R ES E A R C H Open Access
Water quality impacts of small-scale
hydromodification in an urban stream in
, Daniel S. Smith
, Anthony P. Benaquista
, Dylan M. Rossi
, Betsy M. Kadapuram
, Man Lok Yu
Andrew S. Partlow
and Nathan R. Burtch
Introduction: Construction activities in and along urban streams increase the sediment input into surface waters,
causing an overall decline in water quality and aquatic ecosystems. In this case study, we investigate the water
quality impacts of local hydromodification in an urban stream (discharge 0.4 m
/s). At the site of interest, workers
removed a stream crossing consisting of an embankment with culverts and replaced it with a small bridge (single
span of 25 m) in an effort to improve flow capacity.
Methods: Water samples were taken at four sites along the North Branch Park River in Connecticut, Northeastern
United States. Turbidity and dissolved oxygen (DO) were measured in situ, and nitrate and total phosphorus (TP)
were measured in the laboratory. Benthic macroinvertebrate samples were also collected and analyzed for taxon
richness and Shannon-Weaver species diversity. Data were compared between upstream and downstream sites and
before, during, and after hydromodification. We used one-way ANOVA combined with the post hoc Turkey test to
derive statistical significance.
Results: During construction, turbidity increased temporarily by 60.9% [from 2.48 Nephelometric Turbidity Units
(NTU) over ambient to 4.00 NTU]. Once construction was completed, DO increased locally from 11.0 to 13.0 mg/L.
Benthic macroinvertebrate taxon richness and species diversity declined by 61.6 and 32.6% respectively, with no
recovery observed in the year following construction. Water quality was only affected within 50 m downstream.
Nitrate and TP concentrations were unaffected.
Conclusions: Small-scale hydromodification temporarily increased the turbidity as a result of increased sediment input,
approaching the maximum level for clean water (5 NTU). Benthic macroinvertebrate communities declined in the immediate
downstream vicinity of construction but are expected to recover soon given that turbidity recovered to pre-construction
levels, and DO increased. These outcomes emphasize that environmental assessment is important not only for large-scale
hydromodification but also for smaller scale stream modifications.
Keywords: Urban streams, Pollution, Hydrologic services, Water quality, Benthic macroinvertebrates, North Branch Park River
* Correspondence: firstname.lastname@example.org
Department of Biology, University of Hartford, 200 Bloomfield Avenue, West
Hartford, CT 06117, USA
Full list of author information is available at the end of the article
© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made.
Zhu et al. Ecological Processes (2018) 7:11