By Adam Lehmann
In Hamilton County, we are very fortunate to have a wealth of data on the health of our local creeks and rivers. With respect to the quality of the water flowing through our streams, Southwest Ohio has one of the largest networks of volunteer water quality monitoring programs in the country. Volunteer water quality monitoring programs perform a critical function of monitoring water quality more frequently (monthly in southwest Ohio) than that for which most local governments are able to budget. This is particularly important with monitoring water quality which, unlike metrics of aquatic wildlife and physical habitat, may be expected to fluxuate significantly over short periods of time in response to stormwater runoff or other pollution events. Our local volunteer water quality monitoring programs also make their data easily accessible to the public at StreamBank.info.
But, water quality is not the only determinant of stream health – if suitable physical habitat does not exist in a stream, that stream cannot support a healthy ecosystem no matter how “good” or “pure” the water. Our urban and suburban landscapes are built in ways that alter the natural flow of water through the landscape. Resulting “flashy stream flows” cause excessive streambank erosion, which in turn, result in large amounts of sediment filling in the void-spaces between rocks upon which aquatic wildlife rely for shelter. These urban/suburban altered flow patterns also result in streams that used to flow year-round drying-out; this wide-spread problem constitutes a complete loss of aquatic habitat. Another major cause of habitat degradation is clearing of trees around streams – robing the streams of temperature regulating shade and critical inputs of food sources and habitats in the form of leaf litter and woody debris.
Beginning in 2011, The Metropolitan Sewer District of Greater Cincinnati began contracting the Midwest Biodiversity Institute to assess the health of our local creeks in rivers. Assessments were conducted at hundreds of sites throughout Hamilton County. This was a huge effort that took 4-years to complete. In 2016, MSD began another 4-year follow-up study to assess changes over time. The product of these assessmentsis a wealth of information on the chemical, physical, and biological health of our local streams. This effort has revealed that nearly 65% of the County’s streams are impaired biologically.
Together, the high frequency volunteer water quality data and the professional biological assessments, provide a key insight into the primary factors affecting the health of our local creeks and rivers. When these data are viewed side-by-side on the accompanying maps, we see that, while water quality is pretty good in Hamilton County (lots of green and blue dots on the Volunteer Water Quality Monitoring Map), the health of aquatic wildlife continues to suffer (lots of red and yellow dots on the Aquatic Life Use Attainment Map). This tells us that the primary factor impacting aquatic wildlife in Hamilton County is not water pollution but degradation of physical habitat (including flow patterns) caused by the way that we build our urban and suburban environments.
This finding is consistent with state-wide and even global statistics on causes of “stream impairment”. In Ohio EPA’s 2018 Integrated Report, they report that three of the top five (including the top two) causes of biological “impairment” are related to physical habitat. Similarly, in 2018, the World Wildlife Fund’s Living Planet Reportestimated that there has been an 83% decline in population abundance (number of induvial) of freshwater animals across the globe between the years of 1970 and 2014. Eighty-three percentin 45-years – that’s huge! So, what was found to be the most significant cause of this decline? You got it – habitat loss/degradation.
In the United States, we have come a long way from the days of burning rivers. Since the 1972 amendments to the Federal Water Pollution Control Act (known as the Clean Water Act), the water quality in our creeks and rivers has improved dramatically largely due to regulation of discharges from industrial facilities and wastewater treatment plants. But, progress in improving stream health has leveled-off (remember: an estimated 65% of Hamilton County’s streams are impaired biologically). Continued restoration of stream health will require a re-focusing on factors that are impairing the physical habitat within our creeks and rivers. In addition to government-led installation of large-scale stormwater management projects, addressing impairments to in-stream physical habitat at the landscape scale will require public policy to put in place meaningful incentives for private property owners to better manage stormwater and re-forest our riparian corridors.