Tales of Stream Monitoring Fun
Lake Accotink Park
Friends of Lake Accotink Park
Friends of Accotink Creek

Friends of Accotink Creek and Friends of Lake Accotink Park hold biological stream monitoring workdays four times per year.
Thanks to all the volunteers who have joined us for this important data-collecting activity!

December 12, 2015 Stream Monitoring:

Thirteen volunteers gathered under exceptionally mild December conditions. Our group was a mix of students, Master Naturalists, biologists, and Accotink enthusiasts.

We were pleased that our first net yielded a large enough catch to meet the minimum of 200 invertebrates. In fact, we almost doubled the minimum, with a total of 399. Our finds were limited in number of species however, consisting almost entirely of impairment-tolerant netspinners and aquatic worms, plus a handful of midges and a couple leeches.

As usual, Accotink Creek received a numeric stream health score well down in the unacceptable range, 4 on the scale of 12. The Master Naturalists related a recent monitoring experience on a local stream which scored a 12, sending waves of envy pouring over those who must content themselves with the condition of poor old Accotink Creek.

Our September 12, 2015 Stream monitoring:

Drizzle & sputtering rain threatened to wash out our monitoring session, but at no time became heavy enough to discourage the volunteers.

A Channel 16 video crew spent some time wandering about in search of our location before joining us in connection with the Elly Doyle Award Friends of Accotink Creek will receive in November.

The creek was rather low after long weeks of unusually dry weather. Our catch was dominated by netspinner caddisfly larvae, a species tolerant of impaired waters. One unusual find was a damselfly larva. Our nets also caught numerous prematurely fallen leaves and much algae, complicating the search for invertebrates. Encouraged by the wet weather, many critters tried climbing out of the ice cube trays.

As usual, Accotink Creek scored in the "unacceptable" range, with a 5 on the 0 - 12 scale of stream health.

Sediment resulting from excess runoff from paved surfaces is the major factor degrading the health of our creek. Spare a thought for Accotink Creek in your land use decisions.  

Mussel Rescue June 23, 2015:

Heavy downpours sent the USGS stream gauge on Accotink Creek at Braddock Road above 2000 cubic feet per second June 21st. This flow volume is enough to push freshwater mussels out of the creek and leave them stranded on the banks and gravel bars. Allowing two days for the water level to drop sufficiently, we set out to rescue stranded mussels on the afternoon of the 23rd.

We found eleven stranded mussels and returned them to the creek. We concluding our search just before another thunderstorm rolled in. Freshwater mussels are found only in a remnant population in a short stretch of Accotink Creek just downstream from the dam.

See the rest of the mussel rescue photos here.

Learn more about freshwater mussels.

Our June 13, 2015 stream monitoring:

We enjoyed a sunny warm day for our stream monitoring session. Invertebrates were in abundance, as we caught 1110 with a single net, an unusually high number. It was quantity without quality, however, as 87% of the invertebrates were common netspinner caddisfly larvae, a species tolerant of impaired water conditions. All the other invertebrates we collected were also tolerant species. One nice surprise was a tiny crayfish, something we don't often see here.

In addition to our standard monitoring, today in collaboration with Audubon Naturalist Society, we invited our guests to try out the new Creek Critters smartphone app. The app guides users through the steps for sampling stream invertebrates and reporting results.

The scoring formula gave Accotink Creek a rating of 6 on a scale of 12, which is down in the "unacceptable" range. The score was nudged upward from our usual 4 by the high percentage of insects (netspinners).

Erosion and sediment caused by paved surface runoff are what are holding Accotink Creek down by making life difficult for the vital invertebrates at the base of the food chain.

Monitoring Flag Run, March 26, 2015:

Flag Run is the beleaguered tributary of Accotink Creek which enters Lake Accotink right next to the marina. Gathering some data seemed like a good idea in anticipation of the master plan revisions later this year for Lake Accotink Park.

We endured off and on showers for our morning of monitoring. Water was rising in Flag Run, but not so high that we were unable to carry on.

Periodic high water flows that scour the bottom and deposit smothering sediment, however, 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 nowhere near the minimum number of 200 invertebrates needed for a meaningful count. The abundance of invertebrates was so pitiful one of the nets had exactly zero.

The nearby industrial park just upstream is also a suspect in the poor condition of the stream, as there may be unknown contaminants in the runoff.

Flag Run achieved a sad numeric health score of 1, far from the acceptable range.

See the monitoring results here.

Our March 21, 2015 stream monitoring:

High water forced rescheduling from our original date of March 14.

The creek was still a bit high and muddy after light rain and snow the day before, but it was a fine day of biological monitoring along Accotink Creek.

One net wonder! - An uncommon bit of luck enabled us to collect more than the minimum 200 invertebrates with only one net.

But it was quantity without quality today, as a full 80% of our catch was one single species, the Common Netspinner caddisfly, a species tolerant of poor water quality. We did have an unusual catch of three aquatic beetles.

As usual, Accotink Creek achieved a biological health numeric score of 4, in the unacceptable range.

Back to our main Monitoring Page