One of foundational initiatives of the Watershed Alliance is our stream-monitoring program—we’ve been keeping a close eye on the health of key Adams County streams for decades.

Thanks to a grant from Keep Pennsylvania Beautiful and the Giant Company, in 2023 we’re expanding our stream-monitoring initiative to encompass more testing sites on more local streams.

The primary reason why we monitor our local streams is that we care deeply about protecting their health. Being able to look back on decades of stream-monitoring data enables us to pinpoint times when a stream’s health begins to decline—or recover. For this reason, our volunteers collect and test stream-water samples every month using highly standardized and validated procedures.

Temperature. When our volunteers arrive at a stream to test its waters, one of the first things they do is measure the water’s temperature. Why? Aquatic plants and animals have adapted to survive only within a particular range of temperatures, so we want to know whether our streams are maintaining those healthy temperatures. In addition, the rate of photosynthesis in algae and other aquatic plants increases in warm water and decreases in cooler water; this can impact other aquatic life. And finally, the sensitivity of organisms to pollution, parasites, and diseases increases as water temperature rises—within an acceptable range, cooler water means a healthier stream.

Acidity or pH. Aquatic organisms require a specific level of acidity or pH to survive. Most aquatic organisms have adapted to survive in water that has a pH range between 6.5 and 8.5. Very high or very low pH can be a sign of severe pollution.

Conductivity. Measuring a stream’s conductivity (or the number of charged ions in the water) can provide a snapshot of the severity of pollution in the water. For example, a failing sewage system leeching into a stream will raise conductivity due to the presence of chloride, phosphate, and nitrate in the effluent. Road salt washing into a stream raises conductivity due to the presence of ionized materials in the salt. Warmer water temperatures also increase conductivity. Basically, significant changes (usually increases) in conductivity may indicate that a discharge or some other source of disturbance has decreased the health of the stream.

Nitrates. All aquatic organisms require nitrates to live. However, high levels of nitrates in water can cause excessive algae and aquatic plant growth. As these algae and aquatic plants die, they’re decomposed by bacteria that use and remove oxygen from the water. If oxygen levels in the water fall low enough, aquatic creatures will die. The natural process of excessive plant growth is called eutrophication; high levels of nitrates added to the water by human activity greatly speed up this process.

Phosphates. While phosphorus is an indispensable nutrient for plants and animals, excessive phosphorus in streams and rivers can—like excessive nitrate levels—cause explosive growth of aquatic plants and algae, resulting in a variety of water-quality problems including low oxygen levels.

Sulfates. Sulfates are a naturally occurring compound that come primarily from sedimentary rocks. However, as sulfates in the form of sulfuric acid enter streams and rivers, they can decrease the pH of the water to the extent that aquatic life perishes.