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Monitoring Salt Lake County streams

The importance of monitoring water quality in Salt Lake County streams

By Watershed Planning & Restoration | The Watershed Watch

Reliable water quality data is critical to understanding the overall health of our watershed, specifically how development and other landscape-altering activities can impact the health of our streams. To gain a better understanding of water quality data and trends, Salt Lake County Watershed Planning & Restoration has been collecting chemical and biological data in county streams since 2009.

Routine monitoring of water quality allows the Watershed Program to analyze stream segments where watershed conditions appear to be changing, identify potential areas of concern, and plan restoration activities to address impacts and improve stream health. It also helps to understand the impacts of seasonal high flows, as well as irrigation and storm drain in flows to streams.

The distribution of the County’s sampling sites is based on the availability of water, therefore not all streams are monitored on the same schedule and at the same intensity. The goal is to regulate both sampling frequency and sampling density per each creek subwatershed to accurately establish the best estimate of overall watershed health. But there are limiting factors. Some west side streams flow only during irrigation season from April to October. Some east side streams are unsafe to access during winter months. Stream hard freeze, construction activities, instrument failure, and so on, can all inhibit data collection. Considering these barriers, the County collects as many samples as possible.

The chemical data collected include temperature, pH, dissolved oxygen, conductivity, total dissolved solids, and turbidity. The biological data include E. coli bacteria and aquatic macroinvertebrates (a.k.a. bugs). Aquatic bugs are an especially helpful tool, as the presence and/or absence of certain species provides a clear picture of the overall health of the stream ecosystem. In addition to water quality monitoring, the Watershed Program maintains a network of stream flow and rain gauges placed strategically throughout the watershed. Understanding the flow of water in streams plays a vital role in flood protection, water supply, pollution control, and environmental management. Stream flow measurements are key to modeling watershed pollutant loads and flow data are also used to assess the relationship between precipitation and stream flow (e.g., how quickly stream flow reaches its peak), which can vary significantly depending on the level of development in the watershed.

While the County data are collected to provide a general assessment of water quality, and not to meet any regulatory requirements, the Watershed Program does work with agencies collecting data for regulatory reasons. The Utah Division of Water Quality collects water quality data at various locations in the county for the purpose of supporting regulatory programs. Salt Lake City Public Utilities collects water quality data for the purposes of drinking water source protection and treatment.

Ultimately, the goal of Salt Lake County’s ongoing water quality monitoring is to serve as a check and measure of the stresses put on our urban streams, help understand the type and severity of water quality impairments, and guide decisions regarding stream restoration. Specifically which stream restoration techniques are appropriate, and where.