Archive for June, 2020


When we think about where to site green stormwater infrastructure (GSI), we far too often look only at places that receive the most runoff or regularly experience flooding. While these factors are important from a stormwater management perspective, they do not tell us anything about how that community may be uniquely impacted by flooding. For example, neighborhoods with high rates of asthma or low rates of health insurance coverage are especially impacted by mold that results from flooding, and communities that faced redlining and disinvestment struggle to find resources to deal with stormwater management. 

Our small, seven square mile Nine Mile Run watershed is a microcosm of Pittsburgh and most urban areas across the country, showing stark differences in prosperity, opportunity, health, and safety for residents only a few blocks from each other. This is a result of issues that continue to surface across economic, social, and environmental systems. As we look to the future, we know we need to understand better how to allocate scarce resources so that we are doing the most good for the people and communities that are most in need. 

We developed the Nine Mile Run Environmental Equity Study as a tool to find areas within the Nine Mile Run sewershed that are the most vulnerable to environmental issues based on public health, social vulnerability, environmental quality, and the urban landscape. Each of these four categories contain multiple datasets that were analyzed individually and the raw data values were reclassified on a scale from 1 to 5. For example, areas within 50 feet of a bus stop were given a score of 5. After ranking each individual dataset, a weighted overlay was created for each category showing the areas that are most vulnerable based on multiple datasets. This data dictionary shows the data sources and how they were reclassified.

This figure shows the weighted overlay process. For our analysis we used a scale from 1 to 5 instead of 1 to 3 to reclassify the data. 

Increasing green spaces can lead to increased outdoor physical activity in communities.  According to the EPA, an increase in outdoor activities can positively impact people suffering from chronic diseases such as obesity, heart disease, type II diabetes, and high blood pressure. In addition, several studies have found links between exposure to natural landscapes and reduced stress levels. We chose data for the public health category based on the potential positive impact that GSI could have on people who suffer from childhood asthma, type II diabetes, hypertension, obesity, anxiety, and depression. This data was limited by the fact that it only represents people with health insurance plans. For this reason, we included data on the number of people without health insurance as well.

The CDC’s Social Vulnerability Index (SVI) was included in this study to provide greater insight into which areas of our community are the most vulnerable to natural disasters based on 15 factors. 

Figure showing the 15 factors used in the CDC’s SVI

The annual rainfall in Pittsburgh reached record levels in the past few years and will likely continue to increase. We must consider which communities are the most vulnerable to natural disasters to inform our decisions on where to build GSI. 

In addition to increasing rainfall, Pittsburgh has the 8th highest levels in the US of the air pollutant PM2.5 which is known to cause serious health problems. Environmental quality data was included in this study to determine the areas that have the greatest amount of air pollution, highest surface temperature, and the most impervious surfaces within the sewershed. Several studies state that increasing urban tree canopy cover through the use of street trees and green spaces can help to decrease pollution and surface temperature. 

While the first three categories in this study looked at which areas are most vulnerable, we also had to consider what areas are feasible for siting GSI. The urban landscape category included data on bus stops, schools, vacant parcels, parks, and plantable area. After running a weighted overlay for this category we were ready to create the overall GSI Suitability Index.  

The overall GSI Suitability Index was created by running a weighted overlay on all four of the categories giving equal weighting to each category. This result was then used to determine areas where we would focus on building GSI. We used the GSI Suitability Index in conjunction with CivicMapper’s Watershed Hydrology Tool to generate catchment areas in places that scored highest on the suitability index. We found 10 areas within the Nine Mile Run sewershed where we should focus our efforts to build GSI.

Moving forward, we plan to use this project to guide our decision making on where to build GSI in a data driven way, based on equity and environmental justice. One of the strengths of this project is the ability to adapt it to incorporate updated datasets for our watershed as well as others. 

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Look out Pittsburgh, here comes the dreaded Spotted Lanternfly (SLF).  Beautiful and repugnant, this destructive invasive pest has been sighted in Allegheny County. First sighted in the US in Pennsylvania in 2014  in Berks County (and believed to have arrived sometime in 2012), SLF wreaks havoc wherever it goes.  Allegheny County is one of many in the state under SLF quarantine.  To learn more about the quarantine, permits, etc., please visit the PA Dept. of Agriculture’s website

It is important to note that this insect does not bite or sting and poses no physical threat to humans. 

SLF is native to parts of Asia, including India, Bangladesh, China, and Vietnam.

It is considered invasive in other parts of Asia, such as Japan and Korea.  Researchers believe that it was introduced to the US via a stone shipment with SLF eggs laid on it.   SLFs are really good hitchhikers and spread easily.  Adults can easily hold on to a tractor trailer or train and egg masses are often well hidden out of sight and/or camouflaged. While SLF does not harm humans directly, its presence can have major repercussions. 

SLF feed in swarms through sucking the sap out of plants.  While their preferred food source is Ailanthus altissima, commonly known as tree of heaven, they are known to feed on a number of plants, many of which are profitable agricultural and timber crops in Pennsylvania.  (Fun fact: did you know that ranks number one among the 50 United States in the production of export grade hardwood?)  Plants they enjoy include, but are not limited to grape, apple, peach, black walnut, sycamore, maple, staghorn sumac, various vegetables, blueberries, and hops.  SLP also releases a substance called honeydew, a sticky, sugary liquid that sticks to natural and manmade surfaces alike.  Honeydew attracts stinging insects (such as yellowjackets) and leads to the growth of sooty mold.  Sooty mold is damaging to plants in that it covers leaves, blocks light, and makes photosynthesis less efficient.

So, what can you do to stop the spread of SLF?  First and foremost, be vigilant about checking your vehicle, landscaping materials, and landscaping for these insects.  Over the winter, you can check for eggs masses, which consist of rows of small oblong grey brown eggs and a grey putty-like covering (usually) that may be smooth or cracked.  They blend in very well, so be careful!  Starting in April, eggs will begin hatching.  The young SLF nymphs (1st-3rd instars) are small and black with white spots.  They transform into 4th instar nymphs around July and will be bigger, and black and red with white spots.  Adult SLF can be spotted starting in July. 

If you find a SLF specimen in any stage, please do the following:

  1. Take a picture (with GPS activated, if possible)
  2. Destroy it!
    1. Scrape eggs into a plastic bag with alcohol or sanitizer and place inside ANOTHER bag.  Or simply smash them thoroughly. 
    2. Kill all nymphs and adults
  3. Report it to the Penn State Extension https://extension.psu.edu/have-you-seen-a-spotted-lanternfly

Please don’t hesitate to contact Lindsey-Rose at if you have any questions.  





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This post was written by Rayden, a Wilkinsburg resident, Penn State Master Watershed Steward, and Nine Mile Run member since 2019.

May the watershed always find you.

A few years ago we made the big decision to go through the county’s Vacant Property Recovery Program to acquire the vacant house adjacent to ours and demolish it to expand our yard. Squirrels and stray cats frequented the gloomy vine-covered house and sometimes people would dump tires there. We estimate it had been empty and exposed to the elements for at least 30 years.

This spring, we hired some skilled friends to build a fence around the side yard, as a corral for our toddler. One friend was very particular about the correct depth of the post holes: if there were bricks or concrete or other fun stuff buried in the way, that meant getting a jackhammer to work through it. After many years working in vacant properties converted to community garden sites, I thought I had seen everything there was to see buried in the dirt around here.

However, much to my surprise, we did find something in one whole that was very intriguing. After blasting through a 6″ layer of concrete, the bottom dropped out and there it was – a portal to another world? – no! Of course it could only be Nine Mile Run.

Our house was built in 1892, around the same time that large sections of the stream were “culverted” (directed into pipes or bricked tunnels below ground) to make way for development.

Culverting in process on Conemaugh Street

What a joy to discover that the stream had been there flowing beneath us the whole time! I visited the hole in the ground frequently to put my ear close to the dirt and listen or shine a flashlight in to get a better sense of the depth and movement of the water. I invited my kid to “come visit the stream!” in all kinds of weather. Once, when asked what street we live on, my two year old matter-of-factly responded, “Nine Mile Run”. I couldn’t bear to plug it up again.

One day maybe there will be enough funding and political will to “daylight” more sections of the stream, to restore Nine Mile Run to its previous stormwater-mitigating, habitat-supporting glory. But until then, we are very happy to have found a simple compromise: a galvanized pipe with a 90 degree elbow on top that reaches down past the fence post into the culvert. We can continue to listen to the stream quietly gurgling on dry days and energetically crashing by on stormy days. The pipe also provides access to a bonus sensory experience: you can smell it on wet weather days.

This yard portal marks clearly how human activity has permanently transformed our watershed. And also it reminds me the stream is always there, serving only its own ever-present desire to flow downhill.

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