Drought Page

Rivers Alliance
of Connecticut
Connecticut's United Voice for River Conservation

Drought Monitor

High Flow                          Low Flow
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Streamflow in CT (click to go to the data page)

May 15, 2012: Connecticut's streams and rivers are still almost the driest they have been since the drought of 2010 or earlier (click here for an analysis). Although the flow in most rivers and streams in Connecticut peaked well above average during and after the rains of the previous couple weeks, the flow rates in most cases drops back to below average very quickly. Even if we get more rain over the next months, we need to monitor streamflow, hoping that the flows will be well above average more than they are below average. If streamflows are below average more than they are above, this will indicate that groundwater supplies have not returned to normal. Of the four groundwater monitoring stations in CT, only one shows levels anywhere near average for this time of year. If groundwater levels do not return before the normally driest time of year, streamflows may not be adequate to maintain aquatic life. Two-month rainfall at the end of March was 63-83% below average. Although long-range weather forecasts show rainfall returning to more normal conditions, it will take above average amounts of rain for a significant period of time to avoid damage to stream ecology. The seasonal outlooks only give a one in three chance of above normal rainfall with a better than 60% chance of normal or above normal temperatures.

The State of CT Drought Preparedness and Response Plan authorizes the state to issue a Drought Advisory if the majority of the following criteria are met:

Criteria to Declare Drought Advisory Situation Sources

Precipitation: Two months cumulative below 65% of normal, Climate stations report 31% to 69% of normal, averaging 55% of normal as of the end of April. Note the 3-month average is 35% of normal http://www.ct.gov/waterstatus/lib/waterstatus/PrecipReport_2012-4.pdf

Ground Water: Three consecutive months below normal, Groundwater depths have been below average much more often than above over the last three months. See the 3-month graphs below. http://waterdata.usgs.gov/ct/nwis/current/?type=gw

Streamflow: Two out of three months below normal, From Feb 14 through May 14 2012, Burlington Brook has only had above average flow on 4 days. Its daily flow has averaged 54% below normal http://www.riversalliance.org/bbrookdaylies.xls

Reservoirs: Average levels less than 80% of normal. At the end of April, 10 of the 34 public water supply reservoirs were below their historic average levels for April, only one of them below 80% of normal. http://www.ct.gov/dph/lib/dph/drinking_water/pdf/Status_Summary.pdf

Palmer Drought Severity Index:
-2.0 to -2.99 (moderate drought) For the week ending May 12, the Index listed CT in the range of
-1.9 to +1.9 (near normal) http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/regional_monitoring/palmer.gif

Crop Moisture Index:
-1.0 to –1.99 (abnormally dry)

Fire Danger: Moderate.

An informal look at these criteria indicates an Advisory could be issued. Although public water supply reservoirs were at full capacity in March, this will change if we do not get normal rainfall soon. The May 8, 2012 US Drought Monitor still maps all of CT in either their "D2 Drought - Severe" category or "D1 Drought - Moderate"

Watch for adverse affects on stream and river ecosystems, public and private water supplies, and recreation.