Nitrogen Sequence Surface Water Test

Overview

Nitrogen doesn't exist in a lake as one thing. It cycles through several chemical forms, and which form dominates tells you where it came from and how available it is to algae. This panel measures the three that matter most: nitrate, ammonia, and total Kjeldahl nitrogen. Read together they are a sequence, not three separate numbers — hence the name. Methods EPA 300.0 for nitrate, EPA 350.1 for ammonia, and EPA 351.2 for TKN, all reported in parts per million.

What problem does this solve for our lake?

Total nitrogen alone is a blunt instrument. The forms are what carry the information. • Nitrate (EPA 300.0; MDL 0.01 ppm, RL 0.1 ppm) is the fully oxidized, highly mobile form. It travels easily through soil and groundwater, which makes it the signature of external inputs — lawn and agricultural fertilizer, and septic leachate that has had time and oxygen to convert. Elevated nitrate points outward, to the watershed. • Ammonia (EPA 350.1; MDL 0.04 ppm, RL 0.05 ppm) is the reduced form, and it means something quite different. It indicates either fresh organic input — recent sewage, manure, decaying material — or low-oxygen conditions in the lake itself, where ammonia is released from bottom sediments during summer stratification. Elevated ammonia often points inward, to the lake's own internal cycling. It is also directly toxic to fish at elevated levels, particularly when pH and temperature are high. • Total Kjeldahl Nitrogen (EPA 351.2; MDL 0.249 ppm, RL 0.5 ppm) captures organic nitrogen plus ammonia — nitrogen bound up in living algae, bacteria, and decaying material. A high TKN with low nitrate typically means the nitrogen has already been taken up and converted into biomass. The pattern across the three is the diagnosis. High nitrate with low ammonia and low TKN suggests active watershed loading into a lake that hasn't yet used it. Low nitrate with high TKN suggests the lake has consumed available nitrogen and turned it into algae. High ammonia suggests either a fresh contamination source or an oxygen problem at depth.

What's included?

• A complete nitrate, ammonia, and TKN 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.
• Phosphorus. If you want the full nutrient picture, order the Nutrient Profile Surface Water Test or add a Total Phosphorus Test.
• Nitrite, measured separately
• Depth-stratified sampling, which is what you need if you suspect ammonia release from bottom sediments

Requirements

• A sample collected from open water at a consistent depth
• Same-day shipment after collection, kept cold — ammonia in particular is unstable and will change if the sample warms or sits
• 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.