St. Mary's River Watershed Association urges watershed restoration action strategy after long-term monitoring shows summer low-oxygen events

The St. Mary's River Watershed Association presented data from more than a decade of monitoring showing recurring summer low dissolved-oxygen events and reduced water clarity in the St. Mary's River and urged the county to join a two-year watershed restoration action strategy (RAS) to compile past studies and set restoration priorities.

Bob Paul (St. Mary's River Watershed Association) and Joe Anderson (chair, St. Mary's River Watershed Association) told the planning commission the association has collected multi-year data at numerous tidal and non-tidal sites since 1999 and that the evidence points to land-use runoff and episodic high-precipitation events as the primary drivers of algal blooms, sediment loads and summer bottom-water oxygen depletion. Paul said the association’s work shows the river has “depressed oxygen down here in the bottom part of the river” during summer months and that secchi-disk measurements frequently fall below a one-meter threshold that limits light penetration and harms submerged aquatic vegetation.

Why it matters

Paul said the watershed is large (about 45,000–46,000 acres) and contains roughly 84 miles of tidal shoreline and more than 300 miles of stream channels. The association samples many small tributaries because sediments and nutrients from those streams are ultimately delivered to the tidal river. The group said the pattern of high spring runoff followed by summer algal growth, subsequent die-off and decomposition leads to low oxygen at the bottom and harms oysters and other bottom-dwelling organisms.

Recommendations and next steps

The association proposed the county sponsor a Watershed Restoration Action Strategy (RAS) for the St. Mary’s River, modeled on the Breton Bay RAS and expected to take about two years to complete. The RAS would compile disparate prior studies (DNR, Army Corps, colleges, state agencies), set community-level loading caps, and recommend land-use, stormwater, buffer and retrofitting priorities. The presenters said they had already begun initial organization and sought a partnership among the county Department of Land Use and Growth Management, St. Mary's College, citizen groups and state agencies.

The association also pointed to a recent U.S. EPA Office of Inspector General report (dated Sept. 10, 2007) warning that new development is increasing nutrient and sediment loads faster than restoration efforts are reducing them; the association used that finding to argue for more proactive watershed-scale planning and funding for on-the-ground stormwater and buffer practices.

Commission response and follow-up

Commissioners asked for the presentation slides and for follow-up on how the RAS would be resourced and coordinated with the county’s comprehensive-plan update. Paul and Joe Anderson said the association would participate in the comprehensive-plan process and provide the data and recommendations. Staff offered to circulate the presentation slides and the cited EPA inspector-general report to commissioners and agreed to discuss coordination with the comprehensive-plan update.

Sources and attribution

This article summarizes the presentation given by Bob Paul and Joe Anderson for the St. Mary's River Watershed Association and the subsequent Q&A with planning commissioners and county staff during the planning commission meeting. Direct figures and quotations come from the association's presentation and the meeting transcript.