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Cottonwood Marsh photo by Peter Burke

Prewitt Reservoir State Wildlife Area - Washington County
Ownership: None Listed
Description: This is one of the very few State Wildlife Areas that charge an entrance fee. The SWA is comprised of two basic habitats: the extensive riparian habitat below the dam, and the reservoir with its associated mudflats.

The area below the dam consists of an extensive mosaic of Russian Olive thickets, mature cottonwood groves, and assorted swampy habitats. It is a four- or five-mile walk from one end of this area to the other, so budget five or six hours to cover it all thoroughly. The area can be accessed from either of two parking lots, one of which is in Washington County and the other of which is in Logan. The county line situation at Prewitt can be confusing, so county listers should check their maps carefully. Most vagrants are found within the first mile or two of the Washington County parking lot, but that is probably because this area tends to get the most birding coverage.

When planning your attack on this big place, keep in mind that the cottonwood forest is usually the least productive. The thickets and swamps, on the other hand, can be full of landbirds; practically every migrant on the Colorado list has shown up here. Fall trips can usually produce at least one good eastern warbler. Spring trips can also be good, but are less consistent. Even if migration is not in swing, Eastern Screech-Owl is common to abundant, but often hard to find—whistling will occasionally elicit a response. During the warmer months Red-headed Woodpecker can also be abundant, and both rails can be found in the cattail marshes.

Even if the landbird migration isn't good, there are usually thousands of shorebirds on the extensive mudflats that form around the reservoir most years in late summer. Anything is possible here; in particular, Prewitt is known for being one of the most reliable spots in Colorado for juvenile Short-billed Dowitchers and Buff-breasted Sandpipers in fall. The large concentrations of shorebirds and dabbling ducks attract Peregrine Falcons, and Sabine's Gull can often be found amid thousands of Franklin's Gulls and many Black Terns. Keep an eye out for Caspian Tern and rare gulls and waders.

Habitat: Lake/Pond/Reservoir, Lowland Riparian, Hedgerow/Shelterbelt, Marsh
Directions: From the Merino exit off I-76 (exit 102), go one mile north to CO 6 and turn right (east). The main entrance (Washington County portion) is 3.5 miles down CO 6 on the right. The Logan County portion can be reached by going a quarter mile past the main entrance and turning right onto CR 2.5, which parallels the dam at some distance and eventually leads to the Logan County parking lot.
Other Wildlife:
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CBRC Records from Prewitt Reservoir State Wildlife Area

SpeciesAccession No.Date(s)
Black-billed Cuckoo2011-117 9/11/2011
Black-billed Cuckoo2015-087 07/19/2015
Red Knot1998-0489/19/1998
Red Knot2018-067 08/22/2018
Curlew Sandpiper2005-096 9/18/2005 - 9/19/2005
Buff-breasted Sandpiper19-82-409/5/1981
Buff-breasted Sandpiper1998-0509/19/1998
Buff-breasted Sandpiper2000-0377/31/2000
Buff-breasted Sandpiper2001-0799/21/2001
Buff-breasted Sandpiper2005-088 9/4/2005 - 9/5/2005
Buff-breasted Sandpiper2012-104 8/25/2012
Short-billed Dowitcher2004-0807/25/2004
Red Phalarope21-82-429/5/1981
Red Phalarope21-90-219/19/1990
Red Phalarope2005-086 9/4/2005
Jaeger sp.22-76-11711/24/1976
Long-tailed Jaeger2005-089 9/5/2005 - 9/15/2005
Long-tailed Jaeger2005-097 9/19/2005
Black-legged Kittiwake23-88-911/25/1987
Little Gull1998-0579/11/1998
Laughing Gull1997-03510/21/1997
Laughing Gull2009-065 9/27/2009
Laughing Gull2010-163 12/14/2010
Laughing Gull2013-184 07/14/2013
Western Gull2012-028 3/17/2012
Western Gull2012-038 3/29/2012
Western Gull2016-060 06/17/2016
Iceland Gull2012-023 3/11/2012
Iceland Gull2012-024 3/11/2012
Iceland Gull2012-027 3/17/2012
Iceland Gull2012-039 3/29/2012
Glaucous-winged Gull2012-022 3/11/2012
Glaucous-winged Gull2012-035 3/25/2012
Great Black-backed Gull23-88-511/25/1987
Least Tern23-77-58 17 Jul 1977
Neotropic Cormorant2011-100 7/10/2011 - 8/6/2011
Brown Pelican3-96-58/21/1996
Brown Pelican2008-095 8/11/2008 - 10/4/2008
Little Blue Heron2009-059 8/29/2009 - 8/30/2009
Reddish Egret2002-1359/1/2002
Eastern Wood-Pewee34-75-247/17/1975
Eastern Wood-Pewee34-88-368/21/1988
Alder Flycatcher2011-070 5/29/2011
Alder Flycatcher2011-071 5/29/2011
Blue-headed Vireo2008-058 5/13/2008
Philadelphia Vireo2006-116 8/27/2006
Philadelphia Vireo2012-204 09/09/2012
Philadelphia Vireo2013-205 09/10/2013
Cave Swallow2013-183 07/17/2013
Gray-cheeked Thrush2012-054 5/19/2012
Wood Thrush44-90-429/17/1990
Worm-eating Warbler2000-1365/7/2000
Louisiana Waterthrush52-96-845/17/1996
Prothonotary Warbler52-78-649/5/1978
Prothonotary Warbler1999-1439/8/1999
Connecticut Warbler2001-142 9/1/2001
Connecticut Warbler2013-195 09/02/2013
Cape May Warbler52-83-445/20/1983
Bay-breasted Warbler52-74-13910/27/1974
Blackburnian Warbler2011-113 9/4/2011
Black-throated Blue Warbler2019-061 17 Sep 2022
Pine Warbler2006-117 8/27/2006
Canada Warbler2006-118 8/27/2006
Canada Warbler2011-125 9/23/2011
Canada Warbler2014-133 08/27/2014
Scarlet Tanager2006-136 9/29/2006