Facts and Information About the Mortimore Lane Bridge Gage Along the Middle Fork of the Popo Agie River


 Mortimore Lane Gage


     On October 30th 2008, City of Lander and NWS/NOAA installed a river gage on the downstream side of the Mortimore Lane Bridge. The gage will be used to monitor high water in order save lives and property in Lander during the next flood of the Popo Agie. NWS/NOAA forecasters and Lander emergency managers will use the data from the gage to help better predict when and how to warn the public during high water events. The City of Lander paid for the majority of the gage hardware. The NOAA hydrologist and individuals from the City Works Department worked together closely to plan, prepare, and install the gage.


Gage Facts

    The river gaging system automatically logs river level information every 15 minutes and the data is transmitted via satellite every hour. During very high water, the system can be programmed to transmit river stage information every 5 to 15 minutes. The data will be accessible to both NOAA/NWS and Lander Emergency Managers via NOAA’s hydrology web site. The gage operates like a mini stilling well using a 7-inch diameter PVC pipe as the well. Inside the well (PVC pipe), is a cylinder float, metal tape, and a counter weight.

Picture 1. PVC pipe and float used in mini stilling well at Mortimore Lane Gage.

     Attached to the PVC pipe is a metal box that houses a shaft encoder wheel that measures to the nearest 0.01’ the change in river level that is directly monitored by the float.


Picture 2. Shaft encoder used inside metal box--attached to top of PVC pipe.


Picture 3. Metal box attached to top of PVC pipe--houses shaft encoder.



Picture 4. PVC stilling well attached to Mortimore Lane Bridge.
Note: Float is visible inside pipe at opening.


Picture 5. PVC stilling well attached to Mortimore Lane Bridge.
Note: Attached metal box housing shaft encoder.


     The PVC pipe also has numbers painted on the outside. These numbers refer to stage heights that will correspond to what the shaft encoder/float system is recording. The numbers on the outside are primarily used as a reference gage and as a backup staff gage in case the automated system malfunctions.

     At this time, it is estimated that 4.0 feet near the gaging site is the bankfull level of the river. (bankfull meaning the channel capacity of the river--with no overflow/flooding). The site will be formally site surveyed in the Spring 2009 (before the runoff) to establish a more accurate bankfull stage as well as a solid flood stage.

     Finally, the river stage data (to the nearest .01’) from the stilling well is encoded and transmitted via satellite from the tower/antenna. There is also an air temperature sensor attached to the mast assembly and hourly air temperature is also encoded and transmitted hourly.


Picture 6. Antenna/Mast assembly---transmitting river and temperature data via satellite.
Note: the temperature sensor located behind antenna.



Where to Find Data from Gage


Data from the river gage can be found at 2 main places: The raw data can be found at:




 >> Point to Wyoming on the map of the USA




>> Click on “Decode Data” button >> Note: The data is stored in GMT time (Mountain time = GMT - 6/7) with the most current decoded data at the bottom


>> Also note the codes: HG = river stage data; TA = air temperature data; VB = battery voltage of logger/transmitter


A graphical display of the data can be found at:



Scroll down and you will find a map, photos, flood impacts, etc. Since this is a new gage, this web site is a constant “work-in progress”. Also, it is the works to have graphical forecasts generated from this site by Spring 2009.

Final Words

     Enhanced flood monitoring and early warning response due to high water from the Popo Agie River is the major goal with installing the Mortimore Lane river gage. If one life can be saved and/or property can be spared during the next flood along the Popo Agie River, than the goal has been met. By working together and establishing a firm partnership, a federal government agency (NOAA/NWS) is working with a local government agency (City of Lander) to better serve the citizens of Lander--that is the ultimate purpose of the Mortimore Lane river gage project.




Respectfully Submitted,


Jim Fahey
Wyoming NOAA hydrologist
Work #307-857-3898 ext 493
Cell #307-709-8778



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