Bends and Banks: Sensitive Species in a Restored Stream Site

The Stream Valley Drive subwatershed lies within the Rock Creek Watershed. In the Stream Valley Drive tributary, historic agricultural practices, a power line crossing, and road crossings had increased stormwater flow damage in the stream such as bank erosion, and increased sediment problems. It had also incised the stream’s channel-bottom, and degraded instream habitat for fish and other creatures.

Today we went back to the Stream Valley Drive stream to evaluate how successful its 2004 restoration project has been in bringing back biological life. In 2004, DEP completed restoration on 2,380 feet of the stream at a cost of approximately $250,000. The restoration project’s goals were to:

Protect stream quality of an important headwater tributary to Rock Creek

Stabilize eroding stream banks

Enhance a riparian buffer

Improve fish passage

Enhance floodplain access

Establish vernal pools

Improve instream aquatic habitat conditions and

Restablish a stable historical channel

The large boulders (rip rap) are used to stabilize the bank and prevent additional erosion.

Rock installed at the toe of the stream bank slope stabilized the stream channel where it has erosive stresses from fast-flowing water. The slopes above the reinforced toes were graded back to create new floodplain terraces. During high flows the water could loose its erosive energy by spreading out over these floodplain terraces. The restoration project returned the stream to its original, gently meandering path, and installed rock weirs which created pools for additional wetland habitat.

Cross Vanes (lines of stone or logs which are carefully laid down at an angle) were incorporated into the restoration sections, to help turn the flow of water toward the center of the stream.  These vanes channel fast-flowing water away from the banks which prevents erosion and maintains stream bed elevation. 

Meghan looking at a log cross vane, it helps to direct flow away from banks and towards pools. These pools are critical fish habitat.

A good part of our post-restoration monitoring focused on the stream station. While assessing habitat, we saw some evidence that the stream restoration was working well – the stream appeared to have more natural bends and flow and the banks appeared stable in areas were rip rap was placed.

Biologists examining whether the rock cross vane functions adequately.

Just as we did at the created wetland, we looked at the biological indicators to tell us the full story on the success of the restoration project. We observed some benthic macroinvertebrates (aquatic insects, worms, crustaceans, and mollusks) as well as salamander reproduction which were particularly encouraging. We observed both larval northern two-lined salamanders and northern two-lined salamander egg masses when we collected our benthic macroinvertebrate sample.

Stream salamander eggs attached to the bottom of a rock that was sampled during benthic macroinvertebrate collection. The presence of eggs and larvae tell us that the water quality is good enough to allow for successful reproduction in this restored stream.

 The benthic macroinvertebrate sample will be processed back at the lab and compared to the pre-restoration sample and other post-restoration samples to examine how the community has changed over the life of the restoration project.

Stonefly larvae in the family Perlidae. Stoneflies are one of the most pollution-sensitive benthic macroinvertebrate groups. This stonefly's presence indicates that the water quality is good.

Overall, we had another great day out in the field, seeing indications of some level of success at this restoration site, collaborating with colleagues, and enjoying the sights and sounds of springtime. 

 

Spring Beauty: One of the wildflowers we encountered at the restoration site.

To learn more about the Stream Valley Drive Restoration Project, please see the Stream Valley Restoration Fact Sheet.

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Life is Thriving at a Restored Stream Site

Restoration monitoring  is one of our main jobs as County aquatic biologists.  Following stream restoration, where the shape, channel, and habitat of a stream has been historically damaged (usually by destructively fast-flowing stormwater in urban areas), we monitor the site to assess whether the restoration efforts have been effective in reaching their stated goals (which can include: whether biological life is thriving again, and whether stream life is recovering).

The project we visited today is in the Rock Creek watershed.  As part of the restoration, wetlands were artificially constructed into the stream’s floodplains.  This is critical habitat for frogs, salamanders, and toads, particularly in their reproduction phase.

A man-made wetland pool at a stream restoration site in Gaithersburg

 Although stream conditions in the Upper Rock Creek watershed tend to be good to excellent, the Stream Valley Drive tributary was suffering from development impacts resulting from historic agricultural practices, a power line crossing, and road crossings. These impacts caused the stream to experience increased stormwater flows, erosion, high sedimentation, incised channels, and degraded stream habitat. Important forest and floodplain habitat was also lost.

We visited the site to evaluate one of the man-made wetland pools, assess stream habitat, and collect a benthic macroinvertebrate sample to use as an indicator of water quality.  This is the last time this site will be monitored and it marks the fifth year following restoration activities. 

Environmental scientists gathering data from the edge of the restored, created wetland.

The man-made wetland pool we were monitoring was alive with activity! Before arriving at the pool, we could hear the calls of northern spring peepers! We also heard several calling birds: downy, red-bellied, and pileated woodpeckers, Carolina wren, and tufted titmouse, among others. We even caught a glimpse of the red-bellied and pileated woodpeckers actively in search of food amongst the treetops.

Once at the pool, we began collecting data on the conditions of the pool and the animals and plants associated with it. The first thing noticed were over a thousand tadpoles throughout the pool – and we were thrilled!

Underwater shot of the tadpoles in the man-made wetland pool captured by Jenny. How neat is it to see the tadpoles schooling like fish for protection?

We captured a few of the tadpoles to confirm what species were present in the pool. The representatives we caught were all toad tadpoles. 

A closer view of one of many tadpoles observed at the restoration site. Although tiny, we could tell it was a toad tadpole based on the body, coloration, and tail shape.

 While examining the wetland pool we also found several spotted salamander egg masses! It is a great sign to see that this pool is being utilized by this very sensitive species. Spotted salamanders require seasonal pools for successful breeding, and the pools must have good water quality and remain wet long enough for the larvae to develop. Additionally, the adults retreat to upland forested habitat following breeding so this component must be present as well. Spotted salamander egg masses have been observed every year of monitoring following construction of the wetland pool, telling us that installation of this particular pool was successful. We did not take any pictures of the egg masses at this site because they were too far from the water’s edge to capture a clear photograph. We wanted to minimize disturbance to the pool so we did not enter it.

As we continued to examine the pool, we got on our hands and knees and peered closer into the pool and found many invertebrates that told us the pool is doing well – copepods, predaceous diving beetles, and water striders. These invertebrates were too quick and small to get a picture of this time!

 In addition to examining the pool itself, we looked at the area surrounding the pool. The majority of the trees and other vegetation appeared to be fairing well.

A tree planted as part of the restoration at the Stream Valley Drive Project. The tube at its base stabilizes it and protects it from hungry deer and other wildlife

 As part of our assessment, we also searched for adult amphibians and reptiles around the pool’s edge by looking under cover objects such as logs and rocks. In doing so, we found another treat – a young northern brownsnake!

The northern brownsnake we caught was just as interested in observing us as we were in it. Its tongue was constantly flicking to pick up smells and gather information while Rachel snapped pictures.

 Northern brownsnakes are a fairly common species of snake that feed primarily on earthworms. This species is very docile and does not bite when captured. They also very rarely musk (release a foul smell from their cloaca), so they are great ambassadors to folks who may be leery of snakes. Although relatively common, we do not encounter them very frequently and were excited to see another animal contributing to the biodiversity of the site and using the restored habitat.

Rachel examining her catch -- a young brownsnake

 

Jennifer St. John with a brown snake

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Vernal Pools

Here’s what a seasonal pool looks like.  They’re often just depressions and natural wet spots that fill with water in the wet spring, in forested areas.  They’re all over the landscape, near streams, in forests.  The majority of amphibians and reptiles live in and around streams, or in these seasonal pools.  These seasonal pools often dry up in the heat of the summer.  But in the springtime, they are a key wildlife habitat, and provide critical breeding grounds for our amphibians and reptiles.

seasonal wetland pool in early spring

We’re finding a number of calling frogs such as wood frogs, northern spring peepers, pickerel frogs and toads, as well as spotted salamanders, out this time of year. We’re noting their numbers, and looking for any anomalies on their bodies.

  The presence of adult frogs and salamanders doesn’t offer a complete assessment. We’re also searching pools for signs of successful breeding, such as egg masses or larvae, to make sure these species are surviving. Some spotted salamanders often return to the same pool annually for several years to breed…and they can live over 20 years.

Looking for tadpoles in a vernal pool 

These pools are critical in the stream network. Pools are also a key wildlife habitat, and they are critical for breeding success. 

When monitoring frogs and salamanders, County biologists follow strict protocols to sanitize boots and equipment to minimize the risk of introducing diseases, pathogens and invasive species into the seasonal wetland pools.   

Tadpole Detail in a vernal pool

 These tadpoles have hatched from the egg masses within the past week. 

Interested in looking for vernal pools and their frogs and salamanders?  Please help maintain the ecological balance of pools by staying out of the pools and their surrounding moisture zones.  Interested residents can check with the County’s nature centers about guided walks and educational materials on seasonal pools and their wildlife.  Visit: ww.mcparkandplanning.org/Parks.

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