LAKE CHICOT

A helicopter view of the blue water of upper lake and the muddy water of lower lake Photo.
Photo: B. Morrison  
 
 

A. LOCATION

Arkansas, USA. 33:6 - 33:3 N, 91:0 - 91:7 W; 31.5 m above sea level.

B. DESCRIPTION

Lake Chicot is an oxbow lake that was created more than 600 years ago by the meandering of the Mississippi River. It is located in Chicot County in southeastern Arkansas adjacent to the present Mississippi River. As the largest natural lake in Arkansas, it earned an early reputation for its good fishing and recreational value.
A flood in 1927 partially created a natural earth dam dividing the lake into a large lower lake and a considerably smaller upper lake. This dam was completed by the State of Arkansas. Development of a levee system forced the enlargement of the lake's watershed to its present 350 square miles.
Initially this alteration affected only the volume flow through the lake, drastically reducing the water residence time. Because the watershed was located in one of the most agriculturally productive regions in the world, the land, predominantly comprised of clay and fine silts, quickly became more intensively farmed. The use of agricultural chemicals increased, large amounts of sediments were produced and the lake began to become severely impacted by this activity.
In the early 1960's Congress enacted legislation authorizing the Corps of Engineers to begin planning a method of restoring the lake. Plans were made to construct three structures; a dam to prevent poor quality water from entering the lake, a combination gravity flow-pump facility to divert the poor quality water through the levee into the Mississippi River, and a dam on the outflow to regulate lake levels and regulate discharge. The structures were placed into operation during March 1985 and are operational according to a plan to improve the water quality in the lake. These structures and plans have resulted in a nearly complete restoration of the lake (Q).

C. PHYSICAL DIMENSIONS (1)

     
    Surface area [km2] 17
    Volume [km3] 0.0625
    Maximum depth [m]
    (Upper lake) 4.5
    (Lower lake) 8.3
    Mean depth [m]
    (Upper lake) 3.0
    (Lower lake) 3.8
    Water level Regulated
    Length of shoreline [km] 58.2
    Residence time [yr] 0.4
    Catchment area [km2] 906
     
 

D. PHYSIOGRAPHIC FEATURES (1)

D1 GEOGRAPHICAL Bathymetric map: Fig. NAM-19-01. Names of main islands: None. Number of outflowing rivers and channels (name): 1 (Ditch Bayou).
D2 CLIMATIC Climatic data at Stoneville, 1983-1987
Mean temp [deg C]
     
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    3.71 7.96 11.79 16.71 22.23 26.03 27.37 27.02 23.41 18.03 12.45 6.9 16.97
     
    Precipitation [mm] 
    Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann.
    66 144 115 106 168 112 52 53 47 118 197 128 1,306
     
Solar radiation: 16.47 MJ m-2 day-1.

    Fig. NAM-19-01
    Bathymetric map (Q).
 

Water temperature [deg C] Station 1, January 1983-September 1987

     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    6.7 9.7 15.7 21.2 25.0 28.9 30.4 31.2 26.1 22.5 17.0 11.3
     
Station 2, January 1983-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    6.2 8.8 14.9 19.8 23.9 28.6 29.5 31.0 26.9 22.7 16.7 11.2
    Freezing period: None. Mixing type: Polymictic. Notes on water mixing and thermocline formation The lake stratifies during the summer and is in a continuous mixing state from late fall to early spring.
 

E. LAKE WATER QUALITY (1)

In March 1985 the U.S. Army Corps of Engineers placed three structures into operation. A downstream dam and gate regulates the lake level, an upstream dam and gate prevents poor quality water from entering the lake and a combination pump-gravity flow facility diverts poor quality water to the adjacent Mississippi River. This changed the water quality in the lower lake (station 2) after this date. For this reason, the water quality data over the past five years is separated into two time-frames.
E1 TRANSPARENCY [m] Station 1, September 1982-March 1985
     
    Depth Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    .20 .40 .21 .36 .33 .52 .43 .39 .45 .33 .47 .35
     
Station 2, September 1982-March 1985
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    .17 .08 .11 .10 .08 .10 .12 .32 .45 .38 .31 .15
     
Station 1, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    .60 .40 .28 .38 .55 .58 .31 .29 .27 .30 .48 .48
     
Station 2, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    .53 .78 .80 .51 .75 .70 .50 .56 .51 .46 .57 .51
     

E2 pH Station 1, September 1982-March 1985

     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    7.3 7.6 7.5 7.9 7.3 7.7 8.4 7.4 7.8 7.6 7.2 7.3
     
Station 2, September 1982-March 1985
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    6.8 7.1 6.9 7.6 6.6 7.2 7.7 7.5 8.5 7.9 6.8 6.7
     
Station 1, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    8.0 8.2 8.2 8.0 8.2 8.4 8.9 8.5 8.4 8.2 8.0 8.0
     
Station 2, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    7.7 8.6 8.5 7.7 7.9 8.0 8.0 8.3 8.2 8.0 8.2 8.0
     

E3 SS [mg l-1] September 1982-March 1985 Station 1

     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    34.7 92.2 112.3 41.7 49.8 12.3 17.0 13.0 20.2 48.0 56.2 71.3
     
Station 2
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    143.6 283.2 325.3 330.3 324.3 267.3 138.3 39.6 27.8 67.7 44.0 208.7
     
April 1985-September 1987 Station 1
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    26.0 30.0 56.0 31.4 51.9 25.5 20.7 17.0 30.5 24.3 51.2 114.2
     
Station 2
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    10.0 85.5 23.0 117.9 66.1 37.3 18.6 14.8 18.1 31.3 19.3 38.8
     
E4 DO [mg l-1] Station 1, September 1982-March 1985
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    11.7 11.6 10.2 10.3 9.6 8.0 8.7 7.2 5.2 9.2 9.9 11.3
     
Station 2, September 1982-March 1985
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    7.7 5.7 8.3 8.7 8.2 7.6 6.7 7.8 9.3 9.3 8.6 8.7
     
Station 1, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    11.2 10.2 11.4 9.5 10.1 11.5 12.0 8.7 8.8 7.7 7.9 10.6
     
Station 2, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    11.3 11.5 11.9 9.1 9.0 8.5 8.3 9.3 7.5 8.4 8.8 10.5
     
E6 CHLOROPHYLL CONCENTRATION [micro g l-1] Station 1, September 1982-March 1985
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    25.3 45.4 46.2 41.2 36.7 44.0 69.0 82.4 95.8 110.5 72.0 41.6
     
Station 2, September 1982-March 1985
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    1.8 4.2 1.8 2.8 1.7 20.3 16.3 13.4 39.0 24.8 5.6 1.6
     
Station 1, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    47.5 0.2 0.8 19.2 32.2 25.5 91.0 100.4 120.0 142.0 82.3 48.7
     
Station 2, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    27.7 26.3 16.8 14.3 15.1 11.0 35.7 47.6 53.5 56.5 35.2 18.3
     
E7 NITROGEN CONCENTRATION Total-N [mg l-1] Station 1, September 1982-March 1985
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    1.3 1.4 1.4 1.3 1.7 1.8 1.6 1.8 1.6 1.6 1.4 1.2
     
Station 2, September 1982-March 1985
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0.8 1.2 1.3 1.5 1.2 1.2 1.2 0.9 0.8 0.8 0.6 1.1
     
Station 1, April 1985-September 1987
     
    Depth Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    1.0 0.6 0.8 0.9 1.0 1.6 2.4 2.6 2.9 2.4 2.0 1.4
     
Station 2, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    0.7 0.4 0.5 0.7 0.7 0.7 1.0 1.3 1.3 1.0 1.0 0.7
     
E8 PHOSPHORUS CONCENTRATION Total-P [mg l-1] Station 1, September 1982-March 1985
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    .125 .105 .157 .095 .146 .109 .104 .125 .151 .165 .133 .128
     
Station 2, September 1982-March 1985
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    .246 .219 .354 .342 .593 .389 .202 .106 .097 .149 .118 .314
     
Station 1, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    .074 .191 .108 .087 .088 .111 .146 .223 .266 .183 .148 .166
     
Station 2, April 1985-September 1987
     
    Depth[m] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    .044 .035 .035 .193 .128 .105 .096 .140 .335 .138 .072 .069
     
 

G. SOCIO-ECONOMIC CONDITIONS (3)

G1 LAND USE IN THE CATCHMENT AREA 1987

     
    [%]
    Natural landscape
    Others 8
    Agricultural land 90
    Residential area 2
    Total 100
     
Main kinds of crops: Cotton, soybean, rice, wheat, milo. Levels of fertilizer application on crop fields: Moderate.
G3 POPULATION IN THE CATCHMENT AREA 1987
     
    Population Major cities
    Population density [km-2] (population)
    Rural 19,000 21.0 Lake Village
     
 

H. LAKE UTILIZATION (2)

H1 LAKE UTILIZATION Sightseeing and tourism, recreation (swimming, sport-fishing) and fisheries.
H2 THE LAKE AS WATER RESOURCE 1987
     
    Use rate [m3 sec-1]
    Irrigation 1.4-2.5
     
 

M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS

M1 NATIONAL AND LOCAL LAWS CONCERNED (2) Names of the laws (the year of legislation)
  1. Flood Control Act of 1968 Responsible authorities
  2. U.S. Army Corps of Engineers (Dept. of Army) Main facilities of control
  3. 6500 CFS Pumping Plant
  4. Control Dam
  5. Regulating Dam
M2 INSTITUTIONAL MEASURES (the year of establishment) (2)
  1. Lake Chicot Rural Development Authority, Lake Village, Arkansas (1973)
M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES (1) Primary research conducted by
  1. Agricultural Research Laboratory at Durant, Oklahoma
  2. Army Engineer District, Vicksburg, Mississippi Supplementary research by
  3. Agricultural Research Laboratory at Oxford, Mississippi
  4. Agricultural Research Laboratory at Beltsville, Maryland
  5. Ouachita Baptist University at Arkadelphia, Arkansas
  6. University of Minnesota at Minneapolis, Minnesota
  7. University of Mississippi at Oxford, Mississippi
  8. University of Oklahoma at Norman, Oklahoma
  9. Northeast Louisiana University at Monroe, Louisiana
  10. University of Arkansas at Monticello, Arkansas
 

N. SOURCES OF DATA

  1. Questionnaire filled by Hydrologic Technician B. Morrison, Water Quality and Watershed Research Laboratory, Durant, Oklahoma, with the support of J. E. Wesson, Secretary/Treasurer, Lake Village Chamber of Commerce, based on the following sources.
  2. The USDA Agricultural Research Laboratory.
  3. Goodson, L., U.S. Army Corps of Engineers Vicksburg District.
  4. Keener, B., Soil Conservation Service.