Instream Flows

April 1, 2016

Brackenridge Park

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Map

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SAWS Reuse Water

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Dos Rios Discharge at Brackenridge Park

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2.00 2.00 2.00 2.04 2.03 2.00 2.10 2.04 2.28 2.03 2.04 2.04

0.00

2.00

4.00

6.00

8.00

10.00

Mar-15 Apr-15 May-15 Jun-15 Jul-15 Aug-15 Sep-15 Oct-15 Nov-15 Dec-15 Jan-16 Feb-16

Permit Limit = 10 mg/l

Graph Courtesy of San Antonio Water Systems

Erosion Over Sidewalk

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Bridge Stops Some of the Floating Debris

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Floating Debris

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Lower San Antonio River Instream Flows Project

Senate Bill 2

Goal – Conduct Scientific and Engineering Studies to Determine Flow Regimes (both Water Quality , Quantity and Timing) Necessary to Support a Sound Ecological Environment

Established the Instream Flows Program

Multi-Agency Team

Multi-Discipline Approach

Hydrology and Hydraulics

Biology

Physical Processes

Water Quality

Connectivity

Stakeholder ProcessStakeholders are a critical component of the Texas Instream Flows Program.

Stakeholder meetings held 2008

Flow Recommendations

Integrated Approach

Flow Recommendations

Subsistence flows

Base flows (dry, average and wet)

High pulse flows

Over bank flow

Seasonal component

Lower San Antonio River and Cibolo Creek Instream Flow Study

Upcoming Stakeholder Process

We have: •Data•Analysis •Modeling

We need: •You!

Please Save the Date

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Thursday, October 27, 2016or

Friday, October 28, 2016Location: TBD

Time: TBD(one will be an evening and one will be

daytime)

Environmental Flows

Amount of water that should remain in stream or river for benefit of environment, bay, & estuary while balancing human needs.House Bill 3 and Senate Bill 3 – manage and preserve water resources of state and protect instream and freshwater inflows.Developed Environmental Flows Advisory Group and Science Advisory Committee

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Guadalupe, San Antonio, Mission, & Aransas Rivers and Mission, Copano, Aransas, & San Antonio Bays Basin & Bay Expert Science Team (BBEST)

Blanco River @ Wimberley, TX

Plum Creek near Luling, TX

Guadalupe River @ Cuero, TX

Sandies Creek near Westhoff, TX

Guadalupe River @ Victoria, TX

Guadalupe River near Spring Branch, TX

Medina River @ San Antonio, TX

San Antonio River near Falls City, TX

Cibolo Creek near Falls City, TX

Mission River @ Refugio, TX

San Antonio River @ Goliad, TX

San Marcos River @ Luling, TX

San Antonio River near Elmendorf, TX

Medina River @ Bandera, TX

Guadalupe River @ Comfort, TX

Guadalupe River @ Gonzales, TX

GSA BBASC Recommendations

Subsistence

Flows (cfs)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Qp: 1,410 cfs with Average

Frequency 2 per season

Regressed Volume is 11,400

Duration Bound is 13

746591 591

400 400

Base Flows

(cfs)

791

Overbank

Flows

Qp: 36,700 cfs with Average Frequency 1 per 5 years

Regressed Volume is 492,000

Duration Bound is 70

Qp: 24,400 cfs with Average Frequency 1 per 2 years

Regressed Volume is 306,000

Duration Bound is 57

Qp: 14,300 cfs with Average Frequency 1 per year

Regressed Volume is 165,000

Duration Bound is 43

High Flow

Pulses

Qp: 4,140 cfs with Average

Frequency 1 per season

Regressed Volume is 48,300

Duration Bound is 29

Qp: 6,590 cfs with Average

Frequency 1 per season

Regressed Volume is 58,400

Duration Bound is 24

727

796

Qp: 1,760 cfs with Average

Frequency 1 per season

Regressed Volume is 14,800

Duration Bound is 14

Qp: 4,330 cfs with Average

Frequency 1 per season

Regressed Volume is 41,200

Duration Bound is 23

Qp: 1,150 cfs with Average

Frequency 2 per season

Regressed Volume is 9,640

Duration Bound is 13

Qp: 3,250 cfs with Average

Frequency 2 per season

Regressed Volume is 26,900

Duration Bound is 17

Qp: 950 cfs with Average

Frequency 2 per season

Regressed Volume is 7,060

Duration Bound is 10

210 210 210

Summer FallWinter Spring

180

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TCEQ Environmental Flow Standards

Subsistence

Flows (cfs)

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

210 210 210

Summer FallWinter Spring

180

Base Flows

(cfs)

High Flow

Pulses

796

Qp: 1,150 cfs with Average

Frequency 2 per season

Regressed Volume is 9,640

Duration Bound is 13

Qp: 3,250 cfs with Average

Frequency 2 per season

Regressed Volume is 26,900

Duration Bound is 17

Qp: 1,760 cfs with Average

Frequency 2 per season

Regressed Volume is 14,800

Duration Bound is 14

Qp: 1,410 cfs with Average

Frequency 2 per season

Regressed Volume is 11,400

Duration Bound is 13

746791 727

1) Hardy Base flow adjustment.2) 50% Rule between Base and Subsistence.3) Pulse Exemption Rule.

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TCEQ Environmental Flow Standards for SARB

Mid-Basin Surface Water Project

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Lower Basin New Appropriation

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Mid-Basin Project Firm Yield

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TCEQ Standards

Next Steps

TCEQ implementing Environmental Flow Standards on new/amended water rights.

SARA continues to fund and support scientific studies to refine numbers appropriate for instream and environmental flows.

Revisions to standards made in ten years from adoption. (2022)

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Questions

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