West Holland River gets a failing grade

News

Posted By Miriam King

Posted 1 month ago

The Lake Simcoe Region Conservation Authority has released the 2009 update to the Lake Simcoe Watershed Report Card – a summary of the health of all the subwatersheds that feed into the lake, and Lake Simcoe itself.

The Report Card monitors natural vegetation, diversity of fish populations, Benthic invertebrates (aquatic insects and crustaceans), and phosphorus loading.

Natural vegetation prevents erosion, screens out pollutants, provides shade for aquatic species and habitat for wildlife. Only Hawkestone Creek in Oro-Medonte scored an "A" on the report card, and about one-third of the whole watershed scored a "B." But many areas rated a "D" - including the West Holland River Subwatershed, where only 45.1% to 55% of streamside areas were vegetated.

Most of the watershed – including the West Holland River – scored a "B" for health and diversity of fish populations, and an "A" or "B" for Benthic invertebrates.

But phosphorus levels were another story. Less than 20% of the watershed scored an "A" on the LSRCA report card, meeting the Province's standard of under 0.03 mg of Phosphorus/L. The Lover's Creek Subwatershed in Innisfil, Black River, Pefferlaw River and Uxbridge Brook all scored a "B" (0.03 to 0.10 mg/L) and East Holland River and Maskinonge, a "C" (0.11-0.17 mg/L).

The West Holland got a "D."

The Ministry of the Environment found that the phosphorus either ends up incorporated into the sediments, or is taken up by plants and algae in Lake Simcoe – leading to excessive weed growth and algal blooms that annoy residents and boaters, and that contribute to low levels of dissolved oxygen in deep water, harming the coldwater fishery.

The high level of agricultural activity, modifications to the Holland Marsh to maintain the polder system, the use of water for irrigation, the presence of large urban centres with high levels of impervious surfaces, water consumption, and inputs of nutrients and contaminants into area watercourses "have caused the West Holland to become one of the most stressed subwatersheds in the Lake Simcoe watershed," the LSRCA concluded - and a major source of phosphorus loading in Lake Simcoe.

The LSRCA noted that 31% of the West Holland subwatershed is covered by natural vegetation, 57% by agricultural lands that include the Holland Marsh - and identified a need to balance the demands of improved water quality in Lake Simcoe, with other demands "such as urban growth, agriculture, industrial and recreational uses."

A new Subwatershed Plan, for the 354 sq. km. drained by the West Holland River, has been proposed in an attempt to address the problems.

There is a need to develop an integrated Watershed management framework, said Dr. Ben Longstaff, Manager of Integrated Watershed Management – to enhance natural vegetation, minimize the impact of development, improve water quality, and to reduce the phosphorus loading from the Holland Marsh without negatively impacting agriculture. The goal is to "strive for Best Practices," Dr. Longstaff said, yet "not be restrictive" of either approved development, or agricultural uses.

And the main focus, he said, will be reduction of phosphorus loading. "No surprise to anyone, Phosphorus is the key water quality concern we're dealing with." The Plan recommends tree plantings and development of "good riparian streamside vegetation," and control of sources of atmospheric phosphorus, like the recent dust storms in the Holland Marsh.

"We need to find some solutions to the amount of phosphorus entering from the Holland Marsh," Dr. Longstaff said. "We need to be working collaboratively with all stakeholders within the subwatershed."