NEWTOWN SQUARE, PA — From 2018 through 2021, the Watershed Protection Program of Willistown Conservation Trust (WCT) conducted monthly monitoring at ten sample sites in three tributaries to the Delaware River in northeastern Chester County: the headwaters of Darby, Crum, and Ridley Creeks. Following 41 monitoring visits and over 7,500 different measurements, they found that the water quality is moderately impaired at all sample sites. The entirety of the Watershed Protection Team’s research has since been summarized in a 48-page “State of our Streams Report.”
Most notably, the Team’s water chemistry analysis demonstrated the presence of elevated chloride concentrations, excess nitrogen and phosphorus, and high water temperatures in these waterways — all of which can harm native brook trout, freshwater mussels, and stream insects.
There are a variety of causes for this pollution, and human activity is the primary driver. Elevated chloride concentrations are a result of winter road salts making their way into waterways. Chloride concentrations were highest in the sample areas that had a greater percentage of impervious surfaces — such as roads, buildings, and parking lots that do not allow water to pass through — confirming that increased development leads to higher rates of pollution, and further highlighting the importance of conserving open space to protect water quality.
High levels of nitrogen and phosphorous levels were uncovered, likely as a result of fertilizer runoff, animal waste, and leaky septic and sewer systems. An excess of these nutrients in streams can trigger a process called eutrophication — where vegetation and algae grows rapidly in waterways before dying and decomposing, which results in a depletion of dissolved oxygen. Dissolved oxygen is necessary for the survival of stream life.
Water temperature was elevated at all sample sites, especially during spring and summer months, stressing sensitive aquatic organisms such as trout and freshwater mussels. High water temperatures can be linked to tree and shrub removal along streams, which exposes streams to direct sunlight. Impervious surfaces heat up stormwater before it flows into streams. Hotter summers and heat waves are also to blame. As temperature increases, water holds less dissolved oxygen, and pollution from salt and nutrients becomes more harmful to sensitive species.
Compared to more urbanized areas with higher levels of water quality impairments, the concentration of open space within the study area — the product of over 40 years of land protection in the Willistown region — has resulted in only moderate impairments to water quality overall.
Since 1996, WCT has been dedicated to protecting open space in the region, and this has proven to be one of the most effective methods for preserving water quality. WCT Executive Director Kate Etherington states, “It is reassuring to confirm through this study that WCT’s mission to conserve land has had such a far-reaching impact, and it’s clear we must continue to invest in conservation.” To see substantial improvements in downstream waterways, land protection must be paired with municipal dedication to best management practice recommendations, such as restoring degraded landscapes and improving stormwater management.
WCT’s Director of Watershed Protection Program Lauren McGrath encourages individuals to consider how their actions can make a positive difference in local streams. During the winter months, when salting driveways and sidewalks, people can sweep up road salts after the snow and ice has melted. This practice saves streams and money as the salt can be used for the next storm. Residents should also contact their local municipalities if they notice large piles of salt on the roads.
For residents with lawns, eliminate fertilizers altogether or make the switch from chemical fertilizers to compost, and avoid spreading fertilizer right before a rainstorm. Help reduce nutrient contamination in waterways through regular maintenance and annual inspection of septic tanks to ensure that waste is not leaking and polluting waterways. Additionally, dog owners should properly dispose of dog waste.
One of the most important factors to help minimize stream pollution is to plant native species. Restoring trees and shrubs along stream banks and planting rain gardens alongside roads and driveways can help slow, collect, and filter stormwater, thanks to the long roots that help rain soak into the soil. Unlike turf grasses found in most yards, native species help absorb excess nutrients and filter out contaminants before they enter streams. Native plants do not require fertilizer and many are drought tolerant and do not need to be watered after becoming established.