After reading the description, you can click on the parameter to see the results of each site on a map.
An abbreviated version of the presentation discussed at the General Meeting can be downloaded here (PDF format, 2.4MB file).
Temperature:
Most of the water temperature readings fell between 60 – 64 deg F, which is normal for April. The site at Thomas Point, which is basically Bay water, was the coolest, at 51 deg.
pH:
pH is a measure of acidity. The low pH in the upper portion of the watershed suggests that most of the streamflow was from groundwater. The high pH (blue dots) in the middle of the river signal that there was an algae bloom underway.
Bacteria:
23% of the samples in South River failed the EPA single test limit of 104 cfu/100ml. While this is much higher than we would like to see, it is a significant improvement from last year, when it rained the day before the Snapshot. In 2007, over 50% of the samples failed the EPA criterion, and 7 samples were greater than 500 cfu/100ml. This year, no samples were above 500. This is further evidence that stormwater is a big contributor of bacteria in our area. Read more about bacteria testing.
Turbidity:
Turbidity is a measure of water clarity. Clear water has low turbidity, while murky or cloudy water has high turbidity. The turbidity readings from this year’s Snapshot were remarkably better than last year’s, primarily due to the fact that there had been no rain for nearly a week. Again, this shows that the creeks and streams are in much better shape when not impacted by stormwater.
Nutrients:
Nutrients are essential to all plant life within the Bay, but an excess of nutrients can be harmful. They stimulate algae blooms which block sunlight and consume dissolved oxygen. The two types of nutrients measured for the Snapshot are nitrate and phosphate.
Nitrate:
Primary sources of nitrate are septic systems, atmospheric deposition (from vehicle emissions and power plants), pet waste, and runoff. This year’s Snapshot recorded very low levels of nitrate in the upper headwaters of the South River. The highest levels were found near the mouth of the river, where nutrients may be coming in from the Bay, and the urban areas in the Church Creek drainage.
Phosphate:
Contrary to the nitrate readings, the phosphate levels at the mouth of the South River were very low. The highest reading was again in an urban drainage area of Church Creek. Potential sources of phosphate are fertilizer, detergents, and eroding streambanks.
Visual Assessment:
Volunteers rated 7 parameters on numeric scale to give a total score for the visual assessment of each site. These parameters included factors such as vegetation, bank stability, and buffer width. The two “pockets” of poorly rated sites were in the heavily developed area between Annapolis and Edgewater, and in the rural areas in the eastern part of the watershed.
Litter:
58% of the sites were rated as having “little” or “common” litter or trash. 42% of sites were recorded as having no litter. The most litter was found in the urban Annapolis area and the more rural sites.
Overall Score:
The overall score was generated using the scores for bacteria, nitrate, phosphate, turbidity, visual assessment, and litter. The average score for this year’s Snapshot was 2.2 (on a scale of 1 – 5, with 1 being the best). This represents an improvement from last year’s average of 2.5. The improvement is likely due to the fact that there was no rain prior to the Snapshot this year, and thus the creeks and streams were not affected by stormwater runoff.
Info provided by Chris Trumbauer, Volunteer Snapshot Coordinator.
