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Tales of Stream Monitoring Fun
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Friends of Accotink Creek and Friends of Lake Accotink Park hold biological stream monitoring workdays four times per year. |
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December 19, 2018, Mussel Rescue: Near midnight on December 15, 2018, the USGS stream gauge at Braddock Road went above 2000 cubic feet per second, sending us the signal that a mussel rescue would be needed. Conditions were chilly, with a lingering film of ice on puddles, but otherwise the weather was sunny. Our first rescue of the day was not a mussel, but a Save Lake Accotink sign ignominiously deposited in a trash bin. Cleaned off, it will see service again when the Lake Accotink bond issue goes before voters.
Although the number of mussels we rescue each time is not large, we hope each rescued female is a potential mussel Madonna, bearing hope of a Nativity of hundreds or thousands of progeny to keep the population viable. See the rest of the mussel rescue photos here. Read about our 2015 freshwater mussel biological survey. Learn more about freshwater mussels.
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 Read it and weep - Our pitiful invertebrate tally sheet |
December 8, 2018, Stream Monitoring: Conditions were chilly, but fine for monitoring. Both water and air temperature were at 37 degrees. The weather was sunny, but gloomy black clouds hung over the monitoring results. Each of the nets we collected could be seen at a glance to be ominously devoid of the wriggling and creeping activity that draws our eyes to the invertebrates we've caught. Even after collecting the maximum of four nets, we collected only 84 invertebrates, far from the minimum of 200 required for a valid sample. All the invertebrates collected were of species tolerant of impaired waters. We may speculate on the reasons for such a poor catch of invertebrates. Sometimes, an element of luck is involved, with one net having many invertebrates while another from a few feet away has only a few. The bed of the creek seems to have changed since our last monitoring session in October, deeper riffles and a bottom composed of larger stones and less gravel. Also, we are still transitioning to a new standard method of stirring the stream bottom with raking instead of shuffling through the gravel doing the "stream dance". We shall have to hope today's results were a fluke, rather than a trend. Accotink Creek's numeric health score was only 3, far from the acceptable range. See the tabulated results here.
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October 13, 2018, Stream Monitoring: We postponed our fall monitoring date from September 8th due to high water. The water was still high today, but no so high that we were not able to carry on. Fall weather had certainly arrived, with an overcast day not rising to 60 degrees. The invertebrates were fairly plenitful today and we required only two nets to achive the required minimum count of 200 invertebrates. Our catch was dominated by common netspinner caddisflies, a species tolerant of impaired water. We did find a few very small caddisflies of other species not so tolerant. As usual, Accotink Creek scored in the unacceptable range, receiving a 5 on a scale of 0 to 12. Sediment caused by excessive runoff from paved surfaces is the major factor reducing invertebrate populations and impairing the health of streams in our region. See the tabulated results here.
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 Caddisfly and riffle beetle larvae were uncommon species we encountered today. |
 Through the looking glass - a hemispheric magnifier helps to view invertebrates |
Monitoring Flag Run, October 3, 2018: We had a fine day for monitoring, with sunny skies and temperatures in the mid-70's. Flag Run has a stream restoration project scheduled to begin here sometime in the next few weeks. Today was the last of our "before" monitoring samples. We shall return to take "after" samples some time after the project is complete. Even though we collected the maximum of four nets, we were just shy of the minimum number of 200 invertebrates needed for a valid count. We saw many fewer midges than during our May monitoring here, but the abundance of common netspinner caddisflies made up for the lack of midges. We found one single riffle bettle, an ivertebrate indicative of better water quality, but at the same time found 23 lung snails, indicative of low water quality.
Also not counted were the 51 earthworms we collected, since they are not aquatic. The cause of the high numbers is a mystery, as it had not rained for several days. We encountered similarly high numbers in May. Earthworms are distinguished from their aquatic cousins by being considerably larger and fatter. Flag Run achieved a low numeric health score of 3, far from the acceptable range. See the tabulated results here.
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Mussel Rescue August 24, 2018: Yet another storm passed through, rasing the USGS gauge above 2000 cubic feet per second. Waiting two days for the creek level to drop back to near normal levels, we set out once again to rescue stranded mussels. Proceeding from downstream to upstream, we swept the one-mile stretch of the creek below the dam where mussels are still found in Accotink Creek. We found 67 mussels stranded on gravel bars and returned them to the safety of the creek. We know we can't find all the mussels, either because we are not obervant enough to spot each one among the stones, or because some mussels may have already dug down out of sight as they sought to remain moist, or because they were buried alive by the sediment that is pushed along by the surging floodwaters. It is this shifting sediment that has eliminated mussels from the rest of Accotink Creek. Mussel Rescue August 5, 2018: Just days after our previous rescue, the gauge at Braddock Road went to 2000 cubic feet per second, calling for another rescue. On August 5th we found an additonal 65 stranded mussels and returned them to the creek. Mussel Rescue, July 28, 2018: After heavy thunderstorms the previous Saturday, the USGS stream gauge on Accotink Creek at Braddock Road topped out at 6000 cubic feet per second. Any flow rate over 2000 cfs is enough to push freshwater mussels out of the creek and leave them stranded on the banks and gravel bars. Continued rains kept the water too high for effective searching for a full week. At last, a group of volunteers was able to set out to locate stranded mussels. We found a record 256 stranded mussels and returned them to the creek. This far exceeds any previous rescue total. The reasons for the extra high number are not certain. It was a high flow event, but we have seen higher without finding so many stranded mussels. Some of the mussels may have been in the summer sun a little too long, but most appeared to have a good chance of recovery. There was sad evidence of many mussels that were not found in time, their freshly empty shells gaping open on the banks, picked clean by racoons or other foragers. It is unfortunate that we don't have the resources to rescue even more mussels by doing several successive sweeps of the creek as the water recedes day by day. See the rest of the mussel rescue photos here. Read about our 2015 freshwater mussel biological survey. Learn more about freshwater mussels.
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 Nine mussels found stranded on a single gravel bar, all Eastern Elliptio (Elliptio complanata)  Aquatic angels in disguise, mussels open to reveal their pearly wings as they depart this Earth. |
 That's one impressive leech! |
June 9, 2018 Stream Monitoring: We had a full crew of 15 volunteers today, and fine weather, overcast and in the 70's.
Also joining us today was Audubon Naturalist Society for a display of their Creek Critters. stream monitoring app.
We needed only one net to exceed the minimum of 200 invertebrates required for a valid sample. The vast majority were midge larvae, a species tolerant of stream impairment. The rest of our catch was a small selection of other species tolerant of impaired water, such as netspinners, aquatic worms, and blackfly larvae. Leech! One notable find was the largest leech we've ever encountered, four or five times larger than those we usually see. Sharp-eyed young volunteers also found a baby turtle, likely a Red-eared slider, a species native to the Midwest, but now found worldwide as a result of releases of pets. Accotink Creek achieved a numeric stream health score of 6, equal to the highest score achieved in the past, but still in the unacceptable range. This somewhat improved score was not so much an indication of improved stream health, but was more a fluke of the scoring system. Sediment caused by excessive runoff from paved surfaces is the major factor reducing invertebrate populations and impairing the health of streams in our region. See the tabulated results here. Paved surfaces are the nemesis of Accotink Creek's bentic invertebrate population. All the runoff during rainstorms pours down stormdrains and shoots into the creek, scouring away the banks and smothering stream life in fine sediment. The next big insults to Accotink Creek from the I-66 and Braddock Road widenings will only make things worse. Tell your elected officials "Enough!". Take advantage of financial incentives to become part of the solution with Conservation Assistance.. |
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Monitoring Flag Run, May 19, 2018: We had a fine day for monitoring, with sunny skies and temperatures in the upper 60's. Flag Run has a stream restoration project scheduled to begin here in late 2018. Friends of Accotink Creek are gathering some biological monitoring data before and after. The site we monitored is where the first phase of the restoration will be located, very near the source of Flag Run. Even though we collected the maximum of four nets, we did not reach the minimum number of 200 invertebrates needed for a valid count. We did, however, achieve a much higher count than back in March, due entirely to the abundance of midge larvae this time. Flag Run achieved a low numeric health score of 3, far from the acceptable range. See the tabulated results here.
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 Flag Run is a small stream here where it passes under Elgar Street. |
 Stranded mussel bravely struggled on, leaving a trail as it followed the receeding water |
April 18, 2018 Mussel Rescue: On April 15, 2018, the USGS stream gauge on Accotink Creek went above 2000 cubic feet per second, compared to the typical base flow below 20 cfs. This rushing volume of water is enough to sweep freshwater mussels out of the stream channel and leave them stranded on the banks and gravel bars. Sometimes these stranded mussels can extend their single foot and drag themselves to safety - other times they perish in the sun. After the waters had receeded, we set out to find those exposed mussels and return them to the creek. By closing their shells tightly, stranded mussels can survive a few days out of water. We found a total of 52 live mussels. See the rest of the mussel rescue photos here. Read about our 2015 freshwater mussel biological survey. Learn more about freshwater mussels.
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Monitoring Flag Run, March 11, 2018: We enjoyed good conditions for monitoring, with sunny skies and temperatures in the mid-40's. Flag Run is the beleaguered tributary of Accotink Creek which enters Lake Accotink right next to the marina. The Friends of Accotink Creek are gathering some data in anticipation of the stream restoration project scheduled to begin here in late 2018. The site we monitored is where the first phase of the restoration will be located, very near the source of Flag Run. Periodic high water flows that scour the bottom and deposit smothering sediment are a problem for the biology of Flag Run, if our poor results are any indication. Even though we collected the maximum of four nets, we found a pitiful toal of 53 invertebrates, far from the minimum number of 200 invertebrates needed for a meaningful count. The abundance of invertebrates was sad to consider. Even a tiny headwater like this should be capable of supporting a much greater abundance.
Flag Run achieved a sad numeric health score of 1, far from the acceptable range. See the tabulated results here.
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 We found a single caddisfly larva, a species less tolereant of impaired streams. |
 A procession of volunteers makes its way through the woods. |
March 10, 2018 Stream Monitoring: A chilly but clear day with temperatures in the low 40's made for good monitoring conditions for our nine voluneer monitors. We had a record catch of the delicate flatworms today, their tiny white eyespots gazing up at us as they glided along the bottom of the collection trays. We also had a high catch of six riffle beetles today, a level we've not seen for a decade. We also equaled our record of four mayflies, a species that requires higher quality streams. Despite these unusual results, our collection was mostly the usual species tolerant of impaired stream conditions, such as aquatic worms and netspinner caddisflies. Accotink Creek received a poor numeric stream health score of 3 on a scale of 0 to twelve. See the tabulated results here. Paved surfaces are the memesis of Accotink Creek's benthic invertebrate population. All the runoff during rainstorms pours down stormdrains and shoots into the creek, scouring away the banks and smothering stream life in fine sediment. The next big insults to Accotink Creek from the I-66 and Braddock Road widenings will only make things worse. Tell your elected officials "Enough!". Take advantage of financial incentives to become part of the solution with Conservation Assistance.. |
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Accotink Creek Creatures
A lament for aquatic invertebrates penned
GET YOUR BRAIN WET!
Plan now to volunteer again with others to preserve our oceans and waterways Back to our main Monitoring Page
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We had four volunteers, later joined by a fifth little helper, a gingerbread man puppet we found in the creek, truly dressed for the season in the crown and robes of a Magi. The Gingerbread Magi was pleased to be able to rescue a mussel of his own, despite his stubby arms. We found a total of 34 mussels stranded on the banks and returned them to the creek for a much better Christmas than awaited them otherwise.
An unexpected catch today was a salamander larva, still bearing gills. Our best guess as to species is the 
