6
Implementation Issues

Implementation may be the most important step in any instream flow effort. It is included in the original Programmatic Work Plan (PWP) framework (Figure 4-1) and mentioned in the Technical Overview Documents (TOD), but the Texas instream flow documents hardly address the critical issue of how the instream flow recommendations will be implemented. Implementation issues will be especially important to the Texas instream flow program because it is expected that the state and its citizens will take a number of years to develop and refine mechanisms for instream flows and sound ecological environments in the state’s highly diverse river systems.

Federal and state environmental policies counsel proactive efforts by states to protect instream values. The federal and state Clean Water Acts set broad and ambitious goals for the protection of fishable and swimmable waters nationally. Effective effluent limitations and ambient water quality standards established under these laws depend upon certain minimum base flows. Similarly, the federal Endangered Species Act can significantly constrain water resources management when species found in a waterway are listed as threatened or endangered. Yet, experiences in places like the upper Colorado River basin in Colorado and Utah and on the Platte River in Nebraska suggest that it is possible to conserve fish and wildlife by protecting instream flow regimes and taking other conservation measures while allowing for water resource development. Pro-active conservation efforts that prevent an endangered species listing are almost always less onerous and less resource intensive than is the work needed to conserve and recover a species once it is listed. The same can be said for river health—it is generally easier to protect or maintain a river’s status than to restore a degraded river to a previous or improved condition.

Implementation will occur at two levels in the Texas state-wide instream flow program. First, the state-wide program will be implemented as the river basin studies are conducted and completed. Second, instream flow recommendations developed for specific river systems must be implement-



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The Science of Instream Flows: A Review of the Texas Instream Flow Program 6 Implementation Issues Implementation may be the most important step in any instream flow effort. It is included in the original Programmatic Work Plan (PWP) framework (Figure 4-1) and mentioned in the Technical Overview Documents (TOD), but the Texas instream flow documents hardly address the critical issue of how the instream flow recommendations will be implemented. Implementation issues will be especially important to the Texas instream flow program because it is expected that the state and its citizens will take a number of years to develop and refine mechanisms for instream flows and sound ecological environments in the state’s highly diverse river systems. Federal and state environmental policies counsel proactive efforts by states to protect instream values. The federal and state Clean Water Acts set broad and ambitious goals for the protection of fishable and swimmable waters nationally. Effective effluent limitations and ambient water quality standards established under these laws depend upon certain minimum base flows. Similarly, the federal Endangered Species Act can significantly constrain water resources management when species found in a waterway are listed as threatened or endangered. Yet, experiences in places like the upper Colorado River basin in Colorado and Utah and on the Platte River in Nebraska suggest that it is possible to conserve fish and wildlife by protecting instream flow regimes and taking other conservation measures while allowing for water resource development. Pro-active conservation efforts that prevent an endangered species listing are almost always less onerous and less resource intensive than is the work needed to conserve and recover a species once it is listed. The same can be said for river health—it is generally easier to protect or maintain a river’s status than to restore a degraded river to a previous or improved condition. Implementation will occur at two levels in the Texas state-wide instream flow program. First, the state-wide program will be implemented as the river basin studies are conducted and completed. Second, instream flow recommendations developed for specific river systems must be implement-

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The Science of Instream Flows: A Review of the Texas Instream Flow Program ed. There will be challenges in implementing both the program and the recommendations for flow regimes in specific river systems. This chapter outlines some considerations for instream flow implementation. In regard to implementation of specific flow regimes in specific river systems, the chapter (1) discusses approaches and challenges related to balancing human and ecosystem needs, (2) provides some examples of instream flow work, and (3) briefly discusses the use of models in implementation. This chapter also highlights the importance of adaptive management and on-going peer review, and considers some of the technical recommendations from previous sections of the report in the context of implementing both the state-wide program and flow recommendations for specific river systems. BALANCING HUMAN AND ECOSYSTEM NEEDS A major aspect of implementing an instream flow recommendation requires a deft balance in allocating water among disparate and competing uses. This balance between human and ecosystem needs is reflected in the PWP statement of finding a flow regime that conserves fish and wildlife and human uses of water. Allocating water for a range of water needs and uses is a challenge in many places across the United States. In Texas, specifically, situations exist that further upset this delicate balance, such as the state’s groundwater withdrawal policies and rapidly changing land uses, the state’s many reservoirs, over-allocated rivers compared to rivers where water remains available, non-priority river basins, and climate changes. Anticipating Changes in Groundwater Withdrawal and Land Use in the Watershed Groundwater Groundwater is a critical aspect of instream flow. Springs and seeps contribute a significant portion of the total water that flows in many of the state’s rivers and streams and illustrate how groundwater and surface water function as a unified hydrologic system in many instances. Well pumping can influence groundwater discharge to rivers and streams, with the potential to alter subsistence and base flow conditions. Even though significant, unregulated withdrawals from underground water sources could affect instream flows in significant ways, Texas’s system for the allocation of surface

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The Science of Instream Flows: A Review of the Texas Instream Flow Program and groundwater resources is legally distinct. This disjunction between the unified physical nature of surface and groundwater systems and the bifurcated allocation system for surface- and ground-waters raised some questions about the efficacy of instream flow recommendations that may be affected by groundwater withdrawals. Hopefully, the new and more aggressive framework for managing underground water resources that was established by Senate Bill 1 will prove effective in integrating these two interrelated water resources as Senate Bill 1’s new framework is woven into the state’s larger water resources allocation system. Nevertheless, efforts to establish instream flows on surface rivers and streams could be significantly and adversely affected by future groundwater withdrawals without better integration in protecting these two resources. At a minimum, groundwater models and other tools can be used to assess influences of groundwater pumping on surface flows. Land Use Changes in land use also can have a marked effect on a watershed’s hydrologic behavior, and thus may need to be when protecting or restoring instream flows. As a watershed is converted from its natural vegetative cover into urban areas or farms, infiltration capacity of the watershed is reduced, leading to increases in high flow pulses and overbank flows and decreases of subsistence and base flows. A sound instream flow recommendation will need to anticipate these types of future changes in hydrologic conditions, so that water managers can implement necessary modifications to water management practices or make permitting decisions consistent with instream flow goals. Rivers with Large Reservoirs Opportunities exist for achieving instream flow goals, especially in basins with large storage or hydropower dams. Where permitting activities allow, dam operations can be used to release targeted instream flows (see Savannah River example, Box 6-2). Implementing instream flow recommendations on rivers that are heavily influenced by dam operations will typically require cooperation among the state, stakeholders, and dam managers to integrate instream flow goals with other dam management purposes. Increasingly, water managers, river conservationists, and other stakeholders are exploring ways to modify dam operations to improve releases of water for ecological and recreational benefits in downstream river

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The Science of Instream Flows: A Review of the Texas Instream Flow Program ecosystems (Postel and Richter, 2003; Richter et al., 2003). The use of dams and reservoirs for flood control, water supply, hydropower generation, or recreation in some cases can impose constraints on opportunities for hydrologic restoration, but in many cases some flexibility will exist to change dam operations to improve downstream conditions and serve the original purposes of the dam. Because large dams can have considerable influence on river flows for tens to hundreds of miles downstream, improved dam operations can benefit long stretches of river. The large number of federally-influenced dams in Texas, and their distribution across many different river basins, suggest considerable opportunity for partnership with appropriate federal entities and other partners in attaining instream flow goals through improved dam operations. For example, the U.S. Army Corps of Engineers (USACE) is now collaborating with The Nature Conservancy to evaluate opportunities for modifying operations of USACE dams across the country to improve river health. Under the “Sustainable Rivers Project,” fourteen dams on ten rivers are being assessed for flow restoration opportunities, with the expectation that this number will grow considerably in coming years. Similar partnerships with federal dam managers and river basin authorities are encouraged in Texas. By working closely with the USACE, Bureau of Reclamation, river basin authorities and other dam managers, significant progress toward instream goals can be realized in many of the state’s river basins. In Texas, there may be considerable opportunity to influence the operation of non-federal hydropower dams, particularly when these facilities are applying for re-licensing under the Federal Energy Regulatory Commission (FERC). Instream flow goals for rivers influenced by these hydropower dams can be communicated through participation in FERC relicensing processes. Rivers Where Water Remains Available Water in river basins with un-allocated water presents the opportunity for water to be set aside in some way to attain or maintain instream flow goals. One way to capitalize on available water is through direct appropriations. Direct appropriations have been effectively used in other states (i.e., Colorado [Colo. Rev. Stat. Ann. § 37-92-102(3), 2004]) and may offer a potential guide for states like Texas. Another way to use available water for instream flow purposes is through increased efficiency measures. Other states have encouraged water uses to implement efficiency measures, and Texas could use these existing examples as a guide for its instream flow program. For example, the state of Oregon permits water users to salvage

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The Science of Instream Flows: A Review of the Texas Instream Flow Program water by implementing conservation measures, but requires that twenty-five percent of the salvaged water be made available to the stream (Or. Rev. Stat. § 537.470(3), 2003). The Texas approach to direct and indirect reuse may encourage water users to adopt conservation measures that make water available for both consumptive and non-consumptive uses. Finally, where feasible, the reservation of unappropriated water has the potential for preserving the state's flexibility while it makes decisions about competing demands for water. Over-allocated Rivers Sometimes, instream flow recommendations may exceed, or even significantly exceed, available flows. In these cases, innovation is required to protect instream values. Texas is not the only the only state where rivers are over-appropriated; this is the situation in many parts of the West. Thirteen other western states have put in place statutory or administrative strategies (e.g., Colo. Rev. Stat. Ann. § 37-92-102(3), 2004; Utah Code Ann. § 73-3-3(11), Supp. 2004; Wyo. Stat. Ann. § 41-3-1001-1014, 2003) for instream flow protection. These sister state programs reinforce the notion that instream flow programs can be implemented even in highly arid regions. Other states’ programs also represent a significant reservoir of experience and expertise that Texas policy makers can consult in moving forward (e.g., continued participation in the Instream Flow Council). One of the lessons learned in other western states with more established programs is that a water right or other device for protecting instream flows that is junior to consumptive water rights is limited in its effect. The passage of time accentuates that problem as more and more water is appropriated. On over-appropriated rivers, delay will likely only exacerbate the policy choices facing the state to protect instream flows. On rivers that are not fully appropriated, delay may present fewer opportunities in the future, or opportunities that could be attained only at significantly greater cost than today. The Texas Water Trust1 within the Texas Water Bank is an entity with significant potential: it could facilitate willing buyer/willing seller transactions in which senior consumptive water rights could be acquired and converted to instream uses, either for a term of years or in perpetuity. The state and the Trust also could examine statutory measures that are being used in Colorado (Colo. Rev. Stat. Ann. § 37-80.5-104.4, 2004), Montana (Mont. Code Ann. § 85-20-1001 et seq., 2004), and other western states 1   The Texas Water Trust is established by Texas Water Code Ann. § 15.7031.

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The Science of Instream Flows: A Review of the Texas Instream Flow Program where water users or conservationists enter into agreements for dry-year leases with senior water rights holders to maintain flows in a waterway. Approaches to Instream Flows in Non-priority Basins The Texas instream flow program has identified six priority river basins to initiate the instream flow program. These priority basins represent a small subset of the total number of rivers and streams in the state, and the state may wish to expand the instream flow program to other rivers as it develops instream flow experience. For this expansion, it may be desirable to have some sort of methodology for setting priorities. The Lyons Method or Consensus Criteria for Environmental Flow Needs are good options, but have some limitations (see description of these programs in Chapter 3 and in the following section on Model Use). Ideally, a priority-setting methodology would help water managers determine the order in which additional rivers will be evaluated for instream flow recommendations and weigh a range of alternatives to maximize the state’s future opportunities to protect adequate instream flows. Texas water documents (TWDB, 2002a) and testimony given at open meetings in Austin and San Antonio suggest that existing current water rights cannot be satisfied fully during periods of below-average flows in many river segments. Problems created by low-flow situations may be compounded by the projected increases in population and water demand in Texas. Over the next 50 years, the Texas population is projected to grow dramatically. By the year 2050, as many as 900 cities will need to either reduce demand or develop new water sources in order to meet projected needs during drought or low-flow conditions (TWDB, 2002a). A potentially important consideration in a program with tiered implementation, such as the instream flow program in Texas, is that as demand for water increases, it will be difficult to implement instream flow recommendations on second and third-tier rivers. In the interim, before those second- and third-tier rivers can be studied, Texas may want to consider options that preserve its flexibility to be able to meet future needs on rivers that are not yet considered priority basins. Preserving the status quo, especially on important rivers, may be important at least until the initial period is over and focus can be turned to non-priority river systems’ instream flow requirements. One way to preserve flexibility may be through permits, as was done in the permit for the Guadalupe River in the City of Victoria where instream flows were protected through innovative permitting (see Box 6-1).

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The Science of Instream Flows: A Review of the Texas Instream Flow Program Planning for Climate Change Texas historically has experienced significant drought cycles that have complicated water providers’ efforts to meet human needs. National and international scientists who study the phenomenon of climate change have concluded that climatic perturbations may exacerbate that existing drought cycle and consequently reduce the amount of water available for both human needs and ecosystems beyond what has been observed in the period of record. This trend is particularly worrisome for a state that anticipates dramatic population and economic growth over the same time period during which atmospheric scientists anticipate that the effects of climate change will begin to manifest themselves. The combination of population and economic growth and an intensified drought cycle may seriously stress river systems and the water supplies available for both human and instream needs. It could force adoption of mitigation measures, such as conservation and efficiency as well as even more aggressive drought planning than the state already has undertaken. In addition, reduced precipitation, increased evaporative losses, and reduced storage all would act to reduce minimum flows that are integral elements of both effluent standards and water quality standards. One potential result of climate change would be significantly increased costs to provide potable water to human populations and for agricultural production. IMPLEMENTATION EXAMPLES Despite the challenges of balancing human and ecosystem needs in implementing an instream flow recommendation, many examples exist of how it has been done successfully. Most commonly, an instream flow recommendation is aimed to either protect some existing instream value or restore flow to a targeted value. In protection mode, managers need to guard against changing hydrologic conditions beyond the thresholds represented by the instream flow recommendations. In restoration mode, managers need to bring back hydrologic conditions to a desired condition. Three examples are presented that show how instream flow recommendations were implemented for protection or restoration purposes. The first example shows how instream flow goals could be attained through permitting activities; the second highlights the importance of flow variability in instream flow recommendations; and the last example shows how models can be used to restore targeted flows. The first example is from Texas. In Chapter 3, the “percent of flow” approach is described as a way to determine instream flow recommendation

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The Science of Instream Flows: A Review of the Texas Instream Flow Program values as appropriate levels of allowable flow depletion (typically expressed as percentages of the natural flow). The innovative language of a permit issued by the Texas Natural Conservation Commission (TNRCC, now TCEQ) to the City of Victoria in 1996 for withdrawals from the Guadalupe River affords a significant degree of protection to instream flows (including subsistence flows, base flows, high flow pulses, and overbank flows; see Box 6-1) with the effect of protecting instream flows in a manner similar to the “percent of flow approach.” Although not initially intended as an instream flow effort, the City of Victoria permit shows how instream flow recommendations could be implemented in Texas. The Savannah River in Georgia and South Carolina provides another example relevant to Texas. The Savannah River is a managed river with large dams, not unlike many rivers in Texas. Dam operations were used to maintain in-channel flow in the river all year at higher than natural levels (Table 6-2). River systems are dynamic, and more water in the river is not always “better” for the river ecosystem. High flows in the Savannah kept floodplain soils too moist too consistently for floodplain trees to reproduce. The Savannah River example shows the importance of flow variability, not merely presence of water in the channel, in protecting riverine ecosystems. The Upper Peace River in Florida shows how a flow restoration project worked using hydrologic models. Here, hydrologic simulation models were used to explore potential strategies for recovering instream flow conditions to a targeted level. In the Upper Peace River, a number of water and land use strategies are being employed for the purpose of recovering subsistence and base flows to targeted levels (see Box 6-2). MODEL USE IN INSTREAM FLOW IMPLEMENTATION Hydrologic simulation models that estimate hydrologic changes associated with future development are extremely useful in designing water management strategies and can help water managers assess the potential effectiveness of attaining instream flow goals. Different types of hydrologic simulation models can be used to assess changes in watershed runoff, groundwater flow, or reservoir operations. When applied interactively, these models can estimate cumulative interaction of these water and land use changes on a river’s hydrologic regime. These interactions can be used to determine the likelihood or degree that hydrologic changes relate to instream flow requirements.

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The Science of Instream Flows: A Review of the Texas Instream Flow Program BOX 6-1 Example of a Texas Water Permit with Instream Flow Protection In May 1993, the City of Victoria, Texas, applied to the Texas Natural Resources Conservation Commission for a permit to build a 1,000 acre-feet capacity off-channel reservoir and to divert up to 20,000 acre-feet of water per year from the Guadalupe River to fill the reservoir to be a water supply source for the city. The permit was granted by the Commission in January 1996, with restrictions as to how the water could be withdrawn from the river. The permit defines the annual volume of water which can be diverted (20,000 acre-feet per year), and also the rate at which it can be diverted depending on the observed discharge at the USGS stream gage for the Guadalupe River at Victoria (Gage 08176500). The following restrictions apply: When the observed discharge is at or above the “normal” flow level, the diversion can be up to 150 cfs, where normal flow is defined in Table 6-1 below. When the diversion of water would reduce the flow below normal, the diversion is limited to the difference between the observed flow and normal flow plus 10% of the remaining flow, the total diversion not to exceed 150 cfs. When the flow at the gage is below normal, the diversion is limited to 10% of the gaged flow. When the observed discharge drops below the “low” flow, diversion must cease. The “low” flow is defined in Table 6-1. TABLE 6-1 Flow Statistics for the Guadalupe River at Victoria by Month Month Normal Flow (cfs) Low Flow (cfs) January 387 150 February 440 150 March 660 200 April 687 250 May 1260 200 June 995 250 July 540 300 August 414 300 September 490 200 October 353 150 November 357 150 December 374 150   SOURCE: Adapted from data presented in City of Victoria 1996 water withdrawal permit. Provided by Steve Densmore, TCEQ, 2004.

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The Science of Instream Flows: A Review of the Texas Instream Flow Program The method used to define normal flows is a combination of the Lyons Method based on monthly median flows, and ecological flow needs of the Guadalupe Estuary as follows: “normal flows, based on gaged records, will be described as 40% of the monthly median streamflow in the months of October through February; 60 percent of the monthly median flow in months of March, April, July, August and September; and a flow rate for the months of May and June based on a prorated share of the minimum flow values calculated to maintain beneficial inflows for the living resources and ecological integrity of the Guadalupe Estuary.” Moreover, the “low flow” is defined as the “amount of flow for each month needed to protect water quality in the river, and to a limited extent provide, on a short-term basis, dissolved oxygen levels for sustaining fish and wildlife species.” Figure 6-1 provides a graphical interpretation of these diversion limitations. FIGURE 6-1 Graphical representation of diversion limitations for the Guadalupe River at Victoria, TX.

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The Science of Instream Flows: A Review of the Texas Instream Flow Program TABLE 6-2 Savannah River Comparison of Existing Conditions with Instream Flow Recommendations2   Existing Conditions Instream Flow Recommendations Base Flows: January 5,190–12,320 cfs 7,500—12,000 cfs February 5,200—13,350 cfs 7,500—13,500 cfs March 5,500—12,500 cfs 7,500—13,500 cfs April 5,850—13,000 cfs 7,500—13,500 cfs May 5,790—13,100 cfs 6,200—13,500 cfs June 7,040—13,330 cfs 6,200—8,500 cfs July 5,700—13,000 cfs 6,200—8,500 cfs August 4,950—13,050 cfs 5,500—8,500 cfs September 4,930—13,200 cfs 5,500—8,500 cfs October 4,700—12,030 cfs 5,500—9,000 cfs November 4,880—11,540 cfs 6,200—9,000 cfs December 5,210—10,060 cfs 6,200—9,000 cfs High Flow Pulses: Magnitude 0—34,500 cfs 16,000—30,000 cfs Frequency 0—11 events per year 2—6 events per year Overbank Flows Magnitude > 50,000 cfs 50,000—70,000 cfs Frequency 7 in 50 years (1:7) once every 3 years (1:3)   SOURCE: Existing condition data from USGS gaging station #02198500 near Clyo, GA. Water availability models have been developed by the TCEQ for each of the 23 major river basins in Texas. These models are used to assess whether sufficient water remains available within each basin to satisfy existing surface water withdrawal permits and instream flow requirements as estimated with the Lyons Method (see Chapter 3). Sometimes, however, the Lyons Method can generate instream flow estimates that are less than half of the average base flows in some months of the year (see Box 6-3). The Lyons Method in water availability modeling may also result in under-estimation of the instream flow needs that might be defined in a more detailed instream flow study. Another possible incompatibility exists between Lyons Method-based water availability models and the type of instream 2   These existing and recommended flows pertain to the “floodplain reach” of the Savannah River. Instream flow recommendations for dry, average, and wet years have been lumped in this table for simplicity. It is clear from the monthly base flow summaries that current base flow conditions occasionally drop below the targeted levels, and at other times are higher than specified by the instream flow recommendations.

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The Science of Instream Flows: A Review of the Texas Instream Flow Program flow recommendations contemplated in this report. The water availability models operate on monthly time steps, but instream flow recommendations are commonly based upon daily targets or withdrawal limits, or include high flow pulse or overbank flow recommendations intended to last only a few hours to days (see Box 6-3). For purposes of statewide water planning and water permitting in basins for which detailed instream flow studies have not been conducted, a statistical hydrology method may better characterize normal monthly base flow and high flow conditions. Therefore, the current water availability models could be reviewed to determine whether they can operate on daily time steps in addition to or in lieu of the current monthly time steps. This review could also evaluate water availability model utility in exploring a broad range of water management and restoration options, interactions of surface and groundwater systems, and if necessary, other computer tools to enable assessments of strategies for attaining instream flow goals. ADAPTIVE MANAGEMENT The crux of adaptive management is to learn from early instream flow studies and make changes, accordingly, as more information is amassed. In order to do so, it will be critically important to put in place a systematic and consistent mechanism for monitoring flow levels and biological responses. A set of ecological indicators responsive to streamflow variations and a systematic monitoring program for these indictors can help to adaptively manage and chart progress towards maintaining a sound ecological environment for each river. These indicators could also be monitored in rivers statewide to track changes and measure progress towards maintaining a sound ecological environment in Texas. It is anticipated that much will be learned from the application of the recommended approach during the early years of the program. It should be expected that the Texas agencies will want to modify the final study framework or specify different kinds of initial technical assessments or detailed technical studies in subsequent instream flow studies. With state-level oversight of subbasin studies, information gleaned from earlier studies can be shared and discussed and as necessary, modified, for future activities.

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The Science of Instream Flows: A Review of the Texas Instream Flow Program BOX 6-2 Restoring Instream Flows on the Upper Peace River, Florida The Florida Water Act of 1972 directed the state’s water management districts to set “minimum flows and levels” for all streams, rivers, and natural lakes to ensure that water withdrawals do not result in significant harm to water resources and ecological health. When existing conditions or 20-year projections suggest that targeted instream flows or lake levels will be violated, the Water Act requires that a recovery or prevention strategy be developed. When instream flow requirements for the upper Peace River were established in 2002, the Southwest Florida Water Management District (SWFWMD) realized that a recovery strategy would need to be implemented to restore necessary base flow conditions. Groundwater withdrawals from the Floridian aquifer, primarily for agriculture and phosphate mining, have lowered the potentiometric surface by 30-40 feet in the aquifer. These groundwater declines have resulted in several detrimental impacts to the water resources of the area, including the cessation of flow from in a major spring and reductions in Peace River base flows. The recovery strategy for the upper Peace River includes a variety of measures designed to reduce existing demands or augment available supply. The measures to be implemented in the Peace River watershed have been selected after using hydrologic simulation models to evaluate the cost-benefit ratios of a large number of possible restoration options. The SWFWMD has estimated that the selected restoration projects could provide as much as 75 cfs of additional flow to the upper Peace River during a 90-day low flow period. Some of these measures include: CONTINUING REVIEW OF THE PROGRAM An instream flow program has scientific parts that nest within a policy context. It is particularly important for the program and for the recommendations that the scientific aspects be as free of technical dispute as possible. Close access to and open communication with a wide range of technical experts on instream flow science can help assure that the science is and remains objective and at the state of the science. A valuable role for scientists who are not directly working on studies within the instream flow program is to review the sampling methodologies, results of the individual technical studies, and progress of the overall instream flow program. Results from these reviews can be communicated to the involved scientists, instream flow scientific community at large, and stakeholders. Review by an independent group of scientists will help track the progress and efficacy

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The Science of Instream Flows: A Review of the Texas Instream Flow Program Water Conservation—Many different water conservation strategies are being implemented in the urban, agricultural, industrial, and mining sectors. These strategies include increased use of reclaimed wastewater, a variable water fee structure based on volume of use, education, and other demand management initiatives. Flow Enhancement—More than 30,000 acres of un-reclaimed phosphate mine lands exist within the SWFWMD, much of which causes surface runoff in the watershed to pond in settling areas or pit lakes instead of contributing to Peace River flows. Some of these areas will be reconnected to the river; others will be used as reservoirs that will store runoff during periods of high flow and subsequently release water to the river during periods of low or no flow. Wetland Restoration—20,000 acres of wetlands that were historically altered or destroyed by agricultural activities will be restored by acquiring fee interest or conservation easements on the lands and then restoring their natural hydrologic functions. This is expected to improve surface water storage in floodplain areas during floods, enhance aquifer recharge, and improve base flow conditions. SOURCE: SWFWMD 2002, 2004 of the instream flow program over time, just as the initial peer review was designed to provide, “the highest level of confidence for all interested and affected parties that the framework within which these studies will be carried out is scientifically sound.” In order to fulfill this comprehensive program objective that involves scientists from a variety of disciplines, state agencies, and other stakeholders, the creation of an independent, interdisciplinary, periodic peer review process for the instream flow program is recommended. POLICY CONTEXT FOR TECHNICAL RECOMMENDATIONS In the proposed revised instream flow framework (Figure 4-2), the technical aspects of conducting an instream flow study are couched between two policy actions: setting goals and implementing the instream flow

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The Science of Instream Flows: A Review of the Texas Instream Flow Program BOX 6-3 Estimating Instream Flow Needs with Hydrologic Desktop Methods A number of methods exist for estimating instream flow needs when little or no ecological information is available to define ecosystem water requirements. Some of these approaches—called “hydrologic desktop methods”—are based upon statistical characterizations of historic or naturalized flow data. The Lyons Method, used in Texas for surface water permitting, is an example of a hydrologic desktop method. Using the Lyons Method, monthly instream flow requirements are estimated by computing the medians of all daily flows for each month, and then multiplying those monthly medians by a specified factor. For October through February, this factor is 0.40; for other months, a factor of 0.6 is applied. Hydrologic desktop methods can be very useful in obtaining a ballpark estimate of instream flow needs in rivers for which detailed instream flow studies have not yet been conducted. However, they must be applied carefully to ensure that they generate instream flow estimates that are consistent with instream flow protection goals. For example, in Figure 6-2, the median base flow levels for each month for the Guadalupe River at Victoria are shown, along with a line representing the average high flow pulse level.3 The base flow values have been estimated using a “base flow separation technique” which separates the river’s base and subsistence flows from high flow pulses and overbank flows caused by rainfall events. The Lyons Method would protect much of the base flow in some months, but in other months would leave much of the base flow unprotected (Figure 6-2). The uneven levels of base flow protection afforded by the Lyons Method are in part attributable to the different factors that are applied to monthly medians as described above. Use of monthly medians in a hydrologic desktop method can also yield inconsistent degrees of protection for base flows. Monthly medians are computed using all river flows during the month—base flows, high flow pulses, and even floods are all rolled into the calculation of a monthly median. As a result, it is often hard to predict how closely the median, or a method like Lyons, will compare to base flows. The Consensus Criteria for Environmental Flow Needs (CCEFN), adopted by the Texas agencies in 1997 in their guidelines for regional water plan development, suffers from this same shortcoming. The CCEFN provide three different levels of instream flow protection, depending upon estimates of what the naturalized monthly flow would have been.4 The flow protection 3   Based upon USGS gaging station records for 1935-2002. Base flows and high flow pulses are computed by using a base flow separation technique in the “Indicators of Hydrologic Alteration” (IHA) software that separates base flows from high flows in the daily discharge record. 4   The CCEFN protects the monthly median level when naturalized flows are greater than or equal to the monthly median; protects the 25th percentile level when naturalized flows are less than the median but greater than the 25th percentile; and protects a fixed threshold of flow (such as 7Q2) when naturalized flows are less than the 25th percentile.

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The Science of Instream Flows: A Review of the Texas Instream Flow Program offered by the CCEFN can differ considerably from the Lyons Method because the CCEFN is based upon model-calculated estimates of “naturalized” monthly flows instead of the measured historic flows used in the Lyons Method. While the CCEFN do provide some protection for high flow pulses or floods in addition to base flows, they would still protect only about half of the average high flow pulse levels in the Guadalupe River, as shown in Figure 6-2. In sum, hydrologic desktop methods such as the Lyons Method or CCEFN that are based on monthly medians may lead to inconsistent and unreliable protection of base flows while generally under-protecting high flow pulses and overbank flows. Hydrologic desktop estimates can be improved by first applying a base flow separation analysis to the daily data series, and then computing estimates of normal base flows or high flows separately, as illustrated in Figure 6-2. For example, if the instream flow goal is to protect base flows from excessive depletion, an instream flow target can be developed using the base flow median, or some fraction thereof. If a certain number of high flow events are to be protected as well, these can be added to the base flow estimates. FIGURE 6-2 Comparison of base flows, Lyons Method estimations, and CCEFN5 for the Guadalupe River at Victoria. 5   CCEFN data source: Kathy Alexander, TCEQ, personal communication, 2004.

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The Science of Instream Flows: A Review of the Texas Instream Flow Program recommendation. This graphical representation illustrates a reality of instream flow programs—the science exists in a policy context. Likewise, the technical recommendations proffered in this report also exist in a policy context. This section relates some of the previous recommendations to the implementation aspects of an instream flow program and provides a policy context for some of the technical recommendations. A major recommendation of this report is the presentation of a statewide context for individual subbasin studies with two levels of oversight: one at the state level for management and program consistency and one at the subbasin level for goals and approaches that are tailored to the specific needs of the study basin. While the Texas Water Development Board (TWDB), TCEQ, and the Texas Parks and Wildlife Department (TPWD), are key players in statewide water resources planning, a number of other state-created agencies involved with water resources management may have a legitimate interest in becoming involved with instream flow studies on rivers and streams within their jurisdiction (Baty, 1999). The TWDB, TPWD, and TCEQ have developed significant expertise in instream flow science and have demonstrated a clear ability to work cooperatively on a complex and sensitive set of issues. As a result, it seems reasonable that these three agencies would remain responsible for the oversight of the instream flow program, in order to assure (1) that all studies are conducted in conformance with the final instream flow study framework and (2) that methodologies used in setting instream flow recommendations are consistent. In Chapter 4, the recommendation is made that the role and degree of stakeholder involvement should be clarified. The most likely instream flow recommendation to be implemented is one where interested parties participated in the formulation of instream flow goals, provided input on study design, and were briefed on data collected or assembled during the studies. Early and frequent public participation in the instream flow process can be critical to the study’s success, and consistent commitment to public participation can materially enhance the likelihood and acceptance of a flow recommendation’s implementation. From the review of the water quality models used in the Texas total maximum daily load program, the recommendation was made that the instream flow program should be integrated with the water quality, water permitting, and other water-related programs in Texas. Several water-related programs already exist at the state level, including those associated with water quality, streamflows, bays and estuaries, and water permitting. Some of these are overlapping regulatory and planning processes and all of them could have a bearing on instream flow requirements. The instream flow program can build upon or augment these programs. To the extent

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The Science of Instream Flows: A Review of the Texas Instream Flow Program that the instream flow program uses methods and approaches that are consistent with existing programs, both decision makers and stakeholders will have a clear understanding of how the programs can work together to strengthen overall water management in Texas. SUMMARY This chapter presents some of the practical aspects, and challenges, of implementing instream flow programs and recommendations. The act of implementing an instream flow program or study requires deft balance among disparate and competing uses for river water. This balance includes considerations of groundwater, watershed and land uses, planning in an era of climate change and under a range of available (or scarce) water. Three examples of successfully implemented instream flow recommendations underscore a range of important issues such as using permitting to achieve instream flow goals; the importance of flow variability in implementing instream flow recommendations; and use of hydrologic simulation models in flow restoration projects. Hydrologic models play an important role in instream flow science (see Chapter 3) and their role in implementation is described in this chapter. Hydrologic simulation models and water availability models both have relevant uses in instream flow implementation. The limitations of some “hydrologic desktop” methods are also discussed. Large-scale, state-wide instream flow programs, like the one in Texas, are often implemented over a number of years. In these cases, it is expected that the instream flow managers will learn from the early studies and apply those lessons to subsequent studies. Adaptive management strategies allow for modifications in methods or implementation due to more or updated information. As per adaptive management, it is anticipated that much will be learned during the early years of the instream flow program, and the Texas agencies will likely modify the final study framework, and implementation of initial technical assessments or detailed technical studies as the program and studies mature. Over the life of the Texas instream flow program, and through adaptive management, many changes may be made to instream flow methodologies, implementation, or goals of the program. The scientific integrity of the instream flow program through these changes must not be compromised. Review by an independent group of scientists will help track the progress and efficacy of the instream flow program, methodologies, and results from individual studies over time. In order to fulfill this comprehensive program objective that involves scientists from a variety of disciplines, state agencies, and other stakeholders, the creation of an independent, interdisciplinary,

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The Science of Instream Flows: A Review of the Texas Instream Flow Program periodic peer review process for the instream flow program is recommended. Recommendations made earlier in the report are presented in the context of implementing the Texas instream flow program and instream flow recommendations. Specifically, this report recommends that the Texas program have two levels of oversight: one at the state-level for overall program consistency and one at the subbasin level for individual studies. Given the expertise and demonstrated ability to work cooperatively, this chapter observes that the TWDB, TPWD, and TCEQ are well poised to maintain the state-level of oversight for the instream flow program. Stakeholder involvement is discussed in Chapters 3 and 4 in the context of setting goals and building public support for instream flow work; stakeholder involvement in this chapter is acknowledged as important element in realizing the implementation of an instream flow recommendation. Finally, a recommendation was made in Chapter 5 to integrate the instream flow program with water quality, water permitting and other water-related programs in Texas. To the extent that the instream flow program uses methods and approaches that are consistent with existing programs, both decision makers and stakeholders will have a clear understanding of how the programs can work together to strengthen overall water management in Texas. RECOMMENDATION The creation of an independent, interdisciplinary, periodic peer review process for the instream flow program is recommended.