Very clear (6 to 10 m)
Attersee, Traunsee, Hallstätter See. Optical detail inspection possible even in deeper areas. Sonar primarily for structured surveying and sediment capture.
Methodology · Lakes
Underwater Inspection in Lakes — Methodology, Visibility, Depth Profile
Alpine and pre-Alpine lakes differ fundamentally from flowing waters: a calm water column, very clear visibility, often great depths, sensitive slope zones. This methodology-hub page summarises the technical reality with which ScanSustain works at Chiemsee, Attersee, Traunsee, Wolfgangsee, Mondsee, Hallstätter See and Tegernsee. Actual deployments are subject to approval by the responsible local authorities and facility operators.
Visibility Profile by Lake Type
Pre-Alpine and Alpine lakes typically lie in the clear to very clear range. Algae activity in the summer months can reduce visibility — maximum visibility is reached in the transitional months and in late autumn.
Clear (3 to 6 m)
Chiemsee, Wolfgangsee, Tegernsee. ROV optics primary, high-resolution sonar as a complement. Seasonal visibility fluctuations during algae peaks.
Moderately clear (2 to 5 m)
Mondsee. ROV optics primary, sonar complementary for capturing sediment deposition and structured as-built measurements.
Fluctuating / after flooding
After heavy-rain events, even clear lakes can be strongly clouded for a short time — turbidity phases are documented in the deployment log.
Depth Strategy
Most lake deployments concern depths of 1 to 12 metres — jetty piles, berth edges, bathing platforms, boathouses. For gauge and special structures, depths up to 30 metres are inspected, in individual cases deeper still (industrial water connections, anchor structures). Deep-water inspection requires higher positioning accuracy and longer ascent and descent times.
Sonar/Optical Mix by Task
Detail findings (optics primary)
Pile inspection, berth edges, component findings, damage-pattern capture. High-resolution ROV optics with LED lighting, macro shots where local defects occur.
Structured surveying (sonar primary)
Bed surveying, sediment deposition, capture of steep-shore structures, tracing the routes of laid lines. Multibeam for 3D profiles and area findings.
Search & recovery
Multibeam sonar for the search phase, ROV optics for identification and localisation. This task benefits especially from the clear visibility of pre-Alpine lakes.
Habitat mapping
Contactless sonar capture of the bed habitats, complemented by ROV optics for habitat-type determination. Non-invasive and compatible with nature conservation.
Deployment Window by Season
Spring and autumn are the preferred inspection windows, both methodologically and logistically: clear visibility due to low algae activity, low tourism load, low hospitality-sector load on the jetty facilities. Summer deployments are possible and are coordinated with the jetty and landing-stage operators. Winter deployments can be carried out without difficulty on ice-free lakes; the low water temperatures are unproblematic for the ROV systems.
Characteristic Structures in Pre-Alpine Lakes
Ship landing stages
Landing stages of the respective lake shipping lines. Inspection for berth-edge damage, support-pile findings and the bed area.
Jetties and boathouses
Private, commercial, municipal. Findings capture of timber, steel and concrete components, piles, jetty joists, anchorages.
Lido facilities
Municipal lido facilities with jetties, platforms, safety-buoy anchor structures.
Gauge infrastructure
Gauges of the Hydrographic Services — gauge boards, pressure transducers, cable connections in the bed area.
Anchor structures
Floating jetties, marker buoys, navigation markers. Anchor position, anchor sinking into sediment, chain and rope wear.
Industrial water connections
Cooling-water intake and discharge of industrial riparian owners (typical at Traunsee, Hallstätter See). Inspection for corrosion and biofouling.
Frequently Asked Questions
What visibility range is typical in pre-Alpine lakes?
Alpine and pre-Alpine lakes are clear to very clear compared to rivers. Visibility ranges from 2 to 10 metres depending on the season and algae activity. Hallstätter See, Attersee and Traunsee are among the clearest waters in the DACH region. Mondsee and Chiemsee are somewhat clouded in summer by algae growth.
When is the best season for lake inspection?
Spring and autumn are optimal — clear water, low algae activity, no peak tourism load. High-season summer deployments are possible but require longer coordination with jetty and landing-stage operators.
How deep do ROV inspections reach in lakes?
Our ROV systems cover the depths of all lakes presented here, including Traunsee (191 m) and Attersee (169 m). For typical jetty and landing-stage inspections, 1 to 12 m is relevant; gauge and special structures can lie deeper.
When do I need sonar in addition to ROV optics?
Sonar complements the optics in the following cases: surveying large bed areas (3D multibeam), capturing sediment deposition, tracing the routes of laid supply lines, structural as-built capture on steep structure geometry. In clear pre-Alpine lakes, ROV optics is the primary method.
Plan a specific lake deployment
Describe your use case — within 1 to 3 working days you will receive a concrete initial assessment with method selection, a visibility expectation and an effort indication.