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SECTION C. NATURAL ENVIRONMENT AND RESOURCES
INTRODUCTION
The natural environment of Lee County is comprised of multiple
elements or factors that combine to form the environmental setting. The importance and status of the man-made
elements or the state’s roads, water, sewer, businesses, and residential
areas are commonly viewed, or mistaken, as being independent of the natural
environment. Such misconceptions have
led to the residential and commercial development of flood plains and prime
agricultural land, and loss of irreplaceable natural elements such as native
prairies, forests, prominent vistas, and other scenic resources.
The following section will
identify the physical elements that makeup the environmental setting of Lee
County. From the identification and
analysis of the individual elements, areas can be identified as sensitive, or
in need of protection. Lee County,
like all governments bodies, must learn from past mistakes and implement
simple rules and regulations to ensure the protection of elements that have
been destroyed in the past.
The health and stability of Lee
County, and both the natural and man-made environments, can be measured by
the diversity within the system and the ability of the county to develop
responsively to the natural systems, which shape its ultimate path.
The greatest obstacle for Lee County in the future will be continuous
reference to the natural environment elements in this section and in Chapter
3. The information within this
section should be recognized, further developed, and monitored, to ensure a
quality of life and balance for current and future generations alike.
NATURAL ELEMENTS
Climate
According to the 1979 Soil
Survey of Lee County, Iowa, on clear, calm nights, river valleys and
other low areas may be several degrees cooler than upland or urban areas in
the county. In an average year, about
31 days will have maximum temperatures of 90 degrees or higher. The temperatures are too high for optimum
crop production because of excessive water demand.
The annual precipitation
averages nearly 34 inches, making this one of the wettest counties in the
state. Approximately 75 percent of
the annual precipitation occurs during the warm season from April through
September. June is usually the
wettest month, and dry periods in summer are most likely in July.
Topography and Drainage
Elevation ranges from 780 feet in the northern part of Lee County to
490 feet in the southeastern part, where the Des Moines and Mississippi
Rivers join.
An interstream divide, starting
north of Keokuk, widens from less than a mile to more than 10 miles near
Houghton. The topography conforms to
the flat to gently rolling underlying glacial till, but breaks quickly into
narrow, loess-covered ridge tops surrounded by steep glacial till side
slopes. The steepest slopes in Lee
County are along the bluffs bordering the rivers (Soil Survey of Lee
County, Iowa)
Lee County is primarily drained four specific
ways. The northwest portion of Cedar
Township and the small watersheds bordering the Skunk River drain into the
Skunk. The remaining area east of
Highway 218, including Lost Creek and Big Devils Creek, drains into the
Mississippi River. The watershed west
of Highway 218, in which Sugar Creek is the major stream, drains into the Des
Moines River. And the levied area in
Green Bay Township is a drainage district with a network of drainage ditches
leading to a pumping station in the Mississippi River.
Soils
According to the General Soils Map of Lee County (refer to Appendix
B), Lee County is comprised of seven different soil
associations. This general soil map
provides a broad perspective of the soils and landscapes in Lee County. It provides a basis for comparing the
potential of large areas for general kinds of land use. Areas that are, for the most part, suited
to certain kinds of farming or to other land uses can be identified on the
map. Likewise, areas of soils having
properties that are distinctly unfavorable for certain land uses can be
located. However, due to its small
scale, the map does not show the soil at a specific site. Thus, it is not suitable for planning the
management of a farm or field or for selecting a site for a road or building.
Soil
Associations
Grudy-Haig-Arispe Association
[Moderately well drained to poorly drained, nearly level to
moderately sloping soils formed in loess on uplands.] This association consists mainly of nearly
level to moderately sloping soils on wide interstream divides. These divides are at the highest elevation
in Lee County. The larger areas of
the association are in the northwest part of the county and on the main
divide between Little Sugar Creek and Big Sugar Creek. Another is on the divide between the
tributaries of the Skunk and Mississippi Rivers. This association covers about 16 percent of the county.
The soils of this association are among the most productive in Lee
County. These soils have high
available water capacity and relatively high natural fertility. Corn and soybeans are grown almost
continuously on the nearly level and gently sloping soils.
Pershing-Weller Association
[Somewhat poorly drained and
moderately well drained, gently sloping and moderately sloping soils formed
in loess on uplands.] This
association is along the headwaters of the main streams within the northern
part of the county. The landscape is
gently sloping ridge tops and moderately sloping valleys. Trees are scattered along drainage ways
and old fencerows. Along Little Cedar
Creek and Sugar Creek, thick timber growth is common. The soils in this association have a
moderately dark or moderately light-colored surface layer.
This association covers about 4
percent of the county. A large part
of this association is cultivated, and the rest is in permanent pasture or
forest. Most cultivated areas are
subject to severe erosion. Many slopes are long and uniform and can be
terraced or tilled on the contour.
Pershing-Belinda Association
[Moderately well drained to
poorly drained, moderately sloping to nearly level soils formed in loess on
uplands.] This association consists
mainly of moderately sloping, gently sloping, and nearly level soils that
formed under a native vegetation of prairie and forest. It is on relatively narrow interstream
divides and in a band between the prairie soils and the timbered soils.
This association covers about
15 percent of the county. The soils
in this association have moderately high available water capacity and medium
natural fertility. Farming is
diversified. The gently sloping and
nearly level soils are almost continuously cropped with corn and soybeans. The steeper soils can be cropped, but they
generally are in permanent pasture.
Lindley-Weller Association
[Well drained and moderately
well drained, moderately sloping to steep soils formed in glacial till and
loess on uplands.] This association
consists of strongly dissected areas that border the Des Moines, Skunk, and
Mississippi Rivers and areas that border the major streams in the
county. The principal landscape
features are narrow, rounded ridge tops; long, steep, convex side slopes; and
narrow valleys. Most of the area is
covered with forest, but small, irregularly shaped fields are mainly in pasture. The soils of this association formed under
forest vegetation, and they have a light-colored surface layer. This association covers about 14 percent
of the county.
Douds-Clinton-Keomah Association
[Somewhat poorly drained and
moderately well drained, nearly level to moderately steep soils formed in old
alluvial sediment and loess on high benches.] This association consists of loess-covered beaches, the tops of
which are nearly level to moderately sloping and the side slopes and
escarpments of which are generally moderately steep. The material below the loess on side
slopes is sand, silt, and clay, and it originated as alluvial sediment at a
much earlier time. The beaches are
along the major stream valleys and are distinctly higher than the flood plain. The most extensive area of nearly level
beach soils is at the mouth of Sugar Creek, and another large area extends
along most of Big Sugar Creek. And
small areas of beach soils are scattered along the Des Moines River.
This association covers about 5
percent of the county. The steeper
soils have low productivity and are subject to erosion. They are generally in timber or permanent
pasture. Along some beach escarpments
are sand pockets that are large enough to quarry. The beach escarpments along Big Sugar Creek near Franklin have
outcroppings of limestone.
Sparta-Dickinson Association
[Excessively drained to well drained, nearly level to moderately
sloping soils formed in coarse sediment on beaches.] This association consists of soils located
mainly on sandy beaches along the Mississippi and Des Moines Rivers. The edges of the beaches are moderately
steep in some places, but the landscape is typically nearly level to
moderately sloping. Generally, this
association is near the center of bottomlands and is surrounded by finer
textured soils.
This association covers about 3 percent of the county. The soils in this association have low
available water capacity and have high percolation. If rainfall is timely, however, good yields can be expected on
Dickinson soils. Because these soils
warm up early in spring, some areas are used for truck farming (watermelons
and cantaloupe). The steep slopes and
terrace escarpments are generally in grass.
Chequest-Nodaway-Landes Association
[Poorly drained, moderately
well drained and well-drained, nearly level soils formed in recent alluvium
on bottomland.] The soils of this
association are nearly level and are on first and second bottoms. The largest areas are along the
Mississippi River in the northeast portion of the county and south of Fort
Madison. These areas range from 2 to
7 miles in width. Smaller areas are
along the Des Moines River and the major streams in the county. The soils formed in silty and loamy
sediment deposited on the flood plains.
This association covers about
10 percent of the county. This
association is used intensively for corn and soybeans. The available water capacity is high, and
the productivity is higher than the county average. Some of the soils are flooded.
For optimum yields, artificial drainage and flood protection may be
needed.
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