Filtering & Treating–Alerts, Toxins, and Avoidance
Windigo and Rock Harbor are the only two areas on Isle Royale where water can be obtained from spigots and does not need to be filtered or treated. Every other area, inland or on Lake Superior, requires filtering and/or treating. In addition, sources may become unusable as the season progresses due to algal blooms and drought conditions.
Backcountry campgrounds along Lake Superior will use that lake as the designated water source. These include Three-Mile, Daisy Farm, Moskey Basin, Chippewa Harbor, Malone Bay, Siskiwit Bay, Huginnin Cove, Little Todd Harbor, Todd Harbor, McCargoe Cove, and Lane Cove. All campgrounds on smaller islands in Lake Superior will filter from Lake Superior as well. Clearly, this source does not dry up in drought conditions, but some enclosed harbors with shallow water, such as Todd Harbor, can be contaminated with Swimmer’s Itch, rendering the water not advisable to swim in, but this contaminant is removed from drinking and cooking water by filtering with the recommended .4 or smaller micron filter. Filtering from Lake Superior can be hampered by waves which make it difficult to mechanically operate a filter that uses a hose apparatus. Wading into the water to fill a dirty bag for your gravity filter can also be difficult in waves or cold temperatures in early season. Having more than one method for filtering is recommended.
Interior campgrounds are located along the shores of inland lakes which are the designated water sources. While these sources are generally reliable, Lake Richie and Chickenbone Lake, have experienced algal blooms that make the water unusable for any purpose. The algal blooms release toxins into the water that can neither be filtered nor treated to remove the toxins. Water that appears slimy, thick, or like pea soup, should be avoided. Drinking water contaminated with algal blooms can be fatal. Do not swim in water containing algal blooms. While the Park Service makes every effort to post alerts and warn the public of algal blooms, these contaminants can pop up quickly and may take a day or so to be reported, checked, and posted. Be vigilant of potential contaminants and report them when you see them so that they can be investigated and park visitors alerted of them upon arrival to the island. Never drink water from a source that appears to be contaminated with algal blooms.
The Island Mine water source is a tiny spring-fed rivulet that emerges from the rocks. This small stream is never plentiful, nor have we ever seen it less than the trickle that it is. The water must be filtered like any other. As a flowing tiny stream, it is not prone to algal blooms, but it is not suitable for filling a dirty bag for use with a gravity filter. Best use would recommend a filter with a hose to extend into the tiny pools in the stream.
A few small streams that established trails cross over exist, but these streams are not designated water sources and should not be counted on. These include one near the Little Todd trail marker on the Minong Ridge Trail, one flows between Chickenbone Lake and Lake Livermore between East and West Chickenbone Lake campgrounds, and Grace Creek which crosses the Feldtmann Ridge Trail four miles or so out of Windigo going toward Feldtmann Lake. Creeks not designated as water sources by the NPS cannot be relied on as water sources. While Grace Creek, to our knowledge, has never dried up, the small creeks near Little Todd and connecting Lake Livermore and Chickenbone have dried up in mid- to late-season, making them not reliable. Backpackers who count on small streams to acquire water place themselves at risk of dehydration at certain points in the season and in years with low rainfall.
In essence, paying attention to water concerns will help you stay safe and properly hydrated. Be aware of the challenges of each water source and pay attention at permitting to the current water concerns. On trail, all water must be filtered and treated to reduce the chances of acquiring a waterborne illness. Avoid posted hazards and be alert to possible emerging concerns, such as algal blooms. Ensure that you have gear sufficient to carry three liters of water. Most often, two liters will suffice, but in hot conditions on ridge trails in peak season or on sections of more than eight miles between water sources, three liters may be needed. Depend only on designated sources. The intermittent streams are not designated as water sources because they cannot be counted on. Be vigilant to emerging threats, prepare with appropriate treatments and filters, and ensure that you carry enough water to remain properly hydrated throughout your hike.