Total Phosphorus Test

Overview

Total phosphorus measures every form of phosphorus in the sample — dissolved, particulate, organic, and inorganic. In the large majority of freshwater lakes, phosphorus is the nutrient in shortest supply relative to what algae need, which means it controls how much algae the lake can grow. Change the phosphorus and you change the lake. Method EPA 365.1, reporting limit 0.025 ppm.

What problem does this solve for our lake?

If you can only afford one lab test, this is the one. The relationship between total phosphorus and algal biomass in lakes is one of the most reliable quantitative relationships in freshwater science, established across thousands of lakes worldwide. It is the basis for most state nutrient criteria and most lake management decisions. For orientation: below about 0.010 ppm is an oligotrophic lake — clear, low productivity, often good for cold-water fish. Roughly 0.010 to 0.025 ppm is mesotrophic, moderately productive, the condition most recreational lakes are in or aspire to. Above about 0.025 ppm is eutrophic, where nuisance algae and reduced clarity become common. Above 0.100 ppm is hypereutrophic, where blooms are the normal summer condition. Phosphorus reaches a lake from lawn and agricultural fertilizer, eroding soil, failing septic systems, waterfowl, and — critically — from the lake's own bottom sediments, which release stored phosphorus when the water above them runs out of oxygen in late summer. That last pathway, internal loading, is why some lakes fail to improve even after the watershed has been cleaned up, and it is why establishing a phosphorus record before you spend money on remediation is worth doing. At $52 there is no good reason for a lake to have no phosphorus record.

What's included?

• A complete Total Phosphorus test kit shipped directly to you
• All materials required for clean, contamination-free sample collection
• Step-by-step collection and preservation instructions
• Prepaid 2-day return shipping to our certified partner laboratory
• Analysis by EPA-approved methods at an accredited partner laboratory, with full chain of custody
• Results loaded automatically into your lake's account

What's not included

• Sample collection. You collect the sample; we supply everything you need to do it correctly.
• Boat, dock, or shoreline access to your sampling site
• Depth-profile sampling. This is a single grab sample unless you order multiple kits.
• Ice or a cooler for shipping, which you supply
• Treatment, remediation, or applicator services
• A written management plan. The Boathouse can help you interpret results and decide next steps.
• Nitrogen of any form
• Orthophosphate, the dissolved and immediately available fraction
• Sediment phosphorus, which requires the Total and Reactive Phosphorus Sediment Test or the Phosphorus Fractionation Sediment Test

Requirements

• A sample collected from open water at a consistent depth, away from inflows, docks, and stirred-up bottom
• Same-day shipment after collection, kept cold
• The same site and the same time of year each time, if you want a trend
• A Plus, Lake Admin, or PRO subscription to have results loaded into your Lake Pulse account
• Questions about site selection, timing, or which test fits your lake? Contact the Lake Pulse Boathouse before you order.