When water quality comes to mind, you may first think it means how clean the water is. While clean water is crucial to a healthy river ecosystem, there is more to water quality than just that. In fact, water quality has three characteristics: chemical, physical, and biological.
Water Chemistry: What’s in the Water?
When we monitor water chemistry, we’re looking at what is in the water. Rivers and streams with poor water quality often have water that contains high levels of pollutants.
Such pollutants come from point and nonpoint sources. Point source pollution comes from discharge pipes from wastewater treatment plants and industrial dischargers. The Clean Water Act of 1972 curbed much of the pollution coming from point sources through permits with limits to what can be discharged into waterways. Local wastewater treatment plants work hard to clean wastewater and be good stewards of the streams they discharge to.
Today, most water pollution in our region comes from non-point sources, mostly polluted stormwater runoff. When it rains, pollutants like fertilizer, road salt, animal waste, soil, and fluids that leak from vehicles wash off our landscape, flow into storm drains or detention basins, and drain into nearby bodies of water. Storm drains, including those from detention basins, discharge stormwater directly into rivers and streams without being treated first.
Another important chemical indicator of water quality is dissolved oxygen. Fish and other organisms that live in the water need oxygen just like we do. A healthy stream with good water quality has a proper amount of dissolved oxygen.
Water chemistry parameters we measure:
- Dissolved oxygen (DO)
- Water Temperature
- pH & Hardness
- Nutrients, like phosphorus and nitrogen
- Heavy metals, like copper, mercury, and arsenic
Physical Habitat: Are There Homes for Fish and Bugs? Is the Shoreline Secure?
Physical habitat includes not only the structure under the water, but also the riparian area – the land along the body of water. Streams should have curves, areas with slow water and areas with faster water, deep pools for fish and insects to overwinter or find refuge in the low flows of summer. The bottom of the stream should have gravel and rocks of differing sizes. A more diverse the physical habitat will support a more diverse aquatic community. Ideally, the stream should also be free of obstructions like dams that impede fish from moving through the stream system.
The land along the waterway should have native vegetation. These plants protect water quality by acting as a buffer against stormwater that runs off the landscape and into rivers and streams. Riparian vegetation also stabilizes the shoreline, preventing erosion that adds extra nutrients and turbidity to the water. The riparian area also provides important habitat, especially for aquatic insects (like dragonflies) as they emerge from the water and become winged adults.
Physical indicators of water quality include:
- Substrate, or what is on the bottom of the steam
- Instream cover, such as rocks or woody debris that provide refuge from fast flows and predators
- Channel morphology – the shape of the channel
- Riparian vegetation
- Pools, runs, and riffles
Biology: What Lives in the Water?
The last component of water quality is biological – this is the ultimate measure. The diversity of species of aquatic life typically tells us that a river has both clean water and quality habitat. Why’s that? We can have “clean” water but no habitat (think of a bathtub). Or we can have really nice, diverse habitat but toxic water. Either situation would result in few or no aquatic species.
Some fish and insects are very intolerant to pollution, while others can handle some or a lot of pollution. Some species don’t mind muddy bottoms and cloudy water, while others need clear water, riffles and gravely bottoms. So, certain species can indicate a stream’s water quality, based on what type of water chemistry and habitat they need. For example, if you find a fish that is highly vulnerable to water pollution, it likely indicates that the water is clean.
There are also different groups of fish: fish that eat plants, fish that eat insects and fish that eat other fish (and insects). The same is true for insects – some eat plants and debris and some eat other insects or even small fish and tadpoles. It is important to have representatives from each group to have a healthy aquatic community.
To measure biology, we look at:
- Fish species, such as largemouth bass, bluegill sunfish, and johnny darter
- Macroinvertebrates, which include aquatic insects like midge, mayfly & dragonfly larvae, diving beetles and crustaceans.
Getting the Whole Picture
Our watershed monitoring program includes sampling water chemistry as well collecting data on fish, macroinvertebrates, and habitat in and along the stream. This helps us put together a complete picture of stream health, identify problems and design solutions. As long-term data is collected, we will be able to track progress as improvements are made.
The Connection Between Leaves and Water Quality
As rain falls and flows through piles of leaves, nutrients quickly leach out of leaves and end up in nearby rivers and streams.