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Howard's Branch (HB-01 and HB-02)

About the site:

There are two stations located in the study area on Howard's Branch, bracketing a reach restored in 2000 using a wetland seepage system approach. Sampled since 2007, the data collected are all post-restoration. Impervious surface levels are low, with about 9% found in the drainage area of site HB-01 and about 10% found upstream of HB-02. Typical of the wetland seepage system approach, very large and deep pools are present throughout the restored system making it very difficult to sample using standard County bioassessment techniques because the reach is very deep in some areas.



2018 Summary Report:

Site HB-01
Time FrameBIBI (Condition)FIBI (Condition)RBP (Condition)
2018 Results2.43 (Poor)3.00 (Fair)114 (Partially Supporting)
Cumulative Average (2007-2018)2.56 (Poor)2.55 (Poor)125 (Partially Supporting)
3-year Running Average2.72 (Poor)2.67(Poor)132 (Supporting)
Site HB-02
Time FrameBIBI (Condition)FIBI (Condition)RBP (Condition)
2018 Results2.14 (Poor)2.33 (Poor)124 (Partially Supporting)
Cumulative Average (2007-2018)2.64 (Poor)2.78 (Poor)127 (Supporting)
3-year Running Average2.14 (Poor)2.33 (Poor)136 (Supporting)
1) 2105 and 2016 

Benthic IBI: 

Site HB-01: Located just downstream of the restoration project, the 2018 BIBI was 2.43, in the Poor range. This is lower than the 2016 score of 3.00 in the Fair range. This score is also lower than the cumulative average (2.56) and the three year running average of 2.72. It is unclear for now why this score was obtained, but it is hopeful that the 2019 BIBI score is synonymous with the average results or even higher. The 2018 composition of insects includes chironomids making up majority of the sample and craneflies, clams, and caddisflies about 6-7% each. These amounts are synonymous with 2017 results, except that 2018 had less oligochaetesand more craneflies.

HB-01 Sample of Insects Collected by Sample Year

CY01 Bugs
Click to enlarge

Site HB-02: Located approximately 500 feet upstream of the restoration project area, the 2018 BIBI was in the Poor category at 2.14. Similar to HB-01, benthic macroinvertebrate community conditions appear to be declininghere as the current BIBI score is lower than the cumulative average (2.64) and the three-year running average (2.14).The insect summary for this site shows a strong spike in chironomid  presence (from ~25% in 2017 to almost 35% in 2018) and moderate numbers of riffle beetles, craneflies, and caddisflies.HUnlike HB-01, this shift in chironomid occurrence has occurred in other past samples. The number of clams in 2018 also decreased from approximately 37% in 2017 to 7%.

HB-02 Sample of Insects Collected by Sample Year

CY01 Bugs
Click to enlarge

Fish IBI:

Site HB-01The fish community shows some improvement since 2016, with the FIBI measured at 3.00, or Fair. A total of 110 fish, representing five species, were collected in 2018. Fish found in 2018 include the golden shiner, American eel, pumpkinseed, brown bull head, and the eastern mosquitofish. These same species of fish were found in 2016.

Site HB-02The 2018 FIBI received a score of 2.33, which is in the Poor range. This is the same score from 2016. Species observed in 2018 include golden shiner, American eel, pumpkinseed, brown bullhead, and eastern mosquitofish. The same assemblage of species was observed in 2016.

Physical Habitat: 

Site HB-01RPB conditions also appear to be declining. The 2018 score of 114 (Partially Supporting) was lower than the 2017 score of 138 (Supporting).Scores in epifaunal substrate, sediment deposition, and channel flow status contributed to the overall evaluation. The cumulative average and the three-year running average were125 and 132,, respectively, so the ultimate trajectory in habitat condition is unknown at the present time. Channel cross section conditions are relatively stable. The 2018 measurement shows about a one-foot increase in stream bottom elevation over the 2017 measurement, indicative of a pulse of sediment delivered to the system. Continued measurements will provide insight into stability conditions at this site. This reach is classified as a Rosgen E5 stream type.

HB-01 Cross Section Comparison 

Cross Section
Click to enlarge

Site HB-02Habitat conditions here were  strong in 2018. The site received an RBP score of 124 (Partially Supporting).Scores for pool variability, channel flow conditions, and channel alterations contributed to this outcome Habitat conditions in 2018 have been similar to the cumulative average score of 127 (Supporting), but much lower than the three-year running average of 136 (Supporting).

Geomorphically, this reach has experienced some meaningful changes recently. The 2018 measurement shows that the channel filled with  sediment compared to the 2016 and 2015 measurements. The surrounding floodplain between the monuments also shows classic near channel aggradation associated with a high sediment supply system (Malanson 1993). The on-going impact of this sedimentation is unclear, but excessive sediment is known to decrease the occurrence of sensitive species in stream systems (Waters 1995). This aggradation has possibly contributed to the lowered BIBI score of 2018. Also observed here in 2018, was that the upstream portion of the site was beginning to become braided and expanding. It was due to this that a depression of water was found when extending the right monument, as portrayed by the graph below. It is likely that this second depression following the original stream will be measured in future years. This reach classifies as a Rosgen E5 stream type.

HB-02 Cross Section Comparison 

Cross Section
Click to enlarge

Historical Data Summary:

YearBIBI (Condition)FIBI (Condition)RPB (Condition)
20071.86 (VP)---110 (PS)
20082.43 (P)---116 (PS)
20092.14 (P)---120 (PS)
20102.71 (P)---138 (S)
20112.71 (P)---123 (PS)
20122.71 (P)---127 (S)
20132.43 (P)---119 (PS)
20142.71 (P)---131 (S)
20153.00 (P)2.33 (P)123 (PS)
20163.00 (P)2.33 (P)143 (S)
2017------138 (S)
20182.43 (P)3.00 (F)114 (PS)
YearBIBI (Condition)FIBI (Condition)RBP (Condition)
20072.14 (P)---99 (NS)
20082.71 (P)---134 (S)
20092.71 (P)---115 (PS)
20103.57 (F)---134 (S)
20113.00 (F)---134 (S)
20122.14 (P)---136 (S)
20133.86 (P)---126 (S)
20142.14 (P)---117 (PS)
20153.00 (F)3.67 (F)125 (PS)
20163.29 (F)2.33 (P)144 (S)
20171.00 (VP)---140 (S)
20182.14 (P)2.33 (P)124 (PS)
All Station Summary
 Average BIBI (SD)3-Year Average BIBI (SD)Average RPB (SD)3-Year Average RBP (SD)
HB-012.56 (0.35)2.72 (0.40)125 (10)132 (16)
HB-022.64 (0.78)2.14 (1.14)127 (13)136 (11)

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