Why Does Tributary Level Monitoring Matter?

River health is vital to the function of ecosystems. Tributaries are the connectors between smaller feeder streams and parent streams (mainstem rivers) and they serve many vital roles in the overall health of a river system often referred to as the watershed. In order for researchers to have comprehensive diagnostic information on rivers, there needs to be some form of monitoring that includes high impact tributaries that have major effects on the biological life and river composition. Yellowstone Ecological Research Center initiated RiverNET to work with community members to help monitor the tributaries within the Upper Yellowstone Watershed that play a key role in influencing stream health. And to deliver diagnostic monitoring in a timely, near real-time manner for prevention, planning, and adaptation to stressors like drought.

RiverNET was born from many needs, not the least of which was to track the Proliferative Kidney Disease (PKD) outbreak that killed hundreds of fish but also to track droughts, changing land use patterns, and other watershed impacts. The program works with community members to place monitoring systems on key tributaries in the watershed that help researchers better understand trends in watershed health. This project plays a large role in instigating community support, interaction, and ownership over the conservation of the Yellowstone River. 

RiverNET is vitally important because it was designed to fill needed gaps. First, tributaries, critical indicators for overall watershed health, are nearly always ignored in budget-strapped agency monitoring programs.  Second, river tributaries often show signs of decline before the main stem of the river system. Third, impacts, especially those from human activities occur on specific tributaries (grazing, impoundments, disturbance). Although precipitation or temperature may be somewhat uniform across the tributaries in a valley, human impacts are very specific to a particular watershed. So because river health - and diagnostics - depends on the health of its tributaries, information on individual tributaries tells you where and when the impacts occur so managers can respond.

Thus, tributaries are the most important factor to consider when analyzing the source of pollution in a water system and need to be closely monitored for their data, critical to informing researchers of the baseline conditions and potential risks to water health. Because tributaries are smaller bodies of water they are fragile - drought or pollution are much more apparent in tributary systems. Additionally, the tributaries cover areas of land that are miles away from the mainstem of the river and transport various fertilizers and sediment to the main body of water that could have potentially harmful consequences. YERC’s stream monitoring helps create baseline metrics that can help signal when a tributary is having a negative impact on the overall water quality or when drought is affecting the region. 

Many of the impacts at the tributary level are human caused and have short term solutions that do not rely on overwhelming complex tasks such as reversing climate impacts. In this way, protecting tributaries is within the scope of a landowner or a community. Issues, like pollutants, erosion, and irrigation flows are relatively quick fixes that can be adjusted in response to immediate impacts, whereas climate related events require larger scale responses or long time periods. Tributary monitoring ensures that the problems are recognized quickly and impacts are mitigated as seamlessly as possible. 

YERC’s sensor stations are permanent water monitoring systems that function separately from the gauges employed by the United States Geological Survey (USGS). The USGS created a solid foundation to analyze water metrics - such as temperature and flows - on the various main stems of larger rivers but are unable to fill the gaps in the data when it comes to monitoring tributaries. Chief Scientist, Robert Crabtree, explains that “The USGS stream gauge station network provides the perfect backbone for our tributary scale RiverNET monitoring and prediction system.” YERC is then able to fill the gaps in the various water gauges through a public-private partnership that benefits the system as a whole. More data is given to piece together the puzzle of water health and better manage critical river systems. 

Tributary monitoring provides the utmost protection for fragile parts of our ecosystem that have a widespread influence over a large number of stakeholders due to the interconnectivity of streams. Tributaries dictate the health of streams and monitoring them is the best option for researchers and conservationists to have effective data to make the right decisions in a timely, preventative manner for the community as a whole.