From the Army Corps of Engineers:
Over 10,000 feet above sea level in Sequoia and Kings National Parks dozens of weather station towers are sprinkled amongst a forest of towering trees. These towers house antennas and sensors designed to collect valuable water data used by the U.S. Army Corps of Engineers Sacramento District and many of its partners. Though these stations are built to withstand extreme weather, there comes a time — about every 50 years or so — when the stations need a little more than routine annual maintenance.
This was the case for two USACE-operated weather stations that were rebuilt in 2025: Upper Tyndall near Mt Whitney, in the Kern River watershed, and Mitchell Meadow near Cedar Grove, California, in the Kings River watershed.
In 2017, the Upper Tyndall station began leaning after heavy snowfall that season. Similarly, Mitchell Meadow was found collapsed during an annual maintenance visit in 2023.
Upper Tyndall has continued to collect data in a limited capacity, but Mitchell Meadow has been completely offline. This lapse in data collection affects the inflow forecasting abilities for both watersheds.
For example, if the weather station cannot consistently measure the snowpack and air temperature, water managers may not be able to predict the rate of the snow melt into downstream reservoirs and, in turn, would be unable to help make key flood risk management decisions.
This data helps inform the decisions of not only USACE but the California Department of Water Resources, National Oceanic and Atmospheric Administration, and other agencies. It is also publicly accessible via USACE-operated Access to Water (A2W) and the California Data Exchange Center.
“We maintain [the data] for the use of our reservoirs, but it’s also for anybody that’s out there,” said Jesse Schlunegger, Hydrology and Hydraulics branch chief. “For hikers and folks in the park, it’s a data point for them to use as well. So, it’s a public good.”
Schlunegger acted as the primary point of contact between USACE and the National Park Service during these two rebuild projects ensuring the NPS was kept informed as the projects progressed.
“The goal of getting the weather stations rebuilt was common to everybody,” he said.
Each tower required a 14-day construction period. During those two weeks a 4-person team from the Hydrology and Hydraulics Branch were onsite facilitating construction with a USACE contractor, who had the personnel, equipment and materials ready to begin.
Due to the remote location of the construction sites, the team as well as all necessary equipment and material arrived onsite via helicopter. Part of the team would fly to the weather station, while the rest remained near the helicopter landing zone. In the landing zone, concrete and other materials were airlifted as much as 12 miles to the weather station.
Steven Yates, a Hydrologic Technician in the Water Data Section, a Section in the Hydrology and Hydraulics Branch, was stationed at the landing zone area. Yates provided technical oversight during the permitting process, documented a list of needs at the construction site, and supported logistical coordination during physical construction.
“These were the first construction projects of this magnitude that I have worked on,” Yates said. “So, this was a big learning experience for me across the board, in every facet of the project. It was a big experience builder for me to be able to be on site and taking part in these [projects] every step of the way.”
Once at the construction site, the towers were completely rebuilt from the foundation up. At 30 feet tall, the new towers are 10 feet taller than the previous weather stations to account for the significant amount of snow that often falls at those locations.
A snow pillow, essentially a giant membrane filled with a non-freezing liquid solution, helps measure the snowpack. As snow falls, the snow pillow is squished, pushing liquid up a tube on the tower, where a sensor measures the quantity of liquid in the tube. The measurement reflects how much snow is on the pillow.
Each tower was also built with a new precipitation gauge that measures the amount of rainfall by collecting rain in a small seesaw-like bucket that tips when it collects 0.01 inch of rain. This is similar to rain gauges found in residential backyards that capture rainfall in a bucket with markings measuring the volume of water that tips on its own instead of having to dump it out when it gets full.
A data logger is considered the “brains of the operation” for each tower, according to Yates. The data logger is a small electronic device which controls all the sensors on the tower. Sensors measure liquid precipitation, snow depth, temperature, relative humidity, wind, soil moisture, and solar radiation.
“The reason we gather that information is it tells us how quickly the snow will melt,” Schlunegger explained. “That is the key piece of information we’re trying to figure out.”
The data logger requests these data points from sensors every 15 minutes and stores it internally. The data is then transmitted via satellite to a ground station near the Sacramento District office, where it is added to the database maintained by the Water Data Section. From there, Water Managers use the data to assess water supply conditions and predict snowmelt runoff into the reservoirs.
In California, hundreds of these weather stations are operating and collecting data all the time but because of the combination of their longevity and remote locations, they’re often out of public view.
“I love learning this part of what USACE does,” Schlunegger said. “You don’t often hear about these kinds of scientific instruments being installed and maintained by the Corps of Engineers.”
The value these weather stations brings goes beyond reservoir management and can be vital for the success of other USACE projects. The data from Upper Tyndall, for example, was used in the design of the Isabella Dam Safety Modification Project to help size the new spillway. The data was used to calculate how much water would need to pass through the spillway in an extreme event.
Yates said it was an awesome experience to be part of and is proud to help support the mission by, as he says, “being able to build something that will hopefully last long beyond all of our careers.”
