A Cladophora Survey of Walloon Lake

by

Tip of the Mitt Watershed Council

July, 1998

(revised 8-10-98)

Introduction

A shoreline survey to identify locations of Cladophora growth was conducted on Walloon Lake by the Tip of the Mitt Watershed Council between June 5 and July 3, 1998. The survey was funded by the Walloon Lake Association.

Cladophora is a branched, filamentous green algae that occurs naturally in small amounts in Northern Michigan Lakes. Its occurrence is governed by specific environmental requirements for temperature, substrate, nutrients, and other factors. It is found most commonly in the wave splash zone and shallow shoreline areas of lakes, and can also be found in streams. It grows best on stable substrates such as rocks and logs. Artificial substrates such as concrete or wood seawalls are also suitable. The preferred water temperature is 50 to 70 degrees Fahrenheit. This means that late May to early July, and September and October are the best times for its growth in northern Michigan lakes.

The nutrient requirements for Cladophora to achieve large, dense growths are greater than the nutrient availability in lakes with high water quality, such as Walloon Lake. Therefore, the presence of Cladophora can indicate locations where relatively high concentrations of nutrients, particularly phosphorus, are entering a lake. Sources of these nutrients can be due to natural conditions, including springs, streams, and artesian wells that are naturally high in nutrients due to the geologic strata they encounter; as well as wetland seepages which may discharge nutrients at certain times of the year. However, the majority of Cladophora growths can be traced to cultural sources such as lawn fertilization, malfunctioning septic systems, poor agricultural practices, soil erosion, and wetland destruction. These nutrients can contribute to an overall decline in lake water quality. Additionally, malfunctioning septic systems pose a potential health risk due to bacterial and viral contamination.

A Cladophora survey can be a valuable lake management tool. Coupled with follow-up on-site visits and questionnaires, controllable sources of nutrients to the lake can be identified. Subsequently, a reduction in nutrient loading can often be achieved by working with homeowners to solve problems. These solutions are often simple and low cost, such as regular septic system maintenance, proper lawn care practices, and wise land use along the shoreline. Prevention of problem situations can also be achieved through the publicity and education associated with the survey.

Shoreline Cladophora surveys have been conducted on Walloon Lake at approximately five year intervals since 1979. Periodic repetition of shoreline algal surveys are important for identifying chronic problem sites as well as recent occurrences. They are also valuable for determining long term trends of nearshore nutrient inputs associated with land use changes, and for assessing the success of remedial actions.

Methods

Initially, the shoreline was surveyed using a small motorboat to develop a database of property features and their description as viewed from the water. Property features include developed platted lots, undeveloped (vacant) lots, large undeveloped parcels, parks, preserves, public access sites, and county road endings. However, it was not possible to identify every distinct parcel in this manner.

For the purposes of this survey, developed means the presence of buildings or other significant permanent structures. Included are 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 which may have development in an area far from the water's edge were not considered developed. The length and area of developed vs undeveloped shoreline was not calculated.

The database field containing the property description contains a sometimes cryptic descriptive phrase up to 50 characters long. 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. Wherever known, names of property owners and shoreline address of properties were included in the database. Walloon Lake Association members are expected to complete compilation of names and addresses.

Following completion of the property description phase of the database, the entire shoreline was again closely inspected for Cladophora growths by traveling in a kayak as close to the shoreline as possible (usually within 20 feet). When a Cladophora growth was observed, it was generally described according to criteria used during past surveys--estimating the length (feet) of shoreline it covered and the density or amount of available substrate that was utilized. Categories and densities are as follows:

Light (L)	25-49% coverage

Moderate (M)	50-59% coverage

Moderate to Heavy	60-74% coverage

Heavy (H)	75-99% coverage

Very Heavy (VH)	100% coverage

For this survey, a sixth category (Very Light, VL) was added to identify areas where Cladophora growth was obviously greater than normal, but for which coverage was less than 25%. For example, if Cladophora covered half the rocks along a 25 foot length of shoreline, it would be described MX25.

Although the size of the growth on an individual basis is important in helping to interpret the cause of the growth, growth features of Cladophora are greatly influenced by such factors as current patterns, shoreline topography, size and distribution of substrate, and the amount of wave action the shoreline is subject to. Therefore, the description has limited value when making year to year comparisons at a single location or estimating the relative amount of shoreline nutrient input. Rather, the presence or absence of any significant growth at a single site over several years is the most valuable comparison. It can reveal the existence of chronic nutrient loading problems, and help interpret the cause of the problems and assess the effectiveness of any remedial actions. Comparisons of the total number of algal growths can reveal trends in nutrient input due to changing land use.

Many species of filamentous green algae are commonly found growing in the nearshore regions of lakes. Positive identification of these species usually requires the aid of a microscope. However, Cladophora usually has an appearance and texture that is quite distinct to a trained surveyor, and these were the sole criteria upon which identification was based.

Other species of filamentous green algae can respond to an external nutrient source in much the same way as Cladophora, although their value as an indicator species is not thought to be as reliable. When other species occurred in especially noticeable, large, dense growths, they were recorded on the survey maps and described the same as those of Cladophora.

Among other things, the distribution and size of each Cladophora growth is dependant on the amount of suitable substrate present. The extent of suitable substrate should therefore be taken into account when interpreting the occurrence of individual growths, and assessing the overall distribution of Cladophora along a particular stretch of shoreline. The presence or absence of suitable Cladophora growth substrate was recorded during the survey.

Tributaries are one of the primary conduits through which water is delivered to a lake or river from throughout 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 were present at the mouth of many of the tributaries. Since tributary streams, even very tiny ones, were readily apparent during the survey, their locations were also added to the database.

Results and Recommendations

The survey identified approximately 977 property parcels. Of these, approximately 816 were developed. Habitat generally considered suitable for Cladophora growth was present at 784 properties. Noticeable growths of Cladophora or other filamentous green algae were found in 200 locations. Numbers of each type of Cladophora growth are as folows:

Very Light	87

Light	45

Moderate	21

Moderate to Heavy	7

Heavy	36

Very Heavy	4

When comparing these results with past surveys, it should be noted that the very light density level was not previously reported. Forty tributrary streams were identified. Some of these tributaries appeared to be artificial streams, created for landscaping purposes by pumping water from the lake. The attached database report contains a sequential listing of properties beginning at the public access site on Gruler Road and traveling counterclockwise around the entire perimeter of the lake, as well as all the other information described.

In addition to the Cladophora growths, several other potential problem situations were observed. There were a number of homesites under construction where proper erosion and sedimentation control techniques were not being used, in violation of Part 91 (soil erosion and sedimentation control) of Public Act 451 of 1994. At a few sites, it was apparent that recent rains had washed sediment into the lake. Time constraints did not allow reporting of these violations to the local soil erosion control officer. In Walloon's Mud Lake basin, a deposit of mucky detritus which appeared to originate from the Manthai Veneer Mill was observed. The deposit appears to have built up over a long period of time. This sediment had stimulated a lush growth of emergent and rooted aquatic plant growth. The water and sediment were likely coming from from the veneer mill's log watering operation, which has a permit to discharge wastewater from the Michigan Department of Environmental Quality. However, the sediment and nutrient level associated with the discharge seemed excessive. It is recommended that both of these problem conditions be addressed.

The full value of a Cladophora survey is only achieved when the information is used to educate riparians about preserving water quality, and to help them rectify any problem situations. A "follow-up" effort of this nature has occurred on several other lakes where the Watershed Council has conducted shoreline surveys. This follow up involves sending questionnaires to all property owners having Cladophora growths in a attempt to interpret causes of the growths and offer individualized recommendations for water quality protection. Following the questionnaire survey, site visits coupled with ground water testing are sometimes preformed in an effort to gain more insight into the nature of the Cladophora growth. All information regarding names, specific locations, and findings are kept confidential to encourage property owner participation in this project. The primary recommendation is that follow-up efforts of this nature be pursued after names and addresses of property owners are matched to the property descriptions on the database.

Eventually, the shoreline database developed for this survey could be linked with maps showing parcel lines, tax numbers, and ownership information obtained from the equalization departments of the two counties in which Walloon Lake lies. The database could also be expanded to include the results of past Cladophora surveys as well as other shoreline features such as public access sites, shoreline erosion, wetlands, aquatic plants, and type of bottom substrate. When this database is fully developed it will facilitate identifying the locations of Cladophora growths during repeat shoreline surveys and have wide utility for other water resource management applications.