Measuring Montana's Streams

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And not just one – many rivers run through it. Water is an essential ingredient to Montana’s way of life and our economy. If access to accurate, publicly available, real-time stream flow information is important for your business or personal needs, scroll down for the full story. 

During dry and even normal years, it is crucial for water users and managers to have accurate, real-time information as it allows for informed water administration decisions related to planning and distribution of water. Montanans, after all, depend on water and proper water management to make a living. It simply wouldn't be possible without the stream gages that tell us how much water is flowing at any given time. The primary source of Montana’s stream flow and water temperature information is delivered by a network of stream gages operated by the U.S. Geological Survey (USGS).

Water managers, and the public rely on the system to deliver accurate real-time information on Montana’s stream flows. Local governments, state, tribal and federal agencies also rely on the network for emergency planning and notification as well as longer-term water supply planning.  

For close to 82 years, the  Muddy Creek Stream Gage  station has recorded data. This is one of the longest data sets among USGS gages in Montana. The gage is essential for understanding how much irrigation water is coming off the Fairfield bench, between the towns of Power and Vaughn, and returning to the Sun River. It has also been key in sediment studies. 

The Muddy Creek data was key for the Sun River Watershed Group and Montana's Department of Environmental Quality (DEQ) to complete both the plan to manage sediment load in the river (2004) and the Sun River Watershed Restoration Plan by 2012 which was earlier than many other watersheds. Muddy Creek Stream Gage is funded by USGS, Montana Department of Natural Resources and Conservation (DNRC), and Greenfields Irrigation District. Even though it is an important gage, each year it can be a challenge to find adequate funding to keep the gage going.

 Information about the Sun River Watershed Group is available online. 

Stream discharge is the amount (volume) of water flowing in a stream or river. Discharge increases as more water is added through rainfall, tributary streams, or from groundwater seeping into the stream. Conversely, discharge decreases when the amount of water removed from the stream exceeds the amount of water added. Discharge information is used for: 

• Planning, forecasting, and warning about floods and droughts; 
• Managing water rights; 
• Determining if streams are safe for recreational activities; 
• Assessing water quality and regulating pollutant discharge and; 
• Designing reservoirs, roads, bridges, drinking water and wastewater facilities. 

Explore the Map below and click on the legend button to learn who is funding the USGS stream gage in your watershed. Click on the symbols within the map to learn more about individual gages. For more advanced instructions, see the document linked  here .

One of the most basic services stream gages provide is giving local authorities real time information from areas at risk for flood danger.

Driving from Lewistown to Malta, the expanse of prairie stretches as far as you can see. Only as Highway 191 drops into the Missouri River Breaks and crosses the river, revealing the river carved limestone cliffs rising over 1000 feet that it becomes clear how powerful water can be. 

The  Missouri River Near Landusky gage  has been recording water discharge data for over 38 years. The gage is operated to monitor water going into the Fort Peck Reservoir and partially for the Fergus County Emergency Management. Hydrologists and meteorologists at the National Weather Service (NWS) monitor river conditions around the clock, watching for potential flooding conditions. This is crucial during times of high water particularly for the James Kipp Campground and surrounding recreation area. This area is popular among fisherman and rafters on the Missouri River, and during flood season, there is a lot of camping occurring in the area. Because of the elevation drop from the prairie to the river, there is zero cell service and it doesn’t take much high water for the campground to flood, making it impossible for people to evacuate if they wait too long. If the NWS hydrologists see a problem coming while watching the discharge and gage height data from the Landusky gage, the Fergus County Sherriff’s office is called and a deputy is sent out to the campground to knock on the doors of campers and tents, evacuating the campground. These events can be fast moving and unexpected, the campground has been evacuated at 3 a.m. Historically this occurs about every other year, with the evacuations saving lives and property.

This gage is operated by the USGS Wyoming-Montana Science Center in cooperation with the U.S. Army Corps of Engineers.

A smaller number of USGS gages measure water temperature in addition to discharge. Water temperature exerts a major influence on the diversity and health of aquatic organisms living in Montana’s streams. Fish, insects, and other aquatic species all have a preferred temperature range. As temperatures get too far above or below this preferred range, the number of individuals of the species decreases until finally there are none.

Explore the Map below to learn who is funding the collection of water temperature information in your watershed. 

The North Fork of the Blackfoot River is a major bull trout spawning tributary, and home to the  North Fork of the Blackfoot at Ryan Bridge gage . This gage tracks important flow and temperature data and allows the Blackfoot Challenge, along with Montana’s Fish Wildlife and Parks (FWP) to watch for potential fish passage issues in late summer during low water years.

The hydrology of this river is unique. Water from the North Fork Blackfoot River flows out of the mountains onto Kleinschmidt Flat, a glacial outwash plain. Some sections of the Flat are comprised of coarse porous sediment and rocks that increase surface losses of the river to groundwater during transport. The gage is located at a point that typically represents the lowest river levels in the Kleinschmidt Flat area. Below the gage, this trend reverses and groundwater discharges to surface water and the river gains flow.

The gage data answers how low the river is at its lowest levels at that time, which provides critical information for irrigators and managers concerned with bull trout migration and spawning. Jennifer Schoonen, Water Steward for the Blackfoot Challenge, reports that “Although there are no specific flow-related drought plan restrictions for this tributary, we do ask for voluntary water conservation from North Fork irrigators in years when there may be fish passage concerns for spawning bull trout. Our landowners in this area are very cooperative with voluntarily reducing water use to ensure the bull trout can move in and out of the North Fork in August and September.”

In addition, the North Fork has a temperature trigger, which is followed for the Blackfoot Drought Response Plan. If the water rises above 65 degrees Fahrenheit for more than three consecutive days, FWP may enact partial or all-day fishing restrictions.

 Information about the Blackfoot Challenge is available online .

In addition to the funding of 27 stream gages, FWP funds thermographs that are an add on to several key USGS stream gage stations. These thermographs are used to monitor certain temperature thresholds that help determine whether certain cold water fish species are being stressed during late summer months or when drought is present. When water temperature increases above a certain threshold, dissolved oxygen decreases and creates a stressful condition for fish. FWP has created an administrative rule (ARM 12.5.501-12.5.509) that governs how it responds to streams that experience high temperature thresholds. This response may either result in a Hoot Owl Closure, which prohibits fishing in the afternoon and evening hours (2 p.m. - 12 a.m.), or full angling closure. These temperature thresholds and FWP's response are often included in community drought plans, such as the case in the Big Hole, Jefferson and Blackfoot Rivers.

The gage  Big Hole River Below Big Lake Creek at Wisdom  has a mundane name for such an important device. During the spring of 1988 the ‘Wisdom Gage’ was installed by USGS at the request of FWP because the river consistently was running dry for parts of the summer. In the summer of 1988, the Big Hole River went dry for over 25 days. This gage is a huge part of the collaborative water management efforts involving landowners, water managers, and fishery managers along the river. 

Then, in 1994 the river at the Wisdom Gage was recorded at 1.8 cubic feet per second (CFS). During that year, the U.S. Fish Wildlife Service (USFWS) announced that Arctic grayling were a candidate for the Endangered Species Act, and that the Upper Big Hole River was a critical stronghold for the grayling. Through the work of local ranchers, a committee was formed to find solutions for the water problems they were facing. The committee’s work resulted in the formation of the Big Hole Watershed Committee.  

Working together, ranchers along with representatives from USFWS, FWP, and the DNRC developed tailored water management plans to keep water in the river and the Artic grayling off the Endangered Species list. Through shared sacrifice, when there is a low streamflow, ranchers give up some of their water that year to keep flows in the river.  

This gage alone is the litmus test about how the water conditions are in the Upper Big Hole River. The data from the gage is one of the most viewed in southwestern Montana.

“It is a critical gage to manage water and is ground zero for Grayling fisheries management in the Upper Big Hole watershed.” -Mike Roberts, retired Hydrologist for DNRC. 

An additional benefit of the work that has occurred on the Big Hole River is the riparian areas along the river are much healthier, with vegetation which reduces stream bank erosion and provides shade which leading to lower water temperatures.  

 Information about the Big Hole Watershed Committee can be found online .

Asking the Musselshell Watershed Coalition to pick a favorite gage that they rely on is an impossible task. The people in this watershed rely on all of them for the most accurate information. When the unprecedented flood of 2011 was threatening communities along the Musselshell River, the streamflow gages at Martinsdale, Harlowton, Lavina, Roundup, and Musselshell were continuously transmitting information about rising waters, providing the opportunity for issuing warnings to residents at risk. 

When rains suddenly increase the river's flows, stream gages are used on an hourly basis to determine how much water can be diverted into Martinsdale and Deadman's Basin Reservoirs to boost levels of stored water. During the irrigation season, all the gages are monitored to make sure each water user receives a fair share while a steady flow is maintained along the entire mainstem of the Musselshell to protect the river and its fishery. All of the gages are essential to the safety of residents and to wise management of a scarce resource. 

 Information about the Musselshell Watershed Coalition is available online .

Montana’s  2015 State Water Plan  recognizes that accurate, near real-time, publicly accessible information on stream flows assists both day to day decision making and long-term planning, as well as emergency planning and notification.

As shown in the maps above, the USGS stream gage network is funded by multiple federal, state, tribal, private, and local cost-share partners. Each partner contributes funds to meet their own water priorities. Over the last decade, the cost of maintaining the network has grown faster than the stream gaging budgets of many funding partners. If funds are not available, the USGS has no choice but to remove the gage from service.

The USGS stream gage network provides Montana with the best scientific information available to quantify water supplies and availability. The network’s long historical record provides water managers with the ability to analyze long-term climatic and hydrologic trends. It can drive the understanding for other sciences and helps inform citizens on how we can prepare for changes in our water supply. It is imperative to keep the USGS stream gage network operating to support water management decisions of current and future generations. 

This Story Map is brought to you by the Montana Department of Natural Resources and Conservation. For more information, please visit the following websites:

•  StAGE - Stream and Gage Explorer 
•  USGS WaterWatch 
•  MBMG Surface Water Assessment Program 
•  Why we spell it "gage"