POSTED BY ERIC SPRAGUE ON APRIL 23, 2019

April 23, 2019:  The Dolores River Basin reached peak snowpack at the beginning of April, and since then, the melt has begun in earnest. The annual runoff into McPhee Reservoir has started in turn, and is tracking well with historic median Dolores River flows. McPhee is now growing over a foot in elevation per day, with 44 feet to go before reaching full. April brought below average precipitation, but has been compensated for by the near record snowpack levels. It is still unclear how much last fall’s dry soil moistures will affect the runoff volume.

With all that said, the CBRFC’s forecasts have stayed near 420 KAF for the April through July runoff season. That volume is expected to produce some excess water that will be released for raftable downstream flows; however, the large volume remaining to be filled in McPhee pushes any managed “spill” releases back to around late May or early June.

Managers continue to monitor all changing conditions to confirm the forecast and projected runoff volumes. As the runoff season progresses, the accuracy of the forecasted inflow volumes that drive the spill continues to improve. Based on the lack of information on upcoming conditions and public input, it has not yet been confirmed whether there will be Memorial Day releases. Managers expect to be able to provide a couple weeks’ notice prior to any spill releases based on rising McPhee elevations and near-term CBRFC forecasts. We should receive a forecast update around May 6th, and we’ll follow up with another website update near May 8th.  Please follow all the details at the links below:

Dolores River at Dolores Gage:

https://waterdata.usgs.gov/nwis/uv?cb_00045=on&cb_00060=on&cb_00065=on&format=gif_default&site_no=09166500&period=30&begin_date=2019-04-16&end_date=2019-04-23

McPhee Reservoir Elevation:

http://www.dwr.state.co.us/Surfacewater/data/detail_graph.aspx?ID=MCPRESCO&MTYPE=ELEV

Note that the large flows below McPhee at Slickrock and below are coming from all the low elevation snow melting out of Narraguinnep Canyon, Disappointment Creek and other small tributaries.  Similar large flows sourced from low snow are currently helping to fill McPhee at twice the rate of the Dolores River inflows alone.  It remains unclear how many weeks of higher flows will be sustained by the low snow volumes.