McPhee Downstream Release Update
Early April has improved our weather patterns compared to March and brought some new precipitation to the mountains. Last week’s warm temperatures started the April runoff and a little rain on snow over last weekend jumped up all the local river flows and snow melt. This can be seen in the Lost Canyon gage into McPhee and the gages downstream of McPhee at Slickrock & Bedrock. All the lower snow, below the 9,000 foot elevation, appears to be melting and running off pretty close to normal patterns. This bump in river flows last weekend appears to be slowing down again, partially due to some cool weather at higher elevations and also partially due to the available lower snow having melted out.
The forecasted weekend storm looks promising and could boost inflow if it hits big in the upper Dolores as forecasts are starting to indicate. We remain working off the April 1 forecasts from the Colorado Basin River Basin Forecast Center (CBRFC).http://www.cbrfc.noaa.gov/rmap/wsup/point.php?id=MPHC2. They produce a range of potential runoff probabilities based on future weather conditions through the April to July runoff period based on current conditions and past records. They do not always accurately know all local conditions including the extent of our lower snow pack in the Dolores. They generally have a plus or minus 15% on the McPhee inflows. If runoff falls on the plus side we’ll have a spill, no spill if runoff falls on the minus/low side. Next CBRFC forecast should be out on May 3. So we still need 105,000 AF to fill McPhee, at least 30 plus days of runoff, so no spill in early May. Cold, snow vs. rain & clouds vs. sun combined with our small amount of dust on snow will control how fast McPhee fills, but we should have a week’s notice before having to spill.