FLOOD11107

• County: Statewide
• Basin: Statewide
• Title: Flood Task Force Summary - 3/29/07
• Date: 3/29/2007
• Prepared For: FTF
• Prepared By: CWCB
• Floodplain - Doc Type: Flood Task Force Meeting Materials

o Gunnison Basin - a similar story needing seven times the normal precipitation to even get
to normal peak. We are on our way to really early melt out.
o LaramieINorth Platte Basin- Started off good early this year but since then it has been
pretty flat. There are 10% odds of this basin getting to a normal peak.
o Upper Rio Grande Basin - was doing well until March. There were about 10 days in
March where this basin lost a lot of snowpack. The projections don't look bright for water
supply.
o San Juan, Animas, Dolores Basins - severe impact from dry warm conditions. The
projections have no hope for recovery from a statistical standpoint.
o South Platte Basin - projections are pretty bright for water supply and good chance with
50% odds of getting to the normal peak.
o Yampa/White Basins - The White River Basin just missed a record low by a day and
some late precipitation. There is not a decent chance of getting to normal peak and we
expect a real early melt out.
o Statewide Snowpack Projections - We need seven times the normal precipitation to see a
normal peak. There is a trend of seeing an early melt out.
Early snowmelt trend - Doug Cain, USGS, reported that David Clow with some funding through
the CWCB will complete a study that looks at changes of timing or run off going back 30 years. In
most places the timing has advanced two weeks.
NRCS Snowpack Projections - The snowpack projection graph below shows the minimum of
record and max of record and then within the gray area is the historical record. The boundary lines
within the gray areas are the 10%,30%, 70%, and 90% non exceedance lines. Colorado is often
only one big storm short of being in some kind of drought every year.
On the graphic to the right the NRCS Colorado State-Wide with Non-cxceedence Projections
is now projecting a range of possible 3J 8oc"d""P,~;>;o"ISNOTElD"""fM,,29;m7
outcomes (colored lines extending
from red line) that show expected
SWE meltout based on a wet, medium
or dry future.
NRCS Reservoir storage - It is good
in southwest corner of the state and
else where about average. For the
thirteen month trend the state has
made progress in recovering from the
deficit but still has got some way to
go.
NRCS Runoff Forecasts - The run off
forecasts statewide are average and
they mirror the snowpack conditions.
o Blue Mesa inflow is now looking at 75% of average inflows
o Rio Grande at Del Norte is down to 85% of average
o Southwest Basins are 75% of average volume forecasts.
o Yampa River near Maybell graphs show volumes at 60% of average although they did
have a good February.
o The NRCS is plotting forecast skill on graphs now. The example given was that in the Big
Thompson basin the NRCS doesn't have much skill at doing forecasts in this basin.

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Flood Protection. Water Project Planning and Finance. Stream and Lake Protection
Water Supply Protection. Conservation Planning