Summary Table of Completed TMDLs and I-Plans
On this page:
See Also:
Back to TMDL Projects Completed TMDLs and I-Plans
(In alphabetical order by name of water body or region)
| TMDL Project Parameter—Segments |
Impairments Addressed in Project | Water-Quality Segments Addressed | Assessment Units Addressed |
TCEQ Date of TMDL Adoption | TMDLs Adopted | EPA Date of Action on TMDLs |
TMDLs Approved by EPA | TCEQ Date of I-Plan Approval |
TMDLs Addressed by I-Plan |
|---|---|---|---|---|---|---|---|---|---|
| Aquilla Reservoir Atrazine—1254 |
1 | 1 | 3 | Original 03/23/01; Revised 06/14/02 | 1 | 10/30/02 | 1 | 01/18/02 | 1 |
| Arenosa Creek Bacteria—2453C |
1 | 1 | 1 | 08/11/21 | 1 | 02/02/22 | 1 | 08/11/21 | 1 |
| Armand Bayou in the Houston-Galveston Region Bacteria—1113, 1113A, 1113B, 1113C, 1113D , 1113E |
6 | 6 | 6 | 08/5/15 | 6 | 10/02/15 | 6 | Subsumed in BIG I-Plan approved 1/30/13 | 6 |
| Armand Bayou—Addendum I in the Houston-Galveston Region Bacteria—1113 |
1 | 1 | 1 | Via WQMP 10/18 |
1 | 02/22/19 | 1 | Subsumed in BIG I-Plan approved 01/30/13 | 1 |
| Arroyo Colorado Legacy Pollutants: DDE, Chlordane, Toxaphene—2202 PCBs—2202A |
4 | 2 | 13 | 01/17/01 | 4 | 06/14/01 | 4 | 09/14/01 | 4 |
| Arroyo Colorado Legacy Pollutants: DDT, DDD, dieldrin, endrin, lindane, hexachlorobenzene, heptachlor, heptachlor epoxide—2202 |
8 | 1 | 32 | 07/25/03 | 8 | 05/13/04 | 8 | Same activities as in I-Plan approved 9/14/01 | 8 |
| Austin Area Watersheds Bacteria—Waller Creek, 1429C; Walnut Creek, 1428B; Spicewood Tributary to Shoal Creek, 1403J; and Taylor Slough South, 1403K |
5 | 4# | 5 | 01/21/15 | 5 | 03/18/15 | 5 | 01/21/15 | 5 |
| Austin Area Watersheds Addition Bacteria—Walnut Creek, Segments 1428B_01, 1428B_02, 1428B_03, and 1428B_04 |
4 | 0# | 4 | Via WQMP 04/15 |
4 | 07/27/15 | 4 | Same activities as in I-Plan approved 01/21/15 | 4 |
| Brays Bayou in the Houston-Galveston Region Bacteria—1007B, 1007C, 1007E, 1007L |
5 | 4# | 5 | 09/15/10 | 5 | 09/27/10 | 5 | BIG I-Plan approved 01/30/13 | 5 |
| Brays Bayou—Addendum I in the Houston-Galveston Region Bacteria—1007S, 1007T, 1007U |
3 | 3 | 3 | Via WQMP 04/13 |
3 | 08/28/13 | 3 | Subsumed in BIG I-Plan approved 01/30/13 | 3 |
| Brays Bayou—Addendum II in the Houston-Galveston Region Bacteria—1007W |
1 | 1 | 1 | Via WQMP 01/21 |
1 | 07/29/21 | 1 | Subsumed in BIG I-Plan approved 01/30/13 | 1 |
| Buffalo and Whiteoak Bayous in the Houston-Galveston Region Bacteria—1013, 1013A, 1013C, 1014, 1014A, 1014B, 1014E, 1014H, 1014K, 1014L, 1014M, 1014N, 1014O, 1017, 1017A, 1017B, 1017D, 1017E |
23 | 18^ | 23 | 04/08/09 | 23 | 06/11/09 | 23^ | BIG I-Plan approved 01/30/13 | 23^ |
| Buffalo Bayou—Addendum I in the Houston-Galveston Region Bacteria—1017C |
1 | 1 | 1 | Via WQMP 04/13 |
1 | 08/28/13 | 1 | Subsumed in BIG I-Plan approved 01/30/13 | 1 |
| Buffalo Bayou—Addendum II in the Houston-Galveston Region Bacteria—1017F |
1 | 1 | 1 | Via WQMP 04/15 |
1 | 07/27/15 | 1 | Subsumed in BIG I-Plan approved 01/30/13 | 1 |
| Buffalo Bayou—Addendum III in the Houston-Galveston Region Bacteria—1014C |
1 | 1 | 1 | Via WQMP 01/21 |
1 | 07/29/21 | 1 | Subsumed in BIG I-Plan approved 01/30/13 | 1 |
| Caney Creek Watershed Bacteria—1304, 1304A |
2 | 2 | 2 | 08/11/21 | 2 | 02/02/22 | 2 | 06/14/23 | 2 |
| Carancahua Bay Bacteria—2456 |
1 | 1 | 1 | 08/26/20 | 1 | 10/09/20 | 1 | 08/26/20 | 1 |
| Carters Creek Watershed Bacteria—1209C, 1209D, 1209L |
3 | 3 | 3 | 08/22/12 | 3 | 09/27/12 | 3 | 08/22/12 | 3 |
| Clear Creek Above and Below Tidal Chlordane—1101, 1102 |
2 | 2 | 9 | 01/17/01 | 2 | 06/14/01 | 2 | 09/14/01 | 2 |
| Clear Creek Above and Below Tidal Trichloroethane, Dichloroethane—1101, 1102 |
4 | 2 | 18 | Original 02/9/01; Revised 06/14/02 | 4 | 05/09/03 | 4 | 10/12/01 | 4 |
| Clear Creek and Tributaries in the Houston-Galveston Region Bacteria—1101, 1101B, 1101D, 1102, 1102A, 1102B, 1102C, 1102D, 1102E |
18^ | 9^ | 19 | 09/10/08 | 18^ | 03/06/09 | 18^ | BIG I-Plan approved 01/30/13 | 18^ |
| Clear Creek and Tributaries—Addendum I in the Houston-Galveston Region Bacteria—1101A, 1101C, 1101E, and 1102G |
4 | 4 | 4 | Via WQMP 10/12 | 4 | 03/12/13 | 4 | Subsumed in BIG I-Plan approved 01/30/13 | 4 |
| Clear Creek—Addendum II in the Houston-Galveston Region Bacteria—1102F |
1 | 1 | 1 | Via WQMP 10/18 |
1 | 02/22/19 | 1 | Subsumed in BIG I-Plan approved 01/30/13 | 1 |
| Colorado River Below E.V. Spence Reservoir Chloride, Total Dissolved Solids—1426 |
2 | 1 | 8 | 02/07/07 | 2 | 04/09/07 | 2 | 10/10/07 | 2 |
| Corpus Christi Beaches Cole Park and Ropes Park Beaches Bacteria—2481C |
2 | 1 | 2 | 07/28/21 | 2 | 01/31/22 | 2 | ||
| Cottonwood Branch and Grapevine Creek in the Greater Trinity Region Bacteria—0822A, 0822B |
2 | 2 | 2 | 09/21/11 | 2 | 05/30/12 | 2 | Greater Trinity I-Plan approved 12/11/2013 |
2 |
| Dallas Legacy Chlordane—805, 841 DDD, DDE, DDT, PCBs, Chlordane, Dieldrin, Heptachlor epoxide - 841A |
9 | 3 | 14 | 12/20/00 | 9 | 06/27/01 | 9 | 08/10/01 | 9 |
| Dickinson Bayou Bacteria—1103, 1103A, 1103B, 1103C, 1104 |
8 | 5# | 8 | 02/08/12 | 8 | 06/6/12 | 8 | 01/15/14 | 8 |
| Dickinson Bayou—Addendum I Bacteria—1103, 1103D, 1103E |
3 | 3 | 3 | Via WQMP 07/16 | 3 | 09/30/16 | 3 | Same activities as in I-Plan approved 01/15/14 | 3 |
| Dickinson Bayou—Addendum II Bacteria—1103F, 1103G |
2 | 2 | 2 | Via WQMP 04/22 | 2 | 08/11/2022 | 2 | Same activities as in I-Plan approved 01/15/14 | 2 |
| Eastern Houston in the Houston-Galveston Region Bacteria—1006F, 1006H, 1007F, 1007G, 1007H, 1007I, 1007K, 1007M, 1007O, 1007R |
13 | 10# | 13 | 09/15/10 | 13 | 09/27/10 | 13 | BIG I-Plan approved 01/30/13 | 13 |
| Eastern Houston—Addendum in the Houston-Galveston Region Bacteria—1007V |
1 | 1 | 1 | Via WQMP 04/13 | 1 | 08/28/13 | 1 | Through BIG I-Plan approved 1/30/13 | 1 |
| E.V. Spence Sulfate, TDS—1411 |
2 | 1 | 4 | Original 11/17/00; Revised 06/14/02 | 2 | 05/09/03 | 2 | 08/10/01 | 2 |
| Fort Worth Legacy Chlordane—806, 829 DDE, PCBs, Chlordane, Dieldrin—806A DDE, PCBs, Chlordane, Dieldrin—829A PCBs—806B |
11 | 5 | 11 | 11/17/00 | 11 | 05/24/01 | 11 | 07/13/01 | 11 |
| Gilleland Creek Bacteria—1428C |
1 | 1 | 3 | 08/08/07 | 1 | 04/21/09 | 1 | 02/9/11 | 1 |
| Greater Trinity Region—See entries for Cottonwood Branch & Grapevine Creek, Lower West Fork Trinity River Watersheds, Mountain Creek Lake Upstream Watersheds, Sycamore Creek, and Upper Trinity River | |||||||||
| Greens Bayou in the Houston-Galveston Region Bacteria—1016, 1016A, 1016B, 1016C, and 1016D |
8^ | 5^ | 8 | 06/02/10 | 8^ | 08/12/10 | 8^ | BIG I-Plan approved 01/30/13 | 8^ |
| Guadalupe River Above Canyon Lake Bacteria—1806 |
1 | 1 | 2 | 07/25/07 | 1 | 09/25/07 | 1 | 08/31/11 | 1 |
| Guadalupe River Above Canyon Lake—Addendum I Bacteria—1806D, 1806E |
2 | 2 | 2 | Via WQMP 01/18 | 2 | 05/08/18 | 2 | Same activities as I-Plan approved 8/31/2011 | 2 |
| Guadalupe River Above Canyon Lake—Addendum II Bacteria—1806A |
1 | 1 | 1 | Via WQMP 04/2022 | 1 | 08/1/2022 | 1 | Same activities as I-Plan approved 8/31/2011 | 1 |
| Halls Bayou in the Houston-Galveston Region Bacteria—1006D, 1006I, 1006J |
4 | 3# | 4 | 09/15/10 | 4 | 09/27/10 | 4 | BIG I-Plan approved 01/30/13 | 4 |
| Hillebrandt Bayou Bacteria—0704 |
1 | 1 | 1 | 08/11/21 | 1 | 02/01/22 | 1 | ||
| Houston-Galveston Region Bacteria—See entries for Armand Bayou; Brays Bayou; Buffalo and Whiteoak Bayous; Clear Creek; Eastern Houston; Greens Bayou; Halls Bayou; San Jacinto River, East and West Forks; Sims Bayou; and Lake Houston Watersheds |
|||||||||
| Jarbo Bayou in the Houston-Galveston Region Bacteria—2425B |
1 | 1 | 1 | 01/24/18 | 1 | 03/29/18 | 1 | Subsumed in BIG I-Plan approved 1/30/13 | 1 |
| Lake Austin DO—1403 |
1 | 1 | 1 | 11/17/00 | 1 | 12/05/01 EPA declined to take action on this TMDL |
0 | 07/13/01 | 1 |
| Lake Houston Upstream Watersheds in the Houston-Galveston Region Bacteria—1004E, 1008, 1008H, 1009, 1009C, 1009D, 1009E, 1010, and 1011 |
15 | 9# | 15 | 04/06/11 | 15 | 06/29/11 | 15 | BIG I-Plan approved 01/30/13 | 15 |
| Lake Houston Upstream Watersheds—Addendum I in the Houston-Galveston Region Bacteria—1008B, 1008C, 1008E, and 1011 |
6 | 4# | 6 | Submitted via WQMP 10/13 | 6 | 02/14/14 | 6 | Subsumed in BIG I-Plan approved 1/30/13 | 6 |
| Lake Houston Upstream Watersheds—Addendum II in the Houston-Galveston Region Bacteria—1008J, 1010C |
2 | 2 | 2 | Submitted via WQMP 10/19 | 2 | 03/11/20 | 2 | Subsumed in BIG I-Plan approved 1/30/13 | 2 |
| Lake Houston Upstream Watersheds—Addendum III in the Houston-Galveston Region Bacteria—1008I |
1 | 1 | 1 | Submitted via WQMP 10/20 | 1 | 03/08/21 | 1 | Subsumed in BIG I-Plan approved 1/30/13 | 1 |
| Lake Houston Upstream Watersheds—Addendum IV in the Houston-Galveston Region Bacteria—1010 |
1 | 1 | 1 | Submitted via WQMP 04/22 | 1 | 08/11/2022 | 1 | Subsumed in BIG I-Plan approved 1/30/13 | 1 |
| Lake O’ the Pines DO—0403 |
1 | 1 | 1 | 04/12/06 | 1 | 06/07/06 | 1 | 07/9/08 | 1 |
| Lake Worth Watershed PCBs—0807 |
1 | 1 | 1 | 08/10/05 | 1 | 10/13/05 | 1 | 08/23/06 | 1 |
| Lake Worth Watershed—Addendum I PCBs—0808 |
1 | 1 | 1 | Submitted via WQMP 07/14 | 1 | 11/25/14 | 1 | Same activities as in I-Plan approved 08/23/06 | 1 |
| Lavaca River Above Tidal and Rocky Creek Bacteria—1602, 1602B |
2 | 2 | 2 | 08/14/19 | 2 | 10/25/19 | 2 | 08/14/19 | 2 |
| Lavaca River Above Tidal and Rocky Creek - Addendum I Bacteria—1602 |
1 | 1 | 1 | Submitted via WQMP 01/22 | 1 | 06/08/2022 | 1 | Same activities as in I-Plan approved 08/14/19 | 1 |
| Lower Sabinal River nitrate-nitrogen—2110 |
1 | 1 | 1 | 08/10/05 | 1 | 10/13/05 | 1 | 08/23/06 | 1 |
| Lower San Antonio River Bacteria—1901 |
1 | 1 | 5 | 08/20/08 | 1 | 10/20/08 | 1 | 08/08/18 | 5* |
| Lower West Fork Trinity River Watersheds in the Greater Trinity Region Bacteria—0841, 0841B, 0841C, 0841E, 0841G, 0841H, 0841J, 0841L, 0841M, 0841R, 0841T, and 0841U |
13 | 12# | 13 | 09/24/13 | 13 | 11/07/13 | 13 | Greater Trinity I-Plan approved 12/11/2013 |
13 |
| Mission and Aransas Rivers Bacteria—2001, 2003 |
2 | 2 | 2 | 05/25/2016 | 2 | 08/09/16 | 2 | 05/25/2016 | 2 |
| Mission and Aransas Rivers—Addendum I Bacteria—2004, 2004B |
2 | 2 | 2 | Via WQMP 10/17 | 2 | 02/08/18 | 2 | Same activities as I-Plan approved 05/25/2016 | 2 |
| Mountain Creek Lake Upstream Watersheds in the Greater Trinity Region Bacteria—0841F, 0841K, 0841N, 0841V |
4 | 4 | 4 | 11/02/16 | 4 | 12/07/16 | 4 | Subsumed in Greater Trinity I-Plan approved 12/11/13 |
4 |
| Mountain Creek Lake Upstream Watersheds—Addendum I in the Greater Trinity Region Bacteria—0841Q |
1 | 1 | 1 | Submitted via WQMP 10/19 | 1 | 03/11/20 | 1 | Subsumed in Greater Trinity I-Plan approved 12/11/13 |
1 |
| Mountain Creek Lake Upstream Watersheds—Addendum II in the Greater Trinity Region Bacteria—0841P |
1 | 1 | 1 | Submitted via WQMP 4/22 | 1 | 08/11/2022 | 1 | Subsumed in Greater Trinity I-Plan approved 12/11/13 |
1 |
| Navasota River Below Lake Limestone Bacteria—1209 |
2 | 1 | 2 | 08/28/19 | 2 | 10/25/19 | 2 | 08/28/19 | 2 |
|
Neches River Tidal Bacteria—0601 |
4 | 1 | 4 | 7/19/2023 | 4 | ||||
| North Bosque River Phosphorus (narrative)—1226, 1255 |
2 | 2 | 6 | 02/9/01 | 2 | 12/13/01 | 2 | 12/13/02 | 2 |
| Nueces Bay Zinc in Oyster Tissue—2482 |
1 | 1 | 1 | 11/01/06 | 1 | 12/15/06 | 1 | 10/24/07 | 1 |
| Orange County Watersheds Bacteria, Dissolved Oxygen, pH—0508, 0508A, 0508B, 0508C, 0511, 0511A, 0511B, 0511C, and 0511E |
17 | 9# | 29 | 06/13/07 | 17 | 08/28/07 | 17 | 08/05/15 | 17 |
| Orange County Watersheds *Revised TMDLs Bacteria, Dissolved Oxygen, pH - 0508_01, 0508_02, 0508_03, 0508_04, 0508B_01, 0508C_01, 0511_01, 0511_02, 0511_03, 0511_04, 0511A_02, 0511B_01, 0511C_01, 0511E_01 *These TMDLs are not counted towards the total count because they are revisions to existing TMDLs |
23 | 8 | 23 | 08/26/2020 | 23 | 10/9/2020 | 23 | Same as the original TMDLs | 23 |
| Oso Bay Bacteria—2485 |
1 | 1 | 3 | 08/22/07 | 1 | 06/08/08 | 1 | ||
| Oso Creek Bacteria—2485A |
1 | 1 | 1 | 07/31/19 | 1 | 10/25/19 | 1 | ||
| Petronila Creek Above Tidal Chloride, Sulfate, Total Dissolved Solids—2204 |
3 | 1 | 6 | 01/10/07 | 3 | 03/14/07 | 3 | 10/10/07 | 3 |
| Salado Creek DO—1910 |
1 | 1 | 7 | 10/12/01 | 1 | 08/08/03 | 1 | Creek is supporting the aquatic life use, so IP is not needed. |
N/A |
| San Jacinto River, East and West Forks; Lake Houston; and Crystal Creek in the Houston-Galveston Region Bacteria—1002, 1003, 1004, 1004D |
7 | 4# | 7 | 08/24/16 | 7 | 10/07/16 | 7 | Subsumed in BIG I-Plan approved 1/30/13 | 7 |
| San Jacinto River, East and West Forks; Lake Houston; and Crystal Creek—Addendum I in the Houston-Galveston Region Bacteria—1015A |
1 | 1 | 1 | Via WQMP 10/18 |
1 | 02/22/19 | 1 | Subsumed in BIG I-Plan approved 1/30/13 | 1 |
| Sandy Creek and Wolf Creek Bacteria—0603A, 0603B |
2 | 2 | 2 | 05/18/22 | 2 | 08/18/2022 | 2 | 06/14/2023 | 2 |
| Sims Bayou in the Houston-Galveston Region Bacteria—1007D, 1007N |
4 | 2# | 4 | 09/15/10 | 4 | 09/27/10 | 4 | BIG I-Plan approved 01/30/13 | 4 |
| Sims Bayou—Addendum I in the Houston-Galveston Region Bacteria—1007A |
1 | 1 | 1 | Via WQMP 04/13 | 1 | 08/28/13 | 1 | Subsumed in BIG I-Plan approved 1/30/13 | 1 |
| Sycamore Creek in the Greater Trinity Region Bacteria—0806E |
1 | 1 | 1 | 01/16/19 | 1 | 03/27/19 | 1 | Subsumed in Greater Trinity I-Plan approved 12/11/13 |
1 |
| Tres Palacios Creek Bacteria—1501 |
1 | 1 | 1 | 01/24/18 | 1 | 03/29/18 | 1 | 01/24/18 | 1 |
| Tributaries of the Neches River below Lake Palestine Bacteria—0604A, 0604B, 0604C, 0604M |
4 | 4 | 4 | 10/5/2022 | 4 | 6/7/23 | 4 | In Development | In Development |
| Upper Oyster Creek Bacteria—1245 |
1 | 1 | 3 | 08/08/07 | 1 | 09/28/07 | 1 | 01/15/14 | 1 |
| Upper Oyster Creek Dissolved Oxygen—1245 |
2 | 1# | 2 | 07/28/10 | 2 | 09/21/10 | 2 | 01/15/14 (bacteria and oxygen in same plan) | 2 |
| Upper San Antonio River Bacteria—1910, 1910A, 1911 |
3 | 3 | 13 | 07/25/07 | 3 | 09/25/07 | 3 | 04/06/16 | 3 |
| Upper San Antonio River—Addendum I Bacteria—1910D, 1911B, 1911C, 1911D, 1911E |
7 | 5# | 7 | Via WQMP 04/16 | 7 | 08/09/16 | 7 | Same activities as in I-Plan approved 04/06/16 | 7 |
| Upper San Antonio River—Addendum II Bacteria—1911I |
1 | 1 | 1 | Via WQMP 10/19 | 1 | 03/11/20 | 1 | Same activities as in I-Plan approved 04/06/16 | 1 |
| Upper Texas Coast Oyster Waters—with Attachment (Addendum) 1. Bacteria—2421, 2422, 2423, 2424, 2432, 2439 |
6 | 6 | 6 | 08/20/08 | 6 | 02/04/09 & 04/1/12 | 6 | 08/19/15 | 6 |
| Upper Texas Coast Oyster Waters—Addendum II Bacteria—2435OW |
† | † | † | Via WQMP 01/12 | † | 04/20/12 | † | Same activities as in I-Plan approved 08/19/15 | † |
| Upper Texas Coast Oyster Waters—Addendum III Bacteria—2433OW, 2434OW |
2 | 2 | 2 | Via WQMP 04/12 | 2 | 08/07/12 | 2 | Same activities as in I-Plan approved 8/19/15 | 2 |
| Upper Trinity River in the Greater Trinity Region Bacteria—0805 |
2 | 1# | 2 | 05/11/11 | 2 | 08/03/11 | 2 | Greater Trinity I-Plan approved 12/11/13 |
2 |
| Total Impairments Addressed | Total Segments Addressed | Total Assessment Units Addressed |
Total TMDLs Adopted | Total TMDLs Approved | Total TMDLs Addressed by I-Plan | ||||
| Totals | 331 Impairments |
228 segments |
424 AUs | 331 TMDLs | 326 TMDLs | 320 TMDLs |
†Due to administrative considerations, the two TMDLs for segment 2435 were added by amendment, but are not included in the state's overall count of TMDLs.
#Since 2008, impairments and TMDLs are counted by the number of assessment units (AUs) addressed. Since AUs are sub-sections of segments, the number of impairments addressed may be greater than the number of segments. When there are multiple impaired AUs for a single parameter in a single segment, the segment is counted only once.
^The number of impairments (TMDLs) reported in the summary table is greater than the number shown in the title of the TMDL report. This is due to a change in EPA reporting requirements that was made after the TCEQ’s report of this project was completed and published (see below under "How TMDLs Are Counted").
*Between the time One TMDL for the Lower San Antonio River was adopted and its I-Plan was approved, Segment 1901 was subdivided into five assessment units. Consequently, the I-Plan was written for five TMDLs rather than one.
Back to topHow TMDLs Are Counted
The EPA requires one TMDL for each impairment listed in a water body. An impairment is the combination of the use that is affected (such as support of aquatic life) with the pollutant or condition of concern (such as mercury or low dissolved oxygen). For example, if Jones Creek was listed as not meeting the aquatic life use because of low dissolved oxygen concentrations, and not meeting the fish consumption use because of mercury in fish tissue, two TMDLs would be required for Jones Creek.
Prior to 2008, the number of impairments was reported by water-quality segment, as required by EPA guidance. During that period, the TCEQ used the term “water body” synonymously with “water-quality segment” when reporting how many segments were addressed by TMDLs.
In 2008, the EPA began requiring the TCEQ to develop and record one impairment (and TMDL) for each assessment unit within a water-quality segment. Consequently, the TCEQ reports multiple TMDLs (impairments) where once it would have counted only one. The TCEQ continues to report the number of water bodies addressed through TMDLs by water-quality segment.
A water-quality segment is a geographic portion of a river, lake, or bay that has relatively homogeneous chemical, physical, and hydrological characteristics. A segment is assigned a unique number for the purpose of categorization and provides a basic unit for managing water quality. In some cases, a segment may be the same as the entirety of the water body; for example, a small lake may not be divided into multiple numbered segments.
An assessment unit is a further geographic subdivision of a segment. For example, Segment 0200 may have five assessment units.
Projects Develop Multiple TMDLs
To be most efficient with resources of time and money, the TMDL Program may address the same pollutant in multiple water bodies through a single project, or may address multiple similar pollutants (such as three different pesticides) in one segment through a single project. Hence, a single project may produce many TMDLs.
Federal law requires that the EPA take formal action to approve or disapprove any TMDLs adopted by the states. So, on any particular date, the number of TMDLs adopted by the Commission may differ from the number approved by the EPA.
