Seasonal water quality changes in on-farm water storage systems in a south-central U.S. agricultural watershed

Soil phosphorus (P) built up due to past management practices, legacy P, in the Lake Okeechobee Watershed (LOW) in south-central Florida, U.S.A., is often discussed as the root cause of lake eutrophication. Improvement of the lake’s water quality requires the identification of critical P sources and quantifying their contributions. We performed a global sensitivity analysis of the Watershed Assessment Model (WAM), a common evaluation tool in LOW environmental planning, using the Morris method. A pre-calibrated WAM setup (Baseline) of the LOW sub-watershed, Taylor Creek Nubbin Slough (TCNS), was used as a test case. Eight scenarios were formulated to estimate the contributions of various P sources. The Morris analysis indicated that total phosphorus (TP) loads were highly sensitive to legacy P in improved pastures, the major land use covering 46.2% of TCNS. The scenario modeling revealed that legacy P, inorganic fertilizers, and other sources contribute 63%, 10%, and 32%, respectively, to the Baseline TP load of 111.3 metric tons/y to the lake. Improved pastures, dairies, citrus, and field crops are the top TP load contributors. Our results have important implications for water quality improvement plans in the LOW and highlighted the need for accurate spatial mapping of legacy P and incorporation of such information in modeling efforts for watersheds demonstrating legacy P problems.

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Paleolimnological assessment of long-term water-quality changes in south-central Ontario lakes affected by cottage development and acidification

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f95-171 ◽

1996 ◽

Vol 53 (1) ◽

pp. 1-17 ◽

Cited By ~ 95

Author(s):

Roland I Hall ◽

John P Smol

Keyword(s):

Water Quality ◽

Quality Changes ◽

South Central ◽

Cottage Development

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Water quality changes in south-central Ontario lakes and the role of local factors in regulating lake response to regional stressors

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2011-041 ◽

2011 ◽

Vol 68 (6) ◽

pp. 1038-1050 ◽

Cited By ~ 36

Author(s):

Michelle E. Palmer ◽

Norman D. Yan ◽

Andrew M. Paterson ◽

Robert E. Girard

Keyword(s):

Water Quality ◽

Acidic Deposition ◽

Quality Parameters ◽

Quality Changes ◽

South Central ◽

Chloride Water ◽

Long Term Monitoring ◽

Term Monitoring

The long-term monitoring of eight lakes near Dorset, Ontario, indicates that the water quality has changed significantly over the last 30 years. However, trends in the Dorset lakes may not be representative of changes in other south-central Ontario lakes, as the Dorset lakes are within a small area and span a limited gradient of lake and watershed characteristics. To determine the regional extent of water quality changes, we assessed the chemical changes in 36 diverse lakes that were first sampled between 1981 and 1990 and were resampled in 2004–2005. Similar to trends in the Dorset lakes, changes in the regional lakes included decreasing acidity, calcium, conductivity, metals, and phosphorus, and increasing dissolved organic carbon, nitrogen, sodium, and chloride. Water quality changes were driven by regional stressors, including acidic deposition, climate, and lakeshore residential development. However, stressor-induced responses differed among lakes. Increases in sodium and chloride were greater in developed lakes that were close to winter-maintained roads. Site-specific characteristics, such as lake and watershed morphometry, could not explain heterogeneous changes in the remaining water quality parameters. These results indicate that other factors play an important role in regulating individual lake response to regional stressors.

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Use of Daphnia spp. for the Ecotoxicological Assessment of Water Quality in an Agricultural Watershed in South-Central Chile

Archives of Environmental Contamination and Toxicology ◽

10.1007/s00244-004-0218-6 ◽

2005 ◽

Vol 48 (2) ◽

pp. 191-200 ◽

Cited By ~ 16

Author(s):

K. Cooman ◽

P. Debels ◽

M. Gajardo ◽

R. Urrutia ◽

R. Barra

Keyword(s):

Water Quality ◽

Agricultural Watershed ◽

Central Chile ◽

Ecotoxicological Assessment ◽

South Central

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Snowmelt and Growing Season Phosphorus Flux in an Agricultural Watershed in South-Central Alberta, Canada

Water Quality Research Journal ◽

10.2166/wqrj.2005.044 ◽

2005 ◽

Vol 40 (4) ◽

pp. 402-417 ◽

Cited By ~ 14

Author(s):

Gerald R. Ontkean ◽

David S. Chanasyk ◽

D. Rodney Bennett

Keyword(s):

Water Quality ◽

Total Phosphorus ◽

Surface Water Quality ◽

Agricultural Watershed ◽

Return Flow ◽

Spatial And Temporal Variability ◽

Dissolved Phosphorus ◽

Spring Runoff ◽

South Central ◽

Creek Watershed

Abstract A three-year study was conducted to examine the spatial and temporal variability of phosphorus concentrations and mass loads within four sub-basins in the Crowfoot Creek watershed in southern Alberta, Canada. Monitoring was carried out at the inflows and outflows of the four sub-basins from mid-March until the end of October in 1997 to 1999. Data were collected on flow, total phosphorus (TP) and total dissolved phosphorus (TDP). The TP and TDP concentrations increased and were greatest during spring snowmelt and rainfall runoff events. Median TP concentrations varied from 0.022 to 1.141 mg L-1 and median TDP concentrations varied from 0.005 to 1.031 mg L-1. Within the sub-basins, phosphorus concentrations generally increased between inflow and outflows. The presence of grassland and well-developed crop cover adjacent to the watercourses generally resulted in a greater proportion of TDP in runoff. The proportion of TP as TDP varied from 31 to 97% and appeared to be affected by the timing of the storm and antecedent moisture conditions of the soil. The proportion of phosphorus exported during events made up from 1 to 83% of the total phosphorus load during the post-spring runoff period. Phosphorus concentrations exceeded Alberta surface water quality guidelines most of the time; however, the addition of irrigation return flow water generally improved water quality in Crowfoot Creek.

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