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River Alliance of CT > Priority Topics > Streamflow > Streamflow and Groundwater Overview in CT

Know Your Flow!

Thursday April 18, 2019
Sections of this page updated as needed; refer to dates in each section

Link to webpage

Rivers Alliance thanks Loureiro Engineering Associates, Inc. for their generous sponsorship of the Know Your Flow page.

Current CT Conditions
At A Glance



(Click on any graphic below for more information)
Streamflow in CT Now
(click map to go to the data page)

 [color code for]  color code for  color code for color code for  color code for  color code for  color code for               [color code for]       
   High Flow     Low Flow        Not Ranked
CT Current Streamflow. Click to go to source page.
Recent Flow At a CT Stream
(click graph for details)

Link to Burlington Brook flow data
Groundwater Level
(click graph to see more well data)
USGS monitoring well. Click to see more.
Check your forecast here
(click map to go to state weather page)
Link to NWS graphic page
Graphic courtesy NOAA showing CT area watches and warnings if any.

Streamflow Discussion

Streamflow in Connecticut was high on April 18, with an inch or two predicted for the next three or four days. These storms may produce very different results than the last set of storms. Click here for a list of all weather related watches and warnings in Connecticut, if any.

Although storms April 12-16 dropped 1.5 to 3 inches of rain across the state, there were few reports of flooding, due to the low levels in the streams before the storms hit. A Flood Warning was issued for the Connecticut River not only because of local rain, but also due to snowmelt in the far northern portions of its watershed. The low flow conditions that preceded the storms are described in more detail below.

On April 18, all USGS stream gages in Connecticut were reporting flows above average, though 39 of the 62 gages had fallen to conditions considered near-normal for the time of year.  There were 18 gages still reporting high flows, and another 5 were at very high levels. The high flow stations are listed below.

Go to the Northeast River Forecast Center for flood probabilities at the gaging stations they monitor.

Although all rivers and streams should be watched carefully for flooding whenever there is heavy rain, this is especially true for those with higher than usual levels before the additional runoff from storms. The Nonewaug River at MinortownBroad Brook at Broad Brook, the Willimantic River near Coventry, the Quinebaug River at Quinebaug, and the Natchaug River at  Willimantic, as well as nearby streams without stream gages, were at very high levels Flood control dams can prevent or lessen flooding downstream, but do nothing to lower flash flood risk up stream. 

We define high flow as at or over the stream's 75th percentile for that date, very high at 90th or higher, from the data file at https://waterwatch.usgs.gov/webservices/realtime?region=ct&format=xml when rivers are near their lowest points between storms. Low streamflow is below the 25th percentile or 25% of the mean flow for that date.

Why do we count? The flow between storms is an indicator of long-term stream conditions. Although expansion of a river or stream channel onto its floodplain is a normal, natural occurrence, human interference can cause higher than normal and more frequent flooding. The higher the water level remaining in streams and rivers before a storm, the more likely there will be dangerous conditions, streambed scouring, and other detrimental effects of high water.

When water levels are low, portions of the streambed become too dry to support the aquatic life that usually colonizes those areas. Groundwater seeping from the stream banks can help organisms survive for short times; therefore, well measurements can also be used to identify areas where aquatic life might be in jeopardy.

Data Links
Click here for today's USGS Connecticut stream gage web page with graphs
of flow from every gage for the past 30 days compared to their historic daily flows
.

Cick here for a list of all CT stream gages comparing their flow
right now to their mean and median flows for today's date
.

Click here for a discussion from an archived Know Your Flow!
web page of what streamflow patterns usually look like
.

Check for electronically reported sewage spills in the last three days.
 

Groundwater Discussion

In Connecticut, the USGS has 10 real-time groundwater monitoring wells, six of which have records long enough to compare to other years.

Last fall, all the wells were reporting water levels well above normal for the time of year, some breaking high-water records. The water table has been gradually trending lower since then, at a time of year when it usually rises. By the beginning of March, all of the wells were reporting levels near average for the time of year, then by April 9,  half of the 6 were near-normal, half were below-normal.

On April 16, all the wells except in Greenwich show the expected rise in the water table from the storms April 12 to 15.  Only 1 of the 6 however was brought above-normal, in Southbury.  4 of the 6 were near-normal, and the Greenwich well remains below-normal for the time of year.

The USGS Groundwater Watch website displays data from 57 other wells that are usually measured once a month, comparing the most recent measurements to each well's measurements taken in that month in previous years.

Measurements taken from Mar 21 through Mar 29 show 48 of them (84%) were near or above normal, 9 below-normal:

1 well, in East Windsor, was at a record high level,
2 wells were rated much-above-normal,
9 were above-normal,
36 wells were near-normal for March.

6 wells were below-normal and
3 were much-below-normal.
None were setting low level records. 

 Click here to see the data. 

Groundwater levels influence streamflow. The water level in streams and rivers between storms depends on the flow of water out of the ground into the stream channel. The higher the water table, the more water is available to keep streams flowing. High water tables keep streamflow from dropping very far or very fast between storms, so when the next storm hits, the runoff pushes streams to higher levels with more flooding. 

Precipitation Patterns 

Normal April precipitation across Connecticut ranges from 3 to 5 inches for the month. The storms of April 12-13 and 15-16 put us to near-normal for the first half of April. 30-day precipitation totals are back to near or above normal for most of the state, but southwest Connecticut has received 75% to 90% of normal for the time of year.   On Apr 16, a 15-day computer model was predicting 1 to 3 inches of rain for the rest of April, which would keep us at normal rainfall totals or even above-normal. 

Go to the National Weather Service (NWS) Advanced Hydrologic Prediction Service at this link for updated, detailed maps and data about precipitation amounts for Connecticut at various time frames.

Click here for today's forecast for the next 7 days for the state's geographic center.

Click here for a prediction of total precipitation for the next 15 days.

For technical information about past broad-scale weather patterns, see NOAA's National Centers for Environmental Information State of the Climate Synoptic Discussions

Some General Flood and Heavy Rain Information

The Connecticut Department of Health website has a good guide called:

 Flooding: Information for Homeowners About Private Wells, Sewage and Clean-Up link to DPH flooding guide

Flood predicting. Go to the Northeast River Forecast Center for flood probabilities at the gaging stations they monitor. On Nov 5 they were reporting minor flooding at four locations in the state.  Click here for current CT weather watches and warnings, if any. 

Paddling. Do not attempt to canoe or kayak on floodwaters; there are usually one or two fatalities per year. Our Connecticut Water Trails website and the webpages of the many paddler groups in the state all have good safety procedures.

Your sewage, your well. When a building is located in a floodplain, floodwaters can saturate and fill a leach field, often flushing out untreated sewage. Floodwater also can flow down into wells, introducing pollutants — such as sewage, soil, bugs, leaves, pesticides such as weed killer and insect poison, and even the dog droppings from the backyard — into the well.

Very important: Any well that was flooded should be pumped and flushed out thoroughly and the system sanitized or "shocked."

Heavy rainfall alone can cause sewage to get into waterways even if flooding does not happen.

You really do not want to be downstream when raw untreated human sewage is entering the water. 

Please see our Sewage / Wastewater Treatment Priority Topic webpage
for more information about sewage spills in Connecticut

Public Water Supply Information

Your water utility and town are the best sources of information on the status of your water supply. A few systems post their current capacities regularly on their websites. Aquarion maintains on its website a weekly updated water usage report for their systems in southwest CT. The report includes water demand graphs, system transfers, system capacities, days usable storage remaining, and precipitation. As of Apr 9, their Greenwich reservoir was at normal capacity for the time of year: 97%. Their other reservoirs were at 100%, a little above where each system usually is at this time year based on a 20-year average. As of Apr 1: "MDC reservoirs are at 99.9% of capacity with over 39 billion gallons in storage representing 663 days of supply assuming typical water use and no precipitation." The Regional Water Authority reported as of March 31 that their reservoirs were at 97% of capacity, 6% above normal for the time of year.

The most recent CT Department of Public Health's Monthly Reservoir Status Summary was for Sep 26. At a Water Planning Council meeting, a DPH representative reported that a new, more comprehensive and timely report system should be online in 2019. 

   


Connecticut Stream Gages With High Flows
April 18, 2019

Station Name Some notes regarding flow,
quotes from the USGS Station Yearly Summary are in italics
Station website
BROAD BROOK AT BROAD BROOK Flow regulated by reservoir and mill upstream. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01184490
CONNECTICUT RIVER AT THOMPSONVILLE Flow regulated by power plants, by diversion from Chicopee River Basin and by First Connecticut and Second Connecticut Lakes, Lake Francis, Moore and Comerford Reservoirs, Quabbin Reservoir, and other reservoirs, combined usable capacity, about 107 billion ft³ https://waterdata.usgs.gov/ct/nwis/uv?site_no=01184000
FARMINGTON RIVER AT UNIONVILLE The natural flow regime can be altered by regulation from water-supply reservoirs (Barkhamsted, Lake McDonough, East Branch, Nepaug, and West Branch), flood-control reservoirs (Colebrook River Lake, Highland Lake Reservoir, Sucker Brook Dam, and Mad River Reservoir), and by Otis Reservoir. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01188090
FENTON RIVER AT MANSFIELD No known flow regulation. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01121330
Fivemile River near New Canaan Flow regulated from New Canaan Reservoir by Second Taxing District Water Department https://waterdata.usgs.gov/ct/nwis/uv?site_no=01209761
FRENCH RIVER AT NORTH GROSVENORDALE Flow regulated by Hodges Village and Buffumville Reservoirs, by Lake Chaubunagungamaug and other smaller reservoirs upstream https://waterdata.usgs.gov/ct/nwis/uv?site_no=01125100
HOCKANUM RIVER NEAR EAST HARTFORD Streamflow regulated by Shenipsit Lake, smaller reservoirs, industrial plants, and augmented by releases from upstream waste-water treatment facilities https://waterdata.usgs.gov/ct/nwis/uv?site_no=01192500
Little River at Harrisville Diversion above station for municipal supply of city of Putnam https://waterdata.usgs.gov/ct/nwis/uv?site_no=01125490
LITTLE RIVER NEAR HANOVER, CT No known flow regulation. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01123000
MOUNT HOPE RIVER NEAR WARRENVILLE Occasional regulation from ponds upstream. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01121000
NATCHAUG RIVER AT WILLIMANTIC Peak flows are affected by flood-control regulation at Mansfield Hollow Dam since March 1952. The natural flow regime can be altered by regulation from Mansfield Hollow Dam and Willimantic Reservoir. City of Willimantic diverts flow for municipal supply from Willimantic Reservoir, which is located about 2 mi upstream from the gaging station. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01122000
NONEWAUG RIVER AT MINORTOWN Minor alteration to the natural flow from Lockwood Reservoir and by out-of-basin flow diversion for municipal supply for the town of Watertown https://waterdata.usgs.gov/ct/nwis/uv?site_no=01203600
NORTH BRANCH PARK RIVER AT HARTFORD "Some regulation at small dams upstream and by storage and diversion at a Hartford water supply reservoir on headwater stream. High flow regulated by Bloomfield, Cold Spring, Wintonbury, and Blue Hills Reservoirs, on tributaries of North Branch Park River" https://waterdata.usgs.gov/ct/nwis/uv?site_no=01191000
Quinebaug River at Jewett City The natural flow regime is altered by regulation at East Brimfield Lake, Westville Lake, West Thompson Lake, Hodges Village Reservoir, Buffumville Lake, Lake Chaubunagungamaug, Quaddick Reservoir, and other small reservoirs in the basin, and by a hydropower plant in Jewett City. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01127000
QUINEBAUG RIVER AT PUTNAM The natural flow regime is altered by regulation at East Brimfield Lake, Westville Lake, West Thompson Lake, Hodges Village Reservoir, Buffumville Lake, Lake Chaubunagungamaug, Quaddick Reservoir, and other small reservoirs in the basin. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01125500
QUINEBAUG RIVER AT QUINEBAUG Peak flows are affected by flood-control regulation at East Brimfield Lake and Westville Lake since 1960. The natural flow regime can be altered by regulation at East Brimfield Lake, Westville Lake, and other small reservoirs in the basin. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01124000
QUINEBAUG RIVER AT WEST THOMPSON Peak flows are affected by flood-control regulation at East Brimfield Lake, Westville Lake, and West Thompson Lake since 1960. The natural flow regime is altered by regulation at East Brimfield Lake, Westville Lake, West Thompson Lake, East Brimfield Lake, and other small reservoirs in the basin. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01124151
SHEPAUG RIVER AT PETERS DAM AT WOODVILLE Flow regulated by Shepaug Reservoir. https://waterdata.usgs.gov/ct/nwis/uv/?site_no=01202501
SHETUCKET RIVER AT TAFTVILLE Flow regulated by mills and flood detention reservoirs on Willimantic River, on Natchaug River by pumping for municipal supply for city of Willimantic, by Mansfield Hollow Dam, and by power regulation at Taftville Dam 0.2 mi upstream.  https://waterdata.usgs.gov/ct/nwis/uv?site_no=011230695
SHETUCKET RIVER NEAR WILLIMANTIC The natural flow regime can be altered by regulation from Mansfield Hollow Dam and Willimantic Reservoir. City of Willimantic diverts flow for municipal supply from Willimantic Reservoir. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01122500
STILL RIVER AT ROUTE 7 AT BROOKFIELD CENTER, CT No known flow regulation. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01201487
WEST BRANCH FARMINGTON RIVER AT RIVERTON The natural flow regime can be altered by regulation at Otis Reservoir, Colebrook River Lake, and West Branch Reservoir. More flow information is available from the Farmington River Watershed Association https://waterdata.usgs.gov/ct/nwis/uv?site_no=01186000
WILLIMANTIC RIVER AT MERROW RD. NEAR MERROW No known flow regulation.
 
https://waterdata.usgs.gov/ct/nwis/uv?site_no=01119382
WILLIMANTIC RIVER NEAR COVENTRY Effects of flood-control dams in the Middle River Basin (Ellithorpe Reservoir Dam No. 5, Ellis Reservoir Dam No. 2, Whitney Reservoir Dam No. 1, Shenipsit Reservoir Dam No. 6, Pomeroy Reservoir Dam No. 3, and Bradway Reservoir Dam No. 4) on peak flows are minor. Usable storage at the gaging station from flood control is about 31 acre-feet per square mile. The natural flow of stream can be altered by regulation from Staffordville Reservoir and the flood-control dams. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01119500


Early April 2019 Low Flow Conditions 

Streamflow had been steadily from the last week of March through April 12. On Friday Apr 5, 40 of of the 62 USGS streamgages in Connecticut (65%) were reporting low flows. There was improvement after that as some parts of the state got some rain, so that a week later, 25 out of the 62 (40%) were at low flow status (list is below), mostly in the southeast portion of the state. 36 streamgages were reporting near-normal flows for Apr 12. The one station reporting relatively high flow was the Shepaug River station because the flow in the Shepaug River is maintained at a mandated flow by Waterbury Water Department. 

Stream gages with flows of concern between storms
Friday, April 12
25 out of 62 (40%) low flow, 1 high

Stream gage levels in Connecticut, relative to 30 year average.

01209500: Flow=83.1cfs,Stage=3.61ft,2019-04-12 10:00,<10,SAUGATUCK RIVER NEAR WESTPORT, CT01209700: Flow=36.2cfs,Stage=1.44ft,2019-04-12 10:30,10-24,NORWALK RIVER AT SOUTH WILTON, CT01208990: Flow=32.5cfs,Stage=1.78ft,2019-04-12 10:00,10-24,SAUGATUCK RIVER NEAR REDDING, CT01204000: Flow=115cfs,Stage=3.40ft,Floodstage=9ft,2019-04-12 10:00,10-24,POMPERAUG RIVER AT SOUTHBURY, CT01203600: Flow=26.9cfs,Stage=1.67ft,2019-04-12 10:10,10-24,NONEWAUG RIVER AT MINORTOWN, CT01196500: Flow=183cfs,Stage=3.67ft,Floodstage=10ft,2019-04-12 10:00,10-24,QUINNIPIAC RIVER AT WALLINGFORD, CT01195100: Flow=7.82cfs,Stage=1.95ft,2019-04-12 10:45,10-24,INDIAN RIVER NEAR CLINTON, CT01192883: Flow=39.1cfs,Stage=5.27ft,2019-04-12 10:00,10-24,COGINCHAUG RIVER AT MIDDLEFIELD, CT01189000: Flow=65.9cfs,Stage=1.61ft,2019-04-12 10:15,10-24,PEQUABUCK R AT FORESTVILLE, CT.01188000: Flow=7.34cfs,Stage=2.59ft,Floodstage=7ft,2019-04-12 10:30,10-24,BUNNELL BROOK NEAR BURLINGTON, CT01187800: Flow=39.4cfs,Stage=4.33ft,2019-04-12 10:45,10-24,NEPAUG R NR NEPAUG, CT.01208950: Flow=11.2cfs,Stage=1.36ft,2019-04-12 10:30,25-75,SASCO BROOK NEAR SOUTHPORT, CT01208500: Flow=583cfs,Stage=2.82ft,Floodstage=12ft,2019-04-12 10:30,25-75,NAUGATUCK RIVER AT BEACON FALLS, CT01206900: Flow=200cfs,Stage=2.50ft,2019-04-12 10:30,25-75,NAUGATUCK RIVER AT THOMASTON, CT01205500: Flow=4430cfs,Stage=6.73ft,Floodstage=11ft,2019-04-12 10:30,25-75,HOUSATONIC RIVER AT STEVENSON, CT01200500: Flow=2840cfs,Stage=4.57ft,Floodstage=8ft,2019-04-12 10:00,25-75,HOUSATONIC RIVER AT GAYLORDSVILLE, CT01200000: Flow=396cfs,Stage=2.37ft,Floodstage=9ft,2019-04-12 10:15,25-75,TENMILE RIVER NEAR GAYLORDSVILLE, CT01199050: Flow=67.8cfs,Stage=1.46ft,2019-04-12 10:00,25-75,SALMON CREEK AT LIME ROCK, CT01199000: Flow=1860cfs,Stage=4.13ft,Floodstage=7ft,2019-04-12 10:15,25-75,HOUSATONIC RIVER AT FALLS VILLAGE, CT01196620: Flow=41.3cfs,Stage=1.52ft,2019-04-12 10:15,25-75,MILL RIVER NEAR HAMDEN, CT01194500: Flow=43.0cfs,Stage=2.30ft,2019-04-12 10:45,25-75,EAST BRANCH EIGHTMILE RIVER NEAR NORTH LYME, CT01194000: Flow=42.2cfs,Stage=3.21ft,2019-04-12 10:15,25-75,EIGHTMILE RIVER AT NORTH PLAIN, CT01193500: Flow=212cfs,Stage=3.18ft,2019-04-12 10:15,25-75,SALMON RIVER NEAR EAST HAMPTON, CT01192500: Flow=169cfs,Stage=2.83ft,Floodstage=9ft,2019-04-12 10:30,25-75,HOCKANUM RIVER NEAR EAST HARTFORD, CT01191000: Flow=32.7cfs,Stage=1.94ft,Floodstage=8ft,2019-04-12 10:00,25-75,NORTH BRANCH PARK RIVER AT HARTFORD, CT01189995: Flow=1420cfs,Stage=2.86ft,Floodstage=9ft,2019-04-12 10:15,25-75,FARMINGTON RIVER AT TARIFFVILLE, CT01188090: Flow=1020cfs,Stage=6.34ft,Floodstage=12ft,2019-04-12 10:30,25-75,FARMINGTON RIVER AT UNIONVILLE, CT01187300: Flow=52.3cfs,Stage=2.07ft,2019-04-12 10:30,25-75,HUBBARD RIVER NEAR WEST HARTLAND, CT01186500: Flow=212cfs,Stage=2.74ft,2019-04-12 10:30,25-75,STILL RIVER AT ROBERTSVILLE, CT01186000: Flow=240cfs,Stage=4.06ft,2019-04-12 10:30,25-75,WEST BRANCH FARMINGTON RIVER AT RIVERTON, CT01185500: Flow=245cfs,Stage=3.72ft,Floodstage=8ft,2019-04-12 10:30,25-75,WEST BRANCH FARMINGTON RIVER NEAR NEW BOSTON, MA01184490: Flow=38.3cfs,2019-04-12 10:45,Stage=1.08ft,2019-04-12 09:45:00,25-75,BROAD BROOK AT BROAD BROOK, CT01184100: Flow=14.9cfs,Stage=1.64ft,2019-04-12 10:00,25-75,STONY BROOK NEAR WEST SUFFIELD, CT01184000: Flow=41800cfs,Stage=11.74ft,Floodstage=15ft,2019-04-12 10:30,25-75,CONNECTICUT RIVER AT THOMPSONVILLE, CT01183500: Flow=2370cfs,Stage=6.59ft,Floodstage=13ft,2019-04-12 10:30,25-75,WESTFIELD RIVER NEAR WESTFIELD, MA01127500: Flow=172cfs,Stage=2.55ft,Floodstage=9ft,2019-04-12 10:45,25-75,YANTIC RIVER AT YANTIC, CT01127000: Flow=1770cfs,Stage=7.62ft,Floodstage=17.5ft,2019-04-12 10:30,25-75,QUINEBAUG RIVER AT JEWETT CITY, CT01125500: Flow=869cfs,Stage=4.18ft,Floodstage=9.5ft,2019-04-12 10:45,25-75,QUINEBAUG RIVER AT PUTNAM, CT01124151: Flow=472cfs,Stage=2.32ft,2019-04-12 10:30,25-75,QUINEBAUG RIVER AT WEST THOMPSON, CT01124000: Flow=423cfs,Stage=3.41ft,2019-04-12 10:00,25-75,QUINEBAUG RIVER AT QUINEBAUG, CT01123600: Flow=266cfs,Stage=4.45ft,2019-04-12 10:30,25-75,QUINEBAUG R BL WESTVILLE DAM NR SOUTHBRIDGE, MA01123360: Flow=177cfs,Stage=3.85ft,2019-04-12 10:30,25-75,QUINEBAUG R BL E BRIMFIELD DAM AT FISKDALE, MA01123000: Flow=81.9cfs,Stage=2.24ft,2019-04-12 10:15,25-75,LITTLE RIVER NEAR HANOVER, CT01122500: Flow=1280cfs,Stage=4.42ft,Floodstage=13ft,2019-04-12 10:30,25-75,SHETUCKET RIVER NEAR WILLIMANTIC, CT01122000: Flow=567cfs,Stage=3.95ft,2019-04-12 10:30,25-75,NATCHAUG RIVER AT WILLIMANTIC, CT01121000: Flow=76.8cfs,Stage=2.10ft,Floodstage=7ft,2019-04-12 10:15,25-75,MOUNT HOPE RIVER NEAR WARRENVILLE, CT01119500: Flow=357cfs,Stage=4.22ft,Floodstage=8ft,2019-04-12 10:45,25-75,WILLIMANTIC RIVER NEAR COVENTRY, CT01118500: Flow=861cfs,Stage=5.50ft,Floodstage=7ft,2019-04-12 10:00,25-75,PAWCATUCK RIVER AT WESTERLY, RI01118300: Flow=9.89cfs,Stage=1.54ft,2019-04-12 10:45,25-75,PENDLETON HILL BROOK NEAR CLARKS FALLS, CT01118000: Flow=205cfs,Stage=2.84ft,Floodstage=5ft,2019-04-12 10:15,25-75,WOOD RIVER AT HOPE VALLEY, RI01117800: Flow=96.9cfs,2019-04-12 10:45,Stage=3.64ft,2019-04-12 09:45:00,25-75,WOOD RIVER NEAR ARCADIA, RI01117500: Flow=298cfs,2019-04-12 10:45,Stage=3.11ft,2019-04-12 09:45:00,Floodstage=5ft,25-75,PAWCATUCK RIVER AT WOOD RIVER JUNCTION, RI01111300: Flow=34.9cfs,Stage=3.80ft,2019-04-12 10:15,25-75,NIPMUC RIVER NEAR HARRISVILLE, RI0137449480: Flow=122cfs,Stage=4.50ft,2019-04-12 09:30,Not ranked,EAST BRANCH CROTON RIVER NEAR PUTNAM LAKE NY012112296: Stage=-2.67ft,2019-04-12 10:42,Not ranked,GREENWICH HARBOR AT GRASS ISLAND AT GREENWICH, CT012095493: Flow=5.96cfs,Stage=1.92ft,2019-04-12 10:30,Not ranked,RIDGEFIELD BROOK AT SHIELDS LANE NR RIDGEFIELD, CT012035055: Flow=32.5cfs,Stage=3.10ft,2019-04-12 10:30,Not ranked,POOTATUCK RIVER AT BERKSHIRE011230695: Flow=1520cfs,Stage=7.25ft,2019-04-12 10:00,Not ranked,SHETUCKET RIVER AT TAFTVILLE, CT01374890: Flow=24.9cfs,Stage=2.31ft,2019-04-12 09:30,Not ranked,CROSS RIVER NEAR CROSS RIVER NY01374821: Flow=40.1cfs,Stage=2.21ft,2019-04-12 09:15,Not ranked,TITICUS RIVER AT PURDYS STATION NY01374781: Flow=15.8cfs,Stage=1.98ft,2019-04-12 09:30,Not ranked,TITICUS RIVER BELOW JUNE ROAD AT SALEM CENTER NY01374531: Flow=48.7cfs,Stage=1.65ft,2019-04-12 09:00,Not ranked,EAST BRANCH CROTON RIVER NEAR CROTON FALLS NY01374505: Flow=146cfs,Stage=3.66ft,2019-04-12 09:30,Not ranked,EAST BRANCH CROTON RIVER AT BREWSTER NY01212500: Flow=32.7cfs,Stage=2.31ft,2019-04-12 10:00,Not ranked,BYRAM RIVER AT PEMBERWICK, CT01209901: Flow=34.1cfs,Stage=1.82ft,2019-04-12 10:45,Not ranked,RIPPOWAM RIVER AT STAMFORD, CT.01209788: Stage=-1.98ft,2019-04-12 10:30,Not ranked,STAMFORD HURRICANE BARRIER AT STAMFORD, CT01209761: Flow=1.23cfs,Stage=1.93ft,2019-04-12 10:00,Not ranked,FIVEMILE RIVER NEAR NEW CANAAN, CT01209510: Stage=-2.98ft,2019-04-12 10:54,Not ranked,SAUGATUCK RIVER AT ROUTE 1 AT WESTPORT, CT01209105: Flow=3.25cfs,Stage=2.40ft,2019-04-12 10:00,Not ranked,ASPETUCK RIVER AT ASPETUCK, CT01209005: Flow=37.3cfs,Stage=2.89ft,2019-04-12 10:45,Not ranked,SAUGATUCK R BELOW SAUGATUCK RES NR LYONS PLAIN, CT01208873: Flow=1.70cfs,Stage=2.95ft,2017-10-01 00:55,Not ranked,ROOSTER RIVER AT FAIRFIELD, CT01203805: Flow=40.7cfs,Stage=2.28ft,2019-04-12 10:15,Not ranked,WEEKEEPEEMEE RIVER AT HOTCHKISSVILLE, CT01203510: Flow=44.1cfs,Stage=4.04ft,2019-04-12 10:00,Not ranked,POOTATUCK RIVER AT SANDY HOOK, CT01203000: Flow=11.0cfs,2007-10-01 00:45,Not ranked,SHEPAUG R NR ROXBURY, CT01202501: Flow=119cfs,Stage=2.96ft,2019-04-12 10:15,Not ranked,SHEPAUG RIVER AT PETERS DAM AT WOODVILLE, CT01201487: Flow=104cfs,Stage=7.43ft,2019-04-12 10:45,Not ranked,STILL RIVER AT ROUTE 7 AT BROOKFIELD CENTER, CT01200600: 2016-04-16 19:15,Not ranked,HOUSATONIC RIVER NEAR NEW MILFORD, CT01196561: Flow=5.61cfs,Stage=1.43ft,2019-04-12 10:15,Not ranked,MUDDY RIVER NEAR EAST WALLINGFORD, CT01195490: Flow=24.6cfs,Stage=3.29ft,2019-04-12 10:45,Not ranked,QUINNIPIAC RIVER AT SOUTHINGTON, CT01194815: Stage=-1.28ft,2019-04-12 10:42,Not ranked,CONNECTICUT RIVER NR BRIDGE ST NR OLD SAYBROOK, CT01194796: Stage=0.10ft,2019-04-12 09:55,Not ranked,CONNECTICUT RIVER AT OLD LYME, CT01194750: Stage=0.82ft,2019-04-12 10:20,Not ranked,CONNECTICUT RIVER AT ESSEX, CT01193050: Flow=51100cfs,2019-04-12 10:45,Stage=5.01ft,2019-04-12 10:55:00,Floodstage=7ft,Not ranked,CONNECTICUT RIVER AT MIDDLE HADDAM, CT01192704: Flow=19.0cfs,2000-09-30 00:45,Not ranked,MATTABESSET RIVER AT ROUTE 372 AT EAST BERLIN01190070: Stage=11.26ft,Floodstage=16ft,2019-04-12 10:30,Not ranked,CONNECTICUT RIVER AT HARTFORD, CT01125490: Flow=104cfs,Stage=2.46ft,2019-04-12 10:00,Not ranked,LITTLE RIVER AT HARRISVILLE, CT01125100: Flow=247cfs,Stage=7.69ft,2019-04-12 10:15,Not ranked,FRENCH RIVER AT NORTH GROSVENORDALE, CT01121330: Flow=42.4cfs,Stage=3.79ft,2019-04-12 10:15,Not ranked,FENTON RIVER AT MANSFIELD, CT01120790: Flow=189cfs,Stage=3.60ft,2019-04-12 10:00,Not ranked,NATCHAUG RIVER AT MARCY RD. NEAR CHAPLIN, CT01119382: Flow=280cfs,Stage=2.12ft,2019-04-12 10:15,Not ranked,WILLIMANTIC RIVER AT MERROW RD. NEAR MERROW, CT01115187: Flow=24.5cfs,Stage=1.92ft,2019-04-12 10:00,Not ranked,PONAGANSET RIVER AT SOUTH FOSTER, RIGo to WaterWatch (offsite) for a larger map with additional options
Below
25th percentile,
25% of mean,
or both
Station Name

Some notes regarding flow,
quotes from the USGS Station Yearly Summary are in italics

Station website
pm ASPETUCK RIVER AT ASPETUCK Flows regulated by transfers from the Saugatuck, Aspetuck, and Hemlock Reservoirs. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01209105
p BUNNELL BROOK NEAR BURLINGTON USGS Index Gage (natural flow). Final Streamflow Class 1 (free flowing stream). Flow may be affected by transfers into basin from Torrington.  https://waterdata.usgs.gov/ct/nwis/uv?site_no=01188000
p BYRAM RIVER AT PEMBERWICK No known flow regulation. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01212500
p COGINCHAUG RIVER AT MIDDLEFIELD Infrequent regulation from Beseck Lake https://waterdata.usgs.gov/ct/nwis/uv?site_no=01192883
p EAST BRANCH EIGHTMILE RIVER NEAR NORTH LYME Flow information available in the Eightmile River Watershed Management Plan, from EightmileRiver.org https://waterdata.usgs.gov/monitoring-location/01194000/ 
p EIGHTMILE RIVER AT NORTH PLAIN Flow information available in the Eightmile River Watershed Management Plan, from EightmileRiver.org https://waterdata.usgs.gov/monitoring-location/01194000/
p FENTON RIVER AT MANSFIELD No known flow regulation. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01121330
p Fivemile River near New Canaan Flow regulated from New Canaan Reservoir by Second Taxing District Water Department https://waterdata.usgs.gov/ct/nwis/uv?site_no=01209761
p INDIAN RIVER NEAR CLINTON No known flow regulation. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01195100
p MUDDY RIVER NEAR EAST WALLINGFORD

The natural flow of Muddy River has been altered by flow diversion for municipal supply of Wallingford, CT. Flow regulated by Mackenzie Reservoir directly upstream. 

https://waterdata.usgs.gov/ct/nwis/uv?site_no=01196561
p NEPAUG R NR NEPAUG (New Hartford) Live data began May 2017 but daily average flow is based on 52 years of record.  https://waterdata.usgs.gov/ct/nwis/uv?site_no=01187800
p NORWALK RIVER AT SOUTH WILTON City of Norwalk diverts an indeterminable amount of water from Streets (Popes) Pond ... High flows can be affected by Spectacle Swamp Detention Reservoir, ... More information on Norwalk River flows can be found in the newsletters of the Norwalk River Watershed Association. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01209700
p PEQUABUCK R AT FORESTVILLE Flow regulated by Whigville Reservoir and mills upstream. Diversion for municipal supply of City of New Britain from Whigville Reservoir, Whites Bridge wells, and Copper Mine Brook https://waterdata.usgs.gov/ct/nwis/uv?site_no=01189000
p

POMPERAUG RIVER AT SOUTHBURY

Ground-water diversions can affect the natural flow regime. Out-of-basin flow diversion for municipal supply for the town of Watertown. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01204000
p POOTATUCK RIVER AT BERKSHIRE No known flow regulation.  https://waterdata.usgs.gov/ct/nwis/uv?site_no=012035055
p POOTATUCK RIVER AT SANDY HOOK No known flow regulation. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01203510
p QUINNIPIAC RIVER AT SOUTHINGTON No known flow regulation. More flow information available in the Quinnipiac River Watershed Based Plan https://waterdata.usgs.gov/ct/nwis/uv?site_no=01195490
p QUINNIPIAC RIVER AT WALLINGFORD The natural flow of the Quinnipiac River has been altered by numerous flow diversions. Flow regulated by Wolcott Reservoir, Broad Brook Reservoir, and by mills upstream. Diversion from Wolcott Reservoir for municipal supply of New Britain and diversion into the basin from Merimere and Elmere Reservoirs for municipal supply of Meriden. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01196500
p RIDGEFIELD BROOK AT SHIELDS LANE NR RIDGEFIELD Flows may be affected by flood control structure at Great Swamp https://waterdata.usgs.gov/ct/nwis/uv/?site_no=012095493
p RIPPOWAM RIVER AT STAMFORD The natural flow is altered by Mallard Lake, Trinity Lake Reservoir, Laurel Reservoir, Suscowit Reservoir, and by storage and diversion at North Stamford Reservoir.  https://waterdata.usgs.gov/ct/nwis/uv?site_no=01209901
p SAUGATUCK R BELOW SAUGATUCK RES NR LYONS PLAIN Flow regulated by reservoir releases. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01209005
p SAUGATUCK RIVER NEAR REDDING No known flow regulation. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01208990
p SAUGATUCK RIVER NEAR WESTPORT Flow regulated by storage and diversion at Saugatuck Reservoir by diversion from basin for water supply of Norwalk, and by Aspetuck Reservoir on Aspetuck River. Aquarion Water Co. diverts an indeterminable amount of water from Aspetuck Reservoir.  https://waterdata.usgs.gov/ct/nwis/uv?site_no=01209500
p STILL RIVER AT ROUTE 7 AT BROOKFIELD CENTER, CT No known flow regulation. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01201487
p WEEKEEPEEMEE RIVER AT HOTCHKISSVILLE No known flow regulation. https://waterdata.usgs.gov/ct/nwis/uv?site_no=01203805
High flow SHEPAUG RIVER AT PETERS DAM AT WOODVILLE Flow regulated by Shepaug Reservoir.

https://waterdata.usgs.gov/ct/nwis/uv/?site_no=01202501


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