Understanding The Data Base

The following information, taken from the complete summary, includes keys to the abbreviations used in the data base.

Table 3. Categories and determinations for Cladophora density

Density Category Field Notation Substrate Coverage
Very Light (VL) 0% *
Light (L) 1- 20%
Light to Moderate (LM) 21-40%
Moderate (M) 41-60%
Moderate to Heavy (MH) 61-80%
Heavy (H) 81-99%
Very Heavy (VH) 90-100% *

*Very Light is noted when a green shimmer is noticed on hard substrate, but no filamentous growth present. Very Heavy overlaps with heavy and is distinguished by both high percentage of substrate coverage and long filamentous growth.

Shoreline Features

Property Descriptions were noted on a data sheet, such as building descriptions, public access sites, and county road endings. Due to data sheet space limits, building descriptions were recorded in an abbreviated cryptic style. For example, Red 2 sty, brn rf, wht trm, fldstn chim, lg pine means that the property has a red two-story house with a brown roof, white trim, fieldstone chimney, and a large pine tree in the yard. Whenever possible, names of property owners and addresses were included.

Developed versus Undeveloped parcels were noted during the survey and included as a separate column in the database. Properties described as developed indicate the presence of buildings or other significant permanent structures, including roadways, boat launching sites, and recreational properties (such as parks with pavilions and parking lots). Properties with only mowed or cleared areas, seasonal structures (such as docks or travel trailers), or unpaved pathways were not considered developed. Additionally, relatively large parcels that may have development in an area far from the water's edge were not considered developed. The length and area of developed versus undeveloped shoreline was not calculated.

Greenbelt information was documented during the survey above and below the ordinary high water mark. Greenbelts are vegetated areas along the shoreline that are the critical interface between land and water and which provide many benefits to the lake ecosystem. During this survey, greenbelts were rated based on length and depth. Greenbelt lengths were described using a numbering system representing the percentage of shoreline for a given property that had a greenbelt of any size (depth). Turf grass was not considered as greenbelt. Greenbelt depths were described with a numbering system based on the average distance that the greenbelt extended from the water's edge landward. Due to low lake levels it was necessary to distinguish between greenbelts both above and below the ordinary high water mark on many parcels. Therefore, where applicable greenbelts below the high water mark were rated based on length and depth and referred to as "bottomland vegetation" in the database. The numbering systems used to describe greenbelt and bottomland vegetation length and depth are as follow:

  • Greenbelt Length: 0 = none, 1 = less than 10% of shoreline, 2 = 10 to 25%, 3 = 25 to 75% and 4 = over 75%.
  • Greenbelt Depth: 1= less than 10 feet, 2 = 10 to 40 feet, 3 = greater than 40 feet.

All greenbelt and bottomland vegetation data represent approximations as lengths and depths were estimated rather than measured.

Shoreline Alterations were recorded on field data sheets during the survey and entered into the database. Alterations to the lake shore have the potential to impact water quality in a variety of ways including the loss of riparian vegetation, degraded habitat in nearshore areas, and erosion. Shoreline alterations (structures) were noted with the following abbreviated descriptions:
  • BB = boulder bulkhead
  • CB = concrete bulkhead
  • O = other
  • RR = rock rip-rap
  • S = sand beach
  • SB = steel bulkhead (i.e., seawall)
  • WB = wood bulkhead

Sometimes abbreviations were mixed or vary from what is listed above. "Other" included features such as drainpipes or boathouses. In addition, any erosion observed on the shoreline was noted and included in a separate column in the database as being present or absent.

Substrate or bottom type is an important shoreline feature to document during nutrient pollution surveys because Cladophora growth is generally limited to hard substrates, such as rock, gravel and wood. In areas without hard substrate, such as sand and muck, Cladophora cannot be used as a reliable indicator of nutrient pollution. Thus, documenting substrate type aids in the evaluation of shoreline survey nutrient pollution data. Shoreline area substrates were noted on field data sheets using the following categories and abbreviations:

  • MK = muck
  • S = sand (0.1" diameter or less)
  • G = gravel (0.1" to 2.5" diameter)
  • R = rock (2.5" to 10" diameter)
  • B = boulder (10" or greater diameter)
  • WD = wood

If multiple substrate types were present along the shoreline of a parcel, then all were noted. The database contains separate columns for each substrate type.

Erosion was documented simply by noting the presence or absence of accelerated shoreline erosion. Erosion generally appears as areas of bare soil along the shoreline, leaning or downed trees or trees with exposed roots, undercut banks, slumping hunks of sod, and excessive deposits of sediments. Additional information about the nature of the erosion, such as relative severity (slight, moderate, or severe), height and length of bank, whether it occurs at the toe or the top of the bank, type of soils, rate of recession, and obvious causes, may have been included in the comments column.

Tributaries are one of the primary conduits through which water is delivered to a lake or river from its watershed. Tributaries also carry and deliver a variety of materials from throughout the watershed to the receiving water. This can include pollutants such as sediment, nutrients, bacteria, and toxins from human activities far removed from a lake or river. Cladophora growths and elevated conductivity levels often occur at the mouth of tributaries. Therefore, tributary streams were noted during the survey and included in a "tributary" column in the database. In addition, maps and aerial photographs were used to identify additional tributaries that were not noted during the field survey.