Plum Creek

There are four municipalities whose boundaries contain portions of Plum Creek's watershed.

Those municipalities are:

1. Plum Borough
2. Penn Hills
3. Oakmont Borough
4. Verona Borough

The U.S. Geological Survey's National Hydrography Dataset (NHD) Streams layer shows the major streams that transport water through the watershed and into the Allegheny River.

Using a combination of the Federal Emergency Management Agency (FEMA) 100-year floodplains and, in the absence of a FEMA floodplain, a 35-foot stream buffer, a layer was created to show the Riparian Buffer along the NHD streams.

Zooming in on the map makes it easier to see the streams layer and the underlying riparian buffers.

The Impaired Streams layer shows the streams within the Plum Creek watershed that are not attaining their intended use, as designated by the Pennsylvania Department of Environmental Protection (PA DEP). PA DEP protects 4 water uses for streams:

• Aquatic Life
• Fish Consumption
• Potable Water Supply
• Recreation

If a stream segment is not attaining any one of its 4 uses, it is considered impaired.

Being able to identify impaired streams and the source(s) causing the impairment is helpful in watershed planning so that the correct types of projects can be implemented in the right areas. For example, a stream that is impaired due to siltation might be a good candidate for a streambank restoration project, because this type of project reduces streambank erosion and associated sediment loads.

The Impaired Streams layer was obtained from the PA DEP Integrated List Non-Attaining layer.

Using Tree Canopy data from Tree Pittsburgh, we can see the forested (green) and non-forested (brown) areas within the watershed.

This data, along with the underlying hillshade topography, is useful in planning different types of watershed projects such as riparian plantings and habitat enhancement projects.

Sometimes it's useful to view multiple layers at the same time to identify potential project areas. The tree canopy layer can be used with the riparian buffer layer to identify gaps in the riparian tree canopy. These areas may be good candidates for riparian planting projects.

Of course, all potential project areas will need to be ground-truthed and coordinated with property owners.

Take some time to explore the map.

1. Click the +/- buttons to zoom in/out
2. Click and drag to pan to a different location
3. Clicking on streams and parcels will pop-up information about that feature
4. If at any time you would like to return to the watershed overview, just click on the Home button

Land Cover is another useful data layer in understanding a watershed's characteristics. The land cover data in this map was obtained from the Multi-Resolution Land Characteristics Consortium (MRLC).

Some watershed projects are specific to a type of land cover. For example, Conservation Tillage, Streambank Fencing, and Strip Cropping projects are specific to agricultural land cover. Different types of land cover will also contribute different types and amounts of pollutant loads to downslope receiving streams.

For ease of use, a Simplified Land Cover layer was derived from the MRLC layer. The Simplified Land Cover layer combines similar cover types as follows.

The Agriculture cover class combines Cultivated Crops and Pasture/Hay

The Developed cover class combines Developed High Intensity, Developed Medium Intensity, Developed Low Intensity, and Developed Open Space.

The Forest cover class combines Deciduous Forest, Evergreen Forest, and Mixed Forest.

Feel free to toggle between the  Land Cover  and  Simplified Land Cover  layers to see how they match up.

Soil data is another useful layer when assessing site characteristics. Soil data was obtained from the Natural Resource Conservation Service (NRCS) and classified by Hydrologic Soil Group (HSG).

HSGs describe a soil's ability to infiltrate stormwater and are classified as A, B, C, and D.

Group A soils have high infiltration rates and low runoff potential.

Group B soils have moderate infiltration rates.

Group C soils have low infiltration rates.

Group D soils have very low infiltration rates and high runoff potential.

If a soil is placed in Group D due to high water table, it may be classified as a dual group (A/D, B/D, C/D). In the case of dual HSGs, the first letter represents the soil's group if the area is drained and the second letter (D) represents the soil's group under natural conditions.

Areas with soils that quickly infiltrate stormwater are generally good candidates for projects that reduce stormwater volume, such as rain gardens and infiltration basins.

Click a soil group on the map to identify the soil name, HSG, and description.

Landslide Susceptibility data can also be helpful in identifying sites for potential watershed improvement projects. Reducing the amount of rainfall runoff to landslide-prone areas can be an effective way of preventing future landslide events.

The data in this map was obtained from Allegheny County's Landslide Pomeroy layer.

Click the button below to zoom to Sub-Watershed 1

Municipalities: Penn Hills

Description: First unnamed tributary (UNT) to Plum Creek upstream of the confluence with the Allegheny River. This UNT enters Plum Creek from the south and generally flows from south to northwest. This sub-watershed is 652 acres in size. Land cover consists mainly of residential development with a few larger parcels as well as forested slopes. Several areas of “red bed” soils make much of this sub-watershed susceptible to landslides.

Impairments: Aquatic Life

Impairment Causes:

1. Nutrients (nitrogen and/or phosphorus): nitrogen and/or phosphorus (nutrients) in excessive amounts can cause aquatic plants and microbes to grow too fast, choking waterways, causing potentially harmful algae blooms and creating low-oxygen conditions that can harm fish and other aquatic life. (EPA How's My Waterway)
2. Oil and Grease: oil and grease includes fuel oil, gasoline, vegetable oil, and animal fats. Oils generally enter waterways through spills, leaks, and improper disposal, and can be toxic to plants and animals even in small amounts. (EPA How’s my Waterway)

Proposed Project Types: based on the impairments causes for this sub-watershed, the projects recommended to mitigate these impairments would include stormwater best management practices that reduce runoff and separate any combined storm sewer. Best management practices (BMPs) for stormwater include both gray and green solutions. Gray solutions would involve separating the pipes conveying combined storm and sanitary sewers to streams. Green solutions involve natural solutions that infiltrate the stormwater into the ground, such as detention/retention/infiltration basin(s), bioswales, raingardens and permeable pavers, riparian buffer plantings, and conversion of turf grasses to meadows. These practices increase infiltration into the ground, replenish ground water, and reduce the pollutants causing the above-listed impairments.

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Click the button below to zoom to Sub-Watershed 2

Municipalities: Plum Borough

Description: Enters Plum Creek from the north and generally flows from northeast to southwest. This sub-watershed is approximately 1,590 acres in size. Land cover mainly consists of deciduous forest with low- and medium-intensity residential development mainly occurring in the top third of the watershed. Stream valleys mainly consist of “red-bed” soils. This sub-watershed has had many historic landslides, particularly near the confluence of Bodies Run and Plum Creek.

Impairments: None - streams in this sub-watershed are attaining their designated uses of recreation and aquatic life.

Proposed Project Types: This sub-watershed is listed as attaining its designated uses for recreation and aquatic life, meaning that the streams have been assessed and meet water quality standards for these uses. Recommendations in this sub-watershed should focus on practices that will protect existing water quality. In addition, some restoration practices could be implemented for further benefit to downstream sub-watersheds, including exploring abandoned acid mine drainage (AMD) sources, implementing stormwater practices, and restoring floodplains, streambanks, and buffer areas.

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Click the button below to zoom to Sub-Watershed 3

Municipalities: Penn Hills

Description: Enters Plum Creek from the south and generally flows from southwest to northeast. This sub-watershed is 668 acres in size. Land cover is about half low- and medium-intensity residential development and half forested, with a few larger agricultural fields. The lower portion of the sub-watershed has areas of historic landslides, slopes with soil creep, and “red-bed” soils.

Impairments: Aquatic Life

Impairment Causes:

1. Degraded Habitat: degraded aquatic habitat (habitat alterations) occurs when naturally-occurring stream channels are changed or diverted through manmade channels and/or by removal of native vegetation from shorelines and stream banks. These actions can reduce the habitat that fish and other animals need to reproduce, feed, and find shelter, and can also affect the appearance and value of waterfront property. (EPA How’s My Waterway) 
2. Nutrients (nitrogen and/or phosphorus): nitrogen and/or phosphorus (nutrients) in excessive amounts can cause aquatic plants and microbes to grow too fast, choking waterways, causing potentially harmful algae blooms, and creating low-oxygen conditions that can harm fish and other aquatic life. (EPA How’s My Waterway) 

Proposed Project Types: based on the impairment causes for this sub-watershed, recommended projects should focus on re-establishing aquatic habitat through streambank stabilization, floodplain and riparian restoration, and in-stream habitat installation. Projects recommended for nutrient impairments include stormwater and agricultural  BMPs that reduce runoff. Agricultural BMPs are designed to reduce manure, sediment, and runoff from farmed lands. These could include streambank fencing to limit farm animal access to streams, riparian buffers, and covered manure storage areas. Stormwater BMPs include both gray and green solutions. Gray solutions would involve separating the pipes conveying combined storm and sanitary sewers to streams. Green solutions involve natural solutions that infiltrate the stormwater into the ground such as detention/retention/infiltration basin(s), bioswales, raingardens and permeable pavers, riparian buffer plantings, and conversion of turf grasses to meadows. These practices increase infiltration into the ground, replenish ground water, and reduce the pollutants causing the above-listed impairments.

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Click the button below to zoom to Sub-Watershed 4

Municipalities: Penn Hills and Plum

Description: This sub-watershed consists of the headwaters of Plum Creek above the confluence with it largest tributary, Little Plum Creek. It is approximately 2,670 acres in size. Sub-watershed 4 is significantly more developed than other areas of the Plum Creek watershed resulting in stormwater issues after heavy rain events. Some agricultural fields are present in the upper half of the sub-watershed.  While some areas of soil creep are present, this sub-watershed appears to be less landslide-prone than other areas in the Plum Creek watershed.

Impairments: Aquatic Life

Impairment Causes:

1. Nutrients (nitrogen and/or phosphorus): nitrogen and/or phosphorus (nutrients) in excessive amounts can cause aquatic plants and microbes to grow too fast, choking waterways, causing potentially harmful algae blooms, and creating low-oxygen conditions that can harm fish and other aquatic life. (EPA How’s My Waterway) 
2. Sediment: sediment is a problem when rain washes soil into waterways from fields, construction sites, yards, logging areas, city streets, and other areas. Sediment can carry pollutants and also makes water murky, impacting the health and habitats of fish and other aquatic animals. Murky water also interferes with uses like fishing and swimming. (EPA How’s My Waterway)

Proposed Project Types: Projects in this sub-watershed should focus on reducing the amount of sediment and nutrients entering streams. Practices that focus on slowing and infiltrating stormwater can accomplish reductions in both of these pollutants. Green stormwater solutions that infiltrate the stormwater into the ground can replenish ground water and reduce both sediment and nutrients from entering waterways. Examples of these BMPs are detention/retention/infiltration basin(s), bioswales, raingardens and permeable pavers, riparian buffer plantings, and conversion of turf grasses to meadow.

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Click the button below to zoom to Sub-Watershed 5

Municipalities: Plum Borough

Description: Little Plum Creek is the largest tributary of Plum Creek, which it joins near the community of Unity. Little Plum Creek generally flows from east to west. While many of the tributaries to Little Plum Creek are listed as attaining, the mainstem and headwaters of Little Plum Creek are impaired for aquatic life. The major land cover types in the Little Plum Creek sub-watershed are undeveloped farmland and forest, while minor land cover types include residential areas and reclaimed mine sites. In addition, with much of the land cover being agriculture, associated BMPs for agricultural are recommended to reduce the amount of nutrients entering waterways.

Impairments: Aquatic Life

Impairment Causes:

• Metals: metals can enter waterways from factories, mining, and runoff from urban areas, as well as from natural processes such as erosion of soil and rocks. At high levels, metals such as arsenic, cadmium, chromium, copper, lead, selenium, and zinc can be toxic to aquatic animals and humans. (EPA How’s My Waterway) 
• Nutrients (nitrogen and/or phosphorus): nitrogen and/or phosphorus (nutrients) in excessive amounts can cause aquatic plants and microbes to grow too fast, choking waterways, causing potentially harmful algae blooms, and creating low-oxygen conditions that can harm fish and other aquatic life. (EPA How’s My Waterway) 
• Oil and Grease: oil and grease includes fuel oil, gasoline, vegetable oil, and animal fats. Oils generally enter waterways through spills, leaks, and improper disposal, and can be toxic to plants and animals even in small amounts. (EPA How’s My Waterway)

Proposed Project Types: This sub-watershed is impaired for metals resulting from AMD from our coal mining legacy. This sub-watershed should be assessed for sources and solutions to abandoned mine drainage. This could involve active treatment (the addition of a chemical, such as lye to the water) or passive treatment (using gravity to channel water through layers of compost and limestone) to achieve the desired pH to remove dissolved metals. BMPs for agriculture are designed to reduce manure, sediment, and runoff from farmed lands. These could include streambank fencing to limit farm animal access to streams, riparian buffers, and covered manure storage areas. 

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Municipalities: Plum Borough

Description: Sub-watershed 6 is a tributary to Little Plum Creek. Like much of Little Plum Creek, this sub-watershed is mainly comprised of agricultural land cover with some low-intensity development also present. Sub-watershed 6 is approximately 1,750 acres in size and flows in a northwest direction.  While some historic landslides have been mapped, this sub-watershed does not seem particularly landslide prone.

Impairments: Aquatic Life

Impairment Causes:

1. Metals: metals can enter waterways from factories, mining, and runoff from urban areas, as well as from natural processes such as erosion of soil and rocks. At high levels, metals such as arsenic, cadmium, chromium, copper, lead, selenium, and zinc can be toxic to aquatic animals and humans. (EPA How’s My Waterway) 
2. Acidity: acidity (pH) can range from 0-14 and is a measurement of how acidic or alkaline (basic) the water is. The pH of pure water is 7, and the normal range for pH in water systems is approximately 6.5 to 8.5. In general, water with a pH lower than 7 is considered acidic, and with a pH greater than 7 is considered alkaline (or basic). It is normal for saltier waters (oceans and estuaries) to have a slightly higher pH than surface waters such as rivers, lakes, ponds, streams, and wetlands. Acidity (pH) outside of a certain range (below 6.5 or above 8.5) can harm or kill fish and other aquatic life. Highly acidic or alkaline water can also release pollutants from sediments that can further harm aquatic life. Acidity in waterways is influenced by rock and soils, as well as human sources such as industrial and car emissions, mining, and agricultural runoff. (EPA How’s My Waterway)

Proposed Project Types: Much like Little Plum Creek, this sub-watershed area is impaired for metals and acidity resulting from abandoned mine drainage from our coal mining legacy. This sub-watershed should be assessed for sources and solutions to abandoned mine drainage. This could involve active treatment (the addition of a chemical, such as lye to the water) or passive treatment (using gravity to channel water through layers of compost and limestone) to raise the pH and remove dissolved metals. In addition, agriculture and stormwater BMPs could be implemented to improve conditions downstream of this sub-watershed.

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Click the button below to zoom to Sub-Watershed 7