manatee River are based on the daily average flow at the United States Geological Survey (USGS) Little Manatee River at US 301 near Wimauma, FL Gage No. 02300500, adjusted for withdrawals, for the period of record from April 1, 1939, through December 31, 2021, as set forth in Table 8-28.

Table 8-28 Minimum Flow for the Upper Little Manatee River Based on the Flows from the USGS Little Manatee River at US 301 near Wimauma, FL Gage No. 02300500 Adjusted for Upstream Withdrawals
If Adjusted Flow in cubic feet per second (cfs) on the previous Day is:	Minimum Flow is:
≤ 29 cfs	Flow on the previous day
> 29 cfs and ≤ 96 cfs	29 cfs or 88% of flow on the previous day, whichever is greater
> 96 cfs and ≤ 224 cfs	85 cfs or 87% of flow on the previous day, whichever is greater
> 224 cfs	90% of flow on the previous day

(c) Status assessments of the Minimum Flows for the Upper Little Manatee River will be completed to determine whether the flow is below or projected to fall below the Minimum Flows. Each status assessment is independent from and not a determination of water use permit compliance or environmental resource permit compliance. Permit compliance is a regulatory function that is not within the scope of this subsection. As part of each status assessment, the District will use the following approach:

1. The District will evaluate the Minimum Flow annually to determine the extent to which the flow of the Upper Little Manatee River has been reduced due to withdrawals as of the date of each status assessment at Gage No. 02300500. The annual evaluation will be completed through a review of:

(a) Flow data;

(b) Water withdrawals;

(c) Aquifer water levels;

(d) Rainfall data; and

(e) Hydrologic modeling.

2. The District will also evaluate the Minimum Flows every five years as part of the regional water supply planning process. This evaluation will include the use of hydrologic modeling.

3. If the Minimum Flows are being met based on the annual evaluation or the evaluation performed as a part of the regional water supply planning process, then no further actions are required beyond continued monitoring.

(25) Minimum Flows for the Lower Little Manatee River.

(a) For purposes of this rule, the Lower Little Manatee River in Hillsborough County, FL includes the watercourse from the Hillsborough County Environmental Protection Commission Water Quality Monitoring Station No. 1616 located at 82.40557 W, 27.66662 N, to Tampa Bay, and tributaries to the watercourse.

(b) Minimum Flows for the Lower Little Manatee River are based on the daily average flow at the United States Geological Survey (USGS) Little Manatee River at US 301 near Wimauma, FL Gage No. 02300500, adjusted for withdrawals, for the period of record from April 1, 1939, through December 31, 2021, as set forth in Table 8-29.

Table 8-29 Minimum Flow for the Lower Little Manatee River Based on the Flows from the USGS Little Manatee River at US 301 near Wimauma, FL Gage No. 02300500 Adjusted for Upstream Withdrawals
If Adjusted Flow in cubic feet per second (cfs) on the previous Day is:	Minimum Flow is:
≤ 29 cfs	Flow on the previous day
> 29 cfs and ≤ 96 cfs	29 cfs or 87% of flow on the previous day, whichever is greater
> 96 cfs	84 cfs or 68% of flow on the previous day, whichever is greater

(c) Status assessments of the Minimum Flows for the Lower Little Manatee River will be completed to determine whether the flow is below or projected to fall below the Minimum Flows. Each status assessment is independent from and not a determination of water use permit compliance or environmental resource permit compliance. Permit compliance is a regulatory function that is not within the scope of this subsection. As part of each status assessment, the District will use the following approach:

1. The District will evaluate the Minimum Flow annually to determine the extent to which the flow of the Lower Little Manatee River has been reduced due to withdrawals as of the date of each status assessment at Gage No. 02300500. The annual evaluation will be completed through a review of:

(a) Flow data;

(b) Water withdrawals;

(c) Aquifer water levels;

(d) Rainfall data; and

(e) Hydrologic modeling.

2. The District will also evaluate the Minimum Flows every five years as part of the regional water supply planning process. This evaluation will include the use of hydrologic modeling.

3. If the Minimum Flows are being met based on the annual evaluation or the evaluation performed as a part of the regional water supply planning process, then no further actions are required beyond continued monitoring.

Rulemaking Authority 373.044, 373.113, 373.171 FS. Law Implemented 373.036, 373.042, 373.0421 FS. History–New 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, 5-10-09, 3-23-10, 3-28-10, 7-12-10, 8-2-10 (8), 8-2-10 (15), 10-16-12, 3-20-13(16), 3-20-13(17), 6-20-16, 3-15-18, 6-19-18, 4-15-20, 8-9-20, 4-12-21, 4-7-22, ___.

 

NAME OF PERSON ORIGINATING PROPOSED RULE: Southwest Florida Water Management District

NAME OF AGENCY HEAD WHO APPROVED THE PROPOSED RULE: Southwest Florida Water Management District Governing Board

DATE PROPOSED RULE APPROVED BY AGENCY HEAD: December 12, 2023

DATE NOTICE OF PROPOSED RULE DEVELOPMENT PUBLISHED IN FAR: January 8, 2024