Texas Environmental Flows Dashboard
The health of Texas’ treasured streams, rivers, and estuaries is at serious risk due to the depletion of the amount of water flowing through rivers to the coast. Recognizing that risk, the Texas Legislature, in 2007, enacted potentially far-reaching legislation (Senate Bill 3) providing for protection of environmental flows in Texas.
The protections are meant to cover instream flows (water in rivers and streams) and freshwater inflows (fresh water flowing into bays and estuaries).
The first protections were meant to come into force in 2013. More than a decade later, many aspects of Senate Bill 3 remain under-developed and/or under-enforced. Click on an individual basin below to get an in-depth update on the state of that basin’s environmental flow protections.
Environmental Flows Map
Select a river basin to learn about the status of environmental flow standards in that basin
Rio Grande, Rio Grande Estuary and Lower Laguna Madre
Adequacy of Adopted Environmental Flow Standards
Instream flows, number of measurement points: There were two expert science teams. The expert science team for the upper Rio Grande Basin recommended flow levels at 13 measurement points. For the lower Rio Grande Basin, the Estuary, and the Lower Laguna Madre, the expert science team recommended flow levels at 1 measurement point. TCEQ only adopted flow standards for 4 measurement points, all in the upper Rio Grande Basin. Unfortunately, TCEQ does not require the use of the protected flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, with so few measurement points, assessment of compliance with flow protections at most locations would be based on flow levels at very distant gages, sometimes on a different stream. Because the Rio Grande is considered fully permitted, there are unlikely to be new permits and a focus on proactive strategies to improve flow conditions may be appropriate.
Instream flows, diversions down to subsistence levels: The expert science team for the upper basin recommended that diversions down to subsistence should only be allowed during the driest 10% of months when flows are otherwise below the applicable baseflow level. Because subsistence flows represent very low levels intended to be reached only rarely during droughts, aquatic species are at risk at those levels. The adopted flow standards reflect that recommendation. The science team for the lower basin recommended a minimum flow level with periodic higher flows, which are not included in the standards.
Instream flow, levels of baseflows: The expert science team for the upper basin recommended three different levels of baseflows, representing dry, average, and wet conditions because different species do better with different flow levels. The adopted standards match those recommendations at the few measurement points included in the standards. There were no specific baseflow recommendations for the lower basin and there are no criteria in the standards.
Instream flows, levels of pulse flows: The expert science team for the upper basin recommended multiple levels (2-6 ranging from small to large, depending on location) of pulse flows for protection, with all levels applicable during all flow conditions. The adopted flow standards include only 1 level of pulse flows, either equal to or lower than the lowest level recommended by the science team. The science team for the lower basin recommended a pulse flow criterion aimed at preventing the mouth of the Rio Grande from silting shut, which is not included in the standards.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows, or freshwater inflows, in these flow standards.
Freshwater inflows, drought period criteria: The adopted standards do not include separate bay-related inflow criteria for the Lower Laguna Madre or the estuarine portion of the Rio Grande. The expert science team for the lower basin and estuary recommended a flow regime at the Brownsville gage intended to maintain moderate salinity levels in the Rio Grande estuary and prevent the recurrence of extremely low flows that previously resulted in a buildup of sand blocking the connection of the Rio Grande with the Gulf of Mexico.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards later are amended to be more protective. Although there are no separate inflow protections, increased protections for instream flows would increase protections for inflows in the unlikely event increased flows were actually passed to the estuary.
Freshwater inflows, strategy targets: The expert science team for the lower basin and estuary did recommend consideration of redirecting some wastewater return flows from the Arroyo Colorado, which appears to have artificially elevated flows during dry periods, to the Rio Grande, which has reduced flows much of the time. However, the adopted flow standards do not include targets to guide voluntary proactive strategies, such as purchases of existing water rights or redirected return flows, to increase instream flows or bay inflows.
Overall: match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. There are major differences between the adopted standards and the science team recommendations, especially for number of measurement points, protection of pulse flows and absence of criteria addressing estuary inflows, resulting in less flow protection than the science team recommended.
Nueces River and Corpus Christi and Baffin Bays
Adequacy of Adopted Environmental Flow Standards
Instream flows, number of measurement points: The expert science team recommended instream flow levels at 18 measurement points in the Nueces River Basin, 1 on Oso Creek, and 1 on San Fernando Creek above Baffin Bay. TCEQ adopted flow standards for almost all those measurement points. Unfortunately, TCEQ does not require the use of the protected flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, even with numerous measurement points, compliance with flow protections for individual permits often is based on flow levels at very distant gages, sometimes on a different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The expert science team recommended that diversions down to subsistence levels should be allowed only during the driest 10% of the time. The adopted flow standards allow diversions down to subsistence flow levels, subject to the 50% rule, anytime flow falls below the baseflow level. Because subsistence flows represent very low levels intended to be reached only rarely during droughts, aquatic species are at risk at those levels. Under the adopted standards when impoundment or diversion under older permits without flow protection causes flows to drop below the baseflow level, flow protections applicable for new permits also drop, just when more protection under new permits is most needed. The flow standards do apply a “50% rule” to limit the how quickly flows drop to subsistence levels: the permit holder can divert, or impound, only half of the flow between the subsistence level and the applicable baseflow level. So, if flow at the measurement point is 100 cfs and the subsistence level is 50 cfs, in theory, the permit holder only gets 25 cfs. However, the 50% rule really can only work if there is a nearby measurement point, which is rare.
Instream flow, levels of baseflows: The expert science team recommended three different levels of baseflows, representing dry, average, and wet conditions because different species do better with different flow levels. The adopted flow standards only protect one level of baseflows, which has seasonal flow levels matching the science team recommendations for average hydrological conditions.
Instream flows, levels of pulse flows: The expert science team recommended many levels of pulse flow protections (5 to 8) at the various measurement points. The adopted flow standards protect 2 to 3 levels of pulse flows that generally match the lowest pulse flow recommendations by the science team. However, even within those pulse flow levels, during many seasons the standards do not protect smaller pulses recommended for protection by the science team because TCEQ considered the pulse flow levels to be insufficiently different from baseflow leve
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows in these flow standards.
Freshwater inflows, drought period criteria: The expert science team recommended low volumes of seasonal inflows for the Nueces Bay and Delta that should be met in most years—the recommended attainment frequencies range from 69% to 88% of future seasonal periods. Attainment frequencies define the percentage of time at least those volumes of inflows should occur. The adopted flow standards use the science team recommendations for attainment frequencies solely as targets for voluntary protection efforts. The standards applicable for new permits use far lower attainment frequencies than those the science team recommended as adequate to protect a sound ecological environment. The expert science team indicated that, because of existing low flow inflow levels, among other factors, the Nueces Bay and estuary does not represent a sound ecological environment. There are no drought-period minimum inflows.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards later are amended to be more protective. TCEQ implementation does not provide a mechanism for reopening the freshwater inflow component of new permits.
Freshwater inflows, strategy targets: The standards do include broad attainment frequency targets to guide implementation of voluntary proactive strategies, such as purchases of existing water rights, to increase bay inflows. Because strategies to increase inflows likely will provide relatively small volumes of water, broad targets for attainment frequencies of large inflow volumes, although conceptually important, may have limited utility.
Overall: match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. The instream flow component of the standards differs from many aspects of the science team recommendations, including frequency of diversions down to subsistence levels, fewer baseflow levels, and fewer protected pulse flows. The freshwater inflow component of the adopted standards, although matching the structure of science team recommendations, protects much lower attainment frequencies
Guadalupe, San Antonio, Mission and Aransas River Basins and Mission, Copano, Aransas, and San Antonio Bays
Adequacy of Adopted Environmental Flow Standards
Instream flows, number of measurement points: The expert science team provided recommendations for flow levels at 9 measurement points in the Guadalupe River Basin, 6 in the San Antonio River Basin and 1 in Mission River basin. TCEQ adopted flow standards for all those measurement points. Unfortunately, TCEQ does not require the use of the flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, even with those measurement points, compliance with flow protections for individual permits often is based on flow levels at very distant gages, sometimes on a different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The adopted flow standards for the San Antonio and Mission river basins only allow diversions down to subsistence flow levels during hydrological conditions representing the driest 25% of the time. Because subsistence flows represent very low levels intended to be reached only rarely during drought periods, aquatic species are at risk at those flow levels. In the Guadalupe River Basin, diversion down to subsistence is allowed, subject to the 50% rule, anytime flow falls below the baseflow level. The expert science team recommended the same approach for the Guadalupe Basin as adopted for the San Antonio and Mission basins. Under the adopted standards, however, in the Guadalupe Basin when diversion under older permits without flow protections causes flows to drop below baseflow level, flow protections applicable for new permits also drop, just when more protection under new permits is most needed. The flow standards in that basin do apply a “50% rule” to limit the drop in flow levels: the permit holder can divert or impound half of the flow above the subsistence level. So, if flow at the measurement point is 100 cfs, the baseflow level is 150 cfs, and the subsistence level is 50 cfs, in theory, the permit holder only gets 25 cfs. However, the 50% rule really can only work where there is a nearby measurement point, which is rare.
Instream flow, levels of baseflows: The expert science team recommended three different levels of baseflows, representing dry, average, and wet conditions, for all locations because different species do better with different flow levels. The flow standards adopted by TCEQ match the expert science team recommendations for the San Antonio and Mission basins, but include only one level of baseflow for the Guadalupe Basin, although it is fairly high.
Instream flows, levels of pulse flows: The expert science team recommended five different levels of pulse flow protections at most locations. The adopted flow standards generally protect only the lowest two levels of those pulse flows, and with exceptions that allow some new permits to avoid, based on diversion rate, complying with pulse flow protections.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows in these flow standards.
Freshwater inflows, drought period criteria: The expert science team recommended annual flow regimes for dry periods for San Antonio Bay with accompanying attainment frequencies. Attainment frequencies define how often levels are allowed to be reduced below the recommendations. The adopted flow standards only use the science team recommendations for attainment frequency as targets for voluntary protection efforts. Adopted standards applicable for new permits use much less protective attainment frequencies than those identified by the science team as adequate to protect a sound ecological environment. They also fail to identify minimum flows for drought periods. There are no drought period criteria for Mission Bay, only a single criterion for rare high inflow events.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase inflow protection by a limited amount if flow standards are amended to be more protective. TCEQ implementation does not provide a mechanism for reopening the freshwater inflow component.
Freshwater inflows, strategy targets: There are broad attainment frequency targets to guide voluntary proactive strategies, such as purchases of existing water rights, to increase bay inflows. Because strategies to increase inflows likely will provide relatively small volumes of water, broad targets for attainment frequencies of large volumes, although conceptually important, may have limited utility.
Overall, match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. The instream flow component matches expert science team recommendations for the San Antonio and Mission basins except that protections for most larger pulse flows were omitted or reduced in size. Instream flow components for Guadalupe Basin are less protective than science team recommendations in multiple ways. The freshwater inflow components of the adopted standards, although reflecting the structure of science team recommendations, protect much lower attainment frequencies.
Colorado and Lavaca River Basins and Matagorda and Lavaca Bays
Adequacy of Adopted Environmental Flow Standards
Instream flows, number of measurement points: The expert science team provided recommendations for flow levels at 14 measurement points in the Colorado River Basin, 4 in the Lavaca River Basin and 2 in coastal basins. TCEQ adopted flow standards for all those measurement points. Unfortunately, TCEQ does not require the use of the flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, even with those measurement points, compliance with flow protections for individual permits often is based on flow levels at very distant gages, sometimes on a different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The adopted flow standards only allow diversions down to subsistence flow levels during hydrological conditions representing the driest 5% of the time. Because subsistence flows represent very low levels intended to be reached only rarely during drought periods, aquatic species are at risk at those flow levels. Limiting diversions in that way acknowledges that serious droughts happen naturally while attempting to limit the creation of artificial drought-level flows.
Instream flow, levels of baseflows: The expert science team recommended three different levels of baseflows, representing dry, average, and wet conditions, for most locations because different species do better with different flow levels. Based on existing studies, only two levels of baseflows were recommended for the Colorado River below Austin. The adopted flow standards match the expert science team recommendations.
Instream flows, levels of pulse flows: The expert science team recommended five different levels of pulse flow protections at most locations. The adopted flow standards generally protect the lowest three levels of those pulse flows with some downward adjustment in pulse volume for the highest of the the three levels. For water rights on the Colorado River downstream of Austin, some pulse flow requirements only apply to permits with large diversion rates or impoundment capacity.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows in these flow standards.
Freshwater inflows, drought period criteria: The expert science team recommended minimum monthly inflow levels for Matagorda Bay and minimum seasonal inflows for Lavaca Bay with accompanying attainment frequencies. Attainment frequencies define how often levels can flow below the recommendations. The adopted flow standards use the science team recommendations for attainment frequencies solely as targets for voluntary protection efforts. Flow standards applicable for new permits use lower attainment frequencies which reflect the full exercise of all existing water rights rather than science team recommendations for frequencies adequate to protect a sound ecological environment.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards are amended to be more protective. TCEQ implementation does not provide for reopening the freshwater inflow component.
Freshwater inflows, strategy targets: There are broad attainment frequency targets to guide voluntary proactive strategies, such as purchases of existing water rights, to increase bay inflows. Because strategies to increase inflows likely will provide relatively small volumes of water, broad targets for attainment frequencies of large volumes, although conceptually important, may have limited utility.
Overall: match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. The instream flow component of the standards matches expert science team recommendations except that most larger pulse flow recommendations were omitted or reduced in size. The freshwater inflow component of the standards, although similar in structure to science team recommendations, protects much lower attainment frequencies.
Brazos River and Its Associated Bay and Estuary System
Adequacy of Adopted Environmental Flow Standards
Instream flows, number of measurement points: The expert science team recommended flow levels at 19 measurement points in the Brazos River Basin and 1 measurement point in the San Bernard Basin. TCEQ adopted flow standards for the same number of measurement points, although a different measurement point was substituted for one of the science team recommendations. Unfortunately, TCEQ does not require the use of the protected flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, even with numerous measurement points, compliance with flow protections for individual permits often is based on flow levels at very distant gages, sometimes on a different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The expert science team recommended that diversions below baseflow levels—approaching subsistence levels—should only be allowed during the driest 25% of months. Because subsistence flows represent very low levels intended to be reached only rarely during droughts, aquatic species are at risk at those levels. The adopted flow standards allow diversions down to levels that may approach subsistence levels at any time flows at the relevant measurement point are below the baseflow level. If impoundment or diversion under older permits without flow protections causes flows to drop below baseflow level, flow protections applicable for new permits also drop, just when more protection under new permits is most needed. Consistent with science team recommendations, the flow standards apply a “50% rule” to limit how quickly flows drop to subsistence levels: the permit holder can divert, or impound, only half of the flow between the subsistence level and the applicable baseflow level. So, if flow at the measurement point is 100 cfs and the subsistence level is 50 cfs, in theory, the permit holder only gets 25 cfs. However, the 50% rule really can only work if there is a nearby measurement point, which is rare
Instream flow, levels of baseflows: The expert science team recommended three different levels of baseflows, representing dry, average, and wet conditions because different species do better with different flow
Instream flows, levels of pulse flows: The expert science team recommended multiple levels (5-7 ranging from small to large, depending on location) of pulse flows for protection, with all levels applicable during all flow conditions. The adopted flow standards include only 3 levels of pulse flows and only one of those levels is applicable at any time based on whether flow conditions are dry, average, or wet.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows, or freshwater inflows, in these flow standards.
Freshwater inflows, drought period criteria: There is no separate bay associated with the Brazos River, but there is an estuarine portion of the river. That is also true for the San Bernard River. The expert science team concluded levels protected by the instream flow standards may be adequate to protect the estuary and did not recommend separate freshwater inflow protections. Because there are no separate freshwater inflow standards, only the subsistence flow level for instream flow protections and the 50% rule apply to protect inflows to the estuary during drought periods. And, even that protection depends on whether there are large older permits not subject to instream flow protections downstream of the last measurement point and on how restrictions on new permits in that same reach are managed.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards later are amended to be more protective. Although there are no separate inflow protections, increased protections for instream flows, if those flows were passed all the way to the estuary, would increase protections for inflows.
Freshwater inflows, strategy targets: There are no targets to guide voluntary proactive strategies, such as purchases of existing water rights, to increase instream flows or bay inflows.
Overall: match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. There are some big differences between the adopted standards and the science team recommendations, especially for pulse flows and subsistence-level flows, resulting in less flow protection than the science team recommended.
Trinity & San Jacinto River Basins and Galveston Bay Estuary System
Adequacy of Adopted Environmental Flow Standards
Instream flows, number of measurement points: The expert science team did not reach consensus, providing competing recommendations with just less than half of members recommending flow levels at 4 measurement points in the Trinity River Basin and 2 in the San Jacinto River Basin and the majority recommending use of 6 in the Trinity, 3 in the San Jacinto, and 2 in smaller bayous. TCEQ adopted flow standards for 4 measurement points in the Trinity basin and 2 in the San Jacinto basin. Unfortunately, TCEQ does not require the use of the flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, compliance with flow protections for individual permits often is based on flow levels at very distant gages, sometimes on a different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The adopted flow standards allow diversions down to subsistence flow levels whenever flows at the measurement point are below the seasonal baseflow level. Because subsistence flows represent very low levels intended to be reached only rarely during drought periods, aquatic species are at risk at those levels. If impoundment or diversion under older permits that lack any flow protections causes flows to drop below baseflow level, flow protections applicable for new permits also drop, just when better protection under new permits is most needed.
Instream flow, levels of baseflows: There were competing science team recommendations. A portion of the expert science team recommended only a single baseflow level, with the majority of the members recommending three different levels of baseflows, representing dry, average, and wet conditions, because different species do better with different flow levels. The adopted flow standards only protect a single level of baseflows slightly above the single level recommended by the minority of the expert science team, which approximates the levels recommended by the majority for use in dry conditions.
Instream flows, levels of pulse flows: The majority of the expert science team recommended four different levels of pulse flow protections. The remaining members “conditionally” recommended one level of small pulses. The flow standards adopted by TCEQ protect a single level of pulse flows that is reasonably close to the lowest levels recommended for protection by the members of the expert science team.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows or freshwater inflows in these flow standards.
Freshwater inflows, drought period criteria: The expert science team split on its recommendations for inflows to Galveston Bay. TCEQ developed its own approach that is less protective than either recommendation. The adopted standards do not include criteria for the driest 40% of seasons or the driest 25% of years. That means there are no inflow protections during drought periods.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards are amended to be more protective. TCEQ implementation does not provide for reopening the freshwater inflow component.
Freshwater inflows, strategy targets: There are no targets to guide voluntary proactive strategies, such as purchases of existing water rights, to increase bay inflows.
Overall: match with science team recommendations: The expert science team was charged with developing recommendations adequate to protect a sound ecological environment. Because of split recommendations by the science team, there is no easy answer: various aspects of the adopted standards are more protective than some members recommended and less protective than what the majority of members recommended.
Sabine & Neches River Basins and Sabine Lake Estuary System
Adequacy of Adopted Environmental Flow Standards
Instream flows, number of measurement points: The expert science team recommended comprehensive flow regimes at 6 major measurement points in the Sabine River Basin and 6 major measurement points in the Neches River Basin. TCEQ adopted flow standards for almost all those points. Unfortunately, TCEQ has declined to require the use of those flow regimes as the basis for calculating flow protection levels to be applied at additional flow gages. As a result, determination of compliance with flow protections for individual permits often is based on flow levels at very distant gages that may be located on an entirely different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The adopted flow standards allow diversions down to subsistence flow levels whenever flows at the measurement point are below the seasonal baseflow level. Because subsistence flows represent very low levels intended to be reached only rarely during drought periods, aquatic species are at risk at those levels. If impoundment or diversion under older permits without any flow protections causes flows to drop below baseflow level, flow protections applicable for new permits also drop, just when better protection under new permits is most needed.
Instream flow, levels of baseflows: The expert science team recommended three different levels of baseflows, representing dry, average, and wet conditions because different species do better with different flow levels. Under those recommendations, the lowest levels of protection would apply only during dry conditions when flows naturally are lower, with the highest protection levels applying during wet periods. The flow standards adopted by TCEQ only protect a single level slightly above the level recommended by the expert science team for protection during dry conditions.
Instream flows, levels of pulse flows: The expert science team recommended two different levels of pulse flows, generally representing average, and wet conditions, for protection. However, the adopted flow standards only protect a single level of pulse flow that corresponds to the lowest level recommended for protection by the expert science team.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the voluntary implementation of proactive strategies to improve impaired flow levels. There are no strategy targets for instream flows or freshwater inflows in these flow standards.
Freshwater inflows, drought period criteria: The expert science team evaluated the levels of inflows expected to reach Sabine Lake if its full instream flow protection recommendations were adopted. The science team concluded those recommendations would protect adequate levels of freshwater inflows. TCEQ, although adopting much less protective levels for instream flow than recommended by the expert science team, relied on that science team evaluation as support the agency’s decision not to adopt separate freshwater inflow protections, such as drought period inflow criteria.
Freshwater inflows, strategy targets: There are no targets to guide voluntary proactive strategies, such as purchases of existing water rights, to increase instream flows or bay inflows.
Overall: match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. Levels of protection in adopted flow standards are much lower than recommended by the expert science team.
Status of Flows Standards in Rio Grande, Rio Grande Estuary and Lower Laguna Madre Basin
Instream flows, number of measurement points: There were two expert science teams. The expert science team for the upper Rio Grande Basin recommended flow levels at 13 measurement points. For the lower Rio Grande Basin, the Estuary, and the Lower Laguna Madre, the expert science team recommended flow levels at 1 measurement point. TCEQ only adopted flow standards for 4 measurement points, all in the upper Rio Grande Basin. Unfortunately, TCEQ does not require the use of the protected flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, with so few measurement points, assessment of compliance with flow protections at most locations would be based on flow levels at very distant gages, sometimes on a different stream. Because the Rio Grande is considered fully permitted, there are unlikely to be new permits and a focus on proactive strategies to improve flow conditions may be appropriate.
Instream flows, diversions down to subsistence levels: The expert science team for the upper basin recommended that diversions down to subsistence should only be allowed during the driest 10% of months when flows are otherwise below the applicable baseflow level. Because subsistence flows represent very low levels intended to be reached only rarely during droughts, aquatic species are at risk at those levels. The adopted flow standards reflect that recommendation. The science team for the lower basin recommended a minimum flow level with periodic higher flows, which are not included in the standards.
Instream flow, levels of baseflows: The expert science team for the upper basin recommended three different levels of baseflows, representing dry, average, and wet conditions because different species do better with different flow levels. The adopted standards match those recommendations at the few measurement points included in the standards. There were no specific baseflow recommendations for the lower basin and there are no criteria in the standards.
Instream flows, levels of pulse flows: The expert science team for the upper basin recommended multiple levels (2-6 ranging from small to large, depending on location) of pulse flows for protection, with all levels applicable during all flow conditions. The adopted flow standards include only 1 level of pulse flows, either equal to or lower than the lowest level recommended by the science team. The science team for the lower basin recommended a pulse flow criterion aimed at preventing the mouth of the Rio Grande from silting shut, which is not included in the standards.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows, or freshwater inflows, in these flow standards.
Freshwater inflows, drought period criteria: The adopted standards do not include separate bay-related inflow criteria for the Lower Laguna Madre or the estuarine portion of the Rio Grande. The expert science team for the lower basin and estuary recommended a flow regime at the Brownsville gage intended to maintain moderate salinity levels in the Rio Grande estuary and prevent the recurrence of extremely low flows that previously resulted in a buildup of sand blocking the connection of the Rio Grande with the Gulf of Mexico.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards later are amended to be more protective. Although there are no separate inflow protections, increased protections for instream flows would increase protections for inflows in the unlikely event increased flows were actually passed to the estuary.
Freshwater inflows, strategy targets: The expert science team for the lower basin and estuary did recommend consideration of redirecting some wastewater return flows from the Arroyo Colorado, which appears to have artificially elevated flows during dry periods, to the Rio Grande, which has reduced flows much of the time. However, the adopted flow standards do not include targets to guide voluntary proactive strategies, such as purchases of existing water rights or redirected return flows, to increase instream flows or bay inflows.
Overall: match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. There are major differences between the adopted standards and the science team recommendations, especially for number of measurement points, protection of pulse flows and absence of criteria addressing estuary inflows, resulting in less flow protection than the science team recommended.
Status of Flows Standards in Colorado and Lavaca River Basins and Matagorda and Lavaca Bays
Instream flows, number of measurement points: The expert science team provided recommendations for flow levels at 14 measurement points in the Colorado River Basin, 4 in the Lavaca River Basin and 2 in coastal basins. TCEQ adopted flow standards for all those measurement points. Unfortunately, TCEQ does not require the use of the flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, even with those measurement points, compliance with flow protections for individual permits often is based on flow levels at very distant gages, sometimes on a different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The adopted flow standards only allow diversions down to subsistence flow levels during hydrological conditions representing the driest 5% of the time. Because subsistence flows represent very low levels intended to be reached only rarely during drought periods, aquatic species are at risk at those flow levels. Limiting diversions in that way acknowledges that serious droughts happen naturally while attempting to limit the creation of artificial drought-level flows.
Instream flow, levels of baseflows: The expert science team recommended three different levels of baseflows, representing dry, average, and wet conditions, for most locations because different species do better with different flow levels. Based on existing studies, only two levels of baseflows were recommended for the Colorado River below Austin. The adopted flow standards match the expert science team recommendations.
Instream flows, levels of pulse flows: The expert science team recommended five different levels of pulse flow protections at most locations. The adopted flow standards generally protect the lowest three levels of those pulse flows with some downward adjustment in pulse volume for the highest of the the three levels. For water rights on the Colorado River downstream of Austin, some pulse flow requirements only apply to permits with large diversion rates or impoundment capacity.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows in these flow standards.
Freshwater inflows, drought period criteria: The expert science team recommended minimum monthly inflow levels for Matagorda Bay and minimum seasonal inflows for Lavaca Bay with accompanying attainment frequencies. Attainment frequencies define how often levels can flow below the recommendations. The adopted flow standards use the science team recommendations for attainment frequencies solely as targets for voluntary protection efforts. Flow standards applicable for new permits use lower attainment frequencies which reflect the full exercise of all existing water rights rather than science team recommendations for frequencies adequate to protect a sound ecological environment.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards are amended to be more protective. TCEQ implementation does not provide for reopening the freshwater inflow component.
Freshwater inflows, strategy targets: There are broad attainment frequency targets to guide voluntary proactive strategies, such as purchases of existing water rights, to increase bay inflows. Because strategies to increase inflows likely will provide relatively small volumes of water, broad targets for attainment frequencies of large volumes, although conceptually important, may have limited utility.
Overall: match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. The instream flow component of the standards matches expert science team recommendations except that most larger pulse flow recommendations were omitted or reduced in size. The freshwater inflow component of the standards, although similar in structure to science team recommendations, protects much lower attainment frequencies.
Status of Flows Standards in Brazos River and Its Associated Bay and Estuary System
Instream flows, number of measurement points: The expert science team recommended flow levels at 19 measurement points in the Brazos River Basin and 1 measurement point in the San Bernard Basin. TCEQ adopted flow standards for the same number of measurement points, although a different measurement point was substituted for one of the science team recommendations. Unfortunately, TCEQ does not require the use of the protected flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, even with numerous measurement points, compliance with flow protections for individual permits often is based on flow levels at very distant gages, sometimes on a different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The expert science team recommended that diversions below baseflow levels—approaching subsistence levels—should only be allowed during the driest 25% of months. Because subsistence flows represent very low levels intended to be reached only rarely during droughts, aquatic species are at risk at those levels. The adopted flow standards allow diversions down to levels that may approach subsistence levels at any time flows at the relevant measurement point are below the baseflow level. If impoundment or diversion under older permits without flow protections causes flows to drop below baseflow level, flow protections applicable for new permits also drop, just when more protection under new permits is most needed. Consistent with science team recommendations, the flow standards apply a “50% rule” to limit how quickly flows drop to subsistence levels: the permit holder can divert, or impound, only half of the flow between the subsistence level and the applicable baseflow level. So, if flow at the measurement point is 100 cfs and the subsistence level is 50 cfs, in theory, the permit holder only gets 25 cfs. However, the 50% rule really can only work if there is a nearby measurement point, which is rare.
Instream flow, levels of baseflows: The expert science team recommended three different levels of baseflows, representing dry, average, and wet conditions because different species do better with different flow levels. The flow standards adopted by TCEQ match the science team recommendations.
Instream flows, levels of pulse flows: The expert science team recommended multiple levels (5-7 ranging from small to large, depending on location) of pulse flows for protection, with all levels applicable during all flow conditions. The adopted flow standards include only 3 levels of pulse flows and only one of those levels is applicable at any time based on whether flow conditions are dry, average, or wet.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows, or freshwater inflows, in these flow standards.
Freshwater inflows, drought period criteria: There is no separate bay associated with the Brazos River, but there is an estuarine portion of the river. That is also true for the San Bernard River. The expert science team concluded levels protected by the instream flow standards may be adequate to protect the estuary and did not recommend separate freshwater inflow protections. Because there are no separate freshwater inflow standards, only the subsistence flow level for instream flow protections and the 50% rule apply to protect inflows to the estuary during drought periods. And, even that protection depends on whether there are large older permits not subject to instream flow protections downstream of the last measurement point and on how restrictions on new permits in that same reach are managed.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards later are amended to be more protective. Although there are no separate inflow protections, increased protections for instream flows, if those flows were passed all the way to the estuary, would increase protections for inflows.
Freshwater inflows, strategy targets: There are no targets to guide voluntary proactive strategies, such as purchases of existing water rights, to increase instream flows or bay inflows.
Overall: match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. There are some big differences between the adopted standards and the science team recommendations, especially for pulse flows and subsistence-level flows, resulting in less flow protection than the science team recommended. Status of Flows Standards in Trinity & San Jacinto River Basins and Galveston Bay Estuary System
Instream flows, number of measurement points: The expert science team did not reach consensus, providing competing recommendations with just less than half of members recommending flow levels at 4 measurement points in the Trinity River Basin and 2 in the San Jacinto River Basin and the majority recommending use of 6 in the Trinity, 3 in the San Jacinto, and 2 in smaller bayous. TCEQ adopted flow standards for 4 measurement points in the Trinity basin and 2 in the San Jacinto basin. Unfortunately, TCEQ does not require the use of the flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, compliance with flow protections for individual permits often is based on flow levels at very distant gages, sometimes on a different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The adopted flow standards allow diversions down to subsistence flow levels whenever flows at the measurement point are below the seasonal baseflow level. Because subsistence flows represent very low levels intended to be reached only rarely during drought periods, aquatic species are at risk at those levels. If impoundment or diversion under older permits that lack any flow protections causes flows to drop below baseflow level, flow protections applicable for new permits also drop, just when better protection under new permits is most needed.
Instream flow, levels of baseflows: There were competing science team recommendations. A portion of the expert science team recommended only a single baseflow level, with the majority of the members recommending three different levels of baseflows, representing dry, average, and wet conditions, because different species do better with different flow levels. The adopted flow standards only protect a single level of baseflows slightly above the single level recommended by the minority of the expert science team, which approximates the levels recommended by the majority for use in dry conditions.
Instream flows, levels of pulse flows: The majority of the expert science team recommended four different levels of pulse flow protections. The remaining members “conditionally” recommended one level of small pulses. The flow standards adopted by TCEQ protect a single level of pulse flows that is reasonably close to the lowest levels recommended for protection by the members of the expert science team.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows or freshwater inflows in these flow standards.
Freshwater inflows, drought period criteria: The expert science team split on its recommendations for inflows to Galveston Bay. TCEQ developed its own approach that is less protective than either recommendation. The adopted standards do not include criteria for the driest 40% of seasons or the driest 25% of years. That means there are no inflow protections during drought periods.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards are amended to be more protective. TCEQ implementation does not provide for reopening the freshwater inflow component.
Freshwater inflows, strategy targets: There are no targets to guide voluntary proactive strategies, such as purchases of existing water rights, to increase bay inflows.
Overall: match with science team recommendations: The expert science team was charged with developing recommendations adequate to protect a sound ecological environment. Because of split recommendations by the science team, there is no easy answer: various aspects of the adopted standards are more protective than some members recommended and less protective than what the majority of members recommended.
Status of Flows Standards in Sabine & Neches River Basins and Sabine Lake Estuary System
Instream flows, number of measurement points: The expert science team recommended comprehensive flow regimes at 6 major measurement points in the Sabine River Basin and 6 major measurement points in the Neches River Basin. TCEQ adopted flow standards for almost all those points. Unfortunately, TCEQ has declined to require the use of those flow regimes as the basis for calculating flow protection levels to be applied at additional flow gages. As a result, determination of compliance with flow protections for individual permits often is based on flow levels at very distant gages that may be located on an entirely different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The adopted flow standards allow diversions down to subsistence flow levels whenever flows at the measurement point are below the seasonal baseflow level. Because subsistence flows represent very low levels intended to be reached only rarely during drought periods, aquatic species are at risk at those levels. If impoundment or diversion under older permits without any flow protections causes flows to drop below baseflow level, flow protections applicable for new permits also drop, just when better protection under new permits is most needed.
Instream flow, levels of baseflows: The expert science team recommended three different levels of baseflows, representing dry, average, and wet conditions because different species do better with different flow levels. Under those recommendations, the lowest levels of protection would apply only during dry conditions when flows naturally are lower, with the highest protection levels applying during wet periods. The flow standards adopted by TCEQ only protect a single level slightly above the level recommended by the expert science team for protection during dry conditions.
Instream flows, levels of pulse flows: The expert science team recommended two different levels of pulse flows, generally representing average, and wet conditions, for protection. However, the adopted flow standards only protect a single level of pulse flow that corresponds to the lowest level recommended for protection by the expert science team.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the voluntary implementation of proactive strategies to improve impaired flow levels. There are no strategy targets for instream flows or freshwater inflows in these flow standards.
Freshwater inflows, drought period criteria: The expert science team evaluated the levels of inflows expected to reach Sabine Lake if its full instream flow protection recommendations were adopted. The science team concluded those recommendations would protect adequate levels of freshwater inflows. TCEQ, although adopting much less protective levels for instream flow than recommended by the expert science team, relied on that science team evaluation as support the agency’s decision not to adopt separate freshwater inflow protections, such as drought period inflow criteria.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards later are amended to be more protective. Although there are no separate inflow protections, increased protections for instream flows, if those flows were passed all the way to the estuary, would increase protections for inflows.
Freshwater inflows, strategy targets: There are no targets to guide voluntary proactive strategies, such as purchases of existing water rights, to increase instream flows or bay inflows.
Overall: match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. Levels of protection in adopted flow standards are much lower than recommended by the expert science team.
Status of Flows Standards in Nueces River and Corpus Christi and Baffin Bays
Instream flows, number of measurement points: The expert science team recommended instream flow levels at 18 measurement points in the Nueces River Basin, 1 on Oso Creek, and 1 on San Fernando Creek above Baffin Bay. TCEQ adopted flow standards for almost all those measurement points. Unfortunately, TCEQ does not require the use of the protected flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, even with numerous measurement points, compliance with flow protections for individual permits often is based on flow levels at very distant gages, sometimes on a different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The expert science team recommended that diversions down to subsistence levels should be allowed only during the driest 10% of the time. The adopted flow standards allow diversions down to subsistence flow levels, subject to the 50% rule, anytime flow falls below the baseflow level. Because subsistence flows represent very low levels intended to be reached only rarely during droughts, aquatic species are at risk at those levels. Under the adopted standards when impoundment or diversion under older permits without flow protection causes flows to drop below the baseflow level, flow protections applicable for new permits also drop, just when more protection under new permits is most needed. The flow standards do apply a “50% rule” to limit the how quickly flows drop to subsistence levels: the permit holder can divert, or impound, only half of the flow between the subsistence level and the applicable baseflow level. So, if flow at the measurement point is 100 cfs and the subsistence level is 50 cfs, in theory, the permit holder only gets 25 cfs. However, the 50% rule really can only work if there is a nearby measurement point, which is rare.
Instream flow, levels of baseflows: The expert science team recommended three different levels of baseflows, representing dry, average, and wet conditions because different species do better with different flow levels. The adopted flow standards only protect one level of baseflows, which has seasonal flow levels matching the science team recommendations for average hydrological conditions.
Instream flows, levels of pulse flows: The expert science team recommended many levels of pulse flow protections (5 to 8) at the various measurement points. The adopted flow standards protect 2 to 3 levels of pulse flows that generally match the lowest pulse flow recommendations by the science team. However, even within those pulse flow levels, during many seasons the standards do not protect smaller pulses recommended for protection by the science team because TCEQ considered the pulse flow levels to be insufficiently different from baseflow levels.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows in these flow standards.
Freshwater inflows, drought period criteria: The expert science team recommended low volumes of seasonal inflows for the Nueces Bay and Delta that should be met in most years—the recommended attainment frequencies range from 69% to 88% of future seasonal periods. Attainment frequencies define the percentage of time at least those volumes of inflows should occur. The adopted flow standards use the science team recommendations for attainment frequencies solely as targets for voluntary protection efforts. The standards applicable for new permits use far lower attainment frequencies than those the science team recommended as adequate to protect a sound ecological environment. The expert science team indicated that, because of existing low flow inflow levels, among other factors, the Nueces Bay and estuary does not represent a sound ecological environment. There are no drought-period minimum inflows.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase protection by a limited amount if flow standards later are amended to be more protective. TCEQ implementation does not provide a mechanism for reopening the freshwater inflow component of new permits.
Freshwater inflows, strategy targets: The standards do include broad attainment frequency targets to guide implementation of voluntary proactive strategies, such as purchases of existing water rights, to increase bay inflows. Because strategies to increase inflows likely will provide relatively small volumes of water, broad targets for attainment frequencies of large inflow volumes, although conceptually important, may have limited utility.
Overall: match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. The instream flow component of the standards differs from many aspects of the science team recommendations, including frequency of diversions down to subsistence levels, fewer baseflow levels, and fewer protected pulse flows. The freshwater inflow component of the adopted standards, although matching the structure of science team recommendations, protects much lower attainment frequencies.
Status of Flows Standards in Guadalupe, San Antonio, Mission and Aransas River Basins and Mission, Copano, Aransas, and San Antonio Bays
Instream flows, number of measurement points: The expert science team provided recommendations for flow levels at 9 measurement points in the Guadalupe River Basin, 6 in the San Antonio River Basin and 1 in Mission River basin. TCEQ adopted flow standards for all those measurement points. Unfortunately, TCEQ does not require the use of the flow regimes at those points to calculate protection levels to be applied at additional flow gages. As a result, even with those measurement points, compliance with flow protections for individual permits often is based on flow levels at very distant gages, sometimes on a different stream. That means a diversion that dries up a local stream may “comply” with flow standards if there is flow at the distant measurement point.
Instream flows, diversions down to subsistence levels: The adopted flow standards for the San Antonio and Mission river basins only allow diversions down to subsistence flow levels during hydrological conditions representing the driest 25% of the time. Because subsistence flows represent very low levels intended to be reached only rarely during drought periods, aquatic species are at risk at those flow levels. In the Guadalupe River Basin, diversion down to subsistence is allowed, subject to the 50% rule, anytime flow falls below the baseflow level. The expert science team recommended the same approach for the Guadalupe Basin as adopted for the San Antonio and Mission basins. Under the adopted standards, however, in the Guadalupe Basin when diversion under older permits without flow protections causes flows to drop below baseflow level, flow protections applicable for new permits also drop, just when more protection under new permits is most needed. The flow standards in that basin do apply a “50% rule” to limit the drop in flow levels: the permit holder can divert or impound half of the flow above the subsistence level. So, if flow at the measurement point is 100 cfs, the baseflow level is 150 cfs, and the subsistence level is 50 cfs, in theory, the permit holder only gets 25 cfs. However, the 50% rule really can only work where there is a nearby measurement point, which is rare.
Instream flow, levels of baseflows: The expert science team recommended three different levels of baseflows, representing dry, average, and wet conditions, for all locations because different species do better with different flow levels. The flow standards adopted by TCEQ match the expert science team recommendations for the San Antonio and Mission basins, but include only one level of baseflow for the Guadalupe Basin, although it is fairly high.
Instream flows, levels of pulse flows: The expert science team recommended five different levels of pulse flow protections at most locations. The adopted flow standards generally protect only the lowest two levels of those pulse flows, and with exceptions that allow some new permits to avoid, based on diversion rate, complying with pulse flow protections.
Instream flows, strategy targets: Under the applicable statute (SB 3), flow standards, in addition to establishing criteria for new permits, are intended to establish target levels of river flows and freshwater inflows to bays and estuaries to be met through the implementation of voluntary proactive strategies, such as purchases of water rights, to improve impaired flow levels. There are no strategy targets for instream flows in these flow standards.
Freshwater inflows, drought period criteria: The expert science team recommended annual flow regimes for dry periods for San Antonio Bay with accompanying attainment frequencies. Attainment frequencies define how often levels are allowed to be reduced below the recommendations. The adopted flow standards only use the science team recommendations for attainment frequency as targets for voluntary protection efforts. Adopted standards applicable for new permits use much less protective attainment frequencies than those identified by the science team as adequate to protect a sound ecological environment. They also fail to identify minimum flows for drought periods. There are no drought period criteria for Mission Bay, only a single criterion for rare high inflow events.
Freshwater inflows, reopener mechanism: Senate Bill 3 directs that permits issued after Sept. 1, 2007, can be reopened to increase inflow protection by a limited amount if flow standards are amended to be more protective. TCEQ implementation does not provide a mechanism for reopening the freshwater inflow component.
Freshwater inflows, strategy targets: There are broad attainment frequency targets to guide voluntary proactive strategies, such as purchases of existing water rights, to increase bay inflows. Because strategies to increase inflows likely will provide relatively small volumes of water, broad targets for attainment frequencies of large volumes, although conceptually important, may have limited utility.
Overall, match with science team recommendations: The expert science teams were charged with developing recommendations adequate to protect a sound ecological environment. The instream flow component matches expert science team recommendations for the San Antonio and Mission basins except that protections for most larger pulse flows were omitted or reduced in size. Instream flow components for Guadalupe Basin are less protective than science team recommendations in multiple ways. The freshwater inflow components of the adopted standards, although reflecting the structure of science team recommendations, protect much lower attainment frequencies.
Note: no standards have been adopted for the four basins that don’t flow to the Texas coast: the Canadian River, Red River, Cypress Creek, and Sulphur River.
Key SB 3 Directive
Implementation Status as of 2021
Development and Adoption of Environmental Flow Standards
Partial
Flow standards adopted for most areas. Standards less protective than needed.
Set-Asides
State-owned surface water not previously authorized for other use should be set-aside for flow protection.
No action
Affirmative Strategies
Strategies to help convert some existing perpetual water rights to flow protection purposes
Limited to no action
Some strategy targets established for inflows to some bays. No significant action to implement strategies.
Adaptive Management Process
Periodic reconsideration and adjustment of flow protection efforts on a 10 year cycle.
Reviews of flow standards to begin no later than 2021.
Review process, which is undefined and unfunded, has not begun.
Fishing
Commercial and recreational fishing along the Texas Coast are both threatened by the longterm reduction of freshwater inflows.
Whooping Cranes
Inflows from the Guadalupe and San Antonio Rivers support the only wintering home for the tallest bird in North America (which remains highly endangered).
Recreation
Swimming, kayaking, and fishing are beloved Texas pastimes and large economic drivers that depend on the healthy flow of water throughout the state’s streams and rivers.
Oysters
Oysters have traditionally thrived in Texas bays and estuaries where they provide multiple benefits. Prolonged periods of low freshwater inflows put oysters at risk.
Mussels
Texas rivers are home to more than 50 species of freshwater mussels. A foundational layer of the food pyramid, mussels are vulnerable to highly altered flow regimes and many species in Texas are now in rapid decline.
