Atlantic Multidecadal Oscillation and Minimum Flows and Levels

Dr. Marty Kelly, Manager of the District's Ecological Section, has produced an important report titled "Florida River Flows and Patterns and the Atlantic Multidicadal Oscillation" (the "Report").  The Report was peer reviewed by an independent panel of experts that stated:

"Overall, we find the arguments in the report persuasive, the methods sound, and the conclusions well founded.  We find no serious scientific flaws or technical errors in the work.  The results have profound implications for water management, especially the establishment of instream flows (Minimum Flows and Levels, abbreviated MFLs) and water allocation and, for our understanding of the hydrology and long-term ecosystem dynamics of Florida's river."

"In our opinion, this work represents one of the more important contributions to hydrologic science in Florida (and perhaps elsewhere) in the past several decades…"

The Report is divided into three sections.  It begins with a discussion of river flow patterns throughout Florida, showing a south to north difference in the timing or seasonality of flows.  It then discusses changes in stream flow due to differences in rainfall as influenced by the Atlantic Multidecadal oscillation (AM)) showing how this causes a significant multidecadal south to north difference in river flow volumes across Florida.  Finally, it discusses significant differences in flows for a select number of sites within the District with an emphasis on how climate and anthropogenic factors may have affected these river flows.  The report can be found at www.watermatters.org under the Documents and Publications link.

This work is now reflected in the District's establishment of Minimum Flows for rivers. 

Minimum Flows for the Alafia and Myakka

On December 1, 2005, the Governing Board approved Minimum Flows for the upper segment of the Myakka River, from Myakka City to SR 72, and the freshwater segment of the Alafia River at the USGS Lithia Gage.  As is described more fully under the middle Peace River Minimum Flows, below, the District proposes to establish Minimum Flows based on three blocks - seasonal low, medium and high flow periods.  Short-term and long-term compliance standards are also proposed for the Minimum Flows.

The methodology that was used to establish the proposed Minimum Flows was submitted to peer review.  The peer review panel found particular merit with, and endorsed strongly, several concepts that were incorporated in the Alafia and Myakka River MFLs.  These include:

1.         Identifying benchmark periods, based on different phases of the Atlantic Multidecadal Oscillation (AMO), for identifying the most protective minimum flows  

2.         Applying multiple, independent approaches to identify the most protective minimum flows in each seasonal block, including fish passage depth, wetted perimeter inflection points, habitat availability for several fish species, macroinvertebrate diversity and changes in the number of days of inundation of floodplain features.

 3.         Specifying minimum flows in terms of allowable percent flow reductions that vary by season and flow conditions.

Middle Peace River – Adoption of Minimum Flows

On October 25, 2005, the Governing Board approved Minimum Flows for the middle Peace River.  No petitions for hearing were filed.  The Minimum Flows will become effective in February 2006.  The middle Peace River extends from Zolfo to Arcadia.  The actual flows in the middle Peace River are meeting the minimum flow standards.  Water withdrawals now cannot interfere with the maintenance of the Minimum Flows.

Minimum Flows for the middle Peace River are seasonal and flow dependent.  Two standards are flow based and are applied continuously regardless of the season.  The first is a Minimum Low Flow threshold of 67 cfs at the Arcadia Gage.  The second is a Minimum High Flow threshold of 1,362 cfs at the Arcadia 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 (which runs from April 20 through June 25) and Block 2 (which runs from October 27 of one year to April 19 of the next) Minimum Flows are based on potential changes in habitat availability for fish species and macroinvertebrate diversity.  The Block 3 (which runs from June 26 to October 27) Minimum Flow is based on changes in the number of days of connection with floodplain features.

Water Shortage Rules, 40D-21, F.A.C., Approved by Governing Board

On October 25, 2005, the District's governing board approved amendments to Chapter 40D-21, F.A.C. that substantially rewrite the District's Water Shortage Plan required by Section 373.246, F.S., and incorporate the water shortage measures authorized by Section 373.175, F.S.  All persons and operations that are supplied water by a private well or a utility system are covered by the Water Shortage Plan.  The changes will be effective in February 2006.

The District's water shortage plan was first adopted in 1984.  Since that time the District has gained extensive experience in managing water shortages.  The proposed amendments reflect that experience and knowledge gained as a result of the droughts and other water shortage events that have occurred since 1984.

The proposed amendments include:

Part I includes updated definitions and new definitions.

Part II describes the District's overall program of monitoring conditions in anticipation of and during a Water Shortage.  Part II also identifies and quantifies the factors that the District will consider in declaring or rescinding a Water Shortage.  These indicators include regional rainfall, average stream flow, the Aquifer Resource Indicator, the CPC Predictions, the Palmer Drought index, the 6-month Standard Precipitation Index, and the Weekly U.S. Drought Monitor.  The rules include a method for expressing the severity of a Water Shortage in terms of four Water Shortage phases and procedures for implementing a Water Shortage declaration.  The four phases are Phase I, Moderate Water Shortage, Phase II Severe Water Shortage, Phase III Extreme Water Shortage, and Phase IV Critical Water Shortage.  Other factors have been modified to assure compliance with new requirements of the Florida Department of Environmental Protection set out in Chapter 62-40, Water Resource Implementation Rule, F.A.C. 

Part III establishes the procedures for declaring and implementing a Water Shortage Emergency when the provisions of Part II are not sufficient to protect the water resource and its users. 

Part IV describes how the District, in conjunction with local governmental entities and law enforcement officials, will enforce the provisions of a declared Water Shortage or Water Shortage Emergency.  The proposed rules include clarification of local enforcement and planning responsibilities regarding violations of the Water Shortage Plan and preparation for water shortage events. A new incentive, referred to as a "water shortage mitigation plan," is now included in the Plan.  Under the Plan, local water suppliers are given the option to submit a water shortage mitigation plan to the District for approval.  The plan is customize for the local water supplier’s system and may be implemented in lieu of selected provisions of the Water Shortage Plan.

Part V classifies each user according to the source of water supply, type of water use and method of withdrawal.  These classifications are utilized in conjunction with parts I, II, III and VI.  The use classifications include Indoor Uses, Essential Uses, Commercial and Industrial Uses, Agricultural Uses, Landscape Uses, Cemeteries, Golf Courses, Driving Ranges and Other Athletic Play Areas.

Part VI presents water use restrictions and other response mechanisms for each Water Shortage Phase and Water Use Class.  Various combinations of these response mechanisms may be used by the District to achieve the desired effect during any phase of a Water Shortage or a Water Shortage Emergency. Voluntary water use reduction goals of 5, 10 and 20% for Phases II, III and IV, are included to aid public notice efforts and to engage the public in necessary demand reduction.

The Governing Board may order extensive rewording of the Phases I and II measures and response mechanisms to manage the water shortage, especially Lawn and Landscape irrigation provisions.  The proposed rules add a fourth phase to address a Critical Water Shortage.  

The type of notice, method of delivery and the recipients of a notice of Water Shortage has been updated.  In addition, notice must be mailed to fire and rescue agencies in addition to the public, water use permittees and local governments to alert those agencies of water resource conditions so that they may better coordinated water use activities with the District.

The response mechanisms have been enhanced with science-based enhancements, such as: seasonal shifts in lawn watering days, use of property size to determine watering hours, and a revised establishment period for new plants.

The Water Use Permit “conservation credits” approach within the Southern Water Use Caution Area is an alternative to traditional restrictions for non-mulched crops and is included in the Phase II, III and IV response mechanisms.

A copy of the draft of proposed amendments and supplemental material are available from the District’s website www.watermatters.org.

Southern Water Use Caution Area Draft Rules for Minimum Flows and Levels and Recovery Strategy

The District is nearing completion of rule development for the SWUCA Minimum Flows and Levels and the regulatory portion of the recovery strategy that will address water resource issues related to salt water intrusion, the upper Peace River flows and Lake Wales Ridge lake levels.  The Board set December 9, 2005 as the deadline for comments on the October 3, 2005 draft rules.  The Board is targeting the February 2006 Board meeting for approval of the draft rules.  The current draft rules are on the District's website at www.swfwmd.state.fl.us/waterman/swuca/SWUCA.htm.