Non-profit organization uses KaleidaGraph to provide vital information to policy makers in northwestern Montana

KaleidaGraph is the ideal application because of its large datasheet (many data sets have more than 32,000 rows), its clean and elegant output, its powerful curve fit and statistical functions, and its unexcelled ease of use.

Flathead Lake in northwestern Montana is the U.S.’s largest natural freshwater lake west of the Mississippi River. One of the cleanest lakes of its size and type anywhere in the populated world, vast expanses of its watershed remain as wild as they were when Lewis and Clark passed through Montana on their way to the Pacific 200 years ago. Kerr Dam began regulating the top ten feet of the lake in 1938, perturbing and inverting the lake’s hydrograph.

Water quality (as indicated by primary productivity) in Flathead Lake has been declining steadily since 1977, according to research conducted by the University of Montana’s Flathead Lake Biological Station, due to sediment and nutrient loading from urban sprawl, old and failing septic systems, and agricultural and timber harvest practices.

Introducing the Flathead Lakers

Half a century ago a group of citizens formed a non-profit organization, the Flathead Lakers, which is dedicated to maintaining the very high quality of the water in Flathead Lake and its watershed. The Lakers work closely with state, federal, and local agencies, as well as the researchers at the Flathead Lake Biological Station. The effects of regulation and population growth are of special interest to the Lakers because of their consequences for water quality, recreation, and shoreline erosion.

In the early 1990s, a controversial proposal to lower the lake slightly to reduce erosion on the northern shore precipitated a controversy that was more difficult to resolve than necessary, partly because the lake’s hydrograph was not widely understood. The Lakers’ leaders knew that in the future they needed to educate people by providing solid, objective data on the lake’s hydrograph. They turned to KaleidaGraph.

KaleidaGraph’s plotting and analysis tools generate clean, professional graphs of lake level and streamflow variations

The Flathead Lakers rely on the United States Geological Survey (USGS) for streamflow and lake elevation measurements, which are posted on the agency’s realtime website. Data needed by the Lakers is downloaded from the USGS website, cleaned by BBEdit, and added to Filemaker Pro databases. The data is organized and broken out into sets for analysis and graphing by KaleidaGraph. Lakers webmaster James Conner, a technical editor and KaleidaGraph user since 1995, crunches the numbers. He uses line plots for the annual lake levels and streamflow hydrographs, in which the surface elevation of the lake, or the volume of water in the rivers flowing into and out of the lake, is displayed as a function of time. He also uses box plots and scatter plots to display annual and seasonal variations in the hydrographs, employing error bars as necessary to identify norms. Standard statistics are computed using KaleidaGraph’s datasheet.

Early USGS data sets for the lake contained long periods where measurements were not taken, so hydrographs prior to 1928 contained gaps. Conner used KaleidaGraph’s powerful curve fit features to plot the level of the lake as a function of the streamflow in the river below the lake’s outlet, thus deriving an equation with which he calculated the missing lake levels and reconstructed the lake’s hydrograph. He also used KaleidaGraph’s statistical functions to analyze the (slight) difference between the readings for the USGS gauges at the north and south ends of the lake.

“KaleidaGraph is the ideal application for these tasks because of its large datasheet (many data sets have more than 32,000 rows), its clean and elegant output, its powerful curve fit and statistical functions, and its unexcelled ease of use,” states James Conner.

The plots are displayed on the Flathead Lakers website. They also are made available to interested parties as files for printing and projection. Visitors to the website can download the entire set of lake level measurements and calculated values that are used to produce the graphs. Objective information in graphic form helps shape public policy. KaleidaGraph’s graphs and statistical analysis have helped the Lakers educate people on how and why the level of Flathead Lake varies, an important step in determining how the natural resources near a crown jewel national park in northwestern Montana should be managed. “Making public policy is a lot easier if everyone has ready access to the same set of facts,” says Conner. “Providing all interested parties with objective information on lake levels and related streamflows presented in graphic form, puts everyone on the same page at the beginning of the debate.”

For more information on the Flathead Lakers see

Box plot of water data
Box plot of water data
Line plot of water flow

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