| TMDL End Point: |
THE BIG SIOUX RIVER'S LC IS EXPRESSED THROUGH THE USED OF LOAD DURATION CURVES (LDC) FOR EACH OF THE IMPAIRED SEGMENTS. NUMERIC EXPRESSIONS OF THE LDC ARE GIVEN IN TABULAR FORM FOR EACH POINT SOURCE AND BY HUC12 AND FLOW RANGE FOR LCS. THE NUMERIC TARGET USED TO CALCULATE EACH LDC IS THE SINGLE SAMPLE MAXIMUM E. COLI CONCENTRATION (IA) OR FECAL COLIFORM CONCENTRATION (SD) OF 235 AND 400 COLONY FORMING UNITS (CFU) PER 100 ML RESPECTIVELY. THE TMDL IDENTIFIES REQUIRED REDUCTIONS OF FROM 0 - 99.8% DEPENDING ON SEGMENT AND PERCENTILE OF FLOW EXCEEDANCE TO MEET WQS.
THE EPA CONCURS THAT MEETING THE TMDL TARGETS WILL RESULT IN THE ATTAINMENT OF WQS IN THE BIG SIOUX RIVER.
THE DESIGNATED BENEFICIAL USES FOR ALL SEGMENTS OF THE BIG SIOUX RIVER COVERED BY THIS TMDL ARE: IN IOWA, CLASS A, PRIMARY CONTACT RECREATION, AND CLASS B, AQUATIC LIFE; IN SOUTH DAKOTA, IMMERSION AND LIMITED CONTACT RECREATION, WARM WATER SEMI-PERMANENT FISH LIFE, FISH AND WILDLIFE PROPAGATION, RECREATION AND STOCK WATERING, AND IRRIGATION WATERING. THE USE THAT IS IMPAIRED IS: FOR IOWA, CLASS A PRIMARY CONTACT RECREATION; FOR SOUTH DAKOTA, IMMERSION RECREATION.
IOWA'S WQS FOR E. COLI ARE FOUND AT:
IAC 61.3(3) SPECIFIC WATER QUALITY CRITERIA.
(1) THE ESCHERICHIA COLI (E. COLI) CONTENT SHALL NOT EXCEED THE LEVELS NOTED IN THE BACTERIA CRITERIA
TABLE WHEN THE CLASS ¿A1,¿ ¿A2,¿ OR ¿A3¿ USES CAN REASONABLY BE EXPECTED TO OCCUR.
BACTERIA CRITERIA TABLE (ORGANISMS/100 ML OF WATER)
USE GEOMETRIC MEAN SAMPLE MAXIMUM
CLASS A1
3/15 ¿ 11/15 126 235
11/16 ¿ 3/14 DOES NOT APPLY DOES NOT APPLY
CLASS A2 (ONLY)
3/15 ¿ 11/15 630 2880
CLASS A2 AND B(CW) OR HQ
YEAR-ROUND 630 2880
CLASS A3
3/15 - 11/15 126 235
11/16 - 3/14 DOES NOT APPLY DOES NOT APPLY
CLASS A1 - PRIMARY CONTACT RECREATIONAL USE, CLASS A2 - SECONDARY CONTACT RECREATIONAL USE,
CLASS A3 - CHILDREN¿S RECREATIONAL USE
WHEN A WATER BODY IS DESIGNATED FOR MORE THAN ONE OF THE RECREATIONAL USES, THE MOST STRINGENT CRITERIA
FOR THE APPROPRIATE SEASON SHALL APPLY.
SOUTH DAKOTA'S WQS ARE
74:51:01:50. CRITERIA FOR IMMERSION RECREATION WATERS. THE CRITERIA OF PARAMETERS FOR IMMERSION RECREATION WATERS AND THEIR ALLOWABLE VARIATIONS THAT ARE NOT INCLUDED UNDER § 74:51:01:55 AND APPENDIX B, UNLESS SET UNDER § 74:51:01:24, ARE AS FOUND IN THE FOLLOWING TABLE:
PARAMETER CRITERIA UNIT OF MEASURE SPECIAL CONDITIONS
FECAL COLIFORM
(MAY 1 ¿ SEPTEMBER 30) < 200 /100 ML GEOMETRIC MEAN BASED ON A MINIMUM OF 5 SAMPLES OBTAINED DURING SEPARATE 24-HOUR PERIODS FOR ANY 30-DAY PERIOD, AND THEY MAY NOT EXCEED THIS VALUE IN MORE THAN 20 PERCENT OF THE SAMPLES EXAMINED IN THIS SAME 30-DAY PERIOD
< 400 IN ANY ONE SAMPLE
THE IMPAIRMENT IS APPLICABLE DURING THE IOWA RECREATION SEASON WHICH BEGINS EARLIER, MARCH 15, AND ENDS LATER, NOVEMBER 15, THAN THE SOUTH DAKOTA RECREATION SEASON. THE IOWA SEASON IS APPLICABLE BECAUSE AS A BOUNDARY WATER THE TMDL MUST BE PROTECTIVE OF THE MOST STRINGENT WQS.
THE TMDL TARGETS NUMERIC CRITERIA (SINGLE SAMPLE MAXIMA) FOR BOTH STATES. FOR IOWA THIS IS E. COLI AND FOR SOUTH DAKOTA, FECAL COLIFORM BACTERIA.
REFER TO THE TMDL DOCUMENT FOR SPECIFIC LOADING INFORMATION FOR PERMITTED POINT SOURCES AND NON-POINT SOURCES.
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