This article originally appeared in the October print issue titled "Directors of Data"
A decision by the Albuquerque Metropolitan Arroyo Flood Control Agency (AMAFCA) to upgrade to a real-time monitoring solution has led to more effective and efficient management of storm water discharge and secured the agency’s leading role in efforts to protect the Middle Rio Grande (MRG) Valley watershed.
In the early years of its permit history, the AMAFCA operated with a typical MS4 Phase 1 individual permit that included Minimum Control Measures and best management practices (BMPs) to enhance water quality.
The conventional NPDES permitting approach provided little consideration of upstream sources except as background concentrations of a pollutant. And limited data from grab sampling made it difficult to determine whether BMPs were effective in supporting water quality standards defined by the U.S. EPA. In 2009, based on a report from the National Research Council, the U.S. EPA responded to these concerns with a pilot program that would allow it to explore the complexities and potential benefits of watershed-based permitting (WBP).
The MRG Valley was one of three projects selected nationwide because of existing water-quality impairment in the Rio Grande River and the opportunity to work on the challenges of permitting unique to arid and semi-arid parts of the country.
The flexibility of the permit allowed for the development and implementation of a joint storm water monitoring program (SWMP) among MRG permittees in cooperation with public agencies or private entities. A cooperative watershed framework in the MRG had the potential to produce more effective and efficient improvements in water quality than an uncoordinated, single-source oriented storm water management program. It also created the opportunity to assess both individual and cooperative requirements in the areas of monitoring, education and outreach to identify and address all pollutant sources.
As the lead MRG permittee, AMAFCA worked collaboratively to develop and implement the SWMP, which included a thorough evaluation of monitoring techniques and a move to implement real-time storm water monitoring to collect data on different factors, including:
- The amount and rate of storm water runoff;
- The sources and patterns of pollution loading;
- Non-storm water discharges; and
- Data on every storm event.
In support of the project, the agency initially received five In-Situ Troll 9500 Multiparameter Sondes from the U.S. Geological Survey. The units had internal batteries and onboard data logging, which made them ideal for continuous monitoring. They were deployed at five key sites along the MRG to collect pH, ORP, DO, temperature, turbidity and depth. But while the data loggers provided more data than grab sampling, they had challenges of their own.
As part of environmental conditions for the permit, the U.S. Fish and Wildlife Service required AMAFCA to monitor dissolved oxygen and temperature, recording readings every 15 minutes. Because the units were continually “on,” batteries only lasted two to four weeks. And if batteries died over the weekend, data was lost. Plus, the lack of real-time visibility to sensor status, especially the depth of water over the sonde (critical to pH sensor performance), created more uncertainty, and the storm water team was forced to make frequent site visits to maintain the equipment.
AMAFCA Stormwater Quality Program Engineer Patrick Chavez leveraged the benefits of collective funding and a reduction in the number of monitoring sites required for compliance to increase the quantity, quality and availability of data with an upgrade to monitoring and telemetry system.
The new sondes featured extended battery life, redesigned sensors and a powerful anti-fouling system. The added ability to determine depth of water over the sensors reduced site visits and instilled a heightened sense of security. The telemetry system provided a supplemental power source to ensure data availability. Additionally, the telemetry tubes were non-vented, so flood risk was eliminated.
The agency started with two Aqua Troll 600s and has since added two more. Situated at four points along the Rio Grande, the sondes continuously collect data on dissolved oxygen (DO), temperature, pH, turbidity and level/depth. Telemetry uploads data to HydroVu, In-Situ’s cloud-based data services platform, which enables around-the-clock monitoring and access to data in real time.
With the upgrade to the Aqua Troll 600, tube telemetry and HydroVu, Chavez has seen a reduction in the time required to manage each location even as the flow of data has increased.
“The sondes give us a really nice profile from the top of the urbanized area to the bottom,” says Chavez. “We see fluctuation of parameters in dry and wet weather and have found, for instance, that water quality prior to rain isn’t what we thought it was.”
With HydroVu, he set custom alarms tied to areas of impairment, namely DO and temperature, so he knows immediately if he needs to send notification of exceedance downstream. And in general, the ability to monitor remotely makes it that much easier to keep a handle on things.
“Every morning I sit down with a cup of coffee, open HydroVu and have a little moment with the sondes to see what’s happening over a 30-sq-mile reach,” Chavez said. “You have to have data to see if you’ve exceeded limits and you need data to set that exceedance.”
It takes both a proactive and reactive approach, and strong individual and cooperative monitoring requirements drive both.
That is a concern to Chavez as it remains a question whether the watershed-based program will continue. The permit expires this year and will be administratively continued, but without a permit to drive compliance, it may be more difficult to capitalize on the benefits new technology has to offer, especially for AMAFCA partners with fewer resources. Data drives the background values for water quality standards, but the requirements drive adherence to those standards and the budgets to meet them.
AMAFCA plans to sustain its real-time monitoring program and look at new advancements in wireless data transfer and management. Chavez and his team continuously improve the system and share their lessons with smaller communities. Their progressive approach has positioned the agency as a regional leader. The experiences and information gained give this MS4 a wealth of knowledge to share and a greater ability to protect the water.