Water quality in Johnson Creek is influenced by many challenges, such as urban stormwater, septic systems, and agriculture. In 2015, scientists compiled data from several different agencies, producing a report on Johnson Creek water quality from 2009-2014. Below are brief summaries of the report’s findings; to view details, check out the full report here.
Stream temperature is affected by air temperature, sun exposure, groundwater, and changes to vegetation surrounding the water. Fish and wildlife need cooler streams to thrive: In Oregon, the ideal temperature for rearing salmon and trout is below 64.4°F, but for the majority of the summer, Johnson Creek’s mainstem and tributaries exceed that 64.4° threshold. (One of JCWC’s main goals is to reduce stream temperatures through restoration work such as creekside tree and shrub plantings.) In the map below, areas in red had particularly high temperatures.
In adults and children, lead exposure cause health problems such as damage to the nervous system, learning disabilities, and impaired hearing. Lead reaches urban waterways from soils that contain lead contamination, automobiles, industrial sources, and through sewers that contain lead components. In the Johnson Creek Watershed, concentrations of dissolved lead are generally acceptable and are not a human health concern.
Dissolved zinc is a concerning pollutant in urban waterways. It comes from the production of brass, bronze, automobile parts, and some common herbicides. It can be toxic to algae, bacteria, and invertebrates. The majority of samples collected in the watershed from 2009-2014 met or were above the “good” dissolved zinc concentrations, shown in green in the map below.
Total Suspended Solids
Total suspended solids (TSS) are particles larger than 2 microns that are found in the water column; TSS is thus a measure of water quality and clarity. Particles can include sediments, organic matter, algae and plankton. Water high in TSS is called turbid, and has a reduced amount of light available to aquatic plants, which can affect stream functioning. In the Johnson Creek watershed, total suspended solids vary with weather patterns and with geographic location.
Mercury is toxic to wildlife and humans. At high levels it can cause harm to the brain, heart, kidneys, lungs and immune systems. Mining activities and fossil fuel emissions from coal-burning power plants are the biggest sources of mercury. In the Johnson Creek Watershed, mercury concentrations tend to be high: On the map below, red represents Poor and yellow represents Fair, as measured against EPA standards.
Dissolved copper is a pollutant to waterways that can come from sources related to industry and automobile traffic. It can be toxic to algae, bacteria, and aquatic invertebrates. It is generally in an acceptable range in the Johnson Creek watershed.
E. coli are bacteria found widely in animals, including humans. Often used as an indicator of bacteria levels in water bodies, measuring E. coli is often seen as a way to measure human-caused bacteria issues such as the presence of raw sewage. However, E. coli is also somewhat unreliable as a proxy: High concentrations may come from wildlife as well as humans, and E. coli can live for long periods in the water, outside of animal or human hosts! With those caveats in mind, E. coli concentrations in the Johnson Creek mainstem do appear to be high, and it is certain that human sources are one of the culprits. In the map below, red indicates high concentrations.
Biological communities make great indicators of watershed conditions, because organisms often live in streams throughout the year. Other monitoring, such as for temperature or mercury, often only captures conditions at the time data is collected. But the presence of organisms such as aquatic insects and freshwater mussels can help us understand year-round conditions, and whether those conditions are favorable.
Macroinvertebrates–animals without backbones, that are large enough to see with the naked eye–are especially useful water quality indicators. Certain groups, such as the larvae of stoneflies and many mayflies, can only survive in pristine conditions, while other groups, such as leeches, scuds, and black fly larvae, are hardy and found in both pristine and degraded streams. In the Johnson Creek Watershed, the macroinvertebrate community is highly degraded in the mainstem and in many of the tributaries–only only the hardiest invertebrates are found there (shown in red below). A few headwater areas have healthy communities (shown in blue and green).