Volunteers Help Investigate Water Quality in Wenham Swamp

Nancy Sander and Pike Messenger paddle through the Ipswich River Wildlife Sanctuary stretch of the Ipswich River.

We recently investigated a discovery that was first made by a local scientist, Jim MacDougall, having to do with dissolved oxygen in the river. There is a unique section of the river near the Mass Audubon Ipswich River Wildlife Sanctuary known as the Wenham Swamp. The river winds through this large wetland area that offers many scenic vistas from the Sanctuary and is an ideal paddling destination. Wetlands like this also provide excellent habitat for river life, both in the water and surrounding landscape, so this is an important place to study water quality. 

Dissolved oxygen is essential for life in all types of natural water bodies including the Ipswich River. The amount, or concentration of oxygen in the water is not always the same, depending on many things such time of day, time of year and even from one location to another, even within a short distance along a river. We monitor dissolved oxygen on a monthly basis at bridges and similar fixed sites, but a unique pattern was discovered in the Wenham Swamp which can only be reached by boat. Several years ago, a local scientist discovered an abrupt drop in dissolved oxygen while searching for cold water springs where native brook trout might still be found. This surprising discovery was observed more than once leading to questions as to what the cause might be and what this could mean for life in the river. Our concern is that this could slow or prevent passage by other types of fish such as river herring that need to migrate up and down rivers each year. 

Several volunteers recently spent time paddling this section of river while stopping to measure dissolved oxygen at selected sites. The data they collected showed the same pattern of lower dissolved oxygen on the river between Pine Island and the grounds of the former Patton estate on Asbury St. in Hamilton. While we still do not know the exact cause, we would like to know if oxygen levels begin to increase with the change in seasons. Certainly, high river flows will improve dissolved oxygen levels and this is one of the reasons we are working in many ways to insure there is enough clean water for people and wildlife. Volunteer monitors serve a vital role in helping to collect valuable, long-term data on the river in ways that we might not otherwise be able to such as through monthly testing across the watershed or by investigating unique problems like the one in Wenham Swamp. Please visit our website to learn more about volunteer opportunities.

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