POSTED BY ERIC SPRAGUE ON JUNE 6, 2019
McPhee is currently releasing approximately 1,000 CFS downstream, as flows ramp up to 1,200 CFS by Friday morning.
- On Friday June 7th, releases will continue to ramp up from 1,200 CFS, reaching at least 2,000 CFS by the morning of Saturday June 8th, for optimal boating flows.
- Releases will continue to ramp up from 2,000 CFS, reaching approximately 2,400 CFS by the morning of Sunday June 9th.
- Releases will remain at about 2,400 CFS until the morning of Monday June 10th.
- The morning of Monday June 10th, releases are expected to begin ramping down to target some ecological goals during the middle of the week. Releases on Tuesday, Wednesday, and Thursday are expected to run between 1,800 CFS and 1,200 CFS, depending on forecast conditions.
- Releases are currently expected to ramp up to around 2,000 CFS again around the weekend of June 15th and 16th, though the timing is still uncertain.
Releases will remain at a minimum of 1,200 CFS through Sunday June 23rd, after which flows are yet to be determined. Based on the margin of error in current inflow forecasts, it is possible there will be additional rafting days – this should become more clear in coming weeks. Details on flows following June 23rd should be available the week beforehand. During this period, releases may reach flows of around 2,000 CFS and above on some days. More details will be announced on later posts.
The current release pattern of higher flows on the two upcoming weekends and lower flows mid-week has been adopted in order to achieve two objectives. First, it prioritizes optimal boating flows – around 2,000 CFS – on the weekends, when more recreationalists can get on the water; and second, the variability in river levels can potentially contribute to channel maintenance, encouraging bank destabilization, a long-term ecological benefit.
McPhee is currently approximately 30,000 AF below full capacity and should fill steadily over the next two or three weeks. There remains the possibility that, should inflows increase dramatically beyond what is forecasted, managers will be forced to increase releases to control reservoir elevation. Please continue to check back on this site regularly for new updates, primarily on Mondays and Thursdays.
For details on the forecast, read on.
May was a difficult month for inflow forecasts. A persistent low pressure trough settled over the region during the second half of the month which brought with it both temperatures that were consistently 7-9 degree F below average, as well as extensive, regular cloud cover. The extra cloud cover resulted in a reduction of inflows into the reservoir, which tends to confuse the Colorado Basin River Forecast Center’s (CBRFC) inflow forecasts; worse, that same cloud cover also effectively blinded the satellites used to visually measure snow cover in the mountains, further muddying the forecast. These factors meant that the CBRFC’s model consistently predicted temperatures that were much higher than what occurred and was regularly over-estimating daily flows across SW Colorado.
While the trough is moving away this week, uncertainty persists in forecasting the daily inflows into McPhee. Temperatures are expected to rise to near normal this weekend, however, some cloud cover remains. Around June 9th, a new cold front is expected to pass over Colorado. It will primarily pass north of the Dolores headwaters, but will likely reduce temperatures some. It is too early to predict the influence it will have on inflows. After that front, the CBRFC expects that a significant warm-up is possible around Tuesday to Thursday, June 12th to 13th, with temperatures rising to 5-10 degrees F above average. The CBRFC noted that these high temperatures combined with the substantial amount of snowpack still remaining at high elevations could result in especially high runoff on these days or those immediately after. Accordingly, the CBRFC anticipates many headwater basins will reach their peak runoff next week.
If you have questions, the best way to address DWCD is through the “Contact” page of this website. Otherwise you can try calling 970-882-2164 extensions 5, 1 or 6.
Dolores Gage: https://waterdata.usgs.gov/nwis/uv?09166500
McPhee Elevation & Capacity: http://www.dwr.state.co.us/SurfaceWater/data/detail_tabular.aspx?ID=MCPRESCO&MTYPE=ELEV
Dolores below McPhee: http://www.dwr.state.co.us/SurfaceWater/data/detail_graph.aspx?ID=DOLBMCCO&MTYPE=DISCHRG
Slickrock Gage: https://waterdata.usgs.gov/nwis/uv?09168730
Bedrock Gage: http://waterdata.usgs.gov/nwis/uv?09171100