NC0026441_Report_20231023

RECEIVED
O C T 2 3 2023
Michael Baker We Make gwR/NPDES
INTERNATIONAL
SILER CITY WWTP BENTHIC MACROINVERTEBRATE EVALUATION
October 9, 2023
Michael Baker Intl. (MBI)was contracted by the Siler City Wasterwater Treatment Plant(WWTP)
to conduct four Full Scale Benthic Macroinvertebrate surveys to satisfy the conditions of their NPDES
permit. Samples were collected in Loves Creek and the Rocky River at upstream and downstream
locations relative to the WWTPs discharge pipes. Samples were collected by MBI staff on September 5&
6, 2023. Sample reach locations are shown in Figure 1. Samples were taken to MBI's DEQ Certified
Laboratory for Population Studies of Benthic Macroinvertebrates in Asheville, NC where organisms were
identified to the lowest practical taxonomic level by taxonomist Jason York. A bioclassification was then
assigned to each sample reach according to the criteria defined by the 2016 Division of Water Resources
(DWR) Standard Operating Procedures for the Collection and Analysis of Benthic Macroinvertebrates.
Water quality data was not collected by MBI staff because Siler City WWTP staff were collecting these
data with their own calibrated equipment at the same time as the macroinvertebrate samples were being
collected.
Water levels were very low at the time of sample collection with the exception of the Loves Creek
Downstream sample reach because of the flow provided by the discharge from the WWTP. All sites are
found in the Level IV Ecoregion Carolina Slate Belt where low flow is not uncommon in late summer. These
conditions made conducting a Full Scale sample challenging. At the Loves Creek Upstream reach riffles
large enough to collect a standard kick-net sample were not present so multiple smaller riffles were
sampled using a D-net in lieu of a standard kick-net;however,the overall area sampled met the standard
of approximately 2 square meters. Submerged bank habitat was also limited by the water level at these
locations so multiple sweeps were taken from any available root masses and undercut banks.
Bioclassification ratings ranged from POOR to GOOD:
SITE NAME DWR BIOCLASSIFICATION MBI BIOCLASSIFICATION
Loves Creek Upstream FAIR, 6/24/2003 POOR,9/5/2023
Loves Creek Downstream FAIR,8/23/2022 FAIR,9/5/2023 _
Rocky River Upstream FAIR, 5/2/2018 GOOD-FAIR,9/6/2023
Rocky River Downstream GOOD-FAIR,8/23/2022 GOOD,9/6/2023
Overall taxa richness and EPT taxa richness varied substantially from historic DWR sampling data.
Site data is summarized in Table 1. A complete taxa list is included in Table 2; however, Loves Creek
Upstream has not been sampled by DWR since June 4, 2003, making a comparison of the data at this
location difficult due to both the time between samples and seasonal variation.
The Loves Creek downstream site was sampled on August 23, 2022, by DWR where 36 total taxa
and 4 EPT taxa were collected. The MBI September 5,2023,sample collected 12 total taxa and 4 EPT taxa.
Both the 2022 and 2023 surveys resulted in a bioclassification of FAIR. Variation in these data is most
likely explained by a combination of varying water levels and potential influence of the WTTP.
797 Haywood Rd.Suite 2011 Asheville,NC 28753
MBAKERINTL.COM Project Contact Information:828-380-0118,[e-mail]

Michael Baker We Make a Difference
INTERNATIONAL
The Rocky River Upstream location was sampled by DWR on May 2,2018,where 79 total taxa and
14 EPT taxa were collected. The MBI September 6, 2023, collected 27 total taxa and 11 EPT taxa. The
2022 survey resulted in a bioclassification of FAIR,while the 2023 survey resulted in a bioclassification of
GOOD-FAIR. These data are difficult to compare because of seasonal variation in the assemblage of
macroinvertebrates. The May 2018 DWR taxa richness contains an abundance of Chironomidae which
were not collected in September 2023. Larger watershed conditions may also play a role in the changing
macroinvertebrate assemblages during this five year period; however, the affects of seasonality can not
be overstated.
The Rocky River Downstream location was sampled by DWR on August 23, 2022, where 79 total
taxa and 25 EPT taxa were collected. The MBI September 6,2023 collected 38 total taxa and 18 EPT taxa.
The 2022 survey resulted in a bioclassification of GOOD-FAIR, while the 2023 survey resulted in a
bioclassification of GOOD. The difference in overall richness at the Rocky River sites is mostly accounted
for by a greater diversity of chironomids found in the 2018 and 2022 samples whereas the 2023 samples
were dominated by Polypedilum aviceps and Polypedilum f/avum. Variation in these data is most likely
explained by a combination of seasonality,varying water levels,and potential influence of the WTTP.

Figure 1 . Full Scale Sample Reach Locations
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Michael Baker We Make a Difference
INTERNATIONAL
TABLE 1.SILER CITY WASTEWATER TREATMENT PLANT BENTHIC MACROINVERTEBRATE EVALUATION DATA SUMMARY
Scores based on Tables 5&7 from NC Dept.of Environmental Quality.2016.Standard Operating Procedures for the Collection and Analysis of Benthic Macroinvertebrates.Division of Water Resources.Raleigh,North Carolina.
February 2016.
SAMPLE #OF EPT TAXA EPT TAXA ROUNDIN
SITE NAME SAMPLE DATE NCBI RICH EPTTAXA BI SCORE FOR AVG BIOCLASSIF
TYPE ORGANISMS ABUNDANCE RICHNESS PIEDMONT SCORE FOR SCORE G !CATION
NESS PIEDMONT DECISION
Loves Creek Upstream 9/5/2023 Full Scale 96 28 6.88 21 4 2.0 1.0 1.5 1.5 POOR
Loves Creek Downstream 9/5/2023 Full Scale 141 77 6.52 12 4 2.4 1.0 1.7 2.0 FAIR
Rocky River Upstream 9/6/2023 Full Scale 243 172 6.16 27 11 3.0 2.0 2.5 2.5 GOOD-FAIR
Rocky River Downstream 9/6/2023 Full Scale 388 209 5.44 38 18 4.0 3.0 3.5 3.5 GOOD
797 Haywood Rd.Suite 2011 Asheville,NC 28753
MBAKERINTL.COM Project Contact Information:828-380-0118,[e-mail]

Table 2.Taxa List
SliER art Y W WTP,-LOVES CREEK-UPSTREAM
FINALID _ORDER FAMILY TOLERANCE CLINGER COUNT RCA notes
Corbiculafluminea Bivalvia Corbiculidae 6.6 FALSE 20 10
Cheumatopsychespp Trichoptera Hydropsychidae _ 6.6 TRUE 10 10
Maccaffertium modestum Ephemeroptera Heptageniidae 5.7 TRUE 9 3
Chimarraspp Trichoptera Philopotamidae 3.3 TRUE 8 3
Ephemerellacatowba/dorothea Ephemeroptera Ephemerellidae 4 TRUE 1 1
Argia spp Odonata Coenagrionidae 8.3 FALSE 15 10
Cambarusspp Crustacea Cambaridae 7.5 FALSE 1 1 immature
Chironomusspp Diptera Chironomidae 9.3 FALSE 1 1
Corydalus cornutus Megaloptera Corydalidae 5.2 TRUE 2 1
Polypedilum illinoense gr Diptera Chironomidae 8.7 FALSE 3 3
Stenelmisspp Coleoptera Elmidae 5.6 TRUE 5 3
Rhagovelia t ORDER Veliidae FALSE 3 3
Dicrotendipes spp Diptera Chironomidae 7.2 FALSE 2 1
Tubiiicidoe t ORDER Tubificidae FALSE 2 1 immature
Trepobates t ORDER Gerridae FALSE _ 2 1
Anopheles spp Diptera Culicidae 8.6 FALSE 7 3
Munroessa gyralis t ORDER FAMILY FALSE 1 1
Neozavriela t ORDER Chironomidae FALSE 1 1
Tanytarsusspp Diptera Chironomidae 6.6 FALSE 1 1
Ablabesmyiamallochi Diptera Chironomidae 7.4 FALSE 1 1
Krenopelopia t ORDER Tanypodinae FALSE 1 1
SlIER CITYWWTP LOVES CREEK DOWNSTREAM ' ,;; Yc-i',!g^Y a, v "
FINALID ORDER FAMILY TOLERANCE CLINGER COUNT RCA notes
Cheumatopsychespp Trichoptera Hydropsychidae 6.6 TRUE 48 10
Hydropsyche(H.)betteni Trichoptera Hydropsychidae 7.9 TRUE 18 10
Triaenodes ignitus Trichoptera Leptoceridae 4.8 FALSE 1 1
Hydropsyche(C.)sparna Trichoptera Hydropsychidae 2.5 TRUE 10 10
Corbiculafluminea Bivalvia Corbiculidae 6.6 FALSE 20 10
Argia spp Odonata Coenagrionidae 8.3 FALSE 21 10
Boyeria vinosa Odonata Aeshnidae 5.8 FALSE 1 1
Polypedilum illinoense gr Diptera Chironomidae 8.7 FALSE 7 3
Stenelmisspp Coleoptera Elmidae 5.6 TRUE 9 3
Calopteryxspp Odonata Calopterygidae 7.5 FALSE 2 1
Physa spp Gastropoda Physidae 8.7 FALSE 2 1
Helobdella triserialis Other Glossiphoniidae 9.3 FALSE 2 1

SILER CITY-ROCKY RIVER-UPSTREAM
FINALID ORDER FAMILY TOLERANCE CLINGER COUNT RCA notes
Moccaffertium modestum Ephemeroptera Heptageniidae 5.7 TRUE 99 10
i Cheumatopsyche spp Trichoptera Hydropsychidae 6.6 TRUE 18 10
Hydropsyche(H.)betteni Trichoptera Hydropsychidae 7.9 TRUE 21 10
Triaenodes ignitus Trichoptera Leptoceridae 4.8 FALSE 1 1
Baetis intercalaris Ephemeroptera Baetidae 5 FALSE 7 3
Stenacron pallidum Ephemeroptera Heptageniidae 2.8 TRUE 2 1
Isonychia spp Ephemeroptera Isonychiidae 3.6 FALSE 3 3 bicolor variant
Baetis pluto Ephemeroptera Baetidae 3.4 FALSE 4 3
Ceraclea ancylus Trichoptera Leptoceridae 2.8 FALSE 8 3
`i Neoperla spp Plecoptera Perlidae 2.1 TRUE 6 3
1 Chimarra spp Trichoptera Philopotamidae 3.3 TRUE 1 1
MAI i Neotrichia t Trichoptera Hydroptilidae FALSE 2 1
Physa spp Gastropoda Physidae 8.7 FALSE 1 1 Neotrichia spp.
Menetus dilatatus Gastropoda Planorbidae 7.6 FALSE 4 3
Corydalus cornutus Megaloptera Corydalidae 5.2 TRUE 7 _ 3
Argia spp Odonata Coenagrionidae 8.3 FALSE 11 10
Tipula spp Diptera Tipulidae 7.5 FALSE 2 1
Stenelmisspp Coleoptera Elmidae 5.6 TRUE 8 3
Psephenus herricki Coleoptera _Psephenidae 2.3 _ TRUE 5 3
Polypedilum illinoense gr Diptera Chironomidae 8.7 FALSE 5 3
Hyalella spp Crustacea Talitridae 7.2 FALSE 1 1 azteca
Crangonyx spp Crustacea Gammaridae 7.2 FALSE 1 1
Epitheca spp Odonata Corduliidae 8 FALSE _ 2 1
Caecidotea spp Crustacea Asellidae 8.4 FALSE 1 1
Hylogomphus t Odonata Gomphidae _ FALSE 1 1
Corbiculafluminea Bivalvia Corbiculidae 6.6 FALSE 20 10
Fusconaia cor t Unionida Unionidae FALSE 2 1
SILER CITY-ROCKY RIVER-DOWNSTREAM _
FINALID ORDER FAMILY TOLERANCE CLINGER COUNT RCA notes
Tricorythodes spp Ephemeroptera Leptohyphidae 5 FALSE 33 10
Maccaffertium pudicum Ephemeroptera Heptageniidae 2.1 TRUE 21 10
Baetis intercalaris Ephemeroptera Baetidae 5 FALSE 19 10
Isonychia spp Ephemeroptera Isonychiidae 3.6 FALSE 2 1 bicolor variant
Procloeon spp Ephemeroptera Baetidae 1.9 FALSE 1 1 rubropictum
Caenisspp Ephemeroptera Caenidae 6.8 FALSE 3 3
' Neoperla spp Plecoptera Perlidae 2.1 TRUE 2 1
Chimarra spp Trichoptera Philopotamidae 3.3 TRUE 34 10 obscura _
Cheumatopsyche spp Trichoptera Hydropsychidae 6.6 TRUE 62 10
Hydropsyche(H.)betteni Trichoptera Hydropsychidae 7.9 TRUE 11 10
Polycentropus sensu Iota spp Trichoptera Polycentropodidae 3.1 TRUE 1 1 Cernotina spp
Oecetis persimilis Trichoptera Leptoceridae _ 4.6 TRUE 3 3
Ceraclea spp Trichoptera Leptoceridae 2.2 FALSE 1 1
Hydropsyche(H.)rossi _Trichoptera _Hydropsychidae 4.8 TRUE 2 1
Hydropsyche(H.)demora Trichoptera Hydropsychidae 2.6 TRUE 6 3 _
Hydropsyce(.H)venularis Trichoptera Hydropsychidae 5.1 TRUE 3 3 _
Triaenodes spp Trichoptera Leptoceridae 4.1 FALSE 4 3 ochraceus
Metrobates t ORDER Gerridae FALSE 1 1
Corydalus cornutus Megaloptera Corydalidae 5.2 TRUE 29 10
Argia spp Odonata Coenagrionidae 8.3 FALSE 11 10
Psephenus herricki Coleoptera Psephenidae 2.3 TRUE 1 1
Stenelmisspp Coleoptera Elmidae 5.6 TRUE 36 10
Tipula spp Diptera Tipulidae 7.5 FALSE 1 _ 1
Menetus dilatatus Gastropoda Planorbidae 7.6 _ FALSE 1 1
' Rhagovelia t ORDER Veliidae FALSE _ 1 1
Physa spp Gastropoda Physidae 8.7 FALSE 5 3
Cambarusspa Crustacea Cambaridae 7.5 FALSE 1 1 immature
Simulium spp Diptera Simuliidae 4.9 TRUE 7 3
Epitheca spp Odonata Corduliidae 8 FALSE 2 1
Didymops t ORDER Macromiidae FALSE 1 1
Paratanytarsus spp. Diptera Chironomidae 8 FALSE 5 3
Tanytarsus spp. Diptera Chironomidae 6.6 FALSE 4 3
Polypedilum oviceps Diptera Chironomidae 3.6 FALSE 20 10
Polypedilum flavum Diptera Chironomidae 5.7 FALSE 20 10
Pentaneura inconspicua Diptera Chironomidae 5 FALSE 10 10
Corbiculaflumineo Bivalvia Corbiculidae 6.6 FALSE 20 10
Placobdello papillifera Glossiphoniidae 8.9 FALSE 3 3