2009 SAC report on water for environmental flows

Senate Bill 3 (SB 3), passed by the Texas Legislature in 2007, directed the development of environmental flow recommendations through a new regulatory approach, using a local stakeholder process and the best available science, and culminating in Texas Commission on Environmental Quality (TCEQ) rulemaking. SB 3 directed the use of an environmental flow regime in developing flow standards from the environmental flow recommendations and defined a regime as a schedule of flow quantities that reflects seasonal and yearly fluctuations that typically would vary geographically and that are shown to be adequate to support a sound ecological environment and to maintain the productivity, extent, and persistence of key aquatic habitats. Initial flow recommendations by the local basin and bay expert science teams (BBEST) are to be made without regard to the need for the water for other uses. Although water availability may be an important consideration, at this stage it is not the primary driver of the analysis. Additionally, SB 3 clearly recognizes that in areas with little or no unappropriated water available to meet environmental flow needs, the Environmental Flows Advisory Group (EFAG), along with the Basin and Bay Area Stakeholder Committees and their respective BBEST, are to try to find innovative ways to provide water for environmental needs. The Science Advisory Committee (SAC) published guidance on using hydrologic data as a method to develop initial instream flow recommendations as part of SB 3 efforts (SAC 2009a). One of the approaches outlined is the Hydrology-Based Environmental Flow Regime (HEFR) methodology which uses hydrologic data to populate an initial flow regime matrix consisting of monthly/seasonal schedules for subsistence flows, base flows, high flow pulses, and overbank flows. The hydrology-based approach constitutes one piece of the multidisciplinary process envisioned by SB 3 for the identification of flows needed to maintain a sound ecological environment in Texas rivers and streams. Completion of the process requires input from other scientific disciplines including biology, geomorphology, and water quality to ensure that environmental flow recommendations are broad-based, use the best available scientific information, and are adequate to support all processes and functions that maintain a sound ecological environment. To facilitate the use of other disciplines to inform, confirm, or modify the hydrology-based initial flow regime matrix, the SAC set out to develop guidance documents related to the overlay of biologic, geomorphologic, and water quality information. SAC 2009b presents information regarding geomorphological, specifically sediment transport, considerations. An additional guidance document addressing water quality overlay issues is in preparation. This Biological Overlay document provides guidance on: 1) Assimilating biological information needed to develop a biological overlay within the context of SB 3 (Section 2), 2) Applying biological information to inform the geographic scope of instream flow recommendations (Section 3), 3) Addressing decision points required before and during hydrology-based modeling, (Section 4), 4) Applying a biological overlay for the purpose of refining and/or confirming preliminary hydrology-based instream flow recommendations (Section 5), and 5) Using the biological overlay document in a hydrology-based environmental flow determination (Section 6). Input from BBEST members through the Instream Biology Workgroup helped to inform the development of this document as a tool that the BBESTs can use to apply biological information in their deliberations. The document offers some background information, but more importantly is meant to be utilitarian and provide the essential steps the BBESTs can use to develop instream flow recommendations in the short time prescribed by SB 3

2009 SAC hydrologic methods of instream flow recommendations working draft

Environmental flows, which include flows in rivers and streams and freshwater inflows to bays and estuaries, have not been addressed uniformly in water development project planning and permitting in Texas. Senate Bill 3 (SB 3), passed by the Texas Legislature in 2007, set out a new regulatory approach to protect such flows through the use of environmental flow standards developed through a local stakeholder process culminating in Texas Commission on Environmental Quality (TCEQ) rulemaking. SB 3 directed the use of an environmental flow regime in developing flow standards and defined an environmental flow regime as a schedule of flow quantities that reflects seasonal and yearly fluctuations that typically would vary geographically, by specific location in a watershed, and that are shown to be adequate to support a sound ecological environment and to maintain the productivity, extent, and persistence of key aquatic habitats. This document provides an overview of how hydrologic data may be used in the identification of instream flow recommendations pursuant to the requirements of SB 3. As such, it describes one piece of the collaborative process envisioned by SB 3 for the identification of flows to maintain a sound ecological environment in rivers and streams.1 Other disciplines such as biology, geomorphology, and water quality, although not discussed directly in this report, also warrant specific attention to ensure that instream flow recommendations are based on the broadest set of information available. It is important to recognize that the provisions of SB 3 dealing with environmental flows are structured specifically to provide a mechanism for protecting certain levels of flow for environmental purposes while at the same time allowing for the use of surface water to meet other needs, including human water needs. The discussion in this document pertains only to the scientific aspects of establishing appropriate environmental flow requirements for river and streams and does not consider the needs of other users or uses for which surface water flows may be required. Section 2 of this document provides background information on relevant legislation, flow regime concepts, and hydrologic data. Section 3 highlights resources and methods that can be used to generate instream flow recommendations using hydrologic data. Section 4 introduces decisions that must be made when using hydrologic data to define flow recommendations.2 Clarifying examples are provided throughout this document to provide context to the reader. Such examples are solely intended to illustrate the types of factors that could be considered and should not be construed as recommendations. This document originally was prepared by the Texas Parks and Wildlife Department (TPWD) at the request of the SB 3 Science Advisory Committee (SAC), with comments from the Texas Water Development Board (TWDB) and TCEQ. Members of the SAC have reviewed, edited, and expanded the document and have provided recommendations regarding the application of the information and procedures presented in the document pursuant to the requirements of SB 3

2011 SAC use of hydrologic data in the development of instream flow recommendations for the environmental flows allocation process and the hydrology-based environmental flow regime (HEFR) methodology - third edition

Over the past two years, modifications and improvements have been made to the HEFR method. This third edition includes the most recent changes and additions to the HEFR code and its use. New or updated material in this edition includes: A new example covering the Nueces River below Uvalde siite. This example is more relevant to central and west Texas basins and BBESTs than the earlier example of the Neches River at Evadale. Enhanced statistics for intermittent streams that quantify duration, frequency, and seasonality of subsistence and zero flow events. The addition of a Q95 calculation option for subsistence flows. Enhanced regression diagnostics. An option to calculate flow statistics without zero flow days

2010 SAC lessons learned from initial SB3 BBEST activities

The BBEST and BBASC groups from the Trinity/San Jacinto/Galveston Bay and the Sabine/Neches/Sabine Lake basins have completed and submitted their final reports, and their recommendations are now before the TCEQ for rulemaking on environmental flow standards in these basins. The Science Advisory Committee (SAC) thought it appropriate to reflect and report on lessons learned from the experiences of these first two BBEST groups. It is our hope that these observations will be helpful to the next group of BBEST and BBASC members as they undertake their respective responsibilities under SB3

2009 SAC water quality overlay of hydrology-based instream flow recommendations working draft

SB 3 directed the development of environmental flow recommendations for Texas waters through a science-based determination and stakeholder process, followed by Texas Commission on Environmental Quality (TCEQ) rulemaking. Environmental flow regimes are defined as schedules of flow quantities that reflect seasonal and yearly fluctuations for specific areas of watersheds, support a sound ecological environment, and maintain the productivity, extent, and persistence of key aquatic habitats. The Science Advisory Committee (SAC) provides an overview of how hydrologic data might be used to develop hydrology-based flow regime recommendations (SAC 2009a) and describes one piece of the collaborative process envisioned by SB 3 for the identification of flows to maintain a sound ecological environment in rivers and streams. The document notes that other disciplines such as biology, geomorphology, and water quality also warrant specific attention to ensure that instream flow recommendations are based on the broadest set of information available. The approach taken by the SAC is to have these disciplines addressed as separate assessments or overlays on the hydrology-based analyses. Water quality is the focus of this overlay document. Numeric and narrative criteria developed by the state address matter carried in suspension and solution, such as dissolved and suspended solids, as well as nutrients, toxics, indicator bacteria, temperature, pH, dissolved oxygen, and other parameters. Under some circumstances all might play a role in the determination of an environmental flow regime. Changes in a flow regime can be expected to produce changes in water quality conditions. The challenge is to ensure that the recommended flow regime protects water quality, particularly during low or subsistence flow conditions, and also considers water quality needs during higher flow conditions. It is often assumed that under natural conditions, which may have existed prior to human impacts, the quality of the water supports the desired sound ecological environment. While this may be true it should be recognized that it may be impossible to return to the naturalized flow condition due to land use changes, point and nonpoint source discharges, water supply needs and operational constraints. In addition, ecological changes may have already occurred in response to altered land use patterns and flow regimes. It must also be recognized that natural conditions encompass a substantial range in all of the dimensions of water quality in response to hydrologic, seasonal and weather variations and include a full range of outcomes. The Water Quality Overlay provides an overview of Texas water quality programs along with the programs that collect and make water quality data available. It then discusses various aspects of the relationship between water quality and subsistence flows and water quality and base and higher flow conditions. The document includes a specific example of the relationship between flow and various water quality parameters and provides steps the BBESTs can take to consider water quality issues in their recommended flow regimes.These plans are developed through local stakeholder groups with funding and technical assistance from the TCEQ or the TSSWCB, and the U.S. Environmental Protection Agency

2010 SAC report on consideration of methods for evaluating interrelationships between recommended SB-3 environmental flow regimes and proposed water supply projects

The attached guidance document presents tools and methods which can be employed by BBASC groups, and/or their BBEST if deemed appropriate, and the TCEQ to evaluate to what degree a prescribed instream flow scenario (environmentl flow regime or standard) is satisfied based on some current or future infrastructure/water rights assumptions (Section 3 of the report), and analyze impacts of a proposed E-flow regime on a specific water supply project (Sections 4 and 5 of the report)

2009 SAC freshwater inflow regime methods

Environmental flows, which include flows in rivers and streams and freshwater inflows to bays and estuaries, have not been addressed uniformly in water development project planning and permitting in Texas. Senate Bill 3, passed by the Texas Legislature in 2007, set out a new regulatory approach to protect such flows through the use of environmental flow standards developed through Texas Commission on Environmental Quality (TCEQ) rulemaking. Senate Bill 3 directed the use of an environmental flow regime in developing flow standards and defined an environmental flow regime as a schedule of flow quantities that reflects seasonal and yearly fluctuations that typically would vary geographically, by specific location in a watershed, and that are shown to be adequate to support a sound ecological environment and to maintain the productivity, extent, and persistence of key aquatic habitats. Each Basin and Bay Expert Science Team (BBEST) is charged with developing recommendations for both an instream flow regime and for a complete freshwater inflow regime to protect a �sound ecological environment� and to maintain the productivity, extent, and persistence of key aquatic habitats in bays and estuaries. Instream flow regime requirements have been addressed previously (SAC, 2009a),1 by the Texas Environmental Flows Science Advisory Committee (SAC). The focus of this document is on bay and estuary inflows. This regime will have to be developed recognizing the inherent variability in weather and inflow conditions that have contributed to and sustained these productive estuarine ecosystems over time. Freshwater inflow serves a variety of important functions to coastal estuarine ecosystems by creating and preserving low-salinity nurseries, transporting sediments, nutrients, and organic matter downstream, and affecting estuarine species movements and reproductive timing (Longley 1994, Montagna et al. 2002; SAC, 2004). This document provides background information and discussion of various methods that can be used to develop freshwater inflow recommendations for Texas bays and estuaries. While a few germane references to the literature are made, this document is not intended to be a tutorial on the physics and ecology of estuaries, nor on the range of modeling techniques of potential application. Rather, it attempts to present a succinct summary of methods that are presently sufficiently developed and suitable for application to Texas estuaries, for consideration by the Basin and Bay Expert Science Teams (BBESTs). For detailed background information on estuaries and the coastal environment, the 2004 Science Advisory Committee (formed under Senate Bill 1639) report (SAC, 2004) and citations therein should be consulted. Emphasis here is placed upon delineating the basic approaches of available methods, identifying the necessary supporting data and analyses, and stating their strengths and weaknesses. Section 2 reviews briefly the guidance offered by previous state scientific advisory committees regarding what constitutes a �sound ecological environment� and how that might apply in the bay and estuary context, particularly with regard to flow regimes as noted in Senate Bill 3. Section 3 identifies various sources of available hydrologic, abundance, habitat, salinity and water quality data for Texas bays and estuaries and discusses existing tools that constitute the �State Methodology�, and how they have been used for evaluating these data in the context of establishing appropriate freshwater inflow needs. Various methods for using the available data to develop freshwater inflow recommendations are described in Section 4, with key decision points involved in selecting and applying the various inflow methodologies briefly highlighted along with each method�s strengths and weaknesses. Other considerations, including the role of nutrient and sediment delivery in sustaining the ecological environment of bays and estuaries and the issue of how instream flow recommendations might be integrated with freshwater inflow recommendations in a particular basin, are discussed in Section 5. Finally, SAC observations and recommendations regarding information presented in the document and how freshwater inflow recommendations for the bays and estuaries could be established within the scope and timeframe of Senate Bill 3 are summarized in Section 6. References cited in the text of the document are listed in Section 7, and a list of contributors is presented in Section 8

2009 SAC geographic scope of instream flow recommendations

The purpose of this paper is to address the geographic scope of environmental flow regime recommendations for the Senate Bill 3 (SB 3) process. As defined by SB 3, an environmental flow regime means a schedule of flow quantities that reflect seasonal and yearly fluctuations that typically would vary geographically, by specific locations in a watershed, and that are shown to be adequate to support a sound ecological environment and to maintain the productivity, extent, and persistence of key aquatic habitats in and along the affected water bodies and receiving coastal bay system. The question of geographic scope for the SB 3 process is a matter of recommending the number and spatial distribution of locations where flow regime recommendations will be developed. This document does not address implementation of flow recommendations. In contrast to the SB 3 process, environmental assessments of water rights applications are currently conducted on a case by case basis. Numerous sources are utilized to determine whether special conditions, including streamflow restrictions, are necessary to satisfy environmental concerns. If streamflow restrictions are recommended, an effort is made to tie the restrictions to a nearby active USGS gage. However, this is not always possible or practical. For a diversion or project on an ungaged stream, an effort is made to locate an active gage with at least 20 years of flow data in the same watershed or an adjacent watershed. In addition to proximity, factors such as stream characteristics, ecological characteristics, hydrological characteristics (e.g. whether the gage and project location are influenced by wastewater discharges or reservoir releases), and drainage area size may be taken into consideration in selection of an appropriate gage. Once a gage has been selected and a historical period of record determined, streamflow restrictions for the gaged location are calculated based on median flow values for each month of the year. The resulting monthly restrictions are then prorated to the project location using a drainage area ratio. If streamflow restrictions are placed in the permit, the permittee is responsible for developing a method or installing a reference device to measure the appropriate flow value. There are a number of issues that should be considered in determining the geographic scope of instream flow recommendations for the SB 3 process. For example, flow recommendation locations should consider, and be compatible with, the river segments identified by the Texas Instream Flow Program (TIFP) for Senate Bill 2 (SB 2) studies. In addition, biologic, hydrologic, and geomorphic information, water quality segments, basin management subdivisions and water availability could play a role in these location determinations. There are a broad range of aquatic ecosystems in Texas� rivers and the study methodology for instream flow recommendations may need to be customized for specific river systems (TCEQ et al., 2008). Thus for each river basin, the choices may be different. The document includes general information that could be used to segment a river basin for purposes of determining the number of flow recommendation locations that might be needed to characterize an environmental flow regime in a particular basin. Available information includes the spatial scale units adopted by the TIFP and other general information, such as hydrology, geomorphology, biology and water quality that are available for all river basins and should be considered in location determinations. The document also describes basin specific information that could be added to the general information, or used to enhance this information, using the Trinity River Basin as an example application. The summary outlines a general process for determining geographic scope