SANGAMON RIVER
LOCATION The 250 mile Sangamon River is the
principal tributary of the Illinois River which drains a mostly
rural agricultural area between Peoria and Springfield. The river
develops from several short headstreams in southern McLean County.
The river's course travels through central Illinois, first flowing
east into Champaign County, through Decatur, then turning northwest
to flow along the north side of Springfield. It forms the southern
boundary of Mason County with Menard and Cass counties. It joins
the Illinois River northeast of Beardstown. This gaging station is
located in Decatur, just below the dam that creates Lake
Decatur.
MORAINES
FORMATION The upper Sangamon runs along the face
of the terminal moraine of the Sangamonian Substage of the
Wisconsin Glaciation. During the Sangamonian Substage, the ice
advanced rapidly from east to west, leaving a terminal moraine
parallel to the modern Sangamon River. The ice stagnated and melted
behind this moraine. Along this stretch, the eastern part of the
watershed of the Sangamon therefore consists of short creeks, two
to three miles in length, that drain the face of the moraine. This
forms an asymmetric watershed typical of rivers formed along the
face of a terminal moraine.
CONSTRUCTION OF THE 1920-22 DAM
USE OF RIVER The city of Decatur dammed the
Sangamon River in 1922 to create Lake Decatur which is used as the
city’s source of drinking water. It has a surface area of 3,093
acres and receives its water from the large agricultural Upper
Sangamon River Watershed. It has a drainage area of 925 square
miles, 87% of which is farmland for mainly corn and soybeans.
Watersheds are important as the viability of the watershed directly
affects the health of the communities within that watershed. Water
for human consumption, wildlife, industry and recreation are all
impacted by activities that occur within the watershed.
LOCAL GEOLOGY The area surrounding the river at
this gaging station consists of inland wetlands surrounded by low
bluffs. About a mile upstream is the dam constructed in 1922. The
area between the gaging station and dam is designated as
floodplain. The following images show some of the topography of the
wetlands between these two areas.
FLOODPLAIN
GAGING STATION
USGS 05573540 SANGAMON RIVER AT ROUTE 48 AT DECATUR, IL
Latitude 39°49'52", Longitude 88°58'35" NAD27 Macon County,
Illinois , Hydrologic Unit 07130006
The water data available via NWISWeb is part of the USGS
investigations of the Nation's water resources. Additional
information about the USGS and water resources of the Nation is can
be found at water.usgs.gov This
gaging site is operated in cooperation with the City of Decatur and
is maintained by the USGS Illinois Water Science Center. The U.S.
Geological Survey measures stream discharge at gaging stations.
Through the provided links, you will find real time data; current
conditions of data transmitted from this gaging station.
TOPO
GLOSSARY
• gage height--the height of the water surface above the gage
datum (zero point). Gage height is often used interchangeably with
the more general term, stage, although gage height is more
appropriate when used with a gage reading.
• gaging station--a site on a stream, lake, reservoir or other body
of water where observations and hydrologic data are obtained.
• discharge--the volume of water that passes a given location
within a given period of time. Usually expressed in cubic feet per
second.
• wetlands -- areas where water covers the soil, or is present
either at or near the surface of the soil all year or for varying
periods of time during the year, including during the growing
season
• watershed -- the region or area drained by a river, stream, etc.;
drainage area.
• moraine -- a ridge, mound, or irregular mass of unstratified
glacial drift, chiefly boulders, gravel, sand, and clay.
GAGE HEIGHT 20 FEET
LOGGING REQUIREMENTS
All requirements must be completed in order to claim a
find. Email answers must be submitted at time of
logging.
Post a photo of yourself in front the river near
the coordinates. List the gage height at the time of your visit in
the image name or description.
email me the answers to the following questions:
1. Use
Real-Time Water Data Table to determine what the gage
heightand discharge rate (cfs) was at the
15 minute time interval nearest your visit
2. Use the
USGS Surface-Water Monthly Statistics to determine which
month the average gage height is the
highest and which is the
lowest.
3. Using
Real-Time Water Data Graph, were there any peaks in the gage
height during the previous week?
4. Where is the watershed for this area of the river?
5. What is the biggest pollutant at this point in the river?