Hydrilla sp. - cute name, but not so cute in our lake!
While collecting data around the lake, Mike has also been harvesting -
140 cubic feet of hydrilla.
"Hydrilla is a perennial plant that forms dense colonies and can grow to the surface in water over 20 feet deep. Hydrilla branches profusely and after reaching the surface it extends across it forming thick mats. Hydrilla can reproduce by fragmentation, from seeds, from turions (axillary buds), and from tubers. Leaves are blade-like about 1/8 inch and 3/8 inch long with small tooth margins and spines on the underside of the midrib that make them feel rough. Leaves are usually 4 to 8 in a whorl".
(ref: The Pond Guy)
Feel free to do some harvesting too.
Please make sure it is not disposed of in other water ways.
According to our Water Quality Manager, Mike Casteel, Ph.D.,
we should remain at the CAUTION Level.
The water has been fairly clear algae free however, we should NEVER let down our guard and remain vigilant to any increases in visible algae.
If you see anything you think might be of concern please contact Mike at
or any Board Member.
He will continue to monitor the lake for any changes as well.
The lake water quality is currently at CAUTION level.
Harmful algae / cyanobacteria may be present.
According to the EPA (5), don't let your dog drink or swim in water if:
Call your veterinarian if your animals have sudden or unexplained sickness or signs of poisoning.
Harmful algae / cyanobacteria are present, and blooms are occurring around the lake.
The lake water is most likely unsafe.All contact with water, including swimming, fishing and boating, is discouraged.
Exposure to algal toxins may cause illness.
Call your doctor or veterinarian if you or your animals have sudden or unexplained sickness or signs of poisoning.
Harmful algae / cyanobacteria are present, and extreme conditions exist.
The lake water is unsafe.
The lake is closed to swimming, boating and fishing until further notice.
Do not let pets go into the water.
Do not let pets drink the water or eat scum or material on the shore.
This situation will be monitored closely.
Whether you use the lake, or admire from afar, we have to agree the lake is Greene Acres biggest natural asset.
Being informed with relevant knowlege supported by data, gives us all higher chance of keeping our lake the natural wonder' it is today.
We can all contribute by :
(last accessed 10-18- 20).
2. Konopka, A., and T. D. Brock. 1978. Effect of Temperature on Blue-Green Algae (Cyanobacteria) in Lake Mendota. Applied and Environmental Microbiology, Oct. 1978, p. 572-576.
3. www.dnr.maryland.gov/waters/bay/Pages/algal_blooms/Anabaena-andAphanizomenon.aspx (last accessed 10-18-20).
4. Cires et al., 2013. Overwintering populations of Anabaena, Aphanizomenon and Microcystis as potential inocula for summer blooms. Journal of Plankton Research, 35(6)).
If you have questions, or If you see anything you think might be of concern please contact:
Dr. Mike Casteel at 434-400-8816 (email: firstname.lastname@example.org) or
any GAPOA Board Member.
Who is Dr. Mike Casteel?
Mike is a resident of Greene Acres, and his field of expertise is Water Quality, Microbiology.
Mike sure lives in the best place (as we do!).
Mike volunteers his time to monitor the lake, taking samples of water and other specimens, in key points around the lake.
He has been sourcing data to establish a base line, so any irregularities detected, they can be a trigger for something more serious.
Mike uses different measuring criteria, and always presents a robust report at the GAPOA meetings.
Updates are provided to the website by Mike too... all at the expense of his own time (and passion in his field of Water Quality).
THANK YOU MIKE!
At the present time, pet owners who allow their dogs to swim in the lake, should consider the following information and take the precautions listed below.
Lake Users: It is highly recommended to wash with fresh water after having contact with the lake water. (Included but not limited to swimmers, recreationals, boaters, fishers, pets, water crafts and water floats.....).
According to the ASPCA:
cyanobacteria is most likely to thrive in bodies of fresh water when the weather is warm (over 75°F) and sunny. Algae intoxications happen more during the summer because weather conditions promote the growth of cyanobacteria.
Some researchers reported that when temperatures became less than 68°F, there were insignificant amounts of blue-green algae in a lake studied in Wisconsin.
The surface water temperature of our lake has been ~70°F the past few days (October 13 to present) ,and continues to decrease with the cooler temperatures that are now occurring this time of year. Some visible phytoplankton accumulation continues to be observed, mostly in the lake's coves, but not to the extent seen in August and September (2020), and visible surface growth is not seen in other areas of the lake.
Recent microscopic analysis of some of the coves' material shows the presence of anabaena and aphanizomenon, which, according to the Maryland Department of Natural Resources are filamentous
It is unknown whether the isolates seen by microscopy from our lake are toxigenic or not -
NOTE: Not all cyanobacteria blooms are toxic and even blooms caused by known toxin producers may not produce toxins or may produce toxins at undetectable levels.
It is expected that anabaena, aphanizomenon and other cyanobacterial populations will be shown to be present year-round in our lake, including "over-wintering" in the lake.
Therefore, we are currently at the CAUTION level.
According to our Water Quality Manager Mike Casteel, Ph.D. there have been limited signs of the algae during his daily inspections for several days and he has recommended we all should remain observant and keep an eye out for any occurrence. If you see anything you think might be of concern please contact Mike at
or any Board Member.
He will continue to monitor the lake for any changes as well.
Figure 1. Composite sample of lake water collected on 8-22-2020; the picture on the left shows the sample immediately after collection; the picture on the right shows the same sample that was left undisturbed for 24 hours.
Accumulations of bright green material were observed on the surface of the lake on 8-22-20, and close observation of a composite sample collected on that date clearly showed both blue and green organisms (see Figure 1). These organisms were different than the filamentous algae that is routinely observed and that is abundant on the bottom of the lake (Fig. 2).
A sample showing green, filamentous algae (left picture). This type of algae is abundant on the bottom of the lake and most species are not considered harmful. When this type of algae dies, it floats to the surface and is often referred to as muck, scum, or mats (right picture).
Figure 3. Cyanobacteria attached to a floating, decaying strand of the aquatic plant Hydrilla(left) and other organic material (right).
Based on this information, blue-green algae (i.e., cyanobacteria) were considered to be present; consequently, lake users were cautioned (signs posted at beach / pavilion, mailboxes, and website) in regards to contact with the water. Presumptive cyanobacterial colonies ranging in size from a few millimeters (mm) to several centimeters (cm) (about one to a few inches (in.)) continued to be observed around all areas of the lake from 8-22-20 to 8-30-20, including the shoreline from the beach to the end of dam, and at distances up to 23 meters (m; about 75 feet (ft.)) from the shore. These organisms are occurring at various depths in the water column and are also found at the surface and attached to other organic material and aquatic plants such as Hydrilla (Fig. 3).
Precipitation event of 8-31-20. Runoff from the beach (left) and a large mass of cyanobacteria in the water immediately adjacent to the beach (right).
During and following the precipitation event experienced by the area on 8-30-2020 to 8-31-2020 (Fig. 4), larger colonies (some up to 25-30 cm) of cyanobacteria were observed in the lake, and these colonies have persisted as of 9-3-2020. A large mass of Hydrillaand other material, estimated to be about 3-4 m in diameter and containing cyanobacteria, was observed in the center of the lake on 9-1-2020
A circular (about 3-4 m in diameter) accumulation of Hydrilla and other material in the center of the lake. The beach is seen towards the upper right corner of the picture. Cyanobacterial colonies were observed in this material.
While some physical removal (followed by composting off-site) of accumulated organic material and cyanobacterial colonies along the shoreline from the beach to the dam has been performed (to date, >300 pounds has been removed).
Presumptive cyanobacteria continues to be present, and lake users should continue to heed the warnings and recommendations posted on the signs.
As reported in the October 2019 edition of the GAPOA newsletter, testing of Greene Acres Lake (GAL) provided some preliminary information about the water quality of GAL. Water quality is defined as a measure of the suitability of water for a particular use (e.g., swimming; fishing; boating) based on selected physical, chemical, and biological characteristics. In summary, the 2019 data showed that the water quality of GAL is consistent with other freshwater lakes in North America, and that our lake continues to be safe for recreational purposes. However, further monitoring was recommended, because the results showed that GAL contains a level of phosphorus within or above the upper recommended limits compared to many other lakes in Virginia (different lakes have different limits, depending on location). The data also showed the presence of several different species of algae, some of which are well known to be associated with situations commonly known as harmful algal blooms (HABs).
Algae are microscopic organisms that occur naturally in freshwater ecosystems, including the species associated with HABs. Under certain conditions, algae can quickly multiply or "bloom" to a point where algal colonies become visible without the need for a microscope, and blooms may look like foam, scum, mats, or paint floating on the surface of water. Algal blooms can cause damage to aquatic environments by blocking sunlight and depleting oxygen required by other aquatic organisms, restricting their growth and survival, and some species of algae contain toxins that can cause adverse health effects to humans, wildlife, and other animals such as dogs. When algal blooms impair aquatic ecosystems or have the potential to affect human and animal health, they are known as HABs.
While the 2019 data indicate that there is currently a low risk of occurrence and exposure to HABs in our lake, the frequency and geographic distribution of HABs has been increasing regionally (e.g., Lake Anna; Chris Greene Lake), nationally and globally. Starting this month, some of GAL's water quality parameters will be monitored routinely, including water temperature, water clarity, and levels of phosphorus. In addition, routine visual observation of all areas of the lake will be performed, and local meteorological data will be collected and archived. Such information will be used as an early warning system for the occurrence of an algal bloom in GAL. For example, there is a higher probability for the occurrence of an algal bloom when (i) water and ambient temperatures are highest, (ii) there is an increase above normal levels of phosphorus, (iii) there is a cycle of intense and heavy rainfall followed by drought-like conditions, and (iv) there is a high volume of stormwater runoff in to the lake resulting in increased turbidity (cloudiness or less clarity) of the lake's water. If an algal bloom is observed, remedial action will be taken immediately. This information will also serve as a baseline of results for comparison to future monitoring efforts.
The GAPOA community is encouraged to contact our new Water Quality Manager, Mike Casteel, with any comments or suggestions, or to provide any anecdotal or historical information about GAL. Mike would be happy to discuss any water quality and environmental issues and to talk to residents about how they could participate (i.e., become "citizen scientists"). Working together, we will continue to ensure and protect GAL's water quality.
Michael J. Casteel, Ph.D.
Figure Eight Environmental, L.L.C.
371 High Ridge Road, Stanardsville, VA 22973-2557
Our Lake - Keep it Healthy
When in doubt, stay out!
The Virginia Department of Health lists the following things people should do to prevent illness:
· Avoid contact with any area of the lake where water is green or an advisory sign is posted.
· Do not allow children or pets to drink from natural bodies of water.
· Keep children and pets out of the areas experiencing a harmful algae bloom and quickly wash them off with plenty of fresh, clean water after coming into contact with algae scum or bloom water.
· If you or your animals experience symptoms after swimming in or near an algal bloom, seek medical/veterinarian care.
· To ensure fish fillets are safe to eat, properly clean fish by removing skin and discarding all internal organs, and cooking fish to the proper temperature.
· If you suspect you experienced health-related effects following exposure to a bloom, contact the Virginia Harmful Algal Bloom Hotline at 1-888-238-6154. To learn more about harmful algae blooms or to report an algae bloom or fish kill visit www.SwimHealthyVA.com.