For the Commission TPDES PERMIT NO. WQ0001369000 [For TCEQ office use only - EPA I.D. No. TX0o.57s761
TEXAS COMMISSION ON ENVIRONMENTAL QUALITY

P. 0. Box 13087 Austin, Texas 78711-3087 This is a renewal of TPDES Permit No. WQ0001369000 issued on June 27, 2005. PERMIT TO DISCHARGE WASTES under provisions of Section 402 of the Clean Water Act and Chapter 26 of the Texas Water Code

Lower Colorado River Authority whose mailing address is

2001 Ferguson Road Horseshoe Bay, Texas 78657 is authorized to treat and discharge wastes from Thomas C. Ferguson Power Plant, a steam electric station (SIC 4911) located adjacent to Lake Lyndon B. Johnson, approximately 7 miles west of the City of Marble Falls, and approximately 1 mile north of Ranch Road 2147, Llano County, Texas directly to Lake Lyndon B. Johnson in Segment No. 1406 of the Colorado River Basin only according to effluent limitations, monitoring requirements and other conditions set forth in this permit, as well as the rules of the Texas Commission on Environmental Quality (TCEQ), the laws of the State of Texas, and other orders of the TCEQ. The issuance of this permit does not grant to the permittee the right to use private or public property for conveyance of wastewater along the discharge route described in this permit. This includes, but is not limited to, property belonging to any individual, partnership, corporation, or other entity. Neither does this permit authorize any invasion of personal rights nor any violation of federal, state, or local laws or regulations. It is the responsibility of the permittee to acquire property rights as may be necessary to use the discharge route. This permit shall expire at midnight on December 1, 2016. ISSUED DATE: February 4, 2013EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 001
1. During the period beginning upon date of issuance and lasting through date of expiration, the permittee is authorized to discharge once through cooling water (*1), auxiliary cooling water, stormwater, and previously monitored effluents (PME) subject to the following effluent limitations: The daily average flow of effluent shall not exceed 435 million gallons per day (MGD). The daily maximum flow shall not exceed 435 MGD.
Effluent Characteristics Discharge Limitations Minimum Self-Monitoring Requirements Daily Average Daily Maximum Single Grab Report Daily Average and Daily Maximum lbs/day mg/L lbs/day 1ng/L mg/L Measurement Frequency Sample Type Flow (MGD) (Report) (Report) N/A Continuous Calculated Total Residual Chlorine (*1) N/A N/A 6o.5 0.2 0.2 1/week Grab (*2) Temperature (°F) (*1) (io6) (ilo) N/A Continuous Record (*l) See Other Requirement No. 3. (*2) Samples shall be representative of periods of chlorination.
2. There shall be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.
3. Effluent monitoring samples shall be taken at the following location: At Outfall 001, where once through cooling water, auxiliary cooling water, storm water and PME discharge from the canal to Lake Lyndon B. Johnson.

Page 2 of TPDES Permit No. WQ000l369000 Lower Colorado River AuthorityEFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 101
1. During the period beginning upon date of issuance and lasting through date of expiration, the permittee is authorized to discharge low volume waste sources (*1) from the neutralization basin subject to the following effluent limitations:
Volume: Intermittent and flow variable.
Effluent Characteristics Discharge Limitations Minimum Self-Monitoring Requirements Daily Average Daily Maximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L Measurement Frequency Sample Type Flow (MGD) (Report) (Report) N/A i/week (*2) Estimate Total Suspended Solids 30 100 100 Vweek (*2) Grab Oil and Grease 15 20 20 i/week (*2) Grab (*1) See Other Requirement No. 3. (*2) When discharging.
2. The pH shall not be less than 6.o standard units nor greater than 9.o standard units and shall be monitored 1/week (*2) by grab sample.
3. There shall be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

4. Effluent monitoring samples shall be taken at the following location: At Outfall 101, where low volume waste sources contained in the neutralization basin are discharged prior to mixing with any other waters.

Page 2a of TPDES Permit No. WQ000l369000 Lower Colorado River AuthorityEFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 201
1. During the period beginning upon date of issuance and lasting through date of expiration, the permittee is authorized to discharge low volume waste sources (*1) from the API Separator, basement underdrain, and other sources subject to the following effluent limitations:
Volume: Flow variable.
Effluent Characteristics Discharge Limitations Minimum Self-Monitoring Requirements Daily Average Daily Maximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L Measurement Frequency Sample Type Flow (MGD) (Report) (Report) N/A i/week (*2) Instantaneous Total Suspended Solids 30 too loci 1/week (*2) Grab (*3) Oil and Grease 15 20 20 i/week (*2) Grab (*4) (*1) See Other Requirement No. 3. (*2) When discharging. (*3) If more than one source is associated with this particular waste category, grab samples from each source shall be combined into a single flow weighted sample for analysis and reporting. If more than one source is associated with this particular waste category, the source with the highest oil and grease analysis shall be reported.
2. The pH shall not be less than 6.o standard units nor greater than 9.0 standard units and shall be monitored 1/week (*2) by grab (*3) sample.
3. There shall be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.
4. Effluent monitoring samples shall be taken at the following location: At Outfall 201, where low volume waste sources are discharged from the API Separator, basement underdrains, or other low yob ime waste sources and prior to mixing with any other waters.

Page 2b of TPDES Permit No. WQ000136900o Lower Colorado River AuthorityEFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 301
1. During the period beginning upon date of issuance and lasting through date of expiration, the permittee is authorized to discharge stormwater from the diked oil storage area subject to the following effluent limitations:
Volume: Intermittent and flow variable.
Effluent Characteristics Discharge Limitations Minimum Self-Monitoring Requirements Daily Average Daily Maximum Single Grab Report Daily Average and Daily Maximum mg/L mg/L mg/L Measurement Frequency Sample Type Flow (MGD) (Report) (Report) N/A 1/week (*1) Estimate Total Suspended Solids 3o ioo ioo i/week ("1) Grab Oil and Grease 15 20 20 1/week (*1) Grab (*1) When discharging.
2. The pH shall not be less than 6.o standard units nor greater than 9.0 standard units and shall be monitored 1/week (*1) by grab sample.
3. There shall be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.

q. Effluent monitoring samples shall be taken at the following location: At Outfall 301, where stormwater is discharged from the API Separator prior to commingling with any other waters.

Page 2c of TPDES Permit No. WQ0001369000 Lower Colorado River AuthorityMinimum Self-Monitoring Requirements Report Daily Average and Daily Maximum Measurement Frequency Sample Type i/day (*2) i/day (*2) i/day (*2) i/day (*2) 1/day (*2) Estimate Grab Grab Grab Grab EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Outfall Number 401
1. During the period beginning upon date of issuance and lasting through date of expiration, the permittee is authorized to discharge metal cleaning waste and/or low volume waste sources by a combination of evaporation and infiltration (*1), subject to the following effluent limitations:
Volume: Intermittent and flow variable.
Effluent Characteristics Discharge Limitations Daily Average Daily Maximum Single Grab mg/L mg/L mg/L Flow (MGD) (Report) (Report) N/A Total Suspended Solids 3o 100 100 Oil and Grease 15 20 20 Iron, Total 1.o 1.0 1.0 Copper, Total 0.5 1.0 1.0 (*1) See Other Requirement No. 7. (*2) When discharging.
2. The pH shall not be less than 6.o standard units nor greater than 9.0 standard units and shall be monitored 1/week (*2) by grab sample.
3. There shall be no discharge of floating solids or visible foam in other than trace amounts and no discharge of visible oil.
4. Effluent monitoring samples shall be taken at the following location: At Outfall 401, where metal cleaning waste and/or low volume waste sources are discharged from the retention pond prior to commingling with any other waters.

Page 2d of TPDES Permit No. WQ00013690o0 Lower Colorado River AuthorityLower Colorado River Authority TPDES Permit No. WQ0o01369000

DEFINITIONS AND STANDARD PERMIT CONDITIONS As required by Title 30 Texas Administrative Code (TAC) Chapter 305, certain regulations appear as standard conditions in waste discharge permits. 3o TAC §§305.121- 305.129 (relating to Permit Characteristics and Conditions) aspromulgated under the Texas Water Code (TWC) §§5.103 and 5.105, and the Texas Health and Safety Code (THSC) §§361.017 and 361.024(a), establish the characteristics and standards for waste discharge permits, including sewage sludge, and those sections of 4o Code of Federal Regulations (CFR) Part 122 adopted by reference by the Commission. The following text includes these conditions and incorporates them into this permit. All definitions in Texas Water Code §26.001 and 3o TAC Chapter 305 shall alp-ply to this permit and are incorporated by reference. Some specific definitions of words or phrases uses in this permit are as follows: 1. Flow Measurements

a. Annual average flow - the arithmetic average of all daily flow determinations taken within the preceding 12 consecutive calendar months. The annual average flow determination shall consist of daily flow volume determinations made by a totalizing meter, charted on a chart recorder, and limited to major domestic wastewater discharge facilities with a one million gallons per day or greater permitted flow. b. Daily average flow - the arithmetic average of all determinations of the daily flow within a period of one calendar month. The daily average flow determination shall consist of determinations made on at least four separate days. If instantaneous measurements are used to determine the daily flow, the determination shall be the arithmetic average of all instantaneous measurements taken during that month. Daily average flow determination for intermittent discharges shall consist of a minimum of three flow determinations on days of discharge.

c. Daily maximum flow - the highest total flow for any 24-hour period in a calendar month. d. Instantaneous flow - the measured flow during the minimum time required to interpret the flow measuring device.

e. 2-hour peak flow (domestic wastewater treatment plants) - the maximum flow sustained for a two-hour period during the period of daily discharge. The average of multiple measurements of instantaneous maximum flow within a two-hour period may be used to calculate the 2-hour peak flow. f. Maximum 2-hour peak flow (domestic wastewater treatment plants) - the highest 2-hour peak flow for any 24-hour period in a calendar month. 2. Concentration Measurements a. Daily average concentration - the arithmetic average of all effluent samples, composite or grab as required by this permit, within a period of one calendar month, consisting of at least four separate representative measurements. i. For domestic wastewater treatment plants - When four samples are not available in a calendar month, the arithmetic average (weighted by flow) of all values in the previous four consecutive month period consisting of at least four measurements shall be utilized as the daily average concentration. ii. For all other wastewater treatment plants - When four samples are not available in a calendar month, the arithmetic average (weighted by flow) of all values taken during the month shall be utilized as the daily average concentration. b. 7-day average concentration - the arithmetic average of all effluent samples, composite or grab as required by this permit, within a period of one calendar week, Sunday through Saturday. c. Daily maximum concentration - the maximum concentration measured on a single day, by the sample type specified in the permit, within a period of one calendar month.

Page 3Lower Colorado River Authority TPDES Permit No. W00001369000

d. Daily discharge - the discharge of a pollutant measured during a calendar day or any 24-hour period that reasonably represents the calendar day for purposes of sampling. For pollutants with limitations expressed in terms of mass, the "daily discharge" is calculated as the total mass of the pollutant discharged over the sampling day. For pollutants with limitations expressed in other units of measurement, the "daily discharge" is calculated as the average measurement of the pollutant over the sampling day. The "daily discharge" determination of concentration made using a composite sample shall be the concentration of the composite sample. When grab samples are used, the "daily discharge" determination of concentration shall be the arithmetic average (weighted by flow value) of all samples collected during that day.

e. Bacteria concentration (Fecal coliform, E. coli, or Enterococci) — the number of colonies of bacteria per 100 milliliters effluent. The daily average bacteria concentration is a geometric mean of the values for the effluent samples collected in a calendar month. The geometric mean shall be determined by calculating the nth root of the product of all measurements made in a calendar month, where n equals the number of measurements made; or computed as the antilogarithm of the arithmetic mean of the logarithms of all measurements made in a calendar month. For any measurement of bacteria equaling zero, a substitute value of one shall made for input into either computation method. If specified, the 7-day average for bacteria is the geometric mean of the values for all effluent samples collected during a calendar week. f. Daily average loading (lbs/day) - the arithmetic average of all daily discharge loading calculations during a period of one calendar month. These calculations must be mace for each day of the month that a parameter is analyzed. The daily discharge, in terms of mass (lbs/day), is calculated as (Flow, MGD x Concentration, mg/L x 8.34). Daily maximum loading (lbs/day) - the highest daily discharge, in terms of mass (lbs/day), within a period of one calendar month. 3. Sample Type

a. Composite sample - For domestic wastewater, a composite sample is a sample made up of a minimum of three effluent portions collected in a continuous 24-hour period or during the period of daily discharge if less than 24 hours, and combined in volumes proportional to flow, and collected at the intervals required by 3o TAC §319.9(a). For industrial wastewater, a composite sample is a sample made up of a minimum of three effluent portions collected in a continuous 24-hour period or during the period of daily discharge if less than 24 hours, and combined in volumes proportional to flow, and collected at the intervals required by 3o TAC §319.9(b). b. Grab sample - an individual sample collected in less than 15 minutes. 4. Treatment Facility (facility) - wastewater facilities used in the conveyance, storage, treatment, recycling, reclamation and/or disposal of domestic sewage, industrial wastes, agricultural wastes, recreational wastes, or other wastes including sludge handling or disposal facilities under the jurisdiction of the Commission. 5. The term "sewage sludge" is defined as solid, semi-solid, or liquid residue generated during the treatment of domestic sewage in 30 TAC Chapter 312. This includes the solids that have not been classified as hazardous waste separated from wastewater by unit processes. 6. Bypass - the intentional diversion of a waste stream from any portion of a treatment facility. MONITORING AND REPORTING REQUIREMENTS 1. Self-Reporting Monitoring results shall be provided at the intervals specified in the permit. Unless otherwise specified in this permit or otherwise ordered by the Commission, the permittee shall conduct effluent sampling and reporting in accordance with 3o TAC §§319.4 - 319.12. Unless otherwise specified, a monthly effluent report shall be submitted each month, to the Enforcement Division 

### g.

Page 4Lower Colorado River Authority TPDES Permit No. WQ0001369000

(MC 224), by the loth day of the following month for each discharge that is described by this permit whether or not a discharge is made for that month. Monitoring results must be reported on an approved self-report form that is signed and certified as required by Monitoring and Reporting Requirements No. 10. As provided by state law, the permittee is subject to administrative, civil and criminal penalties, as applicable, for negligently or knowingly violating the Clean Water Act; TWC Chapters 26, 27, and 28; and THSC Chapter 361, including but not limited to knowingly making any false statement, representation, or certification on any report, record, or other document submitted or required to be maintained under this permit, including monitoring reports or reports of compliance or noncompliance, or falsifying, tampering with or knowingly rendering inaccurate any monitoring device or method required by this permit or violating any other requirement imposed by state or federal regulations. 2. Test Procedures

a. Unless otherwise specified in this permit, test procedures for the analysis of pollutants shall comply with procedures specified in 3o TAC §§319.11- 319.12. Measurements, tests, and calculations shall be accurately accomplished in a representative manner. b. All laboratory tests submitted to demonstrate compliance with this permit must meet the requirements of 30 TAC Chapter 25, Environmental Testing Laboratory Accreditation and Certification. 3- Records of Results

a. Monitoring samples and measurements shall be taken at times and in a manner so as to be representative of the monitored activity. b. Except for records of monitoring information required by this permit related to the permittee's sewage sludge use and disposal activities, which shall be retained for a period of at least five years (or longer as required by 4o CFR Part 503), monitoring and reporting records, including strip charts and records of calibration and maintenance, copies of all records required by this permit, records of all data used to complete the application for this permit, and the certification required by 4o CFR §264.73(b)(9) shall be retained at the facility site, or shall be readily available for review by a TCEQ representative for a period of three years from the date of the record or sample, measurement, report, application or certification. This period shall be extended at the request of the Executive Director. c. Records of monitoring activities shall include the following: i. date, time, and place of sample or measurement; ii. identity of individual who collected the sample or made the measurement. iii. date and time of analysis; iv. identity of the individual and laboratory who performed the analysis; v. the technique or method of analysis; and vi. the results of the analysis or measurement and quality assurance/quality control records. The period during which records are required to be kept shall be automatically extended to the date of the final disposition of any administrative or judicial enforcement action that may be instituted against the permittee. 4. Additional Monitoring by Permittee lithe permittee monitors any pollutant at the location(s) designated herein more frequently than required by this permit using approved analytical methods as specified above, all results of such monitoring shall be included in the calculation and reporting of the values submitted on the approved self-report form. Increased frequency of sampling shall be indicated on the self-report form.

Page 5Lower Colorado River Authority TPDES Permit No. WQ0001369000

5. Calibration of Instruments All automatic flow measuring or recording devices and all totalizing meters for measuring flows shall be accurately calibrated by a trained person at plant start-up and as often thereafter as necessary to ensure accuracy, but not less often than annually unless authorized by the Executive Director for a longer period. Such person shall verify in writing that the device is operating properly and giving accurate results. Copies of the verification shall be retained at the facility site and/or shall be readily available for review by a TCEQ representative for a period of three years. 6. Compliance Schedule Reports Reports of compliance or noncompliance with, or any progress reports on, interim and final requirements contained in any compliance schedule of the permit shall be submitted no later than 14 days following each schedule date to the Regional Office and the Enforcement Division (MC 224). 7. Noncompliance Notification a. In accordance with 3o TAC §305.125(9) any noncompliance that may endanger human health or safety, or the environment shall be reported by the permittee to the TCEQ. Report of such information shall be provided orally or by facsimile transmission (FAX) to the Regional Office within 24 hours of becoming aware of the noncompliance. A written submission of such information shall also be provided by the permittee to the Regional Office and the Enforcement Division (MC 224) within five working days of becoming aware of the noncompliance. The written submission shall contain a description of the noncompliance and its cause; the potential danger to human health or safety, or the environment; the period of noncompliance, including exact dates and times; if the noncompliance has not been corrected, the time it is expected to continue; and steps taken or planned to reduce, eliminate, and prevent recurrence of the noncompliance, and to mitigate its adverse effects. b. The following violations shall be reported under Monitoring and Reporting Requirement 7.a.: i. Unauthorized discharges as defined in Permit Condition 2(g). ii. Any unanticipated bypass that exceeds any effluent limitation in the permit. iii. Violation of a permitted maximum daily discharge limitation for pollutants listed specifically in the Other Requirements section of an Industrial TPDES permit.

c. In addition to the above, any effluent violation that deviates from the permitted effluent limitation by more than 4o% shall be reported by the permittee in writing to the Regional Office and the Enforcement Division (MC 224) within 5 working days of becoming aware of the noncompliance. d. Any noncompliance other than that specified in this section, or any required information not submitted or submitted incorrectly, shall be reported to the Enforcement Division (MC 224) as promptly as possible. For effluent limitation violations, noncompliances shall be reported on the approved self-report form. 8. In accordance with the procedures described in 30 TAC §§35.301- 35.303 (relating to Water Quality Emergency and Temporary Orders) if the permittee knows in advance of the need for a bypass, it shall submit prior notice by applying for such authorization. 9. Changes in Discharges of Toxic Substances All existing manufacturing, commercial, mining, and silvicultural permittees shall notify the Regional Office, orally or by facsimile transmission within 24 hours, and both the Regional Office and the Enforcement Division (MC 224) in writing within five (5) working days, after becoming aware of or having reason to believe: a. That any activity has occurred or will occur that would result in the discharge, on a routine or frequent basis, of any toxic pollutant listed at 4o CFR Part 122, Appendix D, Tables II and III (excluding Total Phenols) that is not limited in the permit, if that discharge will exceed the highest of the following "notification levels":

Page 6Lower Colorado River Authority TPDES Permit No. WQo 001369000

i. One hundred micrograms per liter (100 plg/L); ii. Two hundred micrograms per liter (zoo g/L) for acrolein and acrylonitrile; five hundred micrograms per liter (500 pg/L) for 2,4-dinitrophenol and for 2-methyl-4,6-dinitrophenol; and one milligram per liter (

- 1 mg/L) for antimony; iii. Five (5) times the maximum concentration value reported for that pollutant in the permit application; or iv. The level established by the TCEQ. b. That any activity has occurred or will occur that would result in any discharge, on a nonroutine or infrequent basis, of a toxic pollutant that is not limited in the permit, if that discharge will exceed the highest of the following "notification levels": i. Five hundred micrograms per liter (500 μg/L); ii. One milligram per liter (1 mg/L) for antimony; iii. Ten (lo) times the maximum concentration value reported for that pollutant in the permit application; or iv. The level established by the TCEQ. 10. Signatories to Reports All reports and other information requested by the Executive Director shall be signed by the person and in the manner required by 30 TAC §305.128 (relating to Signatories to Reports). ii. All Publicly Owned Treatment Works (POTWs) must provide adequate notice to the Executive Director of the following:

a. Any new introduction of pollutants into the POTW from an indirect discharger that would be subject to CWA §301 or §306 if it were directly discharging those pollutants; b. Any substantial change in the volume or character of pollutants being introduced into that POTW by a source introducing pollutants into the POTW at the time of issuance of the permit; and

c. For the purpose of this paragraph, adequate notice shall include information on: i. The quality and quantity of effluent introduced into the POTW; and ii. Any anticipated impact of the change on the quantity or quality of effluent to be discharged from the POTW. PERMIT CONDITIONS 1. General

a. When the permittee becomes aware that it failed to submit any relevant facts in a permit application, or submitted incorrect information in an application or in any report to the Executive Director, it shall promptly submit such facts or information. b. This permit is granted on the basis of the information supplied and representations made by the permittee during action on an application, and relying upon the accuracy and completeness of that information and those representations. After notice and opportunity for a hearing, this permit may be modified, suspended, or revoked, in whole or in part, in accordance with 3o TAC Chapter 305, Subchapter D, during its term for good cause including, but not limited to, the following: i. Violation of any terms or conditions of this permit; ii. Obtaining this permit by misrepresentation or failure to disclose fully all relevant facts; or iii. A change in any condition that requires either a temporary or permanent reduction or elimination of the authorized discharge.

Page 7Lower Colorado River Authority TPDES Permit No. WQ0001369000

c. The permittee shall furnish to the Executive Director, upon request and within a reasonable time, any information to determine whether cause exists for amending, revoking, suspending, or terminating the permit. The permittee shall also furnish to the Executive Director, upon request, copies of records required to be kept by the permit. 2. Compliance Acceptance of the permit by the person to whom it is issued constitutes acknowledgment and agreement that such person will comply with all the terms and conditions embodied in the permit, and the rules and other orders of the Commission. The permittee has a duty to comply with all conditions of thepermit. Failure to comply with any permit condition constitutes a violation of the permit and the Texas Water Code or the Texas Health and Safety Code, and is grounds for enforcement action, for permit amendment, revocation, or suspension, or for denial of a permit renewal application or an application for a permit for another facility. It shall not be a defense for a permittee in an enforcement action that it would have been necessary to halt or reduce the permitted activity in order to maintain compliance with the conditions of the permit. d. The permittee shall take all reasonable steps to minimize or prevent any discharge or sludge use or disposal or other permit violation that has a reasonable likelihood of adversely affecting human health or the environment. e. Authorization from the Commission is required before beginning any change in the permitted facility or activity that may result in noncompliance with any permit requirements. f. A permit may be amended, suspended and reissued, or revoked for cause in accordance with 3o TAC §§305.62 and 305.66 and TWC §7.302. The filing of a request by the permittee for a permit amendment, suspension and reissuance, or termination, or a notification of planned changes or anticipated noncompliance, does not stay any permit condition. There shall be no unauthorized discharge of wastewater or any other waste. For the purpose of this permit, an unauthorized discharge is considered to be any discharge of wastewater into or adjacent to water in the state at any location not permitted as an outfall or otherwise defined in the Other Requirements section of this permit. h. In accordance with 3° TAC §305.535(a), the permittee may allow any bypass to occur from a TPDES permitted facility that does not cause permitted effluent limitations to be exceeded or an unauthorized discharge to occur, but only if the bypass is also for essential maintenance to assure efficient operation. i. The permittee is subject to administrative, civil, and criminal penalties, as applicable, under Texas Water Code §§7.051- 7.075 (relating to Administrative Penalties), 7.101 - 7.111 (relating to Civil Penalties), and 7.141 - 7.202 (relating to Criminal Offenses and Penalties) for violations including, but not limited to, negligently or knowingly violating the federal CWA §§3o1, 302, 306, 307, 308, 318, or 405, or any condition or limitation implementing any sections in a permit issued under the CWA §402, or any rec uirement imposed in a pretreatment program approved under the CWA §§402(a)(3) or 4026)(8). 3. Inspections and Entry Inspection and entry shall be allowed as prescribed in the TWC Chapters 26, 27, and 28, and THSC Chapter 361. The members of the Commission and employees and agents of the Commission are entitled to enter any public or private property at any reasonable time for the purpose of inspecting and investigating conditions relating to the quality of water in the state or the compliance with any rule, regulation, permit, or other order of the Commission. Members, employees, or agents of the Commission and Commission contractors are entitled to enter public or private property at any reasonable time to investigate or monitor or, if the responsible party is not responsive a.

b.

c.

g.

a.
b.

Page 8Lower Colorado River Authority TPDES Permit No. WQ0001369oo0

or there is an immediate danger to public health or the environment, to remove or remediate a condition related to the quality of water in the state. Members, employees, Commission contractors, or agents acting under this authority who enter private property shall observe the establishment's rules and regulations concerning safety, internal security, and fire protection, and if the property has management in residence, shal_ notify management or the person then in charge of his presence and shall exhibit proper credentials. If any member, employee, Commission contractor, or agent is refused the right to enter in or on public or private property under this authority, the Executive Director may invoke the remedies authorized in TWC §7.002. The statement above, that Commission entry shall occur in accordance with an establishment's rules and regulations concerning safety, internal security, and fire protection, is not grounds for denial or restriction of entry to any part of the facility, but merely describes the Commission's duty to observe appropriate rules and regulations during an inspection. 4. Permit Amendment or Renewal a. The permittee shall give notice to the Executive Director as soon as possible of any planned physical alterations or additions to the permitted facility if such alterations or adcitions would require a permit amendment or result in a violation of permit requirements. Notice shall also be required under this paragraph when: i. The alteration or addition to a permitted facility may meet one of the criteria for determining whether a facility is a new source in accordance with 3o TAC §305.534 (relating to New Sources and New Dischargers); or ii. The alteration or addition could significantly change the nature or increase the quantity of pollutants discharged. This notification applies to pollutants that are subject neither to effluent limitations in the permit, nor to notification requirements in Monitoring and Reporting Requirements No. 9; iii. The alteration or addition results in a significant change in the permittee's sludge use or disposal practices, and such alteration, addition, or change may justify the application of permit conditions that are different from or absent in the existing permit, including notification of additional use or disposal sites not reported during the permit application process or not reported pursuant to an approved land application plan. b. Prior to any facility modifications, additions, or expansions that will increase the plant capacity beyond the permitted flow, the permittee must apply for and obtain proper authorization from the Commission before commencing construction.

c. The permittee must apply for an amendment or renewal at least i8o days prior to expiration of the existing permit in order to continue a permitted activity after the expiration date of the permit. If an application is submitted prior to the expiration date of the permit, the existing permit shall remain in effect until the application is approved, denied, or returned. If the application is returned or denied, authorization to continue such activity shall terminate upon the effective date of the action. If an application is not submitted prior to the expiration date of the permit, the permit shall expire and authorization to continue such activity shall terminate. d. Prior to accepting or generating wastes that are not described in the permit application or that would result in a significant change in the quantity or quality of the existing discharge, the permittee must report the proposed changes to the Commission. The permittee must apply for a permit amendment reflecting any necessary changes in permit conditions, including effluent limitations for pollutants not identified and limited by this permit.

e. In accordance with the TWC §26.029(b), after a public hearing, notice of which shall be given to the permittee, the Commission may require the permittee, :rom time to time, for good cause, in accordance with applicable laws, to conform to new or additional conditions. f. If any toxic effluent standard or prohibition (including any schedule of compliance specified in such effluent standard or prohibition) is promulgated. under CWA §307(a) for a toxic pollutant that is present in the discharge and that standard or prohibition is more stringent than any limitation on the pollutant in this permit, this permit shall be modified or revoked and reissued to conform to the toxic effluent standard or prohibition. The permittee shall comply Page 9Lower Colorado River Authority TPDES Permit No. WQ0001369000

with effluent standards or prohibitions established under CWA §3o7(a)for toxic pollutants within the time provided in the regulations that established those standards or prohibitions, even if the permit has not yet been modified to incorporate the requirement. 5• Permit Transfer

a. Prior to any transfer of this permit, Commission approval must be obtained. The Commission shall be notified in writing of any change in control or ownership of facilities authorized by this permit. Such notification should be sent to the Applications Review and Processing Team (MC 148) of the Water Quality Division. b. A permit may be transferred only according to the provisions of 3o TAC §305.64 (relating to Transfer of Permits) and 3o TAC §50.133 (relating to Executive Director Action on Application or WQMP update). 6. Relationship to Hazardous Waste Activities This permit does not authorize any activity of hazardous waste storage, processing, or disposal that requires a permit or other authorization pursuant to the Texas Health and Safety Code. 7. Relationship to Water Rights Disposal of treated effluent by any means other than discharge directly to water in the state must be specifically authorized in this permit and may require a permit pursuant to Texas Water Code Chapter 11. 8. Property Rights A permit does not convey any property rights of any sort, or any exclusive privilege. 9. Permit Enforceability The conditions of this permit are severable, and if any provision of this permit, or the application of any provision of this permit to any circumstances, is held invalid, the application of such provision to other circumstances, and the remainder of this permit, shall not be affected thereby. to. Relationship to Permit Application The application pursuant to which the permit has been issued is incorporated herein; provided, however, that in the event of a conflict between the provisions of this permit and the application, the provisions of the permit shall control. 11. Notice of Bankruptcy.

a. Each permittee shall notify the executive director, in writing, immediately following the filing of a voluntary or involuntary petition for bankruptcy under any chapter of Title 11 (Bankruptcy) of the United States Code (a USC) by or against: i. the permittee; ii. an entity (as that term is defined in 11 USC, §101(15)) controlling the permittee or listing the permit or permittee as property of the estate; or iii. an affiliate (as that term is defined in 11 USC, §101(2)) of the permittee. b. This notification must indicate: i. the name of the permittee; ii. the permit number(s); iii. the bankruptcy court in which the petition for bankruptcy was filed; and iv. the date of filing of the petition.

Page 10Lower Colorado River Authority TPDES Permit No. W(20°01369000

OPERATIONAL REQUIREMENTS 1. The permittee shall at all times ensure that the facility and all of its systems of collection, treatment, and disposal are properly operated and maintained. This includes, but is not limited to, the regular, periodic examination of wastewater solids within the treatment plant by the operator in order to maintain an appropriate quantity and quality of solids inventory as described in the various operator training manuals and according to accepted industry standards for process control. Process control, maintenance, and operations records shall be retained at the facility site, or shall be readily available for review by a TCEQ representative, for a period of three years. 2. Upon request by the Executive Director, the permittee shall take appropriate samples and provide proper analysis in order to demonstrate compliance with Commission rules. Unless otherwise specified in this permit or otherwise ordered by the Commission, the permittee shall comply with all applicable provisions of 3o TAC Chapter 312 concerning sewage sludge use and disposal and 30 TAC §§319.21 319.29 concerning the discharge of certain hazardous metals. 3. Domestic wastewater treatment facilities shall comply with the following provisions:

a. The permittee shall notify the Municipal Permits Team, Wastewater Permitting Section (MC 148) of the Water Quality Division, in writing, of any facility expansion at least 90 days prior to conducting such activity. b. The permittee shall submit a closure plan for review and approval to the Municipal Permits Team, Wastewater Permitting Section (MC 148) of the Water Quality Division, for any closure activity at least 90 days prior to conducting such activity. Closure is the act of permanently taking a waste management unit or treatment facility out of service and includes the permanent removal from service of any pit, tank, pond, lagoon, surface impoundment and/or other treatment unit regulated by this permit. 4. The permittee is responsible for installing prior to plant start-up, and subsequently maintaining, adequate safeguards to prevent the discharge of untreated or inadequately treated wastes during electrical power failures by means of alternate power sources, standby generators, and/or retention of inadequately treated wastewater. 5. Unless otherwise specified, the permittee shall provide a readily accessible sampling point and, where applicable, an effluent flow measuring device or other acceptable means by which effluent flow may be determined. 6. The permittee shall remit an annual water quality fee to the Commission as required by 3o TAC Chapter 21. Failure to pay the fee may result in revocation of this permit under TWC §7.3o2(b)(6). 7. Documentation For all written notifications to the Commission required of the permittee by this permit, the permittee shall keep and make available a copy of each such notification under the same conditions as self-monitoring data are required to be kept and made available. Except for information required for TPDES permit applications, efluent data, including effluent data in permits, draft permits and permit applications, and other information specified as not confidential in 3o TAC §1.5(d), any information submitted pursuant to this permit may be claimed as confidential by the submitter. Any such claim must be asserted in the manner prescribed in the application form or by stamping the words "confidential business information" on each page containing such information. If no claim is made at the time of submission, information may be made available to the public without further notice. If the Commission or Executive Director agrees with the designation of confidentiality, the TCEQ will not provide the information for public inspection unless required by the Texas Attorney General or a court pursuant to an open records request. If the Executive Director does not agree with the designation of confidentiality, the person submitting the information will be notified.

Page 11Lower Colorado River Authority TPDES Permit No. WQ00013690 00

8. Facilities that generate domestic wastewater shall comply with the following provisions; domestic wastewater treatment facilities at permitted industrial sites are excluded.

a. Whenever flow measurements for any domestic sewage treatment facility reach 75% of the permitted daily average or annual average flow for three consecutive months, the permittee must initiate engineering and financial planning for expansion and/or upgrading of the domestic wastewater treatment and/or collection facilities. Whenever the flow reaches 90% of the permitted daily average or annual average flow for three consecutive months, the permittee shall obtain necessary authorization from the Commission to commence construction of the necessary additional treatment and/or collection facilities. In the case of a domestic wastewater treatment facility that reaches 75% of the permitted daily average or annual average flow for three consecutive months, and the planned population to be served or the quantity of waste produced is not expected to exceed the design limitations of the treatment facility, the permittee shall submit an engineering report supporting this claim to the Executive Director of the Commission. If in the judgment of the Executive Director the population to be served will not cause permit noncompliance, then the requirement of this section may be waived. To be effective, any waiver must be in writing and signed by the Director of the Enforcement Division (MC 149) of the Commission, and such waiver of these requirements will be reviewed upon expiration of the existing permit; however, any such waiver shall not be interpreted as condoning or excusing any violation of any permit parameter. b. The plans and specifications for domestic sewage collection and treatment works associated with any domestic permit must be approved by the Commission, and failure to secure approval before commencing construction of such works or making a discharge is a violation of this permit and each day is an additional violation until approval has been secured.

c. Permits for domestic wastewater treatment plants are granted subject to the policy of the Commission to encourage the development of area-wide waste collection, treatment, and disposal systems. The Commission reserves the right to amend any domestic wastewater permit in accordance with applicable procedural requirements to require the system covered by this permit to be integrated into an area-wide system, should such be developed; to require the delivery of the wastes authorized to be collected in, treated by or discharged from said system, to such area-wide system; or to amend this permit in any other particular to effectuate the Commission's policy. Such amendments may be made when the changes required are advisable for water quality control purposes and are feasible on the basis of waste treatment technology, engineering, financial, and related considerations existing at the time the changes are required, exclusive of the loss of investment in or revenues from any then existing or proposed waste collection, treatment or disposal system. 9. Domestic wastewater treatment plants shall be operated and maintained by sewage plant operators holding a valid certificate of competency at the required level as defined in 3o TAC Chapter 30. 10. For Publicly Owned Treatment Works (POTWs), the 3o-day average (or monthly average) percent removal for BOD and TSS shall not be less than 85%, unless otherwise authorized by this permit. 11. Facilities that generate industrial solid waste as defined in 3o TAC §335.1 shall comply with these provisions:

a. Any solid waste, as defined in 3o TAC §335.1 (including but not limited to such wastes as garbage, refuse, sludge from a waste treatment, water supply treatment plant or air pollution control facility, discarded materials, discarded materials to be recycled, whether the waste is solid, liquid, or semisolid), generated by the permittee during the management and treatment of wastewater, must be managed in accordance with all applicable provisions of 30 TAC Chapter 335, relating to Industrial Solid Waste Management. b. Industrial wastewater that is being collected, accumulated, stored, or processed before discharge through any final discharge outfall, specified by this permit, is considered to be industrial solid waste until the wastewater passes through the actual point source discharge and must be managed in accordance with all applicable provisions of 30 TAC Chapter 335. Page 12Lower Colorado River Authority TPDES Permit No. WQoo0l369000

c. The permittee shall provide written notification, pursuant to the requirements of 30 TAC §335.8(b)(1), to the Corrective Action Section (MC 127) of the Remediation Division informing the Commission of any closure activity involving an Industrial Solid Waste Management Unit, at least 90 days prior to conducting such an activity. d. Construction of any industrial solid waste management unit requires the prior written notification of the proposed activity to the Registration and Reporting Section (MC 129) of the Permitting and Remediation Support Division. No person shall dispose of industrial solid waste, including sludge or other solids from wastewater treatment processes, prior to fulfilling the deed recordation requirements of 3o TAC §335.5.

e. The term "industrial solid waste management unit" means a landfill, surface impoundment, waste-pile, industrial furnace, incinerator, cement kiln, injection well, container, drum, salt dome waste containment cavern, or any other structure vessel, appurtenance, or other improvement on land used to manage industrial solid waste. 1. The permittee shall keep management records for all sludge (or other waste) removed from any wastewater treatment process. These records shall fulfill all applicable requirements of 3o TAC Chapter 335 and must include the following, as it pertains to wastewater treatment and discharge: i. Volume of waste and date(s) generated from treatment process; ii. Volume of waste disposed of on-site or shipped off-site; iii. Date(s) of disposal; iv. Identity of hauler or transporter; v. Location of disposal site; and vi. Method of final disposal. The above records shall be maintained on a monthly basis. The records shall be retained at the facility site, or shall be readily available for review by authorized representatives of the TCEQ for at least five years. 12. For industrial facilities to which the requirements of 3o TAC Chapter 335 do not apply, sludge and solid wastes, including tank cleaning and contaminated solids for disposal, shall be disposed of in accordance with THSC Code Chapter 361.

TCEQ Revision 08/2008

Page 13Lower Colorado River Authority TPDES Permit No. WQ1Doo1369000

OTHER REQUIREMENTS
1. Violations of daily maximum limitations for the following pollutants shall be reported orally or by facsimile to TCEQ Region ii, within 24 hours from the time the permittee becomes aware of the violation followed by a written report within five working days to TCEQ Region 11 and the Enforcement Division (MC 224): POLLUTANT MAL (mg/L) Copper, Total (0.to) Test methods utilized shall be sensitive enough to demonstrate compliance with the permit effluent limitations. Permit compliance/noncompliance determinations will be based on the effluent limitations contained in this permit with consideration given to the minimum analytical level (MAL) for the parameters specified above. When an analysis of an effluent sample for any of the parameters listed above indicates no detectable levels above the MAL and the test method detection level is as sensitive as the specified MAL, a value of zero (o) shall be used for that measurement when determining calculations and reporting requirements for the self-reporting form. This applies to determinations of daily maximum concentration, calculations of loading and daily averages, and other reportable results. When a reported value is zero (o) based on this MAL provision, the permittee shall submit the following statement with the self-reporting form either as a separate attachment to the form or as a statement in the comments section of the form. "The reported value(s) of zero (o) for (list parameter(s)1 on the self-reporting form for (monitoring period date range] is based on the following conditions: 1) the analytical method used had a method detection level as sensitive as the MAL specified in the permit, and 2) the analytical results contained no detectable levels above the specified MAL." When an analysis of an effluent sample for a parameter indicates no detectable levels and the test method detection level is not as sensitive as the MAL specified in the permit, or an MAL is not specified in the permit for that parameter, the level of detection achieved shall be used for that measurement when determining calculations and reporting requirements for the self-reporting form. A zero (o) may not be used. 2. There shall be no discharge of polychlorinated biphenyl compounds such as those commonly used in transformer fluid. 3. DEFINITIONS

a. The flow weighted average temperature (FWAT) shall be computed and recorded on a daily basis. FWAT shall be computed at equal time intervals not greater than two hours. The method of calculating FWAT is as folows: FWAT = SUMMATION (INSTANTANEOUS FLOW x INSTANTANEOUS TEMPERATURE)

SUMMATION (INSTANTANEOUS FLOW) The "daily average temperature" shall be the arithmetic average of all FWAT calculated during the calendar month. The "daily maximum temperature" shall be the highest FWAT calculated during the calendar month.

Page 14Lower Colorado River Authority TPDES Permit No. WQ0001369000

b. The term "total residual chlorine" (or total residual oxidants for intake water with bromides) means the value obtained using the amperometric method for total residual chlorine described in 4o CFR Part 136. Total residual chlorine may not be discharged from any single generating unit for more than two hours per day unless the facility demonstrates to the permitting authority that discharge for more than two hours is required for macroinvertebrate control. Simultaneous multi-unit chlorination is permitted.

c. The term "metal cleaning waste" means any wastewater resulting from cleaning (with or without chemical compounds) any metal process equipment including, but not limited to, boiler tube cleaning. d. The term "low volume waste sources" means wastewaters from, but not limited to: wet scrubber air pollution control systems, ion exchange water treatment system, water treatment evaporator blowdown, boiler blowdown, laboratory and sampling streams, floor drainage, cooling tower basin cleaning wastes, and blowdown from recirculating house service water systems. Sanitary and air conditioning wastes are not included.

e. The term "once through cooling water" means water passed through the main cooling condensers in one or two passes for the purpose of removing waste heat. f. The term "average concentration" as it relates to chlorine discharge means the average of analyses made over a single period of chlorine release which does not exceed two hours. 4. Chronic toxic criteria apply at the edge of the mixing zone. The mixing zone for Outfall 001 is defined as a volume within a radius of too feet from the point of discharge. 5. There shall be no discharge of domestic wastewater. Domestic wastewater shall be routed to the City of Horseshoe Bay wastewater treatment plant for treatment and disposal. 6. Subsequent to this permit issuance date, all new process wastewater ponds shall be lined in compliance with one of the following requirements:

a. Soil Liner: The soil liner shall contain at least 3 feet of clay-rich (liquid limit greater than or equal to 3o and plasticity index greater than or equal to 15) soil material along the sides and bottom of the pond compacted in lifts of no more than 9 inches, to 95% standard proctor density at the optimum moisture content to achieve a permeability equal to or less than x 10

- 7 cm/sec. b. Plastic/Rubber Liner: The liner shall be either a plastic or rubber membrane liner at least 30 mils in thickness which completely covers the sides and the bottom of the pond and which is not subject to degradation due to reaction with wastewater with which it will come into contact. If this lining material is vulnerable to ozone or ultraviolet deterioration it should be covered with a protective layer of soil of at least 6 inches. A leak detection system is also required.

c. Alternate Liner: The permittee shall submit plans for any other pond lining method. Pond liner plans must be approved in writing by the Executive Director of the TCEQ prior to pond construction.
The permittee shall notify the TCEQ Region ii Office upon completion of construction of the pond and at least a week prior to its use. Certification of the lining specifications shall be provided by a Texas licensed professional engineer and shall be available for inspection by TCEQ personnel upon request. For new construction, the certification and the test results of soils forming the bottom and sides of the pond shall be submitted to the TCEQ, Wastewater Permitting Section Page 15Lower Colorado River Authority TPDES Permit No. WQ0001369000

(MC-148) and Regional Office for review prior to discharging any wastewaters into the ponds. Permeability tests shall be made with material typical of the expected use. 7. Dust Suppression and Irrigation The permittee is authorized to utilize effluent from the evaporation/disposal pond associated with Outfall 401 for on-site dust suppression and irrigation of trees at the Thomas C. Ferguson Power Plant. With respect to utilization of effluent for irrigation, the permittee shall comply with the following requirements.

a. Irrigation practices shall be designed and managed so as to prevent runoff, ponding of effluent, or contamination of ground and surface waters and to prevent the occurrence of nuisance conditions in the area. b. Application of effluent for irrigation shall be accomplished only when the area specified is not in use.

c. Spray fixtures for irrigation systems and shall be of such design that they cannot be operated by unauthorized personnel. d. The permittee shall keep records of volumes, times, and areas where effluent is used for irrigation. These records shall be updated daily and maintained onsite for review by Commission personnel for a minimum of three years.

e. Adequate signs shall be erected stating that the irrigation water is from a non-potable water supply. Said signs shall consist of a red slash superimposed over the international symbol for drinking water accompanied by the message "Do not drink the water" in both English and Spanish. 8. The permittee shall continue to operate and maintain the cooling water intake structure (CWIS) configuration consistent with the documents, titled Supplemental Information for 316(b) BTA Determination for T.C. Ferguson TCEQ Permit No. (TX# 0057576), submitted as part of the renewal application received on June 1, 2009, in which is included a description of how the facility meets Best Technology Available (BTA) for minimizing Adverse Environmental Impact (AEI). Specifically, the permittee shall adhere to the following conditions related to the operation, maintenance, and monitoring of the CVVIS

a. Bar grates shall be cleaned as needed but no less frequently than every three years; b. Screen condition shall be visually checked daily;

c. The screens must initiate a cleaning cycle whenever the water level differential (before and after the screens) exceeds eight inches;
d. Screens shall be in proper operating condition whenever the circulating water pumps are withdrawing water. If a screen must be taken out of service for maintenance the differential across the screens must maintain compliance with item c above;

e. Screens shall be rotated through a cleaning cycle a minimum of once per week; f. Water and impinged material resulting from the cleaning process shall enter a concrete trench from which water and material returns to the reservoir. If any material is removed it shall be properly disposed in accordance with TCEQ regulations;

Page 16Lower Colorado River Authority TPDES Permit No. WQ000136900o

g. Routine preventive maintenance shall be conducted to ensure proper operating condition of the screen(s) on an as needed basis, but at a minimum of once each three months;
h. Sediment shall be cleaned from the bottom of the intake structure periodically, but no less frequently than every five years; and i. Records documenting the operation and maintenance described above shall be kept on site for a minimum of three years, and made available to TCEQ personnel upon request. In addition, the permittee submitted the Proposal for Information Collection for Thomas C. Ferguson Power Plant, Lyndon B. Johnson Reservoir, Texas, in August 2005 for review to the Water Quality Standards Team (MC 150) of the Water Quality Assessment Section of the Water Quality Division. If it is later determined that the current CWIS configuration is not representative of BTA for minimizing AEI, the permit may be reopened to incorporate additional requirements. 9. An industrial cooling impoundment for Outfall 001 is defined in this permit within Lake Lyndon B. Johnson as the area of 284 acres contained within the cove delineated on the north by Lighthouse Road on the constructed berm, as illustrated in Attachment A. Numeric temperature criteria in 3o TAC 307.4(f) and 30 TAC 307.10 (Appendix A) do not apply within the industrial cooling impoundment.

Page 17

### ATK I NS 550413ridga Point Pkwy, Ste 200 Austin, Texas 78730 Phone: (512) 327-6640 Fax; (512)327-2453 Legend Line from discharge to shoreline i

- lalf-way point Indoirial Cooling Impoundment Figure 1 Lake LBJ Industrial Cooling Impoundment

File: GISTigure_updated mxdLower Colorado River Authority TPDES Permit No. WQ0001369000

CHRONIC BIOMONITORING REQUIREMENTS: FRESHWATER The provisions of this Section apply to Outfall o01 for whole effluent toxicity testing (biomonitoring).
1. Scope, Frequency and Methodology

a. The permittee shall test the effluent for toxicity in accordance with the provisions below. Such testing will determine if an appropriately dilute effluent sample adversely affects the survival, reproduction, or growth of the test organisms.
b. The permittee shall conduct the following toxicity tests utilizing the test organisms, procedures and quality assurance requirements specified in this Part of the permit and in accordance with "Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms, Fourth Edition" (EPA-821- R-o2-o13), or the most recent update: I) Chronic static renewal survival and reproduction test using the water flea (Ceriodaphnia dubia) (Method loo2.0 or the most recent update). This test should be terminated when 6o% of the surviving adults in the control produce three broods or at the end of eight days, whichever comes first. This test shall be conducted once per quarter. 2) Chronic static renewal 7-day larval survival and growth test using the fathead minnow (Pimephales promelas) (Method 1000.0 or the most recent update). A minimum of five replicates with eight organisms per replicate shall be used in the control and in each dilution. This test shall be conducted once per quarter. The permittee must perform and report a valid test for each test species during the prescribed reporting period. An invalid test must be repeated during the same reporting period. An invalid test is herein defined as any test failing to satisfy the test acceptability criteria, procedures, and quality assurance requirements specified in the test methods and permit. All test results, valid or invalid, must be submitted as described below.

c. The permittee shall use five effluent dilution concentrations and a control in each toxicity test. These additional effluent concentrations are 32%, 42%, 56%, 75%, and wo% effluent. The critical dilution, defined as l00% effluent, is the effluent concentration representative of the proportion of effluent in the receiving water during critical low flow or critical mixing conditions.
d. This permit may be amended to require a Whole Effluent Toxicity (WET) limit, Chemical-Specific (CS) effluent limits, a Best Management Practice (BMP), additional toxicity testing, and/or other appropriate actions to address toxicity. The permittee may be required to conduct additional biomonitoring tests and/or a Toxicity Reduction Evaluation (TRE) if biomonitoring data indicate multiple numbers of unconfirmed toxicity events.

e. Testing Frequency Reduction

If none of the first four consecutive quarterly tests demonstrates significant lethal or sub-lethal effects, the permittee may submit this information in writing and, upon approval, reduce the testing frequency to once per six months
Page 19Lower Colorado River Authority TPDES Permit No. WQoo01369000 for the invertebrate test species and once per year for the vertebrate test species. 2) If one or more of the first four consecutive quarterly tests demonstrates significant sub-lethal effects, the permittee shall continue quarterly testing for that species until four consecutive quarterly tests demonstrate no significant sub-lethal effects. At that time, the permittee may apply for the appropriate testing frequency reduction for that species. 3) If one or more of the first four consecutive quarterly tests demonstrates significant lethal effects, the permittee shall continue quarterly testing for that species until the permit is reissued. If a testing frequency reduction had been previously granted and a subsequent test demonstrates significant lethal effects, the permittee will resume a quarterly testing frequency for that species until the permit is reissued.
2. Required Toxicity Testing Conditions

a. Test Acceptance - The permittee shall repeat any toxicity test, including the control and all effluent dilutions, which fail to meet the following criteria: a control mean survival of So% or greater; 2) a control mean number of water flea neonates per surviving adult of 15 or greater; 3) a control mean dry weight of surviving fathead minnow larvae of 0.25 mg or greater; 4) a control Coefficient of Variation percent (CV%) of 40 or less between replicates for the young of surviving females in the water flea reproduction and survival test; and the growth and survival endpoints in the fathead minnow growth and survival test. 5) a critical dilution CV% of 40 or less for young of surviving females in the water flea reproduction and survival test; and the growth and survival endpoints for the fathead minnow growth and survival test. However, if statistically significant lethal or nonlethal effects are exhibited at the critical dilution, a CV% greater than 4o shall not invalidate the test. 6) a Percent Minimum Significant Difference of 47 or less for water flea reproduction; 7) a Percent Minimum Significant Difference of 3o or less for fathead minnow growth.
b. Statistical Interpretation

For the water flea survival test, the statistical analyses used to determine if there is a significant difference between the control and an effluent dilution shall be Fisher's Exact Test as described in the "Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to
Page 20Lower Colorado River Authority TPDES Permit No. WQ0001369000 Freshwater Organisms, Fourth Edition" (EPA-821-R-02-o13), or the most recent update thereof. 2) For the water flea reproduction test and the fathead minnow larval survival and growth tests, the statistical analyses used to determine if there is a significant difference between the control and an effluent dilution shall be in accordance with the methods described in the "Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms, Fourth Edition" (EPA-821-R-o2-013), or the most recent update thereof. 3) The permittee is responsible for reviewing test concentration-response relationships to ensure that calculated test-results are interpreted and reported correctly. The EPA manual, AMethod Guidance and Recommendation for Whole Effluent Toxicity (WET) Testing (40 CFR Part 136) (EPA 821-B-oo-004) provides guidance on determining the validity of test results. 4) If significant lethality is demonstrated (that is, there is a statistically significant difference in survival at the critical dilution when compared to the control), the conditions of test acceptability are met, and the survival of the test organisms are equal to or greater than 80% in the critical dilution and all dilutions below that, then the permittee shall report a survival No Observed Effect Concentration (NOEC) of not less than the critical dilution for the reporting requirements. 5) The NOEC is defined as the greatest effluent dilution at which no significant effect is demonstrated. The Lowest Observed Effect Concentration (LOEC) is defined as the lowest effluent dilution at which a significant effect is demonstrated. A significant effect is herein defined as a statistically significant difference at the 95% confidence level between the survival, reproduction, or growth of the test organism(s) in a specified effluent dilution compared to the survival, reproduction, or growth of the test organism(s) in the control (o% effluent). 6) The use of NOECs and LOECs assumes either a monotonic (continuous)concentration-response relationship or a threshold model of the concentrationresponse relationship. For any test result that demonstrates a non-monotonic (non-continuous) response, the NOEC should be determined based on the guidance manual referenced in Item 3 above. 7) Pursuant to the responsibility assigned to the permittee in Part 2.b.3, testresults that demonstrate a non-monotonic (non-continuous) concentrationresponse relationship may be submitted, prior to the due date, for technical review. The above-referenced guidance manual will be used when making a determination of test acceptability. 8) Staff will review test results for consistency with rules, procedures, and permit requirements.

c. Dilution Water

Dilution water used in the toxicity tests shall be the receiving water collected as close to the point of discharge as possible but unaffected by the discharge.
Page 21Lower Colorado River Authority TPDES Permit No. WQ0001369000
2) Where the receiving water proves unsatisfactory as a result of pre-existing instream toxicity (i.e. fails to fulfill the test acceptance criteria of item 2.a.), the permittee may substitute synthetic dilution water for the receiving water in allsubsequent tests provided the unacceptable receiving water test met the following stipulations: a) a synthetic lab water control was performed (in addition to the receiving water control) which fulfilled the test acceptance requirements of item 2.a; b) the test indicating receiving water toxicity was carried out to completion (i.e., 7 days); c) the permittee submitted all test results indicating receiving water toxicity with the reports and information required in Part 3 of this Section. The synthetic dilution water shall have a pH, hardness, and alkalinity similar to that of the receiving water or a natural water in the drainage basin that is unaffected by the discharge, provided the magnitude of these parameters will not cause toxicity in a synthetic dilution water control that has been formulated to match the pH, hardness, and alkalinity naturally found in the receiving water. Upon approval, the permittee may substitute other appropriate dilution water with chemical and physical characteristics similar to that of the receiving water.
d. Samples and Composites

The permittee shall collect a minimum of three flow-weighted 24-hour composite samples from Outfall 001. The second and third 24-hour composite samples will be used for the renewal of the dilution concentrations for each toxicity test. A 24-hour composite sample consists of a minimum of 12 effluent portions collected at equal time intervals representative of a 24-hour operating day and combined proportionally to flow, or a sample continuously collected proportionally to flow over a 24-hour operating day. 2) The permittee shall collect the 24-hour composite samples such that the samples are representative of any periodic episode of chlorination, biocide usage, or other potentially toxic substance discharged on an intermittent basis. 3) The permittee shall initiate the toxicity tests within 36 hours after collection of the last portion of the first 24-hour composite sample. The holding time for any subsequent 24-hour composite sample shall not exceed 72 hours. Samples shall be maintained at a temperature of o-6 degrees Centigrade during collection, shipping, and storage. 4) If Outfall 001 ceases discharging during the collection of effluent samples, the requirements for the minimum number of effluent samples, the minimum numbers of effluent portions, and the sample holding time, are waived during that sampling period. However, the permittee must have'collected an effluent composite sample volume sufficient to complete the required toxicity tests with renewal of the effluent. When possible, the effluent samples used for the
Page 22Lower Colorado River Authority TPDES Permit No. WQ0001369o0o toxicity tests shall be collected on separate days if the discharge occurs over multiple days. The effluent composite sample collection duration and the static renewal protocol associated with the abbreviated sample collection must be documented in the full report.
3. Reporting All reports, tables, plans, summaries, and related correspondence required in any Part of this Section shall be submitted to the attention of the Standards Implementation Team (MC 150) of the Water Quality Division. All DMRs, including DMRs with biomonitoring data, should be sent to the Enforcement Division (MC 224).

a. The permittee shall prepare a full report of the results of all tests conducted pursuant to this permit in accordance with the Report Preparation Section of "Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms, Fourth Edition" (EPA-821-R-02-1313), or the most recent update, for every valid and invalid toxicity test initiated whether carried to completion or not. All full reports shall be retained for 3 years at the plant site and shall be available for inspection by TCEQ personnel.
b. A full report must be submitted with the first valid biomonitoring test results for each test species and with the first test results any time the permittee subsequently employs a different test laboratory. Full reports need not be submitted for subsequent testing unless specifically requested. The permittee shall routinely report the results of each biomonitoring test on the Table 1 forms provided with this permit. All Table 1 reports must include the information specified in the Table 1 form attached to this permit. Annual biomonitoring test results are due on or before January loth for biomonitoring conducted during the previous 12 month period. 2) Semiannual biomonitoring test results are due on or before July loth and January 20th for biomonitoring conducted during the previous 6 month period. 3) Quarterly biomonitoring test results are due on or before April 20th, July loth, October loth, and January loth, for biomonitoring conducted during the previous calendar quarter. 4) Monthly biomonitoring test results are due on or before the loth day of the month following sampling.

c. Enter the following codes on the DMR for the appropriate parameters for valid tests only: 1) For the water flea, Parameter TLP3B, enter a "1" if the NOEC for survival is less than the critical dilution; otherwise, enter a "o." 2) For the water flea, Parameter TOP3B, report the NOEC for survival. 3) For the water flea, Parameter TXP3B, report the LOEC for survival. 4) For the water flea, Parameter TWP3B, enter a "i" if the NOEC for reproduction is less than the critical dilution; otherwise, enter a "o."
Page 23Lower Colorado River Authority TPDES Permit No. WQ0oo1369000

5) For the water flea, Parameter TPP3B, report the NOEC for reproduction. 6) For the water flea, Parameter TYP3B, report the LOEC for reproduction. 7) For the fathead minnow, Parameter TLP6C, enter a "1" if the NOEC for survival is less than the critical dilution; otherwise, enter a "0." 8) For the fathead minnow, Parameter TOP6C, report the NOEC for survival. 9) For the fathead minnow, Parameter TXP6C, report the LOEC for survival. lo) For the fathead minnow, Parameter TWP6C, enter a "1" if the NOEC for growth is less than the critical dilution; otherwise, enter a "0." 11) For the fathead minnow, Parameter TPP6C, report the NOEC for growth. 12) For the fathead minnow, Parameter TYP6C, report the LOEC for growth d. Enter the following codes on the DMR for retests only: t) For retest number 1, Parameter 22415, enter a "1" if the NOEC for survival is less than the critical dilution; otherwise, enter a "o." 2) For retest number 2, Parameter 22416, enter a "1" if the NOEC for survival is less than the critical dilution; otherwise, enter a "o."
4. Persistent Toxicity The requirements of this Part apply only when a test demonstrates a significant effect at the critical dilution. A significant effect is defined as a statistically significant difference, at the 95% confidence level, between a specified endpoint (survival, growth, or reproduction) of the test organism in a specified effluent dilution when compared to the specified endpoint of the test organism in the control. Significant lethality is defined as a statistically significant difference in survival at the critical dilution when compared to the survival of the test organism in the control. Significant sublethality is defined as a statistically significant difference in growth/reproduction at the critical dilution when compared to the growth/reproduction of the test organism in the control.

a. The permittee shall conduct a total of 2 additional tests (retests) for any species that demonstrates a significant effect (lethal or sublethal) at the critical dilution. The two retests shall be conducted monthly during the next two consecutive months. The permittee shall not substitute either of the two retests in lieu of routine toxicity testing. All reports shall be submitted within 20 days of test completion. Test completion is defined as the last day of the test. The retests shall also be reported on the DMRs as specified in Part 3.d.
b. If the retests are performed due to a demonstration of significant lethality, and one or both of the two retests specified in item 4.a. demonstrates significant lethality, the permittee shall initiate the TRE requirements as specified in Part 5. The provisions of item 4.a. are suspended upon completion of the two retests and submittal of the TRE Action. Plan and Schedule defined in Part 5.
Page 24Lower Colorado River Authority TPDES Permit No. WQ000136g000
If neither test demonstrates significant lethality and the permittee is testing under the reduced testing frequency provision of Part i.e., the permittee shall return to a quarterly testing frequency for that species.

c. If the two retests are performed due to a demonstration of significant sublethality, and one or both of the two retests specified in item 4.a. demonstrates significant lethality, the permittee shall again perform two retests as stipulated in item 4.a.
d. If the two retests are performed due to a demonstration of significant sublethality, and neither test demonstrates significant lethality, the permittee shall continue testing at the quarterly frequency until such time that the permittee can invoke the reduced testing frequency provision specified in Part i.e.

e. Regardless of whether retesting for lethal or sublethal effects, or a combination of the two, no more than one retest per month is required for a species.
5. Toxicity Reduction Evaluation

a. Within 45 days of the retest that demonstrates significant lethality, the permittee shall submit a General Outline for initiating a Toxicity Reduction Evaluation (TRE). The outline shall include, but not be limited to, a description of project personnel, a schedule for obtaining consultants (if needed), a discussion of influent and/or effluent data available for review, a sampling and analytical schedule, and a proposed TRE initiation date.
b. Within go days of the retest that demonstrates significant lethality, the permittee shall submit a TRE Action Plan and Schedule for conducting a TRE. The plan shall specify the approach and methodology to be used in performing the TRE. A TRE is a step-wise investigation combining toxicity testing with physical and chemical analysis to determine actions necessary to eliminate or reduce effluent toxicity to a level not effecting significant lethality at the critical dilution. The TRE Action Plan shall lead to the successful elimination of significant lethality for both test species defined in item 1.b. As a minimum, the TRE Action Plan shall include the following: 1) Specific Activities - The TRE Action Plan shall specify the approach the permittee intends to utilize in conducting the TRE, including toxicity characterizations, identifications, confirmations, source evaluations, treatability studies, and/or alternative approaches. When conducting characterization analyses, the permittee shall perform multiple characterizations and follow the procedures specified in the document entitled, "Toxicity Identification Evaluation: Characterization of Chronically Toxic Effluents, Phase I" (EPA/600/6-91/oo5F), or alternate procedures. The permittee shall perform multiple identifications and follow the methods specified in the documents entitled, "Methods for Aquatic Toxicity Identification Evaluations, Phase II Toxicity Identification Procedures for Samples Exhibiting Acute and Chronic Toxicity" (EPA/600/R-92/o8o) and "Methods for Aquatic Toxicity Identification Evaluations, Phase III Toxicity Confirmation Procedures for Samples Exhibiting Acute and Chronic Toxicity" (EPA/6o o/R-92/o81). All characterization, identification, and confirmation tests shall be conducted in an orderly and logical progression;

Page 25Lower Colorado River Authority TPDES Permit No. WQ0001.369000
2) Sampling Plan - The TRE Action Plan should describe sampling locations, methods, holding times, chain of custody, and preservation techniques. The effluent sample volume collected for all tests shall be adequate to perform the toxicity characterization/ identification/ confirmation procedures, and chemical-specific analyses when the toxicity tests show significant lethality. Where the permittee has identified or suspects specific pollutant(s) and/or source(s) of effluent toxicity, the permittee shall conduct, concurrent with toxicity testing, chemical-specific analyses for the identified and/or suspected pollutant(s) and/or source(s) of effluent toxicity; 3) Quality Assurance Plan - The TRE Action Plan should address record keeping and data evaluation, calibration and standardization, baseline tests, system blanks, controls, duplicates, spikes, toxicity persistence in the samples, randomization, reference toxicant control charts, as well as mechanisms to detect artifactual toxicity; and 4) Project Organization - The TRE Action Plan should describe the project staff, project manager, consulting engineering services (where applicable), consulting analytical and toxicological services, etc.

c. Within 30 days of submittal of the TRE Action Plan and Schedule, the permittee shall implement the TRE with due diligence.
d. The permittee shall submit quarterly TRE Activities Reports concerning the progress of the TRE. The quarterly reports are due on or before April 2 oth, July 2 oth, October loth, and January l oth. The report shall detail information regarding the TRE activities including: i) results and interpretation of any chemical-specific analyses for the identified and/or suspected pollutant(s) performed during the quarter; 2) results and interpretation of any characterization, identification, and confirmation tests performed during the quarter; any data and/or substantiating documentation which identifies the pollutant(s) and/or source(s) of effluent toxicity; 4) results of any studies/evaluations concerning the treatability of the facility's effluent toxicity; 5) any data which identifies effluent toxicity control mechanisms that will reduce effluent toxicity to the level necessary to meet no significant lethality at the critical dilution; and 6) any changes to the initial TRE Plan and Schedule that are believed necessary as a result of the TRE findings. Copies of the TRE Activities Report shall also be submitted to the U.S. EPA Region 6 office.

Page 26Lower Colorado River Authority TPDES Permit No. WQmoi369000

e. During the TRE, the permittee shall perform, at a minimum, quarterly testing using the more sensitive species; testing for the less sensitive species shall continue at the frequency specified in Part i.b. f. If the effluent ceases to effect significant lethality (herein as defined below) the permittee may end the TRE. A "cessation of lethality" is defined as no significant lethality for a period of 12 consecutive months with at least monthly testing. At the end of the 12 months, the permittee shall submit a statement of intent to cease the TRE and may then resume the testing frequency specified in Part i.b. The permittee may only apply the "cessation of lethality" provision once. This provision accommodates situations where operational errors and upsets, spills, or sampling errors triggered the TRE, in contrast to a situation where a single toxicant or group of toxicants cause lethality. This provision does not apply as a result of corrective actions taken by the permittee. "Corrective actions" are herein defined as proactive efforts which eliminate or reduce effluent toxicity. These include, but are not limited to, source reduction or elimination, improved housekeeping, changes in chemical usage, and modifications of influent streams and/or effluent treatment. The permittee may only apply this cessation of lethality provision once. If the effluent again demonstrates significant lethality to the same species, the permit will be amended to add a WET limit with a compliance period, if appropriate. However, prior to the effective date of the WET limit, the permittee may apply for a permit amendment removing and replacing the WET limit with an alternate toxicity control measure by identifying and confirming the toxicant and/or an appropriate control measure.
g. The permittee shall complete the TRE and submit a Final Report on the TRE Activities no later than 28 months from the last test day of the retest that confirmed significant lethal effects at the critical dilution. The permittee may petition the Executive Director (in writing) for an extension of the 28-month limit. However, to warrant an extension the permittee must have demonstrated due diligence in their pursuit of the TIE/TRE and must prove that circumstances beyond their control stalled the TIE/TRE. The report shall provide information pertaining to the specific control mechanism(s) selected that will, when implemented, result in reduction of effluent toxicity to no significant lethality at the critical dilution. The report will also provide a specific corrective action schedule for implementing the selected control mechanism(s). A copy of the TRE Final Report shall also be submitted to the U.S. EPA Region 6 office. h. Based upon the results of the TRE and proposed corrective actions, this permit may be amended to modify the biomonitoring requirements, where necessary, to require a compliance schedule for implementation of corrective actions, to specify a WET limit, to specify a BMP, and/or to specify CS limits.

Page 27Lower Colorado River Authority TPDES Permit No. WQ0001369000 TABLE 1 (SHEET 1 OF 4)
BIOMONITORING REPORTING
CERIODAPHNIA DUBIA SURVIVAL AND REPRODUCTION

Date Time Date Time Dates and Times No. 1 FROM: TO: Composites Collected No. 2 FROM: TO:

No. 3 FROM: TO:
Test initiated: am/pm date
Dilution water used: Receiving Water Synthetic Dilution Water

NUMBER OF YOUNG PRODUCED PER ADULT AT END OF TEST

*Coefficient of Variation = standard deviation x loo/mean (calculation based on young of the surviving adults) Designate males (M), and dead females (D), along with number of neonates (x) released prior to death.

Page 28eirtTnt oftluunt )

Lower Colorado River Authority TPDES Permit No. WQ0001369000 TABLE 1 (SHEET 2 OF 4)
CERIODAPHNIA DUBIA SURVIVAL AND REPRODUCTION TEST
1. Dunnett's Procedure or Steers Many-One Rank Test or Wilcoxon Rank Sum Test (with Bonferroni adjustment) or t-test (with Bonferroni adjustment) as appropriate: Is the mean number of young produced per adult significantly less (p=o.o5) than the number of young per adult in the control for the % effluent corresponding to significant nonlethal effects? CRITICAL DILUTION (l00%): YES NO
PERCENT SURVIVAL

2. Fisher's Exact Test: Is the mean survival at test end significantly less (p=o.o5) than the control survival for the % effluent corresponding to lethality? CRITICAL DILUTION (l00%): YES NO

3. Enter percent effluent corresponding to each NOEC/LOEC below:

a.) NOEC survival = % effluent b.) LOEC survival = % effluent c.) NOEC reproduction = % effluent d.) LOEC reproduction = % effluent

Page 29L+Lu t

ConcentkatioD

. (%) ygkagg , ititeadAtediatithep4 s Lower Colorado River Authority TPDES Permit No. WQ0oo1369000

TABLE 1 (SHEET 3 OF 4)
BIOMONITORING REPORTING
FATHEAD MINNOW LARVAE GROWTH AND SURVIVAL

Date Time Date Time Dates and Times No. 1 FROM: TO: Composites Collected No. 2 FROM: TO:

No. 3 FROM: TO:
Test initiated: am/pm date
Dilution water used: Receiving Water Synthetic Dilution Water

FATHEAD MINNOW GROWTH DATA

* Coefficient of Variation = standard deviation x loo/mean
1. Dunnett's Procedure or Steel's Many-One Rank Test or Wilcoxon Rank Sum Test (with Bonferroni adjustment) or t-test (with Bonferroni adjustment) as appropriate: Is the mean dry weight (growth) at 7 days significantly less (p=o.o5) than the control's dry weight (growth) for the % effluent corresponding to significant nonlethal effects?

CRITICAL DILUTION (l00%): YES NO

Page 3oday 4811. 44 11 ereefit - ?.atOkehiitribOrS::!: V9 Lower Colorado River Authority TPDES Permit No. WQ0001369000 TABLE 1 (SHEET 4 OF 4)
BIOMONITORING REPORTING
FATHEAD MINNOW GROWTH AND SURVIVAL TEST
FATHEAD MINNOW SURVIVAL DATA

* Coefficient of Variation = standard deviation x 100/mean
2. Dunnett's Procedure or Steel's Many-One Rank Test or Wilcoxon Rank Sum Test (with Bonferroni adjustment) or t-test (with Bonferroni adjustment) as appropriate: Is the mean survival at 7 days significantly less (p.o.o5) than the control survival for the % effluent corresponding to lethality? CRITICAL DILUTION (i00%): YES NO
3. Enter percent effluent corresponding to each NOEC/LOEC below: a.) NOEC survival = % effluent b.) LOEC survival = % effluent c.) NOEC growth = % effluent d.) LOEC growth = % effluent

Page 31Lower Colorado River Authority TPDES Permit No. WQ0001369000

24-HOUR ACUTE BIOMONITORING REQUIREMENTS: FRESHWATER The provisions of this section apply to Outfall 001 for whole effluent toxicity testing (biomonitoring)
1. Scope, Frequency and Methodology

a. The permittee shall test the effluent for lethality in accordance with the provisions in this Section. Such testing will determine compliance with the Surface Water Quality Standard, 3o7.6(e)(2)(B), of greater than 5o% survival of the appropriate test organisms in l00% effluent for a 24-hour period.
b. The toxicity tests specified shall be conducted once per six months. The permittee shall conduct the following toxicity tests utilizing the test organisms, procedures, and quality assurance requirements specified in this section of the permit and in accordance with "Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, Fifth Edition" (EPA-821-R-o2-o12), or the most recent update thereof: 1) Acute 24-hour static toxicity test using the water flea (Daphnia pulex or Ceriodaphnia dubia). A minimum of five replicates with eight organisms per replicate shall be used in the control and in each dilution. 2) Acute 24-hour static toxicity test using the fathead minnow (Pimephales promelas). A minimum of five replicates with eight organisms per replicate shall be used in the control and in each dilution. The permittee must perform and report a valid test for each test species during the prescribed reporting period. An invalid test must be repeated during the same reporting period. An invalid test is herein defined as any test failing to satisfy the test acceptability criteria, procedures, and quality assurance requirements specified in the test methods and permit. All test results, valid or invalid, must be submitted as described below.

c. In addition to an appropriate control, a i00% effluent concentration shall be used in the toxicity tests. Except as discussed in item 2.b., the control and/or dilution water shall consist of standard, synthetic, moderately hard, reconstituted water.
d. This permit may be amended to require a Whole Effluent Toxicity (WET) limit, a Best Management Practice (BMP), Chemical-Specific (CS) limits, additional toxicity testing, and/or other appropriate actions to address toxicity. The permittee may be required to conduct additional biomonitoring tests and/or a Toxicity Reduction Evaluation (TRE) if biomonitoring data indicate multiple numbers of unconfirmed toxicity events.

e. As the dilution series specified in the Chronic Biomonitoring Requirements includes a l00% effluent concentration, the results from those tests may fulfill the requirements of this Section; any tests performed in the proper time interval may be substituted. Compliance will be evaluated as specified in item a. The 5o% survival in l00% effluent for a 24-hour period standard applies to all tests utilizing a l00% effluent dilution, regardless of whether the results are submitted to comply with the minimum testing frequency defined in item b.

Page 32Lower Colorado River Authority TPDES Permit No. WQoom369000

2. Required Toxicity Testing Conditions

a. Test Acceptance - The permittee shall repeat any toxicity test, including the control, if the control fails to meet a mean survival equal to or greater than 90%.
b. Dilution Water - In accordance with item i.c., the control and/or dilution water shall normally consist of standard, synthetic, moderately hard, reconstituted water. If the permittee utilizes the results of a chronic test to satisfy the requirements in item i.e., the permittee may use the receiving water or dilution water that meets the requirements of item 2.a as the control and dilution water.

c. Samples and Composites 1) The permittee shall collect one flow-weighted 24-hour composite sample from Outfall 001. A 24-hour composite sample consists of a minimum of 12 effluent portions collected at equal time intervals representative of a 24-hour operating day and combined proportional to flow, or a sample continuously collected proportional to flow over a 24-hour operating day. 2) The permittee shall collect the 24-hour composite samples such that the samples are representative of any periodic episode of chlorination, biocide usage, or other potentially toxic substance discharged on an intermittent basis. 3) The permittee shall initiate the toxicity tests within 36 hours after collection of the last portion of the 24-hour composite sample. Samples shall be maintained at a temperature of o-6 degrees Centigrade during collection, shipping, and storage. 4) If Outfall 001 ceases discharging during the collection of the effluent composite sample, the requirements for the minimum number of effluent portions are waived. However, the permittee must have collected a composite sample volume sufficient for completion of the required test. The abbreviated sample collection, duration, and methodology must be documented in the full report required in Part 3 of this Section.
3. Reporting All reports, tables, plans, summaries, and related correspondence required in any Part of this Section shall be submitted to the attention of the Standards Implementation Team (MC 150) of the Water Quality Division. All DMRs, including DMRs with biomonitoring data, should be sent to the Enforcement Division (MC 224).

a. The permittee shall prepare a full report of the results of all tests conducted pursuant to this permit in accordance with the Report Preparation Section of "Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, Fifth Edition" (EPA-821-R-o2-o12), or the most recent update thereof, for every valid and invalid toxicity test initiated. All full reports shall be retained for 3 years at the plant site and shall be available for inspection by TCEQ personnel. b. A full report must be submitted with the first valid biomonitoring test results for each test species and with the first test results any time the permittee subsequently employs a different test laboratory. Full reports need not be submitted for subsequent testing unless specifically requested. The permittee shall routinely report the results of each
Page 33Lower Colorado River Authority TPDES Permit No. WQoo01369000

biomonitoring test on the Table 2 forms provided with this permit. All Table 2 reports must include the information specified in the Table 2 form attached to this permit. 1) Semiannual biomonitoring test results are due on or before January loth and July 20th for biomonitoring conducted during the previous 6 month period. 2) Quarterly biomonitoring test results are due on or before January 20th, April loth, July 2oth, and October 20th, for biomonitoring conducted during the previous calendar quarter.

c. Enter the following codes on the DMR for the appropriate parameters for valid tests only: 1) For the water flea, Parameter TIE3D, enter a "o" if the mean survival at 24-hours is greater than 50% in the i00% effluent dilution; if the mean survival is less than or equal to 50%, enter "1." 2) For the fathead minnow, Parameter TIE6C, enter a "o" if the mean survival at 24- hours is greater than 50% in the 100% effluent dilution; if the mean survival is less than or equal to 50%, enter "1."
d. Enter the following codes on the DMR for retests only: i) For retest number 1, Parameter 22415, enter a "o" if the mean survival at 24-hours is greater than 50% in the 100% effluent dilution; if the mean survival is less than or equal to 50%, enter "1." 2) For retest number 2, Parameter 22416, enter a "o" if the mean survival at 24-hours is greater than 50% in the 100% effluent dilution; if the mean survival is less than or equal to 50%, enter "i."
4. Persistent Mortality The requirements of this Part apply when a toxicity test demonstrates significant lethality, here defined as a mean mortality of 5o% or greater to organisms exposed to the 100% effluent concentration after 24-hours.

a. The permittee shall conduct 2 additional tests (retests) for each species that demonstrates significant lethality. The two retests shall be conducted once per week for 2 weeks. Five effluent dilution concentrations in addition to an appropriate control shall be used in the retests. These additional effluent concentrations are 6%, 13%, 25%, 50% and 100% effluent. The first retest shall be conducted within 15 days of the laboratory determination of significant lethality. All test results shall be submitted within 20 days of test completion of the second retest. Test completion is defined as the 24th hour. The retests shall also be reported on the DMRs as specified in Part 3.d. b. If one or both of the two retests specified in item 4.a. demonstrates significant lethality, the permittee shall initiate the TRE requirements as specified in Part 5 of this Section.
5. Toxicity Reduction Evaluation

a. Within 45 days of the retest that demonstrates significant lethality, the permittee shall submit a General Outline for initiating a Toxicity Reduction Evaluation (TRE). The outline shall include, but not be limited to, a description of project personnel, a schedule Page 34Lower Colorado River Authority TPDES Permit No. WQ0001369000 for obtaining consultants (if needed), a discussion of influent and/or effluent data available for review, a sampling and analytical schedule, and a proposed TRE initiation date.
b. Within go days of the retest that demonstrates significant lethality, the permittee shall submit a TRE Action Plan and Schedule for conducting a TRE. The plan shall specify the approach and methodology to be used in performing the TRE. A TRE is a step-wise investigation combining toxicity testing with physical and chemical analysis to determine actions necessary to eliminate or reduce effluent toxicity to a level not effecting significant lethality at the critical dilution. The TRE Action Plan shall lead to the successful elimination of significant lethality for both test species defined in item i.b. As a minimum, the TRE Action Plan shall include the following: 1.) Specific Activities - The TRE Action Plan shall specify the approach the permittee intends to utilize in conducting the TRE, including toxicity characterizations, identifications, confirmations, source evaluations, treatability studies, and/or alternative approaches. When conducting characterization analyses, the permittee shall perform multiple characterizations and follow the procedures specified in the document entitled, "Methods for Aquatic Toxicity Identification Evaluations: Phase I Toxicity Characterization Procedures" (EPA/boo/6-91/003), or alternate procedures. The permittee shall perform multiple identifications and follow the methods specified in the documents entitled, "Methods for Aquatic Toxicity Identification Evaluations, Phase II Toxicity Identification Procedures for Samples Exhibiting Acute and Chronic Toxicity" (EPA/600/R-92/o8o) and "Methods for Aquatic Toxicity Identification Evaluations, Phase III Toxicity ConfirmationProcedures for Samples Exhibiting Acute and Chronic Toxicity" (EPA/600/R92/081). All characterization, identification, and confirmation tests shall be conducted in an orderly and logical progression; 2) Sampling Plan - The TRE Action Plan should describe sampling locations, methods, holding times, chain of custody, and preservation techniques. The effluent sample volume collected for all tests shall be adequate to perform the toxicity characterization/ identification/ confirmation procedures, and chemical-specific analyses when the toxicity tests show significant lethality. Where the permittee has identified or suspects specific pollutant(s) and/or source(s) of effluent toxicity, the permittee shall conduct, concurrent with toxicity testing, chemical-specific analyses for the identified and/or suspected pollutant(s) and/or source(s) of effluent toxicity; 3) Quality Assurance Plan - The TRE Action Plan should address record keeping and data evaluation, calibration and standardization, baseline tests, system blanks, controls, duplicates, spikes, toxicity persistence in the samples, randomization, reference toxicant control charts, as well as mechanisms to detect artifactual toxicity; and 4) Project Organization - The TRE Action Plan should describe the project staff, manager, consulting engineering services (where applicable), consulting analytical and toxicological services, etc.

c. Within 3o days of submittal of the TRE Action Plan and Schedule, the permittee shall implement the TRE with due diligence.

Page 35Lower Colorado River Authority TPDES Permit No. WQ0001369oo0

d. The permittee shall submit quarterly TRE Activities Reports concerning the progress of the TRE. The quarterly TRE Activities Reports are due on or before April 2oth, July loth, October loth, and January loth. The report shall detail information regarding the TRE activities including: 1) results and interpretation of any chemical-specific analyses for the identified and/or suspected pollutant(s) performed during the quarter; 2) results and interpretation of any characterization, identification, and confirmation tests performed during the quarter; 3) any data and/or substantiating documentation which identifies the pollutant(s) and- /or source(s) of effluent toxicity; 4) results of any studies/evaluations concerning the treatability of the facility's effluent toxicity; 5) any data which identifies effluent toxicity control mechanisms that will reduce effluent toxicity to the level necessary to eliminate significant lethality; and 6) any changes to the initial TRE Plan and Schedule that are believed necessary as a result of the TRE findings. Copies of the TRE Activities Report shall also be submitted to the U.S. EPA Region 6 office.

e. During the TRE, the permittee shall perform, at a minimum, quarterly testing using the more sensitive species; testing for the less sensitive species shall continue at the frequency specified in Part
f. If the effluent ceases to effect significant lethality (herein as defined below) the permittee may end the TRE. A "cessation of lethality" is defined as no significant lethality for a period of 12 consecutive weeks with at least weekly testing. At the end of the 12 weeks, the permittee shall submit a statement of intent to cease the TRE and may then resume the testing frequency specified in Part i.b. The permittee may only apply the "cessation of lethality" provision once. This provision accommodates situations where operational errors and upsets, spills, or sampling errors triggered the TRE, in contrast to a situation where a single toxicant or group of toxicants cause lethality. This provision does not apply as a result of corrective actions taken by the permittee. "Corrective actions" are herein defined as proactive efforts which eliminate or reduce effluent toxicity. These include, but are not limited to, source reduction or elimination, improved housekeeping, changes in chemical usage, and modifications of influent streams and/or effluent treatment. The permittee may only apply this cessation of lethality provision once. If the effluent again demonstrates significant lethality to the same species, the permit will be amended to add a WET limit with a compliance period, if appropriate. However, prior to the effective date of the WET limit, the permittee may apply for a permit amendment removing and replacing the WET limit with an alternate toxicity control measure by identifying and confirming the toxicant and/or an appropriate control measure.

Page 36Lower Colorado River Authority TPDES Permit No. WQ0001369000

The permittee shall complete the TRE and submit a Final Report on the TRE Activities no later than 18 months from the last test day of the retest that demonstrates significant lethality. The permittee may petition the Executive Director (in writing) for an extension of the 18-month limit. However, to warrant an extension the permittee must have demonstrated due diligence in their pursuit of the TIE/TRE and must prove that circumstances beyond their control stalled the TIE/TRE. The report shall specify the control mechanism(s) that will, when implemented, reduce effluent toxicity as specified in item 5.g. The report will also specify a corrective action schedule for implementing the selected control mechanism(s). A copy of the TRE Final Report shall also be submitted to the U.S. EPA Region 6 office.
h. Within 3 years of the last day of the test confirming toxicity, the permittee shall comply with 3o7.6(e)(2)(B), which requires greater than 5o% survival of the test organism in l00% effluent at the end of 24-hours. The permittee may petition the Executive Director (in writing) for an extension of the 3-year limit. However, to warrant an extension the permittee must have demonstrated due diligence in their pursuit of the TIE/TRE and must prove that circumstances beyond their control stalled the TIE/TRE. The requirement to comply with 3o7.6(e)(2)(B) may be exempted upon proof that toxicity is caused by an excess, imbalance, or deficiency of dissolved salts. This exemption excludes instances where individually toxic components (e.g. metals) form a saltcompound. Following the exemption, the permit may be amended to include an ionadjustment protocol, alternate species testing, or single species testing.
i. Based upon the results of the TRE and proposed corrective actions, this permit may be amended to modify the biomonitoring requirements where necessary, to require a compliance schedule for implementation of corrective actions, to specify a WET limit, to specify a BMP, and/or to specify a CS limit.

Page 37Lower Colorado River Authority TPDES Permit No. WQ0001369000

TABLE 2 (SHEET 1 OF 2

WATER FLEA SURVIVAL

GENERAL INFORMATION

PERCENT SURVIVAL

Enter percent effluent corresponding to the LC C0 below:
24 hour LC

go = % effluent

age 3Saul le: Collepte

Peieeiit:aftan (

Lower Colorado River Authority TPDES Permit No. WQD0o1369000

TABLE 2 (SHEET 2 OF 2)
FATHEAD MINNOW SURVIVAL

GENERAL INFORMATION

Time (amt ij) Dale

PERCENT SURVIVAL

Enter percent effluent corresponding to the LC5o below:
24 hour LC5o = % effluent

Page 39