Instream Flow Studies of the Upper Middle Brazos River, Palo Pinto, Parker and Hood Counties

PROPOSAL: Instream Flow Studies of the Upper Middle Brazos River, Palo Pinto, Parker and Hood Counties, Texas

J. F. Trungale

Engineering & Science

Instream Flow Studies of the Upper Middle Brazos River, Palo Pinto, Parker and Hood Counties, Texas

A Proposal to the Friends of the Brazos River by

Joseph F. Trungale P.E.

J. F. Trungale Engineering & Science

August 2005

Introduction

The objective of the research described in this proposal is to determine instream flow needs of the Brazos River between Lake Granbury and Lake Whitney. This river is heavily regulated by releases from upstream reservoirs and as such has been significantly modified from its natural conditions. These flow modifications have had serious impacts on the ecological health of the river and the fish and wildlife that that are sustained by it. The river also supports economically important recreational uses which are affected by flow management. The results of this research will provide useful information for developing a balanced approach to the management of water resources in the Brazos basin. The proposal describes four approaches to be used to determine flow targets, including desktop analysis, recreational, ecological and comprehensive instream flow studies. These studies will be undertaken independently but will also be considered in relation to each other. The first study, the desktop analysis, can be initiated immediately. All of the data necessary to undertake this study is currently available. This is the most straightforward and lest expensive study, as such the time and cost estimates associated with it are the most certain. Once this study is underway, the level of effort necessary for the other studies can be better defined. The levels of effort estimated associated with the other studies should be considered preliminary and could potentially require 50% greater or less effort.

Significance of the Study

The Brazos River Authority (BRA) exists to develop, manage and protect the water resources of the Brazos River Basin to meet the needs of Texas. On June 25, 2004, the BRA made an application to the Texas Commission on Water Quality (TCEQ) for approximately 1 million acre feet of water (421,000 of which would be firm and 660,000 would be available on an interruptible basis). This “Systems Operation Permit” would amend their current requirements to allow for more operational flexibility of existing resources, the collection of as yet unrealized wastewater return flows, or reuse, and the use of the bed and bank of the Brazos River for the conveyance of water transferred into the basin. It is a massive permit, probably unprecedented in Texas and would shift much of the responsibility for managing the water resource of the basin from the TCEQ to the BRA. Many of the details as to how the BRA would implement this permit are not included in the permit application, deferring instead to a water management plan to be developed after the permit has been granted.

Flows for the protection of instream economic and environmental benefits are an important component of river basin management. Many methods have been developed for the determination of ecological flow requirements ranging from desktop analysis, cross sectional analysis coupled with habitat preference curves, complex hydrodynamic- habitat modeling and comprehensive studies including a wide diversity of technical expertise and stakeholder involvement. It is recognized that rivers require a range of flows of certain magnitudes, frequencies, durations, timing and rates of change in order to address the issues of hydrology, biology, geomorphology, connectivity and water quality. Furthermore, because the Brazos River experiences a wide range of flow conditions , flow studies need to consider the inter- and intra- annual variation in flows to address flow needs during wet, normal and dry conditions. The studies also need to consider the important sociological and recreational benefits that rivers provide. Water rights in Texas are typically granted in perpetuity. Thus, it is imperative to act quickly to determine the instream flow needs of the Brazos River before new water development proposals add to the current operations to negatively impact on the river basin. If expedited, flow needs will be assessed before the water has been permitted away and proposed water development plan can be developed to adequately address these needs The studies described in this proposal will create a orderly approach to developing answers to the questions that can be addressed immediately and will provide the groundwork to build on these findings as the science of instream flow studies evolves.

Studies

Introduction

The proposal includes four study designs. The four approaches range from the most straightforward and least time consuming to the most comprehensive and complex. They may be undertaken independently though there would be clear advantages to thinking pro-actively about how the results from one might be useful to the others and thus maximize resources.

The first study uses water availability and reservoir operations models to evaluate water management alternatives and help design implementation plans. The first phase of this study is to evaluate the BRA systems operation permit and develop measures to evaluate the ecological impact of implementing this project. The second phase would develop alternatives and an implementation plan and evaluate this plan using the measures developed in the first phase. Future studies described below could be evaluated based on these measures.

The second study design is a recreational flows study. The historical, social and recreational importance of this river segment has been well documented, most notably in John Graves’s classic novel Goodbye to a River. This stretch of the Brazos River offers one of the few great natural recreational opportunities in close proximity to the Dallas-Ft. Worth metroplex. Unfortunately, operations of Lake Granbury have serious decreased flows in this segment making it difficult, if not impossible, and certainly less enjoyable, to canoe the river. This study will determine magnitude and timing of flows necessary to enjoyably paddle this segment of the river and the schedule of releases necessary to provide these flows. A survey of expert users will be conducted to determine minimal and optimal flow levels and cross sectional measurements of velocity and depth will be made to validate the survey results.

The third study design is an ecological flow study. It would address the major riverine flow component needs (hydrology, biology, geomorphology, connectivity and water quality) but would rely heavily on available data and limited field studies. Low flow minimums would largely be determined by water quality requirements. Normal flows would be based on habitat needs of important sports fisheries. High pulse flow requirements will be estimated based on overbanking stage and sediment transport literature. An instream flow recommendation will be developed for the entire range of flows and will identify areas of uncertainty to help prioritize future studies.

The fourth study design will be a more comprehensive instream flow study. The models for this study are provided by the Texas Instream Flow Program and the Nature Conservancy’s Sustainable River Program. These are multi-year, multi-disciplinary studies that would likely require significant outside sponsorship. The purpose of including this study design in this proposal is to illustrate the missing pieces from the more limited studies, described previously, and to identify areas where information from these studies could be collected that might be use of in this more comprehensive study.

Study 1: Desktop Flow Study - Water Availability and Reservoir Operations Alternatives Analysis and Implementation

Objectives

The objectives of this study are to develop water management alternatives to protect instream and recreational water uses and evaluate their impacts. The study will have two parts. The first part will examine and evaluate the natural, current and proposed (BRA systems operation) water conditions and subject them to a set of environmental flow metrics. The second part will develop a daily reservoir simulation model and test alternatives that could lead to improved environmental and recreational flow conditions as well as evaluate their effects on lake levels and water availability.

This study will also help to define the rage of alternatives available to protect the instream uses of the Brazos River, identify the major gaps in data or understanding about the river and define the level of certainty required from the other studies.

Methods

1. Water Availability Model (WAM) will be analyzed to explain how the systems operation permit will effect instream flows and identify key concerns. (40 hours)
2. Daily flow hydrographs for natural, current and proposed conditions will be developed. (24 hours)
3. Reservoir operations model will be developed using WAM model outputs for Lake Granbury; Operational alternatives will be explored and a feasibility analysis will be conducted. The development of this model will require discussions with reservoir operators to fully understand the operational constraints. (40 hours)
4. Impacts analysis will be performed. This analysis will include various performance measures including frequency of meeting the state’s default flow targets (Lyons), appropriate Indicators of Hydrologic Alteration (IHA) and a review of the current understand of flow needs for the Brazos. The analysis will be performed on naturalized, current and proposed flow conditions. Alternatives and impacts of meeting flow targets developed in studies 2-4 would be subjected to the same metrics and would include analysis of the impacts of meeting recreational and environmental flow needs on lake levels and water availability. (40 hours)

Funding Request and Justification

This study will require approximately 1 month of office work. The WAM model has been obtained and there are existing reservoir operations models currently available that can be applied to Lake Granbury. The most uncertain aspects are the level of cooperation from reservoir operators in describing their management procedures (Step 2) and the availability of existing information regarding instream flow needs (Step 4). The findings of this study will be usedto define the subsequent efforts.

Study 2: Recreational Flow Study

Objectives

The objectives of the Recreational Flow Study are to determine the minimum and optimal flow levels to enjoyably canoe the stretch of the Brazos River between Granbury and Whitney.

Methods

The approach of this study will be to conduct surveys of recreational users to determine flows necessary to provide minimal and optimal conditions. These surveys will be validated by cross sectional surveys at key locations. Finally, flow requirements in the study reach will be used to make recommendations for the timing and magnitude of reservoir releases. The study will be conducted in the following steps:

1. Determine Recreational Flow Requirements - Recreational suitability criteria will be developed based on a survey of experiences users. This process will produce a relationship between recreational suitability and flow. (need to coordinate this with someone with expertise in surveys possibly NPS ~ 2 weeks)
2. Reconnaissance trip. The study team will conduct a reconnaissance trip to identify critical segments. These segments will include stretches where it may be necessary to drag a canoe at low flow and areas that may shift between rapid, riffle, run and pool habitats at different flow levels. At this time 5-10 sites will be selected as primary study sites. (5 days)
3. Measure stage and discharge. Stage and discharge will be measured at critical sites and at high, medium and low flows. Semi-permanent benchmarks will be installed at each site. Water surface elevations will be measured with auto-levels. Velocities will be measured and discharge calculated using standard USGS techniques. This effort will require 2 people for 1-2 days (depending on how many sites are identified) per flow rate. It will also require the rental of scientific equipment, including an auto-level, and a Price AA or Acoustic Velocity meter. This effort will produce stage discharge curves at each of the select sites for the range of flow under consideration. (14 days plus rental of scientific equipment)
4. Validate Recreational Flow Requirements – Computer models of estimating velocity and depth will be used to validate the flow estimates derived from the surveys in step 1 above. (5 days)
5. Study report – A report will be produced explaining the recreational benefit as a function of flow, including the timing a release requirements from upstream reservoirs, available information on economic analysis/benefits from literature survey and supply/cost from study #1. (~2 weeks)

Funding Request and Justification

It is anticipated that this study would require approximately 2 weeks conducting the survey of expert users. The field work on the river will require at least a 2 person crew approximately 2 weeks. The analysis and study report could be completed in approximately one month.

Study 3: Ecological Flow Needs Study

Objectives

The objectives of this study are to determine magnitude, duration, frequency timing and/or rate of change of flows needed to maintain or restore a healthy ecological environment. The study will focus on low flows to meet water quality standards, normal flows to maintain habitats and high flows for channel and riparian maintenance. The recommendations will also be tailored for dry, normal and wet conditions.

Methods

The Water Quality component will primarily be a literature review and assembly of available data. The following tasks will be completed:

1. A literature review and examination of current regulatory standards will be use to evaluate various thresholds of important water quality parameters such as dissolved oxygen, temperature, nutrient loads, salinity/turbidity and any other factors thought to contribute to water quality problems in this river, including Golden Algae blooms.
2. Water quality data will be assembled from TCEQ clean river program and Brazos River Authority. Significant gaps will be identified. A Microsoft Access database will be produced.
3. Minimum flow to protect water quality standards will be estimated.

The Habitat component will be the major portion of this study. The habitat study will report the flows required to produce optimal habitat for each species or guild of species being considered. These types of studies can be very costly and time consuming. This study will limit the scope of the biological sampling.

1. Desktop analysis will be preformed to collect existing information including river channel characteristics, and hydrology (regulated and natural). (5 days)
2. A reconnaissance trip will be conducted by the study team to identify critical habitats, determine whether a 1-dimensional (1-D) or 2-dimensional (2-D) model needs to be developed, and identify study reaches. (5 days)
3. Either a 1-D or 2-D hydrodynamic will be developed. 1-D models are developed based on cross sectional measurements of depth and velocity and these cross sections are used to represent habitat over the entire reach. 2-D models can explicitly determine hydraulic and habitat parameters at all points in the study reach and can account for complex flow patterns. A 2-D model is more likely to be accepted as part of the Texas Instream Flow program. A 1-D hydrodynamic model can be developed based on cross sectional data collections of the type used from the recreational flow study validations (although the cross sections representing important ecological habitat may not coincide with the critical recreational cross sections). A 2-D model requires about 2-3 weeks of field work and model development per site as well as significant equipment rental costs.
4. Habitat suitability curves for important sports fishers will be examined and adapted for use on the Brazos River. Ideally HSC curves are developed from site specific data however this requires multiple and extensive biological sampling. This study will review existing suitability curves for important sport fisheries (bass, catfish etc.) and transfer the findings from these studies to the Brazos.
5. Develop a hydrodynamic habitat model to relate flow levels to velocities and depths and finally velocities and depths to habitat. The model results will then be applied to the natural, current, and proposed flow hydrographs to demonstrate the benefits of management to protecting environmental flows.

1. Finally, in addition to a report of the findings on the normal flow needs to protect the existing ecosystem, a literature survey will be performed to gather information about the depleted/extinct status of the native endemic fishery and what it might require to restore some of the endemic species no longer present.

The Channel and Riparian Maintenance component will employ limited data collection and use literature survey to make an estimate of the flow necessary to maintain riparian habitat and transport sediments. Healthy riparian ecosystems exhibit a diversity of plants species and age classes and may require overbanking flows of specific magnitudes and durations at specific times of the year. Instream habitat is strongly affected by the scouring and depositions of sediments. Flows of specific magnitudes are required to mobilize these sediments. The following tasks will be completed: