2017-Discharge-Report

2017 GROUNDWATER

DISCHARGE AND USAGE

2018

2017 Groundwater Discharge and Usage Groundwater discharges from the Edwards Aquifer either as springflow or as pumping from wells. Comal and San Marcos springs, the largest and second-largest springs in Texas, respectively, are fed by the Edwards Aquifer. This springflow greatly benefits the recreational economies in New Braunfels and San Marcos, and both springs provide habitat for several federally protected threatened and endangered species. Figure 1 shows locations of the major springs in the Edwards Aquifer region. Wells drilled into the Edwards Aquifer throughout the region provide water for many diverse uses, including irrigation, municipal water supplies, industrial applications, and domestic/livestock consumption. Estimates of total annual groundwater dis- charge from combined springflow and pumping for the Edwards Aquifer are provided in Table 1 for the period of record (1934–2017). Annual total groundwater discharge estimates range from a low of 388,800 acre-feet in 1955 to a high of 1,130,000 acre-feet in 1992. In 2017, the total groundwater discharged from the Ed- wards Aquifer from wells and springs is esti- mated at 872,206 acre-feet: 493,000 acre-feet as springflow and 379,206 acre-feet as pump- ing from wells. The portion of discharge as springflow is esti- mated by measuring streamflow downstream of the springs and converting the streamflow measurements to spring discharge by subtract- ing any estimated contributions from surface runoff. Total annual spring discharge has var- ied from a low of 69,800 acre-feet in 1956 to a high of 802,800 acre-feet in 1992. Monthly springflow estimates for 2017 at each of the six major Edwards Aquifer springs are provided in Table 2.

In Figures 2 and 3, flows at Comal and San Marcos springs are shown as mean annual flows compared with the long-term historical mean flow for the available period of record. The 2017 mean annual flow was only slightly lower than the historical mean discharge at San Marcos Springs, while the 2017 mean annual flow at Comal Springs was equal to the historical mean discharge. Discharge as well pumping can be classified as either reported or unreported discharge. Reported discharge refers to water pumped from the aquifer by a person or entity holding a groundwater withdrawal permit. These users, who are typically larger quantity users, meter their withdrawals and report the totals to the EAA. Unreported discharge refers to use that does not require a groundwater withdrawal permit from the EAA, such as domestic, live- stock, or federal facility use. Unreported dis- charge is estimated based on numbers of wells and statistical estimates of per-well usage. In 2017, unreported discharge for domestic and livestock wells was estimated at 14,011 acre- feet, and non-reporting federal facility discharge was estimated at 5,343 acre-feet, for a total of 19,354 acre-feet of unreported discharge. Re- ported discharge totaled 359,852 acre-feet. The total of all reported and unreported pump- ing discharge is 379,206 acre-feet, which is just slightly above the 10-year mean and median annual discharges listed at the end of Table 1. Table 3 provides a summary of well and spring discharge for 2017 based on type of use and county. The distribution of discharge from springflows and the different types of pumping for 2017 is shown graphically in Figure 4. Total annual discharge from pumping and springflow are compared in Figure 5 for the period of record from 1934–2017. The years when springflow exceeds pumping tend to be wet years when pumping demand is lowered by more frequent

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E DWARD S AQU I F E R AU THOR I T Y

Caldwell

Guadalupe

San Marcos Springs

Comal Springs

Hays

Wilson

Comal

Hueco Springs

San Antonio Springs

Bexar

Blanco

0 20 30 10 40 Approximate Scale in Miles

Atascosa

San Pedro Springs

Kendall

Medina

Gillespie

Zavala Frio

Bandera

Edwards Kerr

Real

Leona Springs

Figure 1. Major Springs in the Southern Segment of the Balcones Fault Zone Edwards Aquifer.

Uvalde

Fort Clark Springs

(Las Moras Springs)

Kinney

County Boundary

Spring Location

Drainage Area

Recharge Zone

Artesian Zone

Explanation

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20 17 GROUNDWAT E R D I S CHARG E AND U SAG E

years has been limited by the withdrawal per- mit system and critical period pumping reduc- tions implemented under the Edwards Aquifer Authority Act. Table 4 provides a historical list of total annual discharge by type of use for the period 1955–2017.

rainfall and higher aquifer levels produce in- creased springflows. Conversely, during dry years pumping tends to exceed springflow due to increased municipal and agricultural demand and lower aquifer levels. Since 1997, however, the increase in pumping demand during dry

Table 1. Annual Estimated Groundwater Discharge Data by County for the Edwards Aquifer, 1934–2017 (measured in thousands of acre-feet).

Total Wells

Total Springs

Year Uvalde a

Medina Bexar b

Comal c

Hays

Total 437.9 519.6 598.2 571.2 557.8 432.8 416.6 601.2 594.7 539.3 567.4 614.8 583.9 593.5 450.6 479.8 466.7 425.6 424.9 468.3 424.3 388.8 390.9 456.5 617.5 619.0 655.4 683.5 589.0 516.0 474.0 578.9 571.2 557.4 660.0 658.7 727.1 679.5 747.1 838.0 861.2 868.2 853.4 960.9 807.3 914.5 819.4 794.4 786.4 720.1 708.1 856.5 817.3 922.0 909.7

1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988

12.6 12.2 26.6 28.3 25.2 18.2 16.1 17.9 22.5 19.2 11.6 12.4 6.2 13.8 9.2 13.2 17.8 16.9 22.7 27.5 26.6 28.3 59.6 29.0 23.7 43.0 53.7 56.5 64.6 51.4 49.3 46.8 48.5 81.1 58.0 88.5

1.3 1.5 1.5 1.5 1.6 1.6 1.6 1.6 1.7 1.7 1.7 1.7 1.7 2.0 1.9 2.0 2.2 2.2 3.1 4.0 6.3

109.3 171.8 215.2 201.8 187.6 122.5 116.7 197.4 203.2 172.0 166.3 199.8 180.1 193.3 159.2 165.3 177.3 186.9 187.1 193.7 208.9 215.2 229.6 189.4 199.5 217.5 215.4 230.3 220.0 217.3 201.0 201.1 198.0 239.7 207.1 216.3 230.6 262.8 247.7 273.0 272.1 259.0 253.2 317.5 269.5 294.5 300.3 280.7 305.1 277.6 309.7 295.5 294.0 326.6 317.4

229.1 237.2 261.7 252.5 250.0 219.4 203.8 250.0 255.1 249.2 252.5 263.1 261.9 256.8 203.0 209.5 191.1 150.5 133.2 141.7 101.0 70.1 33.6 113.2 231.8 231.7 235.2 249.5 197.5 155.7 141.8 194.7 198.9 139.1 238.2 218.2 229.2 168.2 234.3 289.3 286.1 296.0 279.7 295.0 245.7 300.0 220.3 241.8 213.2 186.6 108.9 200.0 229.3 286.2 236.5

85.6 96.9 93.2 87.1 93.4 71.1 78.4

101.9 103.7 112.7 120.2 120.1 118.9 120.1 136.8 144.6 149.1 147.3 153.3 155.0 167.0 168.7 179.4 193.8 209.7 215.4 229.8 246.2 261.0 321.1 237.3 219.3 234.5 227.1 228.2 267.9 276.4 260.2 256.1 255.9 341.3 251.7 307.5 329.4 406.8 371.3 310.4 377.4 327.8 349.5 380.6 431.8 391.5 491.1 387.1 453.1 418.5 529.8 522.5 429.3 364.1 540.0

336.0 415.9 485.5 451.0 437.7 313.9 296.5 464.4 450.1 390.2 420.1 461.5 428.9 426.5 281.9 300.4 272.9 215.9 209.5 238.5 178.1 127.8 69.8 219.2 398.2 384.5 428.3 455.3 321.1 239.6 213.8 322.8 315.3 216.1 408.3 351.2 397.7 272.7 375.8 527.6 483.8 540.4 503.9 580.3 375.5 523.0 328.3 407.3 333.3 301.6 178.3 334.0 388.0 557.9 369.7

134.3 112.2 97.2 135.3 137.8 134.0 127.6 77.3 89.8 78.3 69.1 78.8 101.4 81.5 64.1 50.4 113.0 155.9 118.5 143.5 140.8 98.8 81.9 73.3 126.3 115.4 82.3 146.8 122.1 149.9 99.1 123.7 164.3 141.1 178.6 164.7 172.0 99.1 157.0 107.9 141.6 105.5 118.5 85.7 144.9 160.4 198.4 116.9

11.1 17.7 11.9 6.6 8.3 7.6 6.4 8.1 9.7 8.6 10.0 10.4 15.2 9.9 13.6 16.5 32.4 28.8 14.9 28.6 22.6 19.4 19.9 38.7 32.9 39.9 26.1 33.4 29.7 46.9 59.2 41.9 15.9 82.2

100.9 117.0 112.6 96.5 133.3 112.0 136.4 156.5 154.3 130.1 151.0 104.2 129.2 107.7 156.9 156.9 91.7 94.9 156.7

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E DWARD S AQU I F E R AU THOR I T Y

Table 1. (continued)

Total Springs

Total Wells

Year Uvalde a

Medina Bexar b

Comal c

Hays

Total 766.5 730.0 790.6

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

156.9 118.1 76.6 76.5 107.5 95.5 90.8 117.6 77.0 113.1 104.0 89.1 68.6 76.2 89.4 91.3 107.4 107.5 64.6 102.0 76.9 53.1 79.6 57.6 43.6 41.5 27.1 46.9 63.0

70.5 69.7 25.6 9.3 17.8 41.1 35.2 66.3 31.4 51.3 49.2 45.1 33.9 40.6 34.8 22.5 37.3 64.9 18.4 48.8 47.3 36.4 57.4 44.3 42.8 43.1 27.6 31.9 43.6

305.6 276.8 315.5 370.5 371.0 297.7 272.1 286.8 260.2 312.4 307.1 283.6 291.6 311.9 331.7 331.9 366.1 289.5 330.2 320.4 265.2 298.5 277.2 267.5 251.0 230.5 256.3 262.6 305.3

147.9 171.3 221.9 412.4 349.5 269.8 235.0 150.2 243.3 271.8 295.5 226.1 327.7 350.4 344.7 341.4 349.3 216.7 331.7 266.6 206.6 312.1 187.7 193.4 154.9 114.5 239.8 320.7 294.0

85.6 94.1 151.0 261.3 151.0 110.6 127.8 84.7 149.2 168.8 143.0 108.4 175.4 202.1 176.3 153.1 175.6 87.9 196.0 108.0 87.8 162.5 91.0 124.2 96.0 97.9 178.8 208.3 166.8

542.4 489.4 436.0 327.2 407.3 424.6 399.6 493.6 377.1 453.5 442.7 414.8 367.7 371.3 362.1 317.4 388.5 454.5 319.9 428.6 395.7 372.6 427.7 384.7 355.8 332.2 325.2 325.3 379.2

224.1 240.6 354.6 802.8 589.4 390.2 361.3 212.0 383.9 464.1 456.1 337.5 529.6 609.9 621.5 622.9 647.1 312.0 621.0 417.1 287.9 490.0 265.2 302.3 232.8 195.4 404.5 545.0 493.0

1130.0 996.7 814.8 761.0 705.6 761.1 917.6 898.8 752.3 890.0 981.2 976.9 940.3 1035.7 766.5 940.9 845.7 683.7 862.6 692.9 687.0 588.6 527.5 729.7 870.3 872.2

For period of record 1934–2017: Median 66.6 18.9

257.7 249.4

234.7 228.3

118.5 123.3

699.3 698.7

328.6 316.3

384.2 382.6

Mean

71.1

24.0

For last 10 years, 2007–2017: Median 55.4

43.4 42.3

266.4 273.5

223.2 214.9

116.1 123.0

711.3 736.0

375.9 372.7

353.4 363.3

Mean

59.1

Data source: Unpublished USGS and Edwards Aquifer Authority files (2017). a = As of 2008, no longer includes Kinney County discharge; prior years include 1,900 acre-feet of discharge for Kinney County. b = Includes reports of Edwards Aquifer irrigators in Atascosa County. c = Includes reports of Edwards Aquifer industrial and municipal users in Guadalupe County. Differences in totals may occur as a result of rounding.

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20 17 GROUNDWAT E R D I S CHARG E AND U SAG E

Table 2. Estimated Spring Discharge from the Edwards Aquifer, 2017 (measured in acre-feet).

Leona Springs and Leona River Underflow

Total Monthly Discharge from Springs

San Pedro Springs

San Antonio Springs

San Marcos Springs

Comal Springs

Hueco Springs

Month

January February March

2.120 1,790 1,970 2,160 1,950 1,910 1,370 1,190 1,260 1,840 1,840 2,060

760 730 870 640 390 312 92 108 122 201 152 198

5,460 5,020 5,770 3,420 763 415

24,100 23,000 25,500 24,500 23,400 20,700 17,900 16,600 16,900 18,000 17,600 17,800

5,300 4,800 5,960 5,070 4,400 2,990 2,500 2,390 1,970 1,570 1,190 1,430

13,900 13,100 14,700 16,200 16,600 14,400 12,500 11,400 13,600 12,500 11,100 10,600

51,700 48,500 54,800 51,900 47,500 40,700 34,300 31,700 33,900 34,000 31,800 32,100

April May June July

0 0 0 0 0 0

August

September October November December

Total

21,500

4,570

20,800

246,000 39,600

161,000

493,000

Data source: USGS unpublished report (2017). Totals might not equal sum of discharge values as a result of rounding.

Comal Springs Annual Mean Flow Compared to Historical Mean Flow for Period of Record from 1933-2017

500

450

400

350

300

250

200

Historical Mean Flow for Period of Record (286 cfs)

Annual Mean Flow for 2017 (286 cfs)

150

Mean Annual Flow in cfs

100

50

0

1933

1935

1937

1939

1941

1943

1945

1947

1949

1951

1953

1955

1957

1959

1961

1963

1965

1967

1969

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007

2009

2011

2013

2015

2017

Year

Figure 2. Mean Annual Discharge at Comal Springs

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E DWARD S AQU I F E R AU THOR I T Y

Table 3. Comprehensive Discharge Summary for Calendar Year 2017 (in acre-feet)

Reported Use (permitted wells)

Unreported Use

Non- Reporting Facilities *

Total Wells and Springs

Total Well Discharge

Spring Discharge

Domestic or Livestock *

County

Irrigation Municipal

Industrial

Atascosa

1,454 4,951

0

0

0

0

1,454

0

1,454

Bexar Comal

244,528

14,948

8,919

5,089

278,435

25,370 285,600

303,805 293,859

42

4,991

2,816

410

0 0

8,259

Guadalupe

0

6

184

0

190

0

190

Hays

117

3,247 6,983 3,182

1,307 3,413

880

254

5,805

161,000

166,805 43,576 62,987 872,206

Medina Uvalde

32,021 35,534 74,119

1,159 2,643

0 0

43,576 41,487 379,206

0

128

21,500 493,000

Totals

262,937

22,795

14,011 5,343

* Federal facilities and domestic and livestock wells do not report annual use (non-reporting); quantities estimated. Differences in totals may occur because of rounding.

San Marcos Springs Annual Mean Flow Compared to Historical Mean Flow for Period of Record from 1957-2017

400

350

300

Historical Mean Flow for Period of Record (175 cfs)

250

200

150

Mean Annual Flow in cfs

100

Annual Mean Flow for 2017 (161 cfs)

50

0

1957

1959

1961

1963

1965

1967

1969

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007

2009

2011

2013

2015

2017

Year

Figure 3. Mean Annual Discharge at San Marcos Springs

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20 17 GROUNDWAT E R D I S CHARG E AND U SAG E

2017 DISCHARGE BY TYPE OF USE:

Unreported 2%

Industrial 3%

Irrigation 8%

Municipal 30%

Springs 57%

Total Well Pumping = 379,206 acre-feet Total Springflow = 493,000 acre-feet

Figure 4. 2017 Discharge by Type of Use

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E DWARD S AQU I F E R AU THOR I T Y

Groundwater Pumping Compared with Total Spring Flow from the Edwards Aquifer, 1934-2017 Well Discharge Spring Discharge

900

800

700

600

500

400

300

200

Annual Discharge in Thousands of Acre-Feet

100

0

1934

1936

1938

1940

1942

1944

1946

1948

1950

1952

1954

1956

1958

1960

1962

1964

1966

1968

1970

1972 Year

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

2010

2012

2014

2016

Figure 5. Groundwater Pumping Compared with Springflow

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20 17 GROUNDWAT E R D I S CHARG E AND U SAG E

Table 4. Annual Estimated Edwards Aquifer Groundwater Discharge by Use, 1955–2017 (measured in thousands of acre-feet).

Domestic/ Stock

Industrial/ Commercial

Year

Irrigation Municipal

Springs

1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996

85.2 127.2 68.8 47.2 60.0 54.9 52.1 72.7 75.4 72.6 68.0 68.2 119.4 59.3 95.2 110.1 159.4 128.8 82.2 140.4 96.4 118.2 124.2 165.8 126.8 177.9 101.8 130.0 115.9 191.2 203.1 104.2 40.9 193.1 196.2 172.9 88.5 27.1 69.3 104.5 95.6 181.3

120.5 138.3 116.1 113.7 118.9 121.1 124.5 143.7 151.8 140.2 138.8 141.8 171.0 146.9 162.0 167.5 196.2 190.5 177.1 174.6 182.5 182.1 205.3 214.2 208.9 256.2 231.8 268.6 249.2 287.2 263.7 266.3 260.9 286.2 285.2 254.9 240.5 236.5 252.0 247.0 255.0 261.3

30.1 28.9 29.8 33.4 31.5 29.1 29.6 28.8 27.8 26.3 27.0 23.3 25.1 25.5 29.2 29.3 28.6 30.8 32.3 33.5 33.6 34.6 38.1 40.3 40.7 43.3 40.9 39.5 38.8 36.2 39.2 42.0 43.5 41.9 38.2 37.9 39.5 34.8 49.9

25.1 22.4 22.6 25.1 24.2 23.3 22.2 22.8 21.8 21.7 22.3 22.6 25.8 20.0 21.1 22.5 22.6 21.1 18.8 15.1 15.3 14.7 13.0 11.5 15.2 13.7 12.6 15.0 14.7 15.2 16.5 16.8 18.7 18.8 22.9 23.7 67.5 29.0 36.1

127.8 69.8 219.2 398.2 384.5 428.3 455.3 321.1 239.6 213.8 322.8 315.3 216.1 408.3 351.2 397.7 272.7 375.8 527.6 483.3 540.4 503.9 580.3 375.5 523.0 328.3 407.3 333.3 301.5 178.3 334.0 388.0 557.9 369.7 224.1 240.6 354.6 802.8 589.4 390.2 361.3 212.0

33.9 11.6* 12.3*

39.3 37.3 38.8

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E DWARD S AQU I F E R AU THOR I T Y

Table 4. (continued)

Domestic/ Stock

Industrial/ Commercial

Year 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

Irrigation

Municipal

Springs

77.4 a/b

253.0 266.5 273.3 261.3 245.9 228.4 237.2 220.3 255.1 259.1 236.0 273.6 247.5 259.9 265.5 257.9 239.5 220.1 247.2 232.6 268.3

12.3 13.4 13.4 13.4 13.4 13.6 13.7 13.8 13.8 13.8 13.8

34.4 41.7 b 42.4 33.8 29.4 32.3 31.7 28.1 34.3 34.5 27.6 28.8 25.7 26.4 23.6 22.6 26.3 22.8 21.9 24.0 22.8

383.9 464.1 456.1 337.5 529.4 609.9 621.5 622.9 647.1 312.0 620.6 417.1 288.0 490.0 265.2 302.3 232.8 195.4 404.5 545.0 493.0

131.9 a 113.6 106.3 79.0 97.1 79.6 55.4 85.3 149.1 42.5 112.7 108.9 72.7 124.9 90.6 76.3 75.3 42.2

13.5** 13.6** 13.6** 13.6** 13.7** 13.7** 13.9** 13.9** 14.0** 14.0**

54.7 74.1

For period of record 1955–2017: Median 95.6

236.5 215.9

13.6** 13.5**

22.8 24.8

383.9 391.5

Mean

101.9

For period of record 2007–2017 (last ten years): Median 75.8 252.7

13.7 13.7

23.8 24.5

353.4 363.3

Mean

83.2

251.2

Data source: USGS unpublished report and Edwards Aquifer Authority files (2017). a = Includes estimates from Atascosa County discharge by Edwards Aquifer users. b = Includes estimates from Guadalupe County discharge by Edwards Aquifer users. * = In 1995 USGS revised the method of calculating domestic/livestock pumpage, which significantly decreased the estimates for 1995 and 1996. ** = Revision based on number of new wells permitted annually and discontinuation of Kinney County estimates in total. Differences in totals may occur as a result of rounding.

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20 17 GROUNDWAT E R D I S CHARG E AND U SAG E