The Question
Dear Colleagues-
StreamWatch, working in Central Virginia and using a famil-level benthic IBI, has developed a region-specific population density/stream health model that predicts "very poor" benthic health for streams draining urban catchments (urban = population > 1,000 per square mile). At a recent presentation to local decision-makers, our City Manager mentioned some "urban" streams he knew of that supported trout populations (Boulder, CO and Durango, CO), and wondered why these cities had "healthy" streams while our city does not. We didn't have time to discuss all the potential differences between cases, (fish versus bugs, cold water versus warm water, population density of the entire catchment versus proximate density, etc.), but his question does prompt me to ask if any of y'all are aware of any truly urban* streams that support healthy** benthic communities.
*urban = > 1,000 humans/sq mile throughout entire watershed draining to sample site
**healthy = supports state's aquatic life standard, measured by benthic samples
Any info would be apprecitated.
John Murphy, Director
StreamWatch
johnmurphy@streamwatch.org
office: (434) 923-8642
cell: (434) 242-1145
Responses
Hi John
I know of a program here in the Minneapolis metropolitan area that monitors the Vermillion River in the SW metro county of Dakota. The Vermillion is managed for trout and volunteers routinely find some of the best macroinvertebrates for the 7 county metro area (also id'd to Family level). I can't be certain if it qualifies for your definition of "urban" but I thought I'd pass along the info. Laura Jester as the Dakota Soil and Water Conservation District would be the person to contact for more information.
http://www.dakotacountyswcd.org/rivers/vrwintro.html
Mary Karius
Hennepin County Environmental Services
612-596-9129
mary.karius@co.hennepin.mn.us
Hi, John,
Here in the East Bay area of San Francisco, we have at least a couple of streams that meet your definition of urban and have healthy rainbow-trout populations -- Codornices and Sausal Creeks. You can find out more about them with a web search on those names, or on Friends of Five Creeks (my group, www.fivecreeks.org) or Friends of Sausal Creek (www.sausalcreek.org). There is some recent BMI and other monitoring information for Codornices on the website of Urban Creeks Council, http://www.urbancreeks.org/CCWRAP_Monitoring_FINAL.pdf. California does not have a single standard for benthic macroinvertebrates. The BMI data above and other findings on similar streams (e.g. in Contra Costa, the next county north), indicate fairly low diversity and dominance by pollution-tolerant taxa. The creeks mentioned, as well as other local creeks with rainbow trout/steelhead or even salmon (but which don't quite meet your definition of fully urban), receive significant amounts of chloraminated water from gardens and from main breaks (a common occurrence in our geologically active area). They also receive the usual residential runoff, including the occasional hosing of concrete waste or soap into storm drains, etc. Thus, it seems to me that there is nothing about urban runoff that intrinsically makes it impossible to have water quality good enough for healthy fish populations.
Susan Schwartz
Friends of Five Creeks
There is a small unnamed stream whose watershed lies completely within Baltimore City which supports a diverse benthic macroinvertebrate community, including stoneflies. The watershed of this stream is almost entirely forested by wild parkland, although it is surrounded by dense urban development. The stream is intermittent and periodic.
Michael Schenk
schenkmj@earthlink.net
Yes, I have seen some healthy urban streams...
There is a stream in central Auckland (New Zealand) that supports very high densities of galaxid fish (very sensitive to water quality) and diverse benthic invertebrates. The catchment is high density
residential but the surrounding riparian veg is dense native bush (it's a park through the area). Most of the streams in Auckland are pretty sad...
Christchurch is repairing their streams by re-establishing healthy riparian communities and naturalising the stream structure. The benthic communities appear to be responding.
I personally think refuge areas are extremely important. Root masses, gravels, tributaries, backwaters.... anywhere the greeblies can escape to and recolonise after disturbance events. Outside of that, they need food and moderately clean water. (I think most bugs can tolerate fairly wide swings in water quality under normal conditions).
Phil Ross
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Updated
Tuesday, 07-Oct-2008 17:10:52 CDT
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