Apr 14, 2023

March 2023 Field Updates: Expanded Streamflow Monitoring

Anyone who has lived in the West is familiar with the ever-present threat of drought and the need for reliable sources of clean water for people and for wildlife. If there is not enough water flowing in our creeks, especially during the dry season, it can affect the health of the plants and animals that live there. The Estuary Program tracks surface flows to determine whether there is enough water present to support sensitive aquatic species year-round. We are expanding our network of sensors to increase our streamflow monitoring capacity.  

How We Measure Streamflow  

There are two primary ways that we can monitor streamflow in our creeks. The first is by taking manual measurements. Staff and volunteers the width of the channel and the depth of the water. Next, we collect the water velocity at different locations across the creek. We can then calculate how much water moves downstream every second, which equates to the flow rate in cubic feet per second (cfs). 

Streamflow can be measured manually using specialized equipment. This photo shows two Estuary Program volunteers measuring streamflow on San Luisito Creek.

Continuous Streamflow Monitoring

While manual streamflow measurements provide important information about flow conditions, they only capture a specific moment in time. To see how streamflow changes over time, the Estuary Program uses continuous monitoring equipment. This specialized equipment allows us to collect data every 15 minutes, year-round. 

For more information about continuous water quality and streamflow monitoring, you can check out this blog post. 

Continuous monitoring equipment allows us to measure streamflow rates all year round. This photo shows a continuous streamflow gauge installed on Pennington Creek.

New Monitoring Sites

This spring, the Estuary Program is partnering with Creek Lands Conservation to install five new streamflow gauges in the Morro Bay watershed. When the project is complete, the Estuary Program will have six continuous streamflow monitoring stations.

How We Install Streamflow Gauges 

Prior to deploying each sensor, we scout the creeks for optimal conditions. Sites with bedrock are ideal since they provide a sturdy anchoring location that will not change too much over time. Once we identify an ideal location, we conduct a survey to develop a site-specific plan and elevation profile.  

We develop site-specific installation plans to suit the needs of each unique site. The photo above shows an installation plan for a location on Chorro Creek.

Alongside the continuous streamflow monitoring equipment, we install a large stationary ruler called a “staff plate.” During site visits, surveyors use this ruler to take visual depth measurements. We then compare these readings to the sensor readings to check accuracy. 

We install the monitoring equipment inside protective tubing to reduce wear and tear. All sensors are installed alongside a stationary ruler called a “staff plate,” which helps us collect depth measurements while we’re in the field. The photo above shows a sensor installed on Pennington Creek.

It’s important that each sensor is installed at a known elevation. As the water levels change over time, this sensor will pick up changes in pressure and depth. The Estuary Program will use this information along with manual streamflow measurements to establish a depth-streamflow relationship.  

Working with Creek Lands Conservation 

Creek Lands Conservation is a local partner who provided crucial technical expertise and sensor installation support for this project. Like the Estuary Program, Creek Lands is a nonprofit organization who works to conserve and restore freshwater and near shore marine ecosystems. Creek Lands is based in Arroyo Grande but is involved in projects throughout California’s Central Coast, ranging from Monterey to Ventura County.  

To learn more about Creek Lands Conservation, you can visit their website at www.creeklands.org. 

Creek Lands Conservation’s team of hydrologists provided their expertise for this project. The photo above shows a staff hydrologist planning for a sensor installation on San Bernardo Creek.

Help us protect and restore the Morro Bay estuary! 

Thank you for helping our beautiful, bountiful, biodiverse bay!