HAB had a productive day and applied 8,400 gallons of alum and 4,200 gallons of sodium aluminate to the lake. HAB’s application equipment is well-suited for the precision required for the Heart Lake project. Any gaps in coverage would allow for phosphorus from untreated lakebed sediments to leach into the overlying water column and stimulate future algal blooms. An onboard computer system ensures that application is complete and uniform by integrating the location of the barge with GPS, the barge speed, water depth and alum flow rates. The exact dose is programed into the software and inline flow sensors measure the flow of alum through the distribution lines in real time. Automated valves, which are controlled by the computer, open and close as needed to adjust for barge speed and location to make certain the prescribed dose is applied. Tadd Barrow (HAB’s application specialist) follows a grid and each application path is recorded and displayed on the guidance monitor to prevent gaps in the application. At the end of the project, HAB produces a coverage map showing every application path and confirms the complete coverage of the lake.
HAB’s precise and flexible application strategy is especially important at Heart Lake. Rough-skinned newts (https://en.wikipedia.org/wiki/Rough-skinned_newt) occur in large numbers at Heart Lake, which has the largest known population of newts on Fidalgo Island. The greatest numbers of newts are in the shallow, southern portions of Heart Lake. HAB’s precision allows us to avoid critical newt habitat. We are also extending the project duration from one to two days to ensure the newt eggs, larvae and adults are undisturbed. Western Washington students and staff are onsite monitoring these areas and we are fortunate to have their involvement in the project.