Bacteria
High counts of fecal coliform bacteria in a stream or lake indicate that fecal matter has entered the water presenting the potential risk to human health. Fecal coliform bacteria are found in the fecal matter of all warm-blooded animals. The primary sources of bacteria in Leesville Lake and its tributaries are cattle and wildlife, but pets and failed septic systems can also be significant contributors. Escherichia coli (E. Coli) became the official standard statewide for bacteria in January 2003. The Virginia instantaneous E. coli standard is 235 colony forming units (cfu) per 100 ml of water.
The “Coliscan” method will be used for detection of E. coli in the citizen monitoring project. Coliscan is technically very simple to perform and requires no expensive equipment. The citizen monitor simply collects a sample of water at each monitoring station; uses a sterile dropper to place a water sample into a bottle of liquid Coliscan medium; and then pours the Coliscan plus water sample into a sterile Petri dish. The Petri dish is pretreated with a chemical that causes the liquid Coliscan to solidify into a gel after 60–90 minutes at room temperature. After the medium has solidified, the plate can be incubated at 37 C (about 100 F) for 24-36 hours and then analyzed.
A paper titled “Escherichia Coli Monitoring with Coliscan” is attached. It provides more background information on bacteria in water and the Coliscan test procedure.
Secchi Depth
Secchi depth is a parameter used to determine the clarity of surface waters. The measurement is made with a “Secchi” disk, a black and white disk that is lowered into the water and the depth is recorded at which it is no longer visible. A Secchi depth recording of 5 ft indicates that the device was last visible at 5 ft below the surface. High Secchi depth readings indicate clearer water that allows sunlight to penetrate to greater depths. Low readings indicate turbid water which can reduce the passage of sunlight to bottom depths. Limited light penetration can be a factor in diminished aquatic plant growth below the surface, thus reducing biological reaeration at lower depths.
Secchi disk readings vary seasonally with changes in photosynthesis and, therefore, algal growth. In most lakes, Secchi disk readings begin to decrease in the spring, with warmer temperature and increased growth, and continue decreasing until algal growth peaks in the summer. As cooler weather sets in and growth decreases, Secchi disk readings increase again.
In lakes that thermally stratify, Secchi disk readings may decrease again with fall turnover. As the surface water cools, the thermal stratification created in summer weakens and the lake mixes. The nutrients thus released from the bottom layer of water may cause a fall algae bloom and the resultant decrease in Secchi disk reading.
Rainstorms also may affect readings. Erosion from rainfall, runoff, and high stream velocities may result in higher concentrations of suspended particles in inflowing streams and therefore decreases in Secchi disk readings.
Secchi disk depth is usually reported in feet to the nearest tenth of a foot, or meters to the nearest tenth of a meter.
Temperature
Temperature affects water quality by imposing a heat burden on aquatic life, and by limiting the level of dissolved gases in water.
The project will determine if there is a relationship between temperature and bacteria and temperature and Secchi depth.
Dissolved Oxygen
Dissolved Oxygen (DO) is one of the most important determinants of habitat suitability for aerobic organisms – those that need oxygen to live. In streams and lakes, the DO concentration is altered by photosynthesis, respiration, nutrient input, re-aeration, and temperature, all of which have seasonal cycles.
pH
One of the primary indicators of water quality is pH. Stream and lake pH depends on local ecology, the presence of inorganic and organic acids, and anthropogenic (man made) influences. Most aquatic organisms can withstand a pH as low as 6, but prefer a range between 7 and 8.5. pH values harmful to aquatic life use are the extremes-- below 5 or above 9.
Conductivity
Conductivity is a measurement used to determine the minerals content of water, which is commonly called total dissolved solids. Elevated dissolved solids can cause "mineral tastes" in drinking water. Corrosion or encrustation of metallic surfaces by waters high in dissolved solids causes problems with industrial equipment and boilers as well as domestic plumbing, hot water heaters, toilet flushing mechanisms, faucets, and washing machines and dishwashers. Agricultural uses of water for livestock watering are limited by excessive dissolved solids and high dissolved solids can be a problem in water used for irrigation.
Monitoring Stations and Frequency
Attached is a chart that shows the DEQ monitoring stations and the LVLA monitoring stations. Below is a list the LVLA monitoring stations and the rationale for choosing them. These monitoring stations were discussed with DEQ and DEQ agrees that they are good locations to monitor.
Station 1 is at Toler’s Bridge (near mile marker 12). This location is downstream of the Pigg River and will provide data on bacteria from the Pigg after it has mixed with water coming out of Smith Mountain Lake.
Station 2 is near mile marker 9 and will provide data on bacteria dilution downstream of station 1.
Station 3 is in the cove near Tri-County Marina. This location will provide data on bacteria near the swimming beach. It may also determine if there are any bacteria entering the water from Terrapin Creek or the homes around the cove.
Station 4 is near mile marker 3. This station will provide a data point upstream of the confluence with Old Woman's Creek (OWC).
Station 5 is near Pit Stop Marina and provides data at the confluence of Old Woman's Creek with lake.
Station 6 is north of Goat Island. It provides data on bacteria dilution as the water from OWC combines with the main river flow.
Station 7 is near mile marker 1. It provides another data point on bacteria dilution downstream of confluence with OWC and provides an indication of bacteria levels at the state park near the dam.
Latitude and longitude has been determined for each station and DEQ assigned DEQ river-mile station IDs.
Monitoring will begin in April. This will give the volunteers experience with sampling and Coliscan procedures before the boating and swimming season begins. From about May 15 through September 15, sampling will be done on a biweekly basis. Samples will also be taken after major rainstorms when water is muddy. Samples taken after major rain events should provide information on peak bacteria levels and how quickly it dissipates.
Data Collection and Reporting
All data will be collected and reported in a format requested by DEQ. This will allow DEQ to use the data and will also facilitate future Association grant requests.
April 15, 2007
Budget:
|
Item |
Quantity |
Cost per Item |
Total Cost |
|
|
|
|
|
|
Secchi disks & Line |
6 |
$30.00 |
$180.00 |
|
Rubbing Alcohol |
10 |
$0.50 |
$5.00 |
|
Fuel Reimbursement |
20 |
$20.00 |
$400.00 |
|
Misc/Contingency |
|
|
$65.00 |
|
|
|
|
|
|
Total |
|
|
$650.00 |