Between 2000-2010, more than 14,005 sites were sampled and rated for biological integrity. The average stream health scores in a subset (10,492) of these of these sampling locations indicated that:
Average 2000-2010 Stream Health in the Chesapeake Bay Sub-watersheds May 29 2013 / Download
Average 2000-2010 Stream Health in the Chesapeake Bay Watershed Jun 25 2012 / Download
Peter Hill and Stephen Reiling from the District Department of the Environment take us on a tour of two successful stream restoration projects in Washington, D.C., and explain why controlling polluted stormwater runoff from cities is so important to Chesapeake Bay restoration.
Closed captions: http://www.youtube.com/watch?v=ToijHlsv9y0
Produced by Steve Droter
An effective way to measure the health of freshwater streams and rivers is to study the many tiny creatures that live in these waters. The abundance and diversity of snails, mussels, insects and other bottom-dwelling organisms – known as benthic macroinvertebrates – are good indicators of the health of streams because these creatures can’t move very far and they respond in certain predictable ways to pollution and environmental stresses.
A healthy Bay watershed would have a majority of streams ranked as fair, good or excellent. Some generalizations about the health of the watershed’s streams can be made:
Healthy freshwater streams are intrinsically linked to a healthy Chesapeake Bay. The watershed’s streams, creeks and rivers eventually flow into the Bay, so their water quality has a direct affect on the entire Bay. Clean local waterways also support a diversity of fish and wildlife and are essential to residents who use them as a source of drinking water and recreational activities.
In general, it can be said that a healthy Bay watershed would have a majority of streams ranked as fair, good or excellent. The Strategy for Protecting and Restoring the Chesapeake Bay Watershed includes a goal to improve the health of streams so that 70 percent of sampled streams sites throughout the Chesapeake watershed rate fair, good, or excellent as measured by the Index of Biotic Integrity by 2025.
Data Collection for this Indicator
Only data collected in a random design (10,492 sites) were used for the analysis portrayed in the pie chart and the static map that shows average B-IBI ratings in Chesapeake Bay Sub-watersheds. Of those 10,492 sites, between 2000 and 2010:
An dynamic map, available under the “Map” tab above, portrays data from 14,005 sites (including the 10,492 random sites and 3,513 targeted-sampling-design sites).
Health of streams was evaluated by the Chesapeake Bay Basin-wide Benthic Index of Biotic Integrity (B-IBI), which was developed from benthic macroinvertebrate data collected across the entire Chesapeake Bay watershed.
Most monitoring programs in the Bay watershed collect benthic macroinvertebrate samples with somewhat similar field methods and calculate a common suite of indicators from the data. However, the programs use state-specific protocols to score and evaluate these indicators to identify “impaired” waters for regulatory requirements that are not comparable across state lines.
The purpose of this indicator is to evaluate benthic community health in non-tidal streams and wadeable rivers in a uniform manner and in the context of the entire Bay watershed. The index is one of several Chesapeake Bay Program analytical tools applied to multi-jurisdictional monitoring data for watershed assessments.
View detailed information about the approach used to develop this stream health indicator.
In the 2000-2010 period, some state monitoring programs (most notably Pennsylvania and New York) collected data from many sampling sites identified as “targeted” (such as sites below an outfall of a pollutant source) and these data were not included in the map averaging scores across the watershed to avoid the presumed bias introduced by targeted site data. Watershed ratings in Pennsylvania and New York are therefore less certain because they are derived from fewer random/systematic sites.
These results show a clear link between the watershed-wide B-IBI scores and land-based activities in individual watersheds.
Stream and River Pollution
There are many different causes of stream and river pollution across the Bay watershed. Benthic macroinvertebrates are generally harmed by pollutants such as metals, acidity, sediment, pesticides, nitrogen and phosphorus. These pollutants come from sources such as mining, agriculture, urban and suburban runoff, automobile and power plant exhaust, and wastewater treatment facilities.
Additional Water Quality Assessment Reports
This indicator is only one example of stream health assessments. Indicators, including water quality and physical in-stream and watershed health parameters, are also used by organizations to characterize stream health.
See the following links for information about other selected stream health assessments produced by Bay Program partners:
The adhoc workgroup that guided the development of this improved indicator deemed it appropriate for regional assessments of benthic macroinvertebrate health. The group also identified the following future work to improve upon the indicator: