1. Introduction
The Hula Valley (between 200 and 60 MASL altitudes) comprising app.7% of the Kinneret Drainage Basin (2730 km2) is part of the Northern section of the Syrian-African Rift Valley. Within the Anthropocene era, the Hula Valley is a compatible interlock of anthropogenic achievement in the national economy, water supply, agriculture, nature protection and tourism management. The Kinneret catchment comprised of three headwaters, Hatzbani, Banyas and Dan, flowing southward down from Mount Hermon and connected together with several other streams, and non-point runoffs, forming the Jordan River [1] [2] [3] . The River Jordan contributes about 63% of the Kinneret water budget and also convey more than 70% of nutrient inputs. Until the late 1950s the Hula Valley was mostly covered by swampy wetlands and old Lake Hula which were drained and land use was modified from the natural environment to agriculture. The agricultural development included field crops, orchards and fish breeding aquaculture.
For 40 years, the drained area was successfully cultivated and the agricultural products were economically produced and nutrient flux into Lake Kinneret did not thoroughly threaten its water quality. Nonetheless, as a result of inappropriate management, drainage canals were blocked; irrigation methods were not suitable for optimal soil structure protection and Ground Water Table (GWT) declined. Consequently, the soil structure of the upper layers (0 - 0.5 m) deteriorated and heavy dust storms occurred frequently which resulted in subsidence of the soil surface and blocking of drainage canals [4] . Due to unsuitable agricultural management, outbreaks of underground fire occurred frequently. Rodent population outbreak caused severe damage to agricultural crops and the stability of drainage canal banks. Part (500 ha) of the drained area, that was most severely deteriorated which made it impossible for beneficial maintenance and thus, was not cultivated [5] . Consequently, a reclamation project, the “Hula Project”, was proposed and implemented. The Hula Project, included increasing soil moisture by elevating GWT, changing the irrigation system and renewing the hydrological canal system throughout the entire valley. Ninety km of drainage canals were reconstructed and a shallow Lake Agmon (0.2 average depth; 82 ha surface area) was created as a wastewater collector and recreational site. A plastic sheet (4 mm thickness) was placed vertically (0 - 4.5 m) along 2.8 km, crossing the valley, to prevent underground nutrients from leaking southward. The present Hula Valley management is a package deal between three sectors: 1) The land owner (farmer) for the Hula Valley area is a source of income for them; 2) Water managers who are responsible for the protection of the Kinneret water quality supplied for domestic usage; and 3) the “greens” Nature ecologists [5] - [10] .
The Hula drainage in relation to the national drinking water resource, Lake Kinneret, gave an ominous warning: a significant enhancement of Nitrate loads migration through river Jordan is supposed to be associated with water quality deterioration. Moreover, without a distinct remedy Lake Kinneret might be unsuitable for drinking water supply, recreation and fish habitats as an object for commercial fishery. The public start to concern about water quality in the Lake Kinneret ecosystem and the continuation of serving as an essential resource for drinking water supply, fishery, and recreation. Consequently, a limnological environmental intensive research carried out by the Kinneret Limnological Laboratory (KLL) and Mekorot, Water Supply Company was established. A case study of Lake Washington, Seattle, [11] guided the Kinneret management authorities. Although KLL and Mekorot maintained a scientific role, a credit accompanied by intensive collaboration was given to the political level of water managers by which a national agency, “Kinneret Drainage Authority” was formed to improve pollution control and Lake management. The collaboration between the scientific and political Kinneret agencies became a model of scientific usage in public policy. It was pointed out that an increase of fish aquaculture and domestic and dairy sewage production in the Hula valley would result in deterioration of the Kinneret water quality. Nevertheless, Peat soil exposure to atmospheric oxidation resulted in the Hula drainage followed by agricultural development might enhance Nitrogen inputs into Lake Kinneret as well. Consequently, essential research was given to define the importance priorities should be given either to aquaculture and sewage or peat soil agriculture for the design of management efforts.
Three case studies exemplify the close collaboration between limnologists and governmental water managers in the practical design of the Kinneret ecosystem:
1) Nitrate inputs enhancement created public awareness and publical “noise”. The invited report concluded eutrophication submitted as three volumes memorandum was calmed down by scientific analysis (“Bob Davis” Case). 2) Subsidized removal of unwanted fish enhanced zooplankton biomass in the lake “Sardin Dilution” Case. 3) Scientific recommendation to lower water level below 214.5 BSL aimed at water withdrawal from lake Kinneret to rescue irrigation of Avocado orchards during exceptional drought regime.
This paper describes a case study where progressed implementation of scientific recommendations is promoted by fruitful collaboration with a civilian-public organization of The Kinneret Authority. An ecological study about the impact of removal of domestic and dairy raw sewage into storage reservoirs and reuse for irrigation, on water quality protection in Lake Kinneret is presented in this paper. Moreover, conversion of land use in the Hula valley from fishpond into orchard and field crops accompanied by agricultural management initiated a reduction of Nitrogen and Phosphorus supply from the Hula valley into the Kineret aimed at Kinneret water quality protection as well [12] .
2. Material and Methods
The data sources about nutrient concentrations and loads in river Jordan and Kinneret Headwaters were periodical and annual reports published by the Monitor Unit Jordan Districts, Mekorot Ltd., Kinneret drainage Basin [1] [2] ; Kinneret Limnological Laboratory, IOLR Ltd. Data Base and annual reports [13] ; Kinneret Drainage Authority Interim Reports; Nutrient dynamics in the Hula Valley runoffs from Hula Project, Migal, annual reports (1995-2018) [6] [8] [9] [10] . River discharges are given in mcm (million cubic meters) = 106 m3; Nutrient data is given in concentration (ppm) or loads (Tons).
3. Results
Annual Nitrogen (NO3 and Total) contribution by the Peat Land Soil area in the Hula Valley (calculated) and in the Jordan discharge (Huri) (measured) during 1962-1981 are shown in Table 1.
The data presented in Table 1 were documented during 24 years after Hula drainage (1957) and prior to the fish-ponds restriction and sewage removal projects that were implemented during the late 1970s and early 1980s. Analysis of Linear Regression between the rain capacity (mm) (independent) and nitrate load inputs (ton) (dependent parameter) indicates a significant relation between rainfall capacity and Nitrate flush from the Peat soil in the Hula Valley (r2 = 0.5996: p = 0.0002). Data in Table 1 indicates that during 24 years after the Hula Drainage the NO3 migration from the Peat soil comprised only 25% and 50% of the TN and NO3 recorded at Huri respectively, and NO3, 51% of the TN measured at Huri. Taking into account that until the late 1970s total fish-pond area in the Hula Valley was 1700 ha whilst in the late 1980’s, 350 ha (80% decline) it is therefore suggested that a significant contribution of Nitrogen was supported by fishpond effluents.
![]()
Table 1. Annual (Hydrological Year: October through next September) input (ton/year) of NO3 and TN contributed from Peat soil and measured at Huri Station [1] ; and Rainfall (Dafna Station); nd, No Data [1] .
Sub-tropical climate dominating the Hula region is characterized by short wet cold winters and long dry and hot summers, The seasonal distribution (winter-summer) of nutrient migrations therefore reflects rainfall and river discharge dynamics. The rainy season in the Hula Valley lasts between October and March. Nitrate flushing and migration dynamics therefore depend upon rain and river discharge dynamics resulting in significant difference between winter and summer as shown in Table 2.
Results in Table 2 indicate nitrate migration from the Kinneret drainage basin in winter comprises about 80% of the annual load recorded in River Jordan (Huri Station).
The Nitrate supported from the Peat Land Soil in relation to the total Kinneret input as documented in a study carried out during the 1970s [1] [2] is shown in Table 3.
Results given in Table 3 indicate the following: winter comprised 55% of the annual loads; Josef loads comprised 27% of Huri loads in winter resulting probably Hula Valley contribution being more than 70% in winter, probably fishponds and sewage sources; nevertheless, annual contribution from Peat Land is 41% of the totally documented in Huri.
The role of Nitrate contributions by the Hydrological resources in the Kinneret Basin from 1969-1981 prior to the implementation of the fishpond restriction and sewage removal projects are given in Table 4.
![]()
Table 2. Annual (October-September) and seasonal (December-April) loads of NO3 (Tons) measured in River Jordan (Huri Station) between 1969-1980 prior to the fishpond restriction and the sewage removal project implementations [1] [2] .
![]()
Table 3. Seasonal (Flood season: December-April) (Flood, annual) and spatial (Josef, Huri, Peat land soil) Nitrate loads (Ton) distribution recorded at River Jordan stations (Huri, Josef) and Peat Land during 1971-1980. Huri Station value contains total annual nutrient content (Ton) migrated from the Kinneret Drainage basin including Hula Valley; Josef Station located on River Jordan discharge at the top northern point of the Hula Valley beyond the headwaters meeting point containing total nutrient loads originated northern to the Hula Valley. Full information for 1972/73.1978/79, is missing when Peat Land Soil contribution was approximated as negligible [1] [2] .
![]()
Table 4. Annual (1969-1981) Nitrate loads (T/Y) migration through River Jordan (Huri), Hazbani, Banias, Dan (Headwaters); small rivers and runoffs (Others) and contributed by Peat Land Soil (Peat) [1] [2] .
Results in Table 4 represent the percentage composition of annual Nitrate migration after the drainage and before the fish pond restriction and sewage removal projects. Nitrate loads migration into the Jordan River (Huri) through Headwaters, Peat Land Soil effluents and other rivers plus runoffs are 43%, 41% and 16% respectively. The high contribution of Nitrate from the Peat Land Soil during this period emphasizes its importance for the evaluation of Nutrient dynamics in the Hula Valley after the drainage and before project implementations of sewage removal, aquaculture restriction and Hula Project.
Results given in Figure 1 indicate temporal decline of River Jordan discharge since the early 1980s and a short periodical (2014-2018) decline in rainfall.
The Data shown in Figure 2 represent a significant correlation between rain capacity as measured in the northern part of the Hula Valley and the discharge in the Jordan River (Huri).
The results shown in Figure 3 indicate significant trend of Nitrate migration enhancement from the Peat Land Soil in relation to the increase of rain capacity.
Results shown in Figure 4 indicate minor decline in Nitrate load migrations from 2014-2018 resulting by decline in rain capacity and a significant correlation between migrated loads (Ton) and concentration (ppm) of Nitrates within the Jordan River discharge.
![]()
Figure 1. Temporal (1970-2018) distribution of rainfal (mm/y) (left panel) (Dafna Station), and Annual discharge (mcmy) of River Jordan (right panel) [13] .
![]()
Figure 2. Linear Prediction (W/CI) (left) (r2 and p values of LR are given) and Lowess Smoother plot (right) between annual discharge in river Jordan (mcm) (Huri) and Rain (mm/y) [13] .
![]()
Figure 3. Linear Prediction (W/Cl) (r2 and p values of LR are given) between annual means of the concentrations of Nitrate originated from the Peat land soil and rain (mm/y)(left) and Lowess Smoother distribution plot of the relations between Nitrate loads migrated from the Peat soil land in the Hula Valley (Ton/Year) and annual rain (mm/Y) (right) during 1963-1981 [1] .
![]()
Figure 4. Linear Prediction (W/Cl) (r2 and p valuesof LR are given) between annual mean concentrations (ppm) and Nitrate (Ton/Year) (left) and temporal distribution (Lowess Smoother plot) of annual loads of Nitrate recorded at Huri station (right) during 1970-2018 [13] .
Results presented in Figures 5-9 indicate decline of migrated nutrients through the Jordan River discharge that originated from domestic and diary sewage as well as effluents of fish ponds: Ammonium (NH4), Total Nitrogen (TN), Organic Nitrogen (NORG) Total Phosphorus (TP) and Total Dissolved Phosphorus (TDP). The distribution of their concentrations and loads is significantly correlated with the river Jordan discharge capacity. Moreover, temporal changes in load contents clearly show the trend of decline from late 1970s-the early 1980s.
Periodical Terms of TP Migration from the entire Kinneret catchment emphasizing the Hula Valley
1) 1968-1985: Post Drainage - Pre aquaculture restriction and Sewage Removal:
Evaluated data [2] of headwater (Hazbani, Banias, Dan) and River Jordan discharges and TP concentrations and loads enabled an insight into the dynamics
![]()
Figure 5. Linear Prediction (W/Cl) (r2 and p values of LR are given) between annual mean concentrations (ppm) and loads (Ton/Year) of ammonium (left) and temporal distribution (Lowess Smoother plot) of annual loads of Ammonium recorded at Huri Station (right) during 1970-2018 [13] .
![]()
Figure 6. Linear Prediction (W/Cl) (r2 and p values of LR are given) between annual mean concentrations (ppm) and loads (Ton/Year) of Total Nitrogen (TN) (left) and temporal distribution (Lowess Smoother plot) of annual loads of Total Nitrogen recorded at Huri Station (right) during 1970-2018 [13] .
![]()
Figure 7. Linear Prediction (W/Cl) (r2 and p values of LR are given) between annual mean concentrations (ppm) and loads of Organic Nitrogen (NORG) (Ton/Year) (left) and temporal distribution (Lowess Smoother plot) of annual loads of Organic Nitrogen recorded at Huri Station (right) during 1970-2018 [13] .
![]()
Figure 8. Linear Prediction (W/Cl) (r2 and p values of LR are given) between annual mean concentrations (ppm) and loads of Total Phosphorus (TP) (Ton/Year) (left) and temporal distribution (Lowess Smoother plot) of annual loads of Total Phosphorus recorded at Huri Station (right) during 1970-2018 [13] .
![]()
Figure 9. Linear Prediction (W/Cl) (r2 and p values of LR are given) between annual mean concentrations (ppm) and loads of Total Dissolved Phosphoprus (TDP) (Ton/Year) (left) and temporal distribution (Lowess Smoother plot) of annual loads of Total Dissolved Phosphorus recorded at Huri Station (right) during 1970-2018 [13] .
of Phosphorous migration during post-Hula drainage and pre-aquaculture restriction and sewage removal operation. The annual (1968-1985) discharge (mcm), mean TP concentrations (ppm) and annual loads (ton/year) in Jordan (Huri) and the headwater (Dan, Hazbani, Banias) are given in Table 5 [2] .
Subtraction of Headwater load from Jordan load resulting in 77 tons of TP attributed to the contribution of the Hula Valley which includes surface runoffs and other small rivers on both sides of the mountain slopes eastern and western of the Hula Valley and fish-ponds and raw sewage effluents within the valley.. Nevertheless, it is clear that TP contributed by the Hula Valley is high due to the contribution of fishpond effluent and untreated domestic and dairy raw sewage released into rivers crossing the Hula Valley. It is confirmed by the very low TP concentration in the high (515 mcm) headwater discharges (0.080 ppm).
2). The entire Period of 1968-2018
For the evaluation of the impact of aquaculture restriction and sewage removal projects carried out during the 1980s, the entire period was split into two periods, before and after the projects implementation: A) 1968-1993 and B) 1994-2018 (Table 6).
Results given in Table 6 indicate sharp distinct lower TP lads and concentrations in Period B which is due to load capacity (Ton: 61%) and concentration (ppm: 44%) whilst climate change is reflected in the reduced Jordan discharge (mcm: 30%). Therefore it is suggested that the TP decline in Period B is partly due to the aquaculture and sewage removal project implementation and partly attributed to the river discharges decrease.
Data shown in Figure 10, Figure 11 indicates a distinct decline of TP migration from the Kinneret basin into Lake Kinneret and the temporal fluctuations of TP in the Jordan discharge for the entire period of 1968-2018 (see Figure 8, right panel).
![]()
Table 5. The annual (1968-1985) discharge (mcm), mean TP concentrations (ppm) and annual loads (ton/year) in Jordan (Huri) and the headwater (Dan, Hazbani, Banias).
*The Jordan discharge includes three headwaters and other minor contributions.
![]()
Table 6. Annual and periodical means of Total Phosphorus (TP) migration (tons and ppm) in River Jordan (Huri) during 1968-1993 (A) and 1994-2018 (B). The absolute and percentage (%) differences (ton, ppm) are given. River Jordan discharge is given in mcm.
![]()
Figure 10. Linear Prediction (W/CI) between annual means of TP load (T) (Left) and concentration (ppm) (right) in Jordan river discharge during 1968-2018 [2] [13] . Linear Regression (r2 and p values are given) are presented.
![]()
Figure 11. Linear prediction (W/CI) (r2 and p values of LR are given) between annual TP load (T) (left) and years Lowess Smoother (right) in Jordan River discharge during 1968-2918 [2] [13] .
4. Discussion
Several prominent environmental modifications resulted from the Hula drainage, among others, are the conversion of the dominant Nitrogen input into Lake Kineret where Nitrate replaced Ammonium; The development of aquaculture and dairy in the valley; Regional population enhancement which was accompanied by an increase of sewage production. Those anthropogenic involvements enhanced the contribution of Organic Nitrogen and Phosphorus to Lake Kinneret. Consequently, elimination of these pollutant sources was likely, designed and implemented. The overall balance of nutrient load export from the Hula Valley declined accompanied by Kinneret nitrogen stock reduction although Nitrate migration was increased. Moreover, available quantitative information about Ammonium and other nutrients migration from the Hula Valley before drainage is very minor [14] . Nevertheless, the higher affinity of Ammonium than that of Nitrate for planktonic algal production is well known [15] . It is therefore suggested that the impact of Ammonium on phytoplankton growth in Lake Kinneret before drainage was not lower and probably even higher than under the present conditions. It is not the outcome of Ivory Tower or egghead scientist epithets. In our case it is a misleading consideration for the reality of ecological trait: The Hula was drained, the natural ecosystem was devastated, but national population dispersion and agricultural food production were improved and enhanced. Accompanied ecological obstacles were eliminated and deterioration of Kinneret water quality was prevented. “Ivory tower” and “Egghead” limnologists help people to understand and cooperate in solving problems of Kineret water quality resulting from Hula drainage. The Kinneret ecosystem, namely water quality deterioration did not pose a threat due to the Hula drainage nevertheless domestic and dairy raw sewage and fish-ponds effluents do. Therefore those risks were anthropologically eliminated and positively resulted.
It is suggested that nutrient loads migrated from the Hula Valley towards Lake Kinneret are highly correlated with hydrological dynamics. The more water is discharged the higher the nutrient concentration and load. Nevertheless, the nutrient composition, especially Nitrogen and Phosphorus, is strongly affected by anthropogenic involvement. The Hula drainage induced the replacement of Ammonium by Nitrates which was later declined due to reduction in Jordan discharge (climate change). The sewage (domestic and dairy) removal and restriction of fish breeding aquaculture enhanced the decline of different forms of Nitrogen and Phosphorus. Shortly after the Hula drainage 1700 ha of the drained land was utilized for commercial fish breeding in constructed ponds. The management of it included the diversion of headwater discharge through the newly constructed fish pond by continuous winter flow aimed at increasing water temperature in the ponds. Consequently, these waters were intensively loaded with nutrients and the pond effluents were directed into Lake Kinneret. Prior to the implementation of the sewage removal project in the late 1980’s-early 1990’s, about 25,000 - 30,000 m3 of raw sewage were daily fluxed into Lake Kinneret. The pollutants within the raw sewage were removed into newly constructed reservoirs resulting in a significant decline of TP, TDP, Organic Nitrogen, Ammonium and TN migration. The implementation of the Hula Project, including renovated Hydrological and agricultural regulations supported an additional impact on the reduction of migrated nutrients from the Hula Valley downward to Lake Kinneret. The conversion of 1700 ha of fishpond into field and orchard crops, the removal of sewage, and partial rehabilitation of natural conditions required strong public backing. A model for public discussion integrated with scientific support came from Lake Washington, Seattle, USA, where a known limnologist, Prof. W.T. Edmondson carried out a similar case (not without dissimilarities) and started a struggle in 1955 [11] . Scientific evidence combined with public-political involvement aimed at lake water quality protection. As one of the first steps forward a survey of the Peat Land Soil feature in the Hula Valley was carried out [16] . The pedological information supported by this survey opened the gate for field and orchard crops and even Fishpond land use which was found later as a source of pollutants. The immediate initiation of a scientific monitor program and limnological research in Lake Kinneret and its drainage basin and the establishment of long-term data records about the impact of nutrient migrations on the water quality in the national drinking water supply, Lake Kinneret, had been given a management tool to water managers. One of the early management decisions was to convert fishpond land use in the Hula Valley into field and orchard crops and to remove sewage. Sewage removal instruction was integrated with the design of reuse of the accumulated sewage for irrigation mostly outside the Kinneret catchment. Those conclusions were successfully implemented. The conversion of Fishpond into field crops and the removal of sewage effluents are likely a tackle the gap of reduction of TP migration from the Hula valley during the post drainage and Hula Project implementation to protect water quality in Lake Kinneret and agricultural management.
The appropriate management of the Hula Valley aimed at both Kinneret water quality protection and the efficient utilization of the Hula Peat Land initiated the achievement of the Hula Project. Therefore, the potential impact of the implemented Hula Project on Nutrient migration is the cardinal interest of water managers. A high correlation was found between nutrient concentrations (ppm) and load capacities (Ton). Concentration and load are dependent factors, the same as, discharge and load factors whilst concentration and discharge are supposed to be independent. Nevertheless, a significant correlation was indicated between those two independents, discharge and concentration. It is therefore suggested that the reason for those relations exists in the Kinneret drainage basin outside the Hula Valley, in the dynamics of the Headwaters, smaller rivers and runoffs. The erosive force of the water dynamic is dominant, and increasing discharge creates erosion enhancement (dissolved and particulate) and consequently-nutrient concentration. The major source of Nitrate migration into Lake Kinneret is the Peat Load Soils in the Hula Valley, which overlaps the Hula Project territory (app 2900 ha). Linear regression analysis of temporal fluctuations of NO3 concentration Vs time during 1993-2018 was found insignificant but significantly correlated with rain intensity. The Peat soil wettability is the dominant factor but not necessarily the river discharge. A significant correlation (r2 = 0.3834; p = 0.0010) was found between NO3 concentration in the effluents of the Hula Project territory and those in the Jordan River (Huri) during 1993-2018. Consequently, it is suggested that the nitrate migration from the Peat Land Soil is a dominant source for the Kinneret Nitrate supply. There is a significant correlation between Nitrate (NO3 Vs TN: r2 = 0.4758; p < 0.0001) and obviously with Total Nitrogen (NO3 Vs Rain: r2 = 0.3050; p < 0.0001) concentration in the Hula Project effluents and Rainfall intensity resulting from breakable linkage of NO3 with soil substances (particles). Nitrate migration from Peat Land Soil source has an impact on River Jordan Nitrate loads whilst TP-rainfall relations are statistically insignificant. Most of the NO3 migration occurs during the rainy season and is minor in the summer months in spite of irrigation activity. The implementation of the Hula Project was initiated during the early 1990s when loads and concentrations of TP, TDP, and Organic Nitrogen in Jordan discharge were declining whilst before the mid-1980s these nutrients exhibited high levels. Consequently, the ecological changes observed in the Hula Valley after the drainage included modification of migrated Nitrogen from Ammonium to Nitrate resulted in by newly oxidative soil environment and Kinneret water quality did not deteriorate [5] . The most effective anthropogenic involvement after the Hula Drainage is due to sewage removal and fishpond restriction whilst removal of Nitrogen other than NO3 and P nutrients through the Agmon Hula system of the Hula Project is negligible [12] . The Hula Project significantly improved the agricultural management and the efficiency of water utilization as well as recreational conditions and nature protection [5] . The correlations between annual mean concentrations of NO3, TN and TP in the Jordan Discharge (Huri) and the Agmon-Hula effluents since the implementation of the Hula Project (1993-2018) are as shown in Table 7.
![]()
Table 7. The correlation coefficients (r2, p values) between annual mean concentrations of NO3, TN and TP in the Jordan Discharge (Huri) and the Agmon-Hula effluents since the implementation of the Hula Project (1993-2018).
The correlation results emphasize the impact of Nitrate contribution by the Peat soil (Agmon-Hula effluents), originated in the Peat soil, on the Jordan water content whilst there is no similar effect on the TP migration. That is probably because the dominant contribution of TP is an outsourcing origin, not in the Hula Valley [17] . Data about N&P nutrient migrations from sewage produced in the Kinneret Drainage Basin and from Fishponds were not routinely monitored. Nevertheless, sporadic data are available [12] [18] [19] : Eighteen reservoirs with a total volume capacity of 4.1mcm were constructed in the Kinneret catchment for sewage collection. During 1996-2007 an annual removal of 83 tons of TN (concentration ranged between 11 - 27 ppm) through the reservoirs operation whilst through the Agmon Hula effluents (Hula Project System) the annual removal of TN was ranged (Max. - Min.) between 11 and 48 tons (concentration range 4.6 - 8.7 ppm). Moreover, during 2000-2005 an annual removal of 3.3 - 5.5 tons of Ammonium through the Agmon-Hula effluents (mean concentration 1.4 ppm) whilst an annual mean of Ammonium migration through the Jordan was 21 tons. During the period of post-drainage and prior to the implementation of the sewage removal project (<1986) 70.2 tons of Ammonium and 718 tons of Nitrates were migrated annually into Lake Kinneret through the Jordan discharge [12] . The very few data about the chemical features of the swampy waters in the Hula Valley before drainage [14] (Jordan annual discharge of 650 mcm) indicates probably an annual potential migration into River Jordan of 293 and 117 tons of Free Ammonia (Gaseous NH3) and Albuminoid Ammonia (Organic Nitrogen) respectively. Conclusively, with regard to the contribution of Ammonium from the Hula Valley, the drainage resulted in a distinct decline of Ammonium and total nitrogen which were further diminished as a result of sewage removal and aquaculture restriction and later additional reduction was the result of the Hula Project implementation. The oxidized peat became a Nitrate-rich source which is probably less effective in phytoplankton growth rate.
Although introducing science into public policy where conflicts of interest are likely [11] , shortly after the Hula drainage awareness initiated a disputed issue public: Does Nitrogen migration (mostly Nitrate) from the drained Peat Land Soil might be risky for the quality of Lake Kinneret water. As a response to the invited consultation a three volumes report was submitted to the national water authority of Israel summarized as (quote): “…There is an extremely serious problem…protect the lake from complete degradation…” [20] Scientific evaluation of ad hoc available limnological information revealed distinct negative responses scientists (Limnologists) and the case was closed.
5. Summary and Conclusion
The Hula Valley was drained during the 1950s and the land use was converted to agriculture and recreational tourism. Primarily, the newly developed land use included fish breeding in constructed ponds. Regional population size was enhanced and the industrial diary as well which implies intensive sewage production. The desire for Kinneret water quality protection implies aquaculture restriction and sewage removal. Collected sewage was conveyed into 18 newly constructed reservoirs and was reused for irrigation outside the Kinneret drainage basin. Supplemental investment aimed at environmental improvement was the Hula Project (HP). HP concluded fishpond restriction and replacement of aquaculture by field crops. These restrictions (81%) together with sewage removal were very effective in pollutant migration control and the Hula Project significantly improved agricultural management. The already implemented management policy in the Hula Valley is following design: maintain high levelm of the GWT and prevent summer dryness by irrigation. Agreement between the land owners and the National Water Authority resulted the “Hula convention” which ensure summer irrigation of cropped and non-cultivated Peat-Soil land against water pricing reduction induced positive support. Nevertheless, accompanied enhancement of Nitrate migration is not risky since lake Kinneret is under Nitrogen insufficiency.
Acknowledgements
Sincere appreciation is given to Mekorot Water Co. Ltd., Kinneret Limnological Laboratory, IOLR Ltd., The Kinneret and Drainage Authority for the Interim and annual reports and data availabilities.
Funding
This research received no external funding.
Data Availability Statement
The data presented in this study are available on request from the corresponding author.