(1990) Waste Load Evaluation for the Wichita River in the Red River Basin, Segment 0214

--- Page 1 --- WASTE LOAD EVALUATION FOR THE WICHITA RIVER IN THE RED RIVER BASIN Segment 0214 WLE 90-03 Texas Water Commission March 1990 --- Page 2 --- TEXAS WATER COMMISSION B. J. Wynne, Ill, Chairman John E. Birdwell, commissioner Cliff Johnson, Commissioner Allen Beinke, Executive Director Authorization for use or reproduction of any original material contained in this publication, i.e., not obtained from other sources, is freely granted. The Commission would appreciate acknowledgement. Published and distributed by the Texas Water Commission Post Office Box 13087 Austin, Texas 78711 --- Page 3 --- ABSTRACT A waste load evaluation for the Wichita River (Segment 0214) has been prepared by the Texas Water Commission. It was adopted by the Texas Water Commission on September 27, 1988 and approved by the United States Environmental Protection Agency on December 22, 1989. The purpose of this evaluation is to recommend waste treatment levels and effluent limitations that will result in the receiving water meeting applicable dissolved oxygen criteria through the year 2005. Recommendations are based on growth projections, water quality data and other information that were available as of June 8, 1987. This report updates and amends any previous waste load evaluations and becomes part of the state water quality management plans. --- Page 4 --- = |. fs | | on er | (aise tour cane bis ol Pree : hot} 1 G r" fe Yee eek eel eden Hazem. ayiedl qenelT ma sen eye oti sina | fst fees ; aie 7 “> ye 11M Vike ravefenrte, vest Tt atts ti: | Ve RE Pa n« melpi i oyeta 4 “| bebr eftectigutiit Trevi Gen Maen}! “eet ueit & Bey Wie WY SS St bitte > wey aso ‘iba iS aitt are nahi OL ott Pox) pal? oe 4 Mech LYSE LS eftw wer 3 fa jrewvre J H wt) ore. ro ow al TS” “fel oP yey a we ¥ tat bas ee yl "Tt { “al Z Py a soqts | YS ae Lies ati oer 2 = eweg Fa Lege) TE a erg Samet a ed atl} yelp 2 4 --- Page 5 --- TABLE OF CONTENTS ABSTRACT 5 bss 3 MRE we Ea HS INTRODUCTION. .........244- SEGMENT DESCRIPTION ....... General Information ...... Geography 5.266 6 & = @ &% Climatology .......+.e4-. Hydrology . «668 6 6 6 6 wes Land Use Patterns ..... Water Quality Standards ..... Desired Water Uses ....... Numerical Criteria ....... Wastewater Discharges ....... Water Quality Conditions ...... Classification ...... ee we DOCUMENTATION OF THE WATER QUALITY MODEL * «@ . * Model Formulation . s «<2: ¢.¥0%8 €l6 © wid ele % General. . 2... 2. 2 eee wee Segmentation «ae « e* Swi HYGPEUNCS 5 si & & 6 te wi * BE Carbonaceous Biochemical Oxygen Nitrogenous Oxygen Demand .. Sediment Oxygen Demand .... Atmospheric Reaeration ..... Photosynthesis/Respiration .. ._ 8« © «@ Demand Page iii 10 AL 12 13 13 --- Page 6 --- TABLE OF CONTENTS (continued) TOMPOTAIUTe «on 6 ee ale ee ee a ew Boundary Conditions . 2.685 6 tte HH % Waste Loads. ....... 5. «= © we we ee Calibration . . 1... 6 eee ew ew ew we eww Survey Discussion .......6+ 26 2 we woe Model Discussion ........262e0e8-4 Verification, i 6 se 6 kaa LER ERS ES Survey Discussion ........6.2-e0005e Model Discussion ........+e246s oe ws WATER: QUALITY PROJECTIONS, ss ce cc ea we Predictive Use of the Model ........2.+2+.20es erwmery CC TOES ove ce: cn we wed ee me eS Waste Load Projections . i. 2 sss ss se 6% Predicted Water Quality for Iowa Park WWTP Ditch and. Buffalo Creek «6353 $s swe!’ s 4 be Predicted Water Quality for Wichita Falls—-Northside WWTP Ditch and Bear Creek ........ Predicted Water Quality for Sheppard A.F.B. WWTP and: Pham Creek «46 < 6 #6 Boe ee ww Ss Predicted Water Quality for the Wichita River ... NONPOINT SOURCE ASSESSMENT ........424.-. ANALYSIS OF ALTERNATIVES «§ ssw oe COW as es Changes in Standards. 26. i 266 & ee e's Bw Selected Treatment Level .......+.24+e6-. Sensitivity Amnelysis-. cc 6 8 wl wee we Ew! we Page 14 14 15 15 15 16 17 17 ot 19 19 19 19 20 21 22 22 24 25 25 25 25 --- Page 7 --- Permit Variances ....+es B! See we age el ® feat ee CONCLUSIONS AND RECOMMENDATIONS ......2.22-8-s Summary of Analysis ......4.-. eros ea ee Recommendations: «4 % 6 & 6 % 8 fe le wD we, HO wh Si rpeT or, © REFERENCES -« «6 i ®@% & Ww € EEE SH EB ee we Re ee 8 FIGURES b, Location of the Wichita River Watershed .... 2s Extent of the Wichita River Watershed .....+s46-s. 3. Location of Stream Stations and Wastewater Dischargers to: the Wichita River... .eoe"s + syle ® iss) Geaele fe 4. Historical Total Wastewater Flows to the Wichita River . 5. Historical Total BOD; Loading to the Wichita River 6. Historical Dissolved Oxygen Trend in the Wichita River SMN Station 0214.0100 at FM 810, West of Byers. T. Model Schematic of the Wichita River ...... +... 5s 8. Wichita River Calibration Plot for Dissolved Oxygen - July 21, 1986 Data ...... 9. Wichita River Calibration Plot for Ultimate BOD - July 21, 1986 Data ....... 10. Wichita River Calibration Plot for Ammonia Nitrogen - July 21, 1986 Data ....... : Wichita River Verification Plot for Dissolved Oxygen - April 7, 1981 Data .... 12. Wichita River Verification Plot for Ultimate BOD - April 7, 1981 Data .....%...-s 1. Wichita River Verification Plot for TABLE OF CONTENTS (continued) Ammonia Nitrogen - April 7, 1981 Data ..... Page 27 30 31 32 37 39 46 48 51 --- Page 8 --- 14, 15. 16. it; 18. 19, 20. 21. 22. 23, TABLE OF CONTENTS (continued) Predicted Dissolved Oxygen Profile for Iowa Park WWTP Ditch and Buffalo Creek No Waste L6@ds ass gs wttheid Peo we Mare os Predicted Dissolved Oxygen Profile for Iowa Park WWTP Ditch and Buffalo Creek Ultimate Permitted Flows with Ultimate Permitted Effluent Limitations . . Predicted Dissolved Oxygen Profile for Iowa Park WWTP Ditch and Buffalo Creek 2005 Projected Flows with 20 mg/L BODs, 15 mg/L NH,-N, and 2 mg/L DO Predicted Dissolved Oxygen Profile for Iowa Park WWTP Ditch and Buffalo Creek 2005 Projected Flows with Projected Effluent Quality Predicted Dissolved Oxygen Profile for Wichita Falls- Northside WWTP Ditch and Bear Creek No Waste Loads ....... <2. 2 # Predicted Dissolved Oxygen Profile for Wichita Falls- Northside WWTP Ditch and Bear Creek Ultimate Permitted Flows with Ultimate Permitted Effluent Limitations ....... Predicted Dissolved Oxygen Profile for Wichita Falls- Northside WWTP Ditch and Bear Creek 2005 Projected Flows with 20 mg/L BODs, 15 mg/L NH,-N, and 2 mg/L DO Predicted Dissolved Oxygen Profile for Wichita Falls- Northside WWTP Ditch and Bear Creek 2005 Projected Flows with 10 mg/L BODs, 15 mg/L NH,-N, and 4 mg/L DO Predicted Dissolved Oxygen Profile for Wichita Falls- Northside WWTP Ditch and Bear Creek 2005 Projected Flows with 10 mg/L BODs, 3 mg/L NH,-N, and 4 mg/L DO. Predicted Dissolved Oxygen Profile for Sheppard A.F. WWTP Ditch and Plum Creek No Waste Loads ........ ai agit gy geese Te ie Page 52 53 54 55 56 57 58 59 60 61 --- Page 9 --- 24. 25. 26. at. 28. 29. 30. 31. 32, 33. 34. TABLE OF CONTENTS (continued) Predicted Dissolved Oxygen Profile for Sheppard A.F.B. WWTP Ditch and Plum Creek Ultimate Permitted Flows with Ultimate Permitted Effluent Limitations ...... Predicted Dissolved Oxygen Profile for Sheppard A.F.B. WWTP Ditch and Plum Creek 2005 Projected Flows with 20 mg/L BOD;s, 15 mg/L NH,-N, and 2 mg/L DO .. Predicted Dissolved Oxygen Profile for Sheppard A.F.B. WWTP Ditch and Plum Creek 2005 Projected Flows with 10 mg/L BODs, 15 mg/L NH,-N, and4mg/L DO ..... Predicted Dissolved Oxygen Profile for Sheppard A.F.B. WWTP Ditch and Plum Creek 2005 Projected Flows with 10 mg/L BODs, 3 mg/L NH,-N, and 4mg/LDO..... Predicted Dissolved Oxygen Profile for Wichita River No Waste Loads . 2. 1. sss ewe eo ew ee wee Predicted Dissolved Oxygen Profile for Wichita River Ultimate Permitted Flows with Ultimate Permitted Effluent Limitations .......+2e-. Predicted Dissolved Oxygen Profile for Wichita River 2005 Projected Flows with 20 mg/L BODs, 15 mg/L NH,-N, and 2 mg/L DO . Predicted Dissolved Oxygen Profile for Wichita River 2005 Projected Flows with 10 mg/L BODs, 15 mg/L NH,-N, and 4 mg/L DO . Predicted Dissolved Oxygen Profile for Wichita River 2005 Projected Flows with 10 mg/L BODs, 3 mg/L NH,-N, and 4mg/L DO. . Predicted Dissolved Oxygen Profile for Wichita River 2005 Projected Flows with Projected Effluent Quality Wichita River Dissolved Oxygen Sensitivity to Stream Baseflow 2005 Projected Flows with Projected Effluent Quality ix Page 62 63 64 65 66 67 68 69 70 71 72 --- Page 10 --- 35. 36. 37. 38. 39. TABLE OF CONTENTS (continued) Wichita River Dissolved Oxygen Sensitivity to Temperature 2005 Projected Flows with Projected Effluent Quality Wichita River Dissolved Oxygen Sensitivity to BOD Decay Rate 2005 Projected Flows with Projected Effluent Quality Wichita River Dissolved Oxygen Sensitivity to Ammonia Decay Rate 2005 Projected Flows with Projected Effluent Quality Wichita River Dissolved Oxygen Sensitivity to Background Sediment Oxygen Demand 2005 Projected Flows with Projected Effluent Quality Vichita River Dissolved Oxygen Sensitivity to Reaeration Rate 2005 Projected Flows with Projected Effluent Quality TABLES Existing, Projected, and Permitted Wastewater Loading to: the Wichita River «4 6 6 Aé5l“e & Oe eg he ARIE « Stream Monitoring Network Data Summary for the Wichita River (October 1, 1983 - September 30, 1987)... . Reach Identification Data for the Wichita River Model. ........+2.64ee86 Summary of Hydraulic Data Wichita River Survey (July 21, 1966) . swe 6 es ww] sé Summary of Hydraulic Data Wichita River Survey (April 7, 1981) . * * . * * . . . . * o . . . . . . Advective Hydraulic Coefficients for the Wichita River Model... 6... ess esses Summary of Flow Measurements for Stream Stations Wichita River Water Quality Survey CURT’ Bk: ROCGT oc wi ow ce we om we eo Oe em Page 73 74 76 77 78 81 82 83 84 85 86 --- Page 11 --- 10. 11. 12. 13. 14, 15. 16. LT 18. 19. TABLE OF CONTENTS (continued) Summary of Field Measurements for Stream Stations Wichita River Water Quality adie! (July 21,1986) «§ «ss es : ‘ ee ee ee Summary of Laboratory Analyses for Stream Stations Wichita River Water Quality Survey (July 21, 1986) . 2... 2. we ee ee ee ee es Summary of Flow Measurements for Wastewater Dischargers Wichita River Water Quality Survey (July 21, 1986) 2 2 sw wee 6 6 8 Bie ww ae ye mh Le Re Summary of Field Measurements for Wastewater Dischargers Wichita River Water Quality Survey (July 21, 1986) 2. 2 ee eee me ee Summary of Laboratory Analyses for Wastewater Dischargers Wichita River Water Quality Survey (duly 21,,1986) . ss ewe eee eww! ET eH He Summary of Self-Reporting Data for Wastewater Dischargers Wichita River (July, 1986) ......4.+.2.42ee-s Model Input for the Wichita River Calibration Run July 21, 1986 Data. 2s ee se wee ee Summary of Flow Measurements for Stream Stations Wichita River Water Quality Survey (April %,, 19881) se eee ee aww! Ee Hwee we Summary of Field Measurements for Stream Stations Wichita River Water Quality Survey (April 7, 1981) 2 i aww « oe ee ee ee Summary of Laboratory Analyses for Stream Stations Wichita River Water Quality Survey (April 7, 1981) ; se 6 6.8 FWSM eR ee HS ww ee Summary of Flow Measurements for Wastewater Dischargers Wichita River Water Quality Survey (April 7, 1981) . 2. 1. 6 ee ee ee ee ee ee ee . Summary of Field Measurements for Wastewater Dischargers Wichita River Water Quality Survey (April 7, 1981) . 2. 2 6 6 6 ee ee ew we ew ww Page 88 90 92 93 94 95 96 106 107 109 111 112 --- Page 12 --- 20. 21. 22. 23. TABLE OF CONTENTS (continued) Summary of Laboratory Analyses for Wastewater Dischargers Wichita River Water sai inal Survey (April 7, 1981) .... ; Summary of Self-Reporting Data for Wastewater Dischargers Wichita River (April, 1981) Model Input for the Wichita River Verification Run April 7, 1981 Data ... Model Input for the Wichita River "No Waste Loads" Alternative * -_ e8« 8 © © @ « Page 113 114 115 125 --- Page 13 --- INTRODUCTION This waste load evaluation for the Wichita River Below Diversion Dam (Segment 0214) was prepared by the Water Quality Division of the Texas Water Commission in accordance with 40 CFR §130.7 as promulgated under Federal Water Pollution Control Act §303(d). It was adopted by the Texas Water Commission on September 27, 1988 and approved by the United States Environmental Protection Agency on December 22, 1989. The purpose of this evaluation is to define wastewater treatment levels and effluent limitations that will result in the receiving water meeting applicable dissolved oxygen criteria through the year 2005. Recommendations are based on growth projections, water quality data, and other information that were available as of June 8, 1987. As authorized under Texas Water Code §26.036, this waste load evaluation becomes part of the state water quality management plan. Pursuant to Texas Water Code §26.037, the Texas Water Commission may use this waste load evaluation in reviewing and making determinations on applications for wastewater discharge permits. All references to the Wichita River in this report refer only to Segment 0214. --- Page 14 --- SEGMENT DESCRIPTION GENERAL INFORMATION Geography Wichita River Below Diversion Lake (Segment 0214) is located in north central Texas in the Red River Basin (see Figure 1). Segment 0214 begins at Diversion Dam in Archer County and flows 177.6 kilometers (110.4 miles) to the confluence with the Red River in Clay County. The Wichita River watershed (see Figure 2) encompasses 3,440 square kilometers (1,328 square miles) of Clay, Wichita, Archer, Foard, Baylor and Wilbarger Counties, and includes the communities of Electra, Iowa Park, and Crowell, as well as the City of Wichita Falls. Due to the extreme western location of Crowell and the absence of any dischargers, Wilbarger and Baylor Counties were omitted from the watershed map for the purpose of clarity. Elevations range from 311 meters (1,020 feet) above mean sea level at Diversion Dam to 265 meters (870 feet) at the confluence of Red River. Principal tributaries to the Wichita River include Buffalo Creek south of Iowa Park, Beaver Creek north of Diversion Lake, Bear Creek north of Wichita Falls, and Holliday Creek south of Wichita Falls. Climatology The climate of the Wichita River watershed is classified as continental. It is characterized by rapid changes in temperature, large daily and annual temperature extremes, and by rather erratic rainfall. In January, the normal daily maximum temperature is 11°C (52°F), and the normal daily minimum temperature is -2°C (28°F). In July, the normal daily maximum temperature is 37°C (98°F), and the normal daily minimum temperature is 22°C (72°F). The normal rainfall is 68 centimeters (27 inches) per year, but the distribution is erratic to such an extent that prolonged dry periods are common. Mean annual relative humidity ranges from fifty to eighty percent. Wind speeds average over 18 km/hr (11 mi/hr), and southerly winds prevail. Climatology for the Wichita River watershed is based on data obtained from the National Climatic Data Center station in Wichita Falls, Texas. Hydrology The Wichita River headwaters originate at Diversion Dam, impounding Lake Diversion. Beginning in March or April, and continuing until September or October, water is released from Lake Diversion via the South Side Canal for agricultural purposes. Irrigation canals and laterals continue the distribution of flow before returning to the Wichita River. The river bottom is composed of fine, hard-pacted sand with little vegetation on the banks. Average slope is 0.0003 ft/ft. River width increases from 6 meters (20 feet) at the headwaters to 25 meters (82 feet) at the confluence with the Red River. River depth increases --- Page 15 --- commensurately from 0.1 meters (0.3 feet) upstream to 0.8 meters (2.6 feet) downstream. The United States Geological Survey (USGS) currently maintains two continuous flow recording gages on the Wichita River. Upstream at Beverly Drive (SH Loop 11) in Wichita Falls (USGS 07312500) discharge records from 1975, corresponding to the completion of Lake Kemp, to 1985 indicate an average discharge of 5.2 m*/s (184 ft3/s), a maximum discharge of 183 m*/s (6,450 ft'/s), and a 7-day 2-year low-flow of 0.586 m?/s (20.7 ft'/s). Downstream at FM 810, near Charlie, Texas (USGS 07312700) discharge records from 1975 to 1985 indicate an average discharge of 6.7 m*/s (236 ft3/s), a maximum discharge of 161 m/s (5,670 ft?/s), a minimum discharge of 0.42 m*/s (15 ft'/s), and a 7-day 2-year low-flow of 1.504 m3/s (53.1 ft/s). Land Use Patterns Approximately sixty-one percent of the watershed is composed of rangeland, including improved pasture. Irrigated and dry cropland account for thirty-five percent of the land area, with the remaining four percent land use devoted to urbanized areas. WATER QUALITY STANDARDS Rules on water quality standards specifying desired water uses and numerical criteria have been developed pursuant to Texas Water Code §26.023 and Federal Water Pollution Control Act §303. These rules were adopted April 7, 1988 by the Texas Water Commission and written in accordance with the Texas Water Code to meet the goals of the Federal Water Pollution Control Act, as amended through 1987 (33 United States Code 1251 et seq.). Those goals require that, where attainable, water quality will support aquatic life and contact recreational uses. The rules concerning Texas Surface Water Quality Standards are contained in 31 TAC §§307.1-307.10. Desired Water Uses The water uses deemed desirable for the Wichita River (Segment 0214) are as follows: Contact Recreation High Quality Aquatic Habitat Numerical Criteria The following are the numerical criteria established for the Wichita River (Segment 0214) and are intended to insure that water quality will be sufficient to maintain the desired uses: --- Page 16 --- Segment 0214 Parameter Criteria Dissolved Oxygen 5.0 mg/L 24-hour average, 3.0 mg/L minimum pH Not less than 6.5 nor more than 9.0 Temperature Not to exceed 90°F Chloride Annual average not to exceed 1,800 mg/L Sulfate Annual average not to exceed 800 mg/L Total Dissolved Solids Annual average not to exceed 5,000 mg/L Fecal Coliform Thirty-day geometric mean not to exceed 200/100 mL The numerical criteria are applicable, except for conditions described in §307.4(j) of the Texas Surface Water Quality Standards whenever the flow equals or exceeds the low-flow criteria described in Appendix B of $307.10 which is defined as either the seven-day minimum average flow with a recurrence interval of two years (7-day 2-year low-flow) or 0.0028 m?/s (0.1 ft'/s), whichever value is higher. Determination of criteria attainment is dependent on depth collection procedures and varies depending on the water body being sampled. For the Wichita River, samples shall be collected one foot below the water surface if the stream exhibits a vertically mixed water column. A depth integrated sample shall be used to determine attainment if the stream is vertically stratified. Where depth is less than 1.5 feet, the collection depth shall be one-third of the water depth measured from the water surface. At least four measurements per year are required to determine compliance for chloride, sulfate, and total dissolved solids. Five or more samples collected over a period of not more than 30 days are required to determine the attainment of the fecal coliform criterion. Reference should be made to the Texas Surface Water Quality Standards for additional numerical criteria that may not have been included here. Specific dissolved oxygen criteria have not been assigned to each individual tributary within the segment based on observed uses. The criterion for these streams will be evaluated as a result of a Texas Water Commission Receiving Water Assessment, which is conducted in response to individual permit actions in unclassified waters. WASTEWATER DISCHARGES A list of the approved, pending, and projected permits for wastewater discharge to the Wichita River as of June 8, 1987 is shown in Table 1 giving the existing (year 1986), projected (year 2005), and permitted loadings. They are ordered numerically by segment number and then by permit number within each segment. Existing loadings are based on monthly self-reported data. Permitted loadings are based on the 30-dav average (or when present, the annual average) value in the permit. Ammonia nitrogen loading is based on an assumed effluent concentration of 15 mg/L NH,-N for those domestic discharges that do not have permitted NH,-N limitations or that did not self-report NH,-N. The totals for continuous discharges are summarized on the last page of Table 1 with the approximate locations of these outfalls shown --- Page 17 --- on the map in Figure 3. The exact location of all outfalls can be obtained from the Texas Water Commission upon request. In general, the current permit limitations required for domestic dischargers to the Wichita River are secondary with commensurate permit limitations for industrial dischargers. There are currently seven approved outfalls for continuous domestic discharge with final permit limitations totaling 1.042 m3/s, 1,823 kg/day BODs and 1,349 kg/day NH,-N (23.8 MGD, 4,020 lb/day BODs, and 2,975 lIb/day NH,-N). In addition, one "no discharge" permit is approved for domestic wastewater. There are two approved outfalls for continuous industrial discharge with final permit limitations totaling 0.004 m'/s, 0.3 kg/day BODs and 0 kg/day NH,-N (0.1 MGD, 0.7 lb/day BODs, and 0 Ib/day NH,;-N). In addition, three intermittent outfalls, are approved for industrial wastewater. The historical wastewater flows and BOD; loadings since 1970 are shown in Figures 4 through 5. Since 1970, total wastewater flow has increased erratically. Conversely, total BODs, loading has generally decreased. The Wichita Falls-River Road wastewater treatment plant contributes approximately 80 percent of the total loading into the Wichita River. The increased flow with the decreased BODs loading is most likely the result of improved treatment at the River Road WWTP. Existing loadings, based on 1986 self-reporting data, indicate that seven continuous domestic outfalls are discharging an average flow of 0.625 m*/s, 463 kg/day BODs and 798 kg/day NH,-N (14.3 MGD, 1,021 lb/day BODs, and 1,760 lb/day NH,-N). The two continuous industrial outfalls are not yet in existence. WATER QUALITY CONDITIONS The Texas Water Commission currently maintains one active monitoring station within Segment 0214: Station 0214.0100 at FM 810, west of Byers. This data is stored in the Stream Monitoring Network (SMN) system. Other entities may also maintain active stations with data stored in the SMN system. All data in the SMN system are available upon request from the Texas Water Commission. A summary of the last four years of data taken at all SMN stations during the period of October 1, 1983 through September 30, 1987 is shown in Table 2 for the parameters having specified numerical criteria. As shown in Table 2, the mean values for all the parameters are within the numerical criteria established for the Wichita River. Station 0214.0100 at FM 810 is approximately 55.6 kilometers (34.5 miles) downstream of the Wichita Falls-River Road WWTP. As shown in Figure 6, five of the past thirteen years have recorded minimum dissolved oxygen measurements of less than 5.0 mg/L. Due to the fluctuation of the minimum dissolved oxygen values there appears to be no discernible trend at the present time. CLASSIFICATION Classification is taken from The State of Texas Water Quality Inventory (1988) --- Page 18 --- prepared by the Texas Water Commission pursuant to Section 305(b) of the Federal Water Pollution Control Act. Segments are classified as "water quality limited" if applicable water quality criteria cannot be met following incorporation of best practicable treatment (BPT) for industries and/or secondary treatment for municipalities. Segments are classified as "effluent limited" if they are presently meeting or will meet applicable water quality criteria following incorporation of best practicable treatment (BPT) for industries and/or secondary treatment for municipalities. The Wichita River (Segment 0214) was classified as "Water Quality Limited". --- Page 19 --- DOCUMENTATION OF THE WATER QUALITY MODEL MODEL FORMULATION General Water quality modeling is basically an attempt to account for the major sources and sinks of a water quality constituent in a system composed of a number of complex interacting subsystems, each with its own set of physical and biological characteristics. In the case of dissolved oxygen, the primary sources are atmospheric reaeration and photosynthesis. The primary sinks for oxygen are carbonaceous demands, nitrogenous demands, sediment oxygen demands, and biological respiration. In addition, dissolved oxygen may be added or removed from the system through inflows or outflows. The steady-state model used for the Wichita River is QUAL-TX, an updated version of QUAL-II developed by the Texas Water Commission. The QUAL-TX model was chosen because of its ability to rapidly predict water quality profiles in an advective and dispersive system and because its precursor, QUAL-II, is well-known and widely used in the field of modeling. QUAL-TX uses a set of interrelated differential mass transport equations to describe the effects of advection, dispersion, decay, sources, and sinks for all water quality constituents being modeled. The transport equations are then solved by numerical integration using an implicit-finite-difference technique under the assumption that transport occurs along the longitudinal axis of the stream channel. QUAL-TX is capable of simulating carbonaceous biochemical oxygen demand (BOD), nitrogenous oxygen demand through the nitrogen cycle, sediment oxygen demand, dissolved oxygen, the nutrient cycles, algae production, coliforms, and conservative and nonconservative materials. The following discussion briefly summarizes the general theory and use of the model QUAL-TX. Further documentation on the theory and detailed use of the model can be found in the QUAL-TX User's Manual. Segmentation The first step in setting up a QUAL-TX water quality model is to divide the stream into segments of uniform characteristics called reaches. Since new hydraulic and biological coefficients can be specified for each reach, the way in which a model is segmented can significantly affect the output. New segments or reaches may be established due to changes in velocity, depth, or dispersion. Additional flow from tributaries or wastewater discharges may require that a new reach be established. A _ spatial variation from sediment oxygen demand or photosynthesis/respiration parameters may also require additional segmentation. Stream distances associated with the reaches have been determined from USGS quadrangle --- Page 20 --- maps and increase from downstream to upstream from some reference point, usually the mouth of the stream or a dam. With the finite-difference numerical technique, reaches are subdivided into computational elements of equal length. Each element is considered to be completely mixed and therefore has uniform water quality characteristics. As element lengths become smaller, the model will more accurately depict the plug-flow regime with a commensurate increase in storage requirements and computational costs. These factors must be balanced to determine element length. A schematic representation of the Wichita River segmentation is shown in Figure 7. Reach identification data including reach lengths and element lengths are shown in Table 3. The Wichita River model was segmented into 41 reaches with 12 headwaters consisting of the mainstem, 7 primary tributaries, and 4 secondary tributaries. The Wichita River was segmented into twenty-three reaches with 1.0 kilometer (0.6 mile) element lengths from Diversion Dam (Km 177.6) in Archer County to the confluence with the Red River (Km 0.0) in Clay County. Beaver Creek was segmented into two reaches with 1.0 kilometer (0.6 mile) element lengths for a distance of 17.0 kilometers (10.6 miles). Deer Creek was segmented into one reache with 0.5 kilometer (0.3 mile) element length for a distance of 0.5 kilometer (0.3 mile). Buffalo Creek was segmented into four reaches with 1.0 kilometer (0.6 mile) element lengths for a distance of 17.0 kilometers (10.6 miles). Upper Plum Creek was segmented into one reach with 0.5 kilometer (0.3 mile) eiement length for a distance of 0.5 kilometer (0.3 mile). Lower Plum Creek was segmented into three reaches with 0.5 kilometer (0.3 mile) element lengths for a distance of 4.0 kilometers (2.5 miles). Holliday Creek was segmented into one reach with 0.5 kilometer (0.3 mile) element lengths for a distance of 0.5 kilometers (0.3 miles). Bear Creek was segmented into two reaches with 1.0 Kilometer (0.6 mile) element lengths for a discharge of 13.0 kilometers (8.1 miles). An unnamed creek to which the City of Iowa Parks WWTP discharges was segmented into one reach with 0.5 kilometer (0.3 mile) element lengths for a distance of 1.5 kilometers (0.9 miles). The South Fork of Buffalo Creek was segmented into one reach with 1.0 kilometer (0.6 mile) element lengths for a distance of 26.0 kilometers (16.2 miles). An unnamed creek to which Sheppard A.F.B. WWTP discharges was segmented into one reach with 1.0 kilometer (0.6 mile) element lengths for a distance of 4.0 kilometers (2.5 miles). An unnamed creek to which the City of Wichita Falls-Northside WWTP discharges was segmented into one reach with 0.5 Kilometer (0.3 mile) element lengths for a distance of 3.0 kilometers (1.9 miles). Hydraulics After a stream has been segmented, it is necessary to specify the hydraulic and physical characteristics of each reach in the stream system. Hydrodynamic factors fix the transport of oxygen and oxygen-demanding materials in and out of each element in the reach through advective and dispersive components. In a river or stream, transport is accomplished --- Page 21 --- primarily by advection. In an estuary or tidal system, dispersion becomes a dominating factor. These parameters are significantly affected by the geometry and shape of each reach in the system. The advective hydraulic characteristics can be described by two exponential equations. These equations represent the relationship of discharge to velocity and depth as follows: V=aQ where: V = mean velocity, m/s Q@ = mean discharge, m°/s D = mean depth, m a, b, c, = constants d,e In free-flowing systems, the velocity and depth equations are best deter- mined from dye study measurements that are typical for the entire reach. When two or more sets of dye study measurements are available for the same reach, the equations can be determined by graphical means or by regression. When only one set of dye study measurements have been taken, the appropriate procedure is to assume a typical exponent and calculate the coefficient that will reproduce the measured values. If no dye study is available, the equations must be estimated. In constant level lakes or pools and in tidal systems, the depth is assumed to be constant and the depth is entered as the coefficient "e" with "c" and "da" left blank. The velocity exponent "b" is set equal to 1.0 and the coefficient "a" is set equal to 1/WxD where W is the width and D is the depth. Two hydraulic surveys with dye study measurements have been conducted on the Wichita River to date. Advective hydraulic coefficients, as shown in Table 6, were estimated based on flows and cross-sections documented in Intensive Survey of the Wichita River Segment 0214 (Draft, 1987). The exponential equation exponents for all reaches were assumed as follows: velocity exponent "b" equal to 0.5 and depth exponent "d" equal to 0.4. The coefficients were then adjusted to predict the measured velocities and depths. --- Page 22 --- The dispersive hydraulic characteristics can be described by one of two equations depending on whether the system is tidally influenced. In a non-tidal stream, the dispersion is calculated by the following equation: E = 18.53 n v p?-838 where: E = longitudinal dispersion, m/s n = Manning's roughness coefficient V = mean velocity, m/s D = mean depth, m A Manning's roughness coefficient of 0.035 corresponding to natural channels in good condition was used for all reaches. The Wichita River is not tidally influenced and tidal dispersion was therefore excluded in the hydraulic considerations. Carbonaceous Biochemical Oxygen Demand One of the major sinks of oxygen in the receiving water is carbonaceous biochemical oxygen demand. Carbonaceous biochemical oxygen demand is a measure of organic material and is usually defined as the amount of oxygen required by bacteria while stabilizing the decomposable carbonaceous portion of organic matter under aerobic conditions. For purposes of discussion herein, biochemical oxygen demand (BOD) will refer to the carbonaceous portion only. Wastewater discharges usually contain significant quantities of BOD which decompose rapidly in the presence of aerobic bacteria. These bacteria are present in most waters and begin the process of decomposition quickly. When dissolved oxygen concentrations become very low, the decomposition process slows down as the bacteria convert to anaerobic pathways. The BOD is typically determined through a laboratory procedure involving the measurement of oxygen consumed by bacteria over a specified period of time. In order to prevent possible interference from nitrogenous compounds which also consume oxygen, the BOD test should utilize a nitrification suppression technique to inhibit nitrifying bacteria. While biochemical oxidation theoretically takes an infinite time to go to completion, the oxidation is usually 95 to 99 percent complete within a twenty-day period. Hence, the ultimate BOD (BODu) may be considered to be the same as the twenty-day BOD (BOD2,9) unless the organic material degrades very slowly. Routine BOD testing typically uses the five-day period because of the shorter time involved in obtaining the 10 --- Page 23 --- results. Oxidation in the five-day BOD (BODs) test is usually from 60 to 70 percent complete. The BOD» has often been assumed to be equal to 1.5 times the BODs. However, statistical analysis of BOD data collected throughout the state indicates that the BOD» is equal to approximately 2.3 times the BODs. This factor is used in this waste load evaluation whenever the conversion of BODs to BODu is required. Documentation of the BOD values actually used in the model is presented in greater detail in the Calibration Section. The rate at which BOD disappears from the system is a combination of two mechanisms: decay and settling. The BOD decay rate is the rate at which BOD is removed due to bacterial decomposition. When the dissolved oxygen concentrations are high, this process proceeds rapidly. At reduced dissolved oxygen concentrations, this process slows considerably. The QUAL-TX model adjusts the BOD decay rates accordingly. The BOD settling rate is based on standard settling kinetics and assumes that a portion of the BOD in the system is settleable. As the soluble fraction of BOD increases, the settling rate may need to be reduced in a commensurate manner. The BOD rates can sometimes be determined from a semi-logarithmic plot of the stream BOD values downstream of a discharger versus the time-of-travel down the stream. The slope of the line is used to determine the rates. This method proves unacceptable when a large number of discharges prevents isolating one BOD profile or when a dispersive system is encountered. In these cases, the rates must be adjusted so that the predicted BOD profiles match the observed BOD profiles. Documentation of the technique used for selection of the BOD rates is presented in greater detail in the Calibration Section. Nitrogenous Oxygen Demands Various nitrogen compounds present in wastewater discharges also exert an oxygen demand in the receiving water as they change from one form to another. These changes in form require the presence of specific bacterial populations. Ammonia nitrogen (NH,-N) is converted to nitrite nitrogen (NO,-N) by the bacteria Nitrosomonas and theoretically consumes 3.43 mg oxygen/mg nitrogen. Nitrite nitrogen is converted to nitrate nitrogen (NO,-N) by the bacteria Nitrobacter and theoretically consumes 1.14 mg oxygen/mg nitrogen. The conversion of organic nitrogen to ammonia nitrogen is accomplished by hydrolysis and therefore consumes no oxygen. Because the conversion of nitrite nitrogen to nitrate nitrogen takes place so rapidly in comparison to the conversion of ammonia nitrogen to nitrite nitrogen, the two processes are combined together as one in the model. This combined process is known as nitrification. The total theoretical oxygen demand for the conversion of ammonia nitrogen to nitrate nitrogen is 4.57 mg oxygen/mg nitrogen. However, a _ small portion of the oxygen can be obtained through inorganic compounds, slightly reducing the total oxygen demand required by the nitrification process. Based on experimental data, the conversion of ammonia nitrogen 11 --- Page 24 --- to nitrate nitrogen requires 4.33 mg oxygen/mg nitrogen. This is the factor utilized in the model. Under certain circumstances, such as low dissolved oxygen concentrations, the nitrifying bacterial populations and/or their activity may be suppressed. Research indicates that dissolved oxygen levels below 2 mg/L _ significantly inhibit nitrification. Under anaerobic conditions, nitrate nitrogen may be converted to nitrogen gas in a process known as denitrification. These kinetics are accounted for in the QUAL-TX model. Nitrification rates can be determined by the same graphical means as described previously for BOD decay rates unless interfering processes such as photosynthesis or denitrification are taking place. The graphical method also proves unacceptable when a large number of discharges are present or when a dispersive system is encountered. In these cases the rates must be adjusted so that the predicted nitrogen and dissolved oxygen profiles match the observed profiles. Documentation of the technique used for the selection of the nitrification rates is presented in greater detail in the Calibration Section. Sediment Oxygen Demand Another major sink of oxygen in the receiving water is sediment oxygen demand. Bottom deposits in the form of settled organics accumulate along the streambed when stream velocities are not sufficient to keep solid particles in suspension and can exert an oxygen demand. Background sediment oxygen demand resulting from nonpoint sources, decaying leaves, and detrital matter can range from 0.05 gm oxygen/m*-day in mineral soils to 2.0 gm oxygen/m’*-day in estuarine muds at 20°C. In addition to background sources, organics discharged from domestic or industrial wastewater treatment plants can settle out below wastewater outfalls creating sediment oxygen demands ranging from 0.05 gm oxygen/m?-day to 10 gm oxygen/m?-day. At higher treatment levels, the sediment oxygen demand will be reduced to background levels due to the reduction in discharged solids. The model can convert settled BOD and organic nitrogen to sediment oxygen demand to account for this increase in sediment oxygen demand below wastewater outfalls. As with BOD decay rates and nitrification rates, low dissolved oxygen concentrations can inhibit the rate of sediment oxygen demand. The QUAL-TX model takes this factor into account. Sediment oxygen demand can be determined based on in situ techniques, laboratory core analyses, or literature values. Documentation of the technique used for selection of the sediment oxygen demands is presented in greater detail in the Calibration Section. 12 --- Page 25 --- Atmospheric Reaeration The process by which dissolved oxygen in the stream is replenished from the overlying air is known as atmospheric reaeration and is the primary source of dissolved oxygen in the receiving water. The reaeration process is generally a function of stream geometry and hydraulics. Several techniques and equations have been developed to estimate reaeration coefficients based on stream geometry and_ stream characteristics. The equations are generally of the following form: where: K, = reaeration rate, per day V = mean stream velocity, m/s D = mean stream depth, m a, b, c = constants The selection of the constants can be determined from previous research done on streams with similar characteristics or from direct measurements. Direct measurements provide the most reliable results and are best deter- mined from krypton-tritium radiotracer techniques. The reaeration equation selected for this model was determined by regression analysis of data obtained from krypton-tritium radiotracer studies on streams throughout Texas. The regressed equation follows the general form given previously using "a" equal to 1.923, "b" equal to 0.273, and "c" equal to 0.894, Photosynthesis/Respiration The presence of algae and aquatic plants can also have an effect on dissolved oxygen in surface waters. During periods of daylight, oxygen is produced as a by-product of photosynthesis and is consumed due to respiration. At night, oxygen production stops while respiration continues. This complex process, involving both a source and sink of oxygen can cause a surplus or deficit of oxygen frequently resulting in diurnal variations of dissolved oxygen concentrations. These variations depend on a number of conditions including light intensities, available nutrients, and turbidity. Planktonic algae are represented in the model by chlorophyll a. Chlorophyll a is one of the chemical pigments which determines the photosynthetic activity of algae. Although present in all algae, it is 13 --- Page 26 --- predominant in green algae. Attached algae and/or rooted plants are presented in the model by macrophytes. Both planktonic algee and macrophytes require certain nutrients for growth. Although other nutrients are necessary, phosphorus and nitrogen are generally the limiting factors and are the ones of primary interest. The utilization of nitrogen in the growth of algae and macrophytes can be an important factor in the nitrogen balance and often complicates attempts to account for other processes such as _ nitrification. For this reason, photosynthesis/respiration must be considered in modeling analyses. Further discussion of the role of photosynthetic activity as related to this model is presented in the Calibration Section. Temperature Many of the reactions which determine water quality in natural systems are dependent on temperature. This dependence is usually considered by changing the various rate constants according to the following equation: Ka = Kyp 07-20) where K,, and Kop are rate constants at a temperature T and 20°C, respectively, and © is a temperature correction factor which depends on the reaction being considered. The default values for temperature correction factors as specified in the QUAL-TX User's Manual were used in this modeling effort. The default value temperature correction factors were obtained from Rates, Constants and Kinetics Formulations in Surface Water Quality Modeling published by the United States Environmental Protection Agency. Four of the more important factors are listed as follows: ©, Temperature Reaction Correction Factor Atmospheric Reaeration 1.017 + 1.024 Carbonaceous Decay 1.047 Nitrogenous Decay 1.083 Sediment Oxygen Demand 1.074 Boundary Conditions Boundary conditions are used to fix water quality at a constant value at the upper and lower bounds of a system. The boundary conditions should be chosen at a point where the quality is unlikely to change regardiess of the upstream conditions or downstream conditions. The 14 --- Page 27 --- upper boundary is represented by the headwaters and should always be an area of advective transport so that dispersion from downstream does not affect it. The lower boundary is required only in dispersive systems. In advective systems, it is unrestrained and does not affect upstream water quality. The lower boundary should be a large body of water that can act as a sink/source of water quality constituents without being affected by the upstream conditions. Because the Wichita River is an advective system, a lower boundary is not required for this model. Waste Loads Whenever possible, the tributaries into which waste loads enter should be modeled. However, sometimes this is not possible due to the complexity of the system. When a waste load must pass through an unmodeled series of streams or ditches before reaching the modeled stream or tributary, the waste load should be degraded to account for this travel time. For the purposes of this model, the waste load from any discharger over 0.5 kilometer (0.3 mile) from a modeled stream is degraded based on a velocity of 0.03 m/s (0.1 ft/s), a BOD decay rate of 0.1 per day, and a nitrification rate of 0.2 per day, which are typical values for small shallow Texas streams. CALIBRATION Survey Discussion The intensive survey field data and water samples used to calibrate the Wichita River model were gathered by the Texas Water Commission during the period of July 21-25, 1986. Laboratory analyses of water samples were conducted by the Texas Department of Health in Austin, Texas. Summaries of flow, field, and laboratory data collected at stream stations are shown in Tables 7 through 9. Summaries of flow, field, laboratory, and self-reporting data collected from wastewater dischargers are shown in Tables 10 through 13. A more detailed presentation of the data is available from the Texas Water Commission in the report Intensive Survey of the Wichita River Segment 0214 (June, 1987). The water quality data were collected over a 12-hour period with composite water samples and field measurements being collected approximately every four hours. The locations of stream stations and wastewater dischargers listed in Tables 7 through 13 are shown in Figure 3. Stream flows in the Wichita River during this survey were erratic and variable. Fluctuating irrigation return flows - high-flow occurs during the summer - and scattered thunderstorms combined to create non-steady state conditions. As shown in Table 7, mainstem stream flows ranged from 0.175 m°/s (6.2 ft/s) to 4.984 m3/s (176 ft'/s). Flow velocities calculated from time-of-travel studies were moderately fast and ranged from 0.103 m3/s (0.34 ft*/s) to 0.357 m%/s (1.17 ft/s). Diurnal dissolved oxygen averages remained above the 5.0 mg/L segment criterion throughout the river. The City of Wichita Falls-River Road WWTP discharge had minimal effect on the water quality of the river lowering 15 --- Page 28 --- the dissolved oxygen diurnal average approximately 1.7 mg/L between SH 240 and River Road. Model Discussion Using the July 21-25, 1986 data presented previously, the Wichita River model was calibrated under stream conditions of high-flows and high temperatures. The input data used for the calibration run are shown in Table 14. The calibration profiles for dissolved oxygen, biochemical oxygen demand, and ammonia nitrogen are shown in Figures 8 through 10. The first step in the calibration process was to set up a flow balance for the Wichita River, stream flows were based on measured values from the survey and adjusted on a flow per unit area basis if the input locations were different from the location of the measured value. Incremental inflows were also determined on a flow per unit area basis. Wastewater discharge flow for the City of Wichita Falls-River Road WWTP was based on measured values from the survey. All other wastewater discharge flows were based on self-reporting data. Biochemical oxygen demand concentrations used in the model were based on self-reporting BOD; data corrected to ultimate BOD except for the City of Wichita Falls-River Road WWTP discharge, where the ultimate BOD and ammonia nitrogen were measured directly during the intensive survey. If data were not available, the values were estimated. Water quality associated with incremental inflows was input using estimated background water quality levels. Following determination of loadings from the tributaries, dischargers, and incremental flows as described above, the actual calibration was begun. Initial estimates of the coefficients were made and then adjusted within acceptable ranges until the predicted profiles provided a reasonable fit to the observed data. Some of the major rate coefficients (base e) for the calibration run excluding those in the tributary reaches are summarized as follows: Rate Coefficient 20°C Value Corrected Value Reaeration comin 9.02 per day Sediment Oxygen Demand 0.30-0.30 g/m?-day 0.58-0.82 g/m?-day BOD Decay 0.10-0.10 per day 0.15-0.16 per day BOD Settling 0.05-0.05 m/day 0.08-0.47 per day Ammonia Nitrogen Decay 0.30-0.30 per day 0.58-0.69 per day 16 --- Page 29 --- As indicated in Figures 8 through 10, reasonable agreement is shown between the predicted and observed values for dissolved oxygen, ultimate biochemical oxygen demand, and ammonia nitrogen. VERIFICATION Survey Discussion The intensive survey field data and water samples used to verify the Wichita River model were gathered by the Texas Department of Water Resources during the period of April 6-9, 1981. Laboratory analyses of water samples were conducted by the Texas Department of Health in Austin, Texas. Summaries of flow, field, and laboratory data collected at stream stations are shown in Tables 15 through 17. Summaries of flow, field, laboratory, and se…