Combined measures in lake restoration: A powerful approach as exemplified from Lake Groote Melanen (the Netherlands)

TY - JOUR

T1 - Combined measures in lake restoration

T2 - A powerful approach as exemplified from Lake Groote Melanen (the Netherlands)

AU - Lürling, Miquel

AU - Mucci, Maíra

AU - Yasseri, Said

AU - Hofstra, Simon

AU - Seelen, Laura M.S.

AU - Waajen, Guido

N1 - Data archiving: on request

PY - 2024/10/1

Y1 - 2024/10/1

N2 - Controlling lake eutrophication is a challenge. A case-specific diagnostics driven approach is recommended that will guide to a suite of measures most promising in restoration of eutrophic lakes as exemplified by the case of the shallow lake Groote Melanen, The Netherlands. A lake system analysis identified external and internal nutrient load as main reasons for poor water quality and reoccurring cyanobacterial blooms in the lake. Based on this analysis, a package of restoration measures was implemented between January 2015 and May 2016. These measures included fish removal, dredging, capping of peat rich sediment with sand and an active barrier (lanthanum-modified bentonite), diversion of two inlet streams, reconstruction of banks, and planting macrophytes. Dredging and sand capping caused temporarily elevated turbidity and suspended solids concentrations, while addition of the lanthanum-modified clay caused a temporary exceedance of the Dutch La standard for freshwaters. Diversion of inflow streams caused 35 % less water inflow and larger water level fluctuations, but the lake remained water transporting with strongly improved water quality as was revealed by comparing five years pre-intervention water quality data with five years’ post-intervention data. Total phosphorus concentration in the water column was reduced by 93 % from 0.47 mg P L-1 before the intervention to 0.03 mg P L-1 after the intervention, total nitrogen by 66 % from 1.27 to 0.21 mg N L-1, total chlorophyll-a by 75 % from 68 to 16 µg L-1, cyanobacteria chlorophyll-a by 88 % from 32 to 4 µg L-1. Turbidity had declined by 58 % from 23.5 FTU to on average 9.9 FTU. No cyanobacteria blooms were recorded over the entire post-intervention monitoring period (2016–2021). Submerged macrophytes increased from complete absence before intervention to around 10 %–15 % coverage after intervention. Repeated fish removal lowered the fish stock to below 100 kg ha-1 with 12 % of bream and carp remaining. Hence, the package of cohesive measures that was based on a thorough diagnosis resulted in rapidly, strongly and enduringly improved water quality. This case provides evidence for the power of combining measures in restoring eutrophic lakes.

AB - Controlling lake eutrophication is a challenge. A case-specific diagnostics driven approach is recommended that will guide to a suite of measures most promising in restoration of eutrophic lakes as exemplified by the case of the shallow lake Groote Melanen, The Netherlands. A lake system analysis identified external and internal nutrient load as main reasons for poor water quality and reoccurring cyanobacterial blooms in the lake. Based on this analysis, a package of restoration measures was implemented between January 2015 and May 2016. These measures included fish removal, dredging, capping of peat rich sediment with sand and an active barrier (lanthanum-modified bentonite), diversion of two inlet streams, reconstruction of banks, and planting macrophytes. Dredging and sand capping caused temporarily elevated turbidity and suspended solids concentrations, while addition of the lanthanum-modified clay caused a temporary exceedance of the Dutch La standard for freshwaters. Diversion of inflow streams caused 35 % less water inflow and larger water level fluctuations, but the lake remained water transporting with strongly improved water quality as was revealed by comparing five years pre-intervention water quality data with five years’ post-intervention data. Total phosphorus concentration in the water column was reduced by 93 % from 0.47 mg P L-1 before the intervention to 0.03 mg P L-1 after the intervention, total nitrogen by 66 % from 1.27 to 0.21 mg N L-1, total chlorophyll-a by 75 % from 68 to 16 µg L-1, cyanobacteria chlorophyll-a by 88 % from 32 to 4 µg L-1. Turbidity had declined by 58 % from 23.5 FTU to on average 9.9 FTU. No cyanobacteria blooms were recorded over the entire post-intervention monitoring period (2016–2021). Submerged macrophytes increased from complete absence before intervention to around 10 %–15 % coverage after intervention. Repeated fish removal lowered the fish stock to below 100 kg ha-1 with 12 % of bream and carp remaining. Hence, the package of cohesive measures that was based on a thorough diagnosis resulted in rapidly, strongly and enduringly improved water quality. This case provides evidence for the power of combining measures in restoring eutrophic lakes.

KW - Biomanipulation

KW - Dredging

KW - Eutrophication control

KW - Nutrient load

KW - System analysis

U2 - 10.1016/j.watres.2024.122193

DO - 10.1016/j.watres.2024.122193

M3 - Article

AN - SCOPUS:85200609933

SN - 0043-1354

VL - 263

JO - Water Research

JF - Water Research

M1 - 122193

ER -