Interactive California Reservoir Levels Dashboard

Posted In: Environment | Water

How much water is in California’s reservoirs?

Check out the California precipitation tracker and compare to historical values

It’s the winter rainy season in California again, so time to check on the status of the water in the California reservoirs. I previously made a “bar graph” showing the overall level of water in the major California reservoirs. This dashboard provides a bit more detail on the state of each of the reservoirs while also showing an aggregate total. It updates hourly using data from the California Department of Water Resources (DWR) website, giving an up-to-date picture of California reservoir levels.

This is a marimekko (or mekko) graph which may take some time to understand if you aren’t used to seeing them. Each “row” represents one reservoir, with bars showing how much of the reservoir is filled (blue) and unfilled (brown). The height of the “row” indicates how much water the reservoir could hold. Shasta is the reservoir with the largest capacity and so it is the tallest row. The proportion of blue to brown will show how full it is, while the red line shows the historical level that reservoir is typically at for this date of the water year. There are many very small reservoirs (relative to Shasta) so the bars will be very thin to the point where they are barely a sliver or may not even show up.

If you are on a computer, you can hover your cursor over a reservoir and the dashboard at the top will provide information about that individual reservoir. If you are on a mobile device you can tap the reservoir to get that same info. It’s not possible to see or really interact with the tiniest slivers. The main goal of this visualization is to provide a quick overview of the status of the main reservoirs in the state and how they compare to historical levels.

You can sort the mekko graph by size – largest at the top to smallest at the bottom – or by reservoir location, from north to south.

Units are in kaf, thousands of acre feet. 1 kaf is the amount of water that would cover 1 acre in one thousand feet of water (or 1000 acres in water in 1 foot of water). It is also the amount of water in a cube that is 352 feet per side (about the length of a football field). Shasta is very large and could hold about 3.5 cubic kilometers of water at full (but not flood) capacity.

Data and Tools
The data on water storage comes from the California Department of Water Resources’ (DWR) Data Exchange Center. Python is used to extract the data from this page hourly and wrangle the data in to a clean format. Visualization was done in javascript and specifically the D3.js visualization library. It was my first time using D3 and it took me a long time to get up to speed. It takes a fair amount of work to make graphs compared to other more plug-and-play libraries but its very customizable, which is a plus. It was the only tool that I could find that would allow me to make a vertical marimekko graph.

california reservoir levels dashboard


12 Responses to Interactive California Reservoir Levels Dashboard

  1. Elz says:

    An improvement: Could you include a bar for “Last year at this date”?
    A question: the “Historical Avg*”, is it the value of year-today or natural year?

  2. Brian says:

    This site is a great tool, especially as we try to climb out of these drought years. Saved to my favorites now. Thanks for developing it, and for sharing it with the rest of us!

  3. David A says:

    Nice! Just a wistful thought, it would be really cool to graph the water release statistics. One of the big challenges in water management is controling the release. Sometimes this is well done sometimes it is poorly done.

    All the best…

  4. Peter Spence says:

    I know this might be difficult to display but I’m very curious on the actual amounts of water consumed on a monthly basis and if this is somehow processed in a certain between what is agricultural and what is non-commercial etc? I’d only be interested in the totals from Oroville and Shasta.

  5. EarthwormSally says:

    I LOVE this site.

  6. Gary says:

    What’s going on with the water level at Oroville?

  7. Ron Griswold says:

    Great Job on this site! Love easy to read and understand information.

  8. John Gardner says:

    This is an excellent tool you have put together. Thanks for taking the time to do that. The only improvement I would ask you to consider is to allow the Y-axis to be Linear or Log, the latter allowing us to see all the small reservoirs quite easily.

  9. Darcy says:

    Also a little nit. “Remaining Capacity” text in the legend should be brown?

  10. Darcy says:

    Love the dashboard! How come the totals disagree with the cal map graphic?

Leave a Reply

Your email address will not be published. Required fields are marked *