Montour Run Watershed Assessment & Implementation Plan

• The Shannon Diversity Index is very similar, however,
Shannon accounts for both abundance and evenness
within a sample set, rather than relative abundance and
evenness. This means that if only one or two organisms
of a particular genus are present, it will impact the
Simpson’s DI value less than the Shannon DI.
Overview: The Montour Run Watershed has been
impacted by Abandoned Mine Drainage (AMD), urban
runoff, and siltation from erosion for many years. While
the quality of the watershed and macroinvertebrate
populations within it appear to be decreasing between
the November 2017 and May 2018 collections (Table
2.2.3), this is most likely due to historic rainfall totals
in the region having caused underground mine pools
with polluted water to overflow into Montour Run. The
headwaters of Montour Run in Subwatershed Areas
2-North Fork and West Enlow and 3-South Fork and Lower
Enlow are impacted by detrimental influences, but have
maintained relatively strong diversity and population
counts. Subwatershed Areas 1-Airport Drainage and
4-Robinson/Beaver Grade are heavily impacted by
runoff from Pittsburgh International Airport, heavy
commercialization downstream of the airport, and
compacted residential areas present throughout. These
tributaries show low population counts, limited diversity,
and the presence of only a few pollution sensitive
organisms.
MR01 –
Mouth
MR02 –
Meeks
MR03 – DS
McClaren
MR04 –
McClaren
MR05 –
Enlow
MR06 – DS
Enlow
MR07 –
South Fork
MR08 –
North Fork
Total
Organisms
Number of
Genera
Shannon
Diversity
Index
Subwatershed Area 5-Meeks, Trout and Salamanders
Head Tributaries run through healthy, relatively
forested areas with low anthropogenic impacts. This
subwatershed area shows high quality water, greater
macroinvertebrate population counts, and greater
diversity with higher populations of pollution sensitive
organisms. Contributions in flow from these tributaries
dilute contaminants in Montour Run further downstream
in Subwatershed Areas 5 and 6, diminishing their impact
on water quality and the macroinvertebrate populations.
This results in Subwatershed Area 6-Lower Montour
Run being relatively healthy compared to the upstream
Subwatershed Areas. Further study will be required to
assess long-term effects of the increased AMD discharges
from the winter of 2018 within this watershed.
Area 1: Airport Drainage - McClaren and East Enlow Fork
McClaren Run are impacted by Pittsburgh International
Airport drainage and ever increasing concentrations of
commercial development along its bank. The drop in the
Shannon Diversity Index score was the largest of all eight
sample sites. These changes likely indicate an increase
in AMD flow within this tributary during heavy storm
flows. Further water and macroinvertebrate testing will be
needed for comparison to confirm this.
The headwaters of the eastern portion of Enlow Fork
Simpson
Diversity
Index
Hilsenhoff Biotic
Index (HBI)
%EPT
-86.59% -54.17% -24.39% -9.22% -3.14% -81.80%
-80.00% -46.43% -17.28% -6.40% -1.90% -9.09%
-65.72% -47.83% -24.52% -53.77% 17.32% -88.51%
-79.78% -47.37% -31.91% -20.82% 5.93% -70.06%
215.66% 57.14% -22.35% -29.34% -20.49% -75.85%
-63.35% -36.36% -28.11% -21.55% 23.37% -88.29%
-10.00% 37.50% -1.74% -2.64% 9.91% -83.06%
43.48% 50.00% 6.14% 0.37% 52.42% -34.19%
begin directly north of Pittsburgh International Airport
and are then tunneled beneath the airport until just
north of Enlow Road. Sediment and urban runoff from
the airport, the I-376 Business Loop, and upstream
development heavily impact this stream, particularly
during precipitation events. This portion of Enlow Fork
was not sampled for macroinvertebrate populations.
Area 2: North Fork Montour and West Enlow- The main
factors impacting the North Fork are urban runoff/sewer
overflow, siltation due to habitat modification, and AMD,
according to the PA DEP. Visual observations in the North
Fork include cloudy water, heavy erosion along the banks,
and high concentrations of development throughout.
These headwater impairments are easily seen in the data
collected for Area 2. North Fork had very low species
abundance counts for November 2017, which increased
in May 2018, as did diversity and species richness metrics.
These increased metrics are due to the extremely low
species abundance counts. West Enlow Fork is impacted
by drainage from Interstates 376 and 576. This upper
region was not sampled for macroinvertebrates.
Area 3-South Fork Montour Run and Lower Enlow-The
South Fork of Montour Run is heavily impacted by
“erosion from derelict land” causing sedimentation on
the outskirts of the landfill at the headwaters. In addition,
AMD throughout and urban runoff/sewer overflow in the
downstream portion have also contributed to erosion.
South Fork increased in Genera Richness between
2017 and 2018, however all other metrics decreased
from 2017 to 2018. Genera Richness was higher in May
than in November, but species abundance decreased
compared to the other Subwatershed Areas. South
Fork changed the least from November 2017 to May
2018. This indicates that there was little change in water
quality at this site, most likely because no additional
AMD overflows occurred upstream of this site between
November 2017 and May 2018. Decreases in diversity
and species abundance could also be attributed to
seasonal differences in populations resulting from
macroinvertebrate lifecycles.
Enlow Fork is impacted by Pittsburgh International
Airport drainage, residential developments, commercial
zoning, and Interstates 376 and 576 with some forested
land bordering West Enlow Fork. These impairments are
shown in November 2017 with extremely low metrics
in both species abundance and diversity. In 2018,
species abundance and average pollutant tolerance
did increase slightly. All other metrics decreased even
further. Compared to other sampling sites, this site
decreased less in quality. Coupled with the increase in
species abundance and decrease in pollution tolerance,
the decrease in diversity could mean water quality has
not been impacted significantly within the sampling
timeframe.
Table 2.2.3-Percent change in macroinvertebrate popluation metrics between November 2017 and May 2018. Green
highlights represent metrics that increased between 2017 and 2018.
Dragonfly nymph found in Montour Run during November 2018 sampling
24 | Assessing and Quantifying Watershed Health Montour Run Watershed Assessment & Implementation Plan | 25