The area north of Henry’s Point flooded each spring, but by July, drained to pasture with Hayden Creek running through it. In 1910, a dike was constructed near Honeysuckle Bay, raising shoreline levels and flooding what is now known as the North Arm. The impounded bay is shallow, making it difficult for the water to properly filter itself. To address this issue, extra attention is being given to the North Arm to improve the water quality.
North Arm Investigation Committee
Recent lake monitoring activities identified the North Arm as a serious area of concern. To protect it, the Hayden Lake Watershed Improvement District commissioned an investigative committee in 2024 to review the conditions in the North Arm and identify gaps in water quality data. The committee members represent a wide range of stakeholders, including the HLWID, Idaho Fish and Game, USFS, DEQ, HLWA, and several residents of the North Arm.
Regulatory Requirements
The state of Idaho has set standards to help maintain the value of our natural surface waters. We work hard to make sure Hayden Lake is living up to those standards. For more information on the beneficial uses of Hayden Lake and the state’s regulatory framework, please refer to the information below.
Harmful Algal Blooms
Cyanobacteria are one of a number of types of phytoplankton that occur naturally in any freshwater lake. They’re not a problem as long as they are kept in check by competitors. Cyanobacteria Blooms, also known as Harmful Algal Blooms (HABs), occur when cyanobacteria grow out of control, as other organisms that compete for their food die off. Such blooms have occurred in the North Arm with alarming frequency over the previous 12 years–much too frequently for a lake where residents draw drinking water, and local families recreate, and tourists use Sportsmans Access for swimming, fishing, and water sports recreation. A HAB can produce extremely dangerous toxins that can sicken or even kill people, pets, livestock and wildlife.
North Arm Water Quality
Research is being conducted as part of the Drinking Water Grant Project to analyze the sources of nutrients that contribute to Cyanobacteria/Harmful Algal Blooms. The results of the lake monitoring done on the North Arm can be downloaded and viewed here.
