DOI: 10.25976/hxqe-py39
title: Lake Winnipeg Community-Based Monitoring Network

description: The Lake Winnipeg Community-Based Monitoring Network (LWCBMN) is a growing network that engages citizen volunteers to collect water samples across Manitoba using scientifically vetted protocols. Samples are then analyzed in a lab to measure phosphorus concentration and calculate the amount of phosphorus begin exported off our landscapes.

While Lake Winnipeg receives its water from a vast watershed, not all areas of the watershed contribute equal amounts of phosphorus. By sampling frequently at many sites, LWCBMN is able to pinpoint phosphorus hotspots – areas that contribute a disproportionate amount of phosphorus to Lake Winnipeg.

Snow melts, floods and heavy rainfall events are responsible for most of the phosphorus that is flushed from the land into our waterways. Special care is taken by network staff and volunteers to ensure phosphorus runoff is captured during these high-water events. And, because these volunteers live, work or commute near their sampling sites, LWCBMN can quickly mobilize citizen scientists to collect samples when it matters most.
description: Water samples are collected using a sampling device (weighted plastic tube and three metre leader) that collects source water directly into the collection bottle (500 mL Nalgene polyethylene bottle). The collection bottle is lowered into the water just before it hits the bottom, the bottle is filled, then brought back to the surface. It is rinsed three times, prior to sample collection. To collect the water sample, the sampler is lowered close to the bottom, then raised to the top of the water while the bottle is filling. From the collection bottle, a 60 mL Nalgene polyethylene bottle is filled with whole water containing 1 mL 4N H2SO4. Next, 20 mL is drawn into a syringe, and filtered through a 45 um filter into a 25 mL scintillation vial containing 0.1 mL of 4N H2SO4. Whole water is analyzed for total phosphorus, and filtered water for dissolved phosphorus. Particulate phosphorus can be inferred by subtracting dissolved phosphorus from the total.

The discharge data is collected by the Water Survey of Canada (WSC). Water level stations are setup across Canada that log water levels every 5 minutes. These water levels can be related to discharge via a mathematical relationship established at each site using manual flow measurements. LWF uses daily discharge averages of the WSC data.

Quality assurance of laboratory methods for the determination of total phosphorus was completed on samples sent from Proficiency Testing Canada. Proficiency testing, conducted every 6 months, allows us to assess the quality of our results as compared to the results of other laboratories across the country. Since November 2023, we have received excellent passing grades on these tests, highlighting the consistency and accuracy of our laboratory methods.

With 2023 data we began determining the limit of detection (LOD) for our laboratory
methods. In our analytical process, we prepare blanks using deionized water and analyze them identically to our samples. Then, we calculate the standard deviation of the blanks and multiply this by three. The LOD tells us that any result higher than the LOD has a 99.7% probability of being clearly distinguishable from random noise in the analysis. The LOD for 2023 data is 0.0395 mg/L.