Source Data for map: Environmental Resources Research Institute at The Pennsylvania State University.
The Generalized Watershed Loading Functions (GWLF) Model was used to predict dissolved and sediment-bound nutrients (nitrogen and phosphorus) for eight subwatersheds of the Spring Creek Watershed. Four of these subwatersheds corresponded to four locations along Spring Creek: Oak Hall, Houserville, Axeman, and Milesburg. The other four subwatersheds corresponded to the four main tributaries to Spring Creek: Logan Branch, Buffalo Run, Cedar Run, and Slab Cabin Run. The map below shows the four locations along Spring Creek and its four tributaries.
Source Data for map: Environmental
Resources Research Institute at The Pennsylvania State University.
As mentioned on the nutrients from the conservationist perspective map, there have not been many water quality samples taken in the Spring Creek Watershed. The tables below compare measured values of dissolved nitrogen and total phosphorus for Spring Creek at Axeman and Logan Branch with GWLF estimates at that location.
Comparison of Measured Dissolved Nitrogen and Total Phosphorus
with GWLF Predictions for Spring Creek at Axeman
| Location | Measured (mg/l) | Predicted (mg/l) |
| Dissolve Nitrogen | 4.3 | 0.7 |
| Total Phosphorus | 0.2 | 0.2 |
Comparison of Measured Dissolved Nitrogen and Total Phosphorus
with GWLF Predictions for Logan Branch
| Location | Measured (mg/l) | Predicted (mg/l) |
| Dissolve Nitrogen | 3.5 | 0.5 |
| Total Phosphorus | 0.1 | 0.1 |
Notice that the total phosphorus predictions were close, but GWLF under predicted the dissolved nitrogen. Once again, more monitoring data is need to evaluate the adequacy of GWLF predictions.
The tables below give nutrient levels predicted by GWLF for the past 20 years using measured weather data and for the next 20 years using simulate weather data.
Predicted Mean Dissolved Nitrogen for Spring Creek
for the Past 20 Years and for the Next 20 Years
| Location | Past 20 Years (tons/ac) | Next 20 Years (ton/ac) |
| Milesburg | 0.68 | 0.76 |
| Near Axeman | 0.72 | 0.82 |
| Houserville | 0.47 | 0.46 |
| Oak Hall | 0.38 | 0.38 |
Predicted Mean Dissolved Nitrogen for Spring Creek Tributaries
for the Past 20 Years and for the Next 20 Years
| Location | Past 20 Years (tons/ac) | Next 20 Years (ton/ac) |
| Logan Branch | 0.47 | 0.47 |
| Buffalo Run | 0.45 | 0.45 |
| Cedar Run | 0.80 | 0.76 |
| Slab Cabin Run | 0.51 | 0.50 |
Predicted Mean Dissolved Phosphorus for Spring Creek
for the Past 20 Years and for the Next 20 Years
| Location | Past 20 Years (tons/ac) | Next 20 Years (ton/ac) |
| Milesburg | 0.11 | 0.13 |
| Near Axeman | 0.12 | 0.16 |
| Houserville | 0.03 | 0.03 |
| Oak Hall | 0.02 | 0.02 |
Predicted Mean Dissolved Phosphorus for Spring Creek Tributaries
for the Past 20 Years and for the Next 20 Years
| Location | Past 20 Years (tons/ac) | Next 20 Years (ton/ac) |
| Logan Branch | 0.03 | 0.02 |
| Buffalo Run | 0.03 | 0.02 |
| Cedar Run | 0.06 | 0.05 |
| Slab Cabin Run | 0.03 | 0.03 |
Predicted Mean Sediment-Bound Nitrogen for Spring Creek
for the Past 20 Years and for the Next 20 Years
| Location | Past 20 Years (tons/ac) | Next 20 Years (ton/ac) |
| Milesburg | 0.11 | 0.14 |
| Near Axeman | 0.12 | 0.15 |
| Houserville | 0.16 | 0.21 |
| Oak Hall | 0.12 | 0.15 |
Predicted Mean Sediment-Bound Nitrogen for Spring Creek Tributaries
for the Past 20 Years and for the Next 20 Years
| Location | Past 20 Years (tons/ac) | Next 20 Years (ton/ac) |
| Logan Branch | 0.26 | 0.34 |
| Buffalo Run | 0.14 | 0.18 |
| Cedar Run | 0.40 | 0.51 |
| Slab Cabin Run | 0.16 | 0.20 |
Predicted Mean Sediment-Bound Phosphorus for Spring Creek
for the Past 20 Years and for the Next 20 Years
| Location | Past 20 Years (tons/ac) | Next 20 Years (ton/ac) |
| Milesburg | 0.04 | 0.05 |
| Near Axeman | 0.04 | 0.06 |
| Houserville | 0.06 | 0.08 |
| Oak Hall | 0.05 | 0.06 |
Predicted Mean Sediment-Bound Phosphorus for Spring Creek Tributaries
for the Past 20 Years and for the Next 20 Years
| Location | Past 20 Years (tons/ac) | Next 20 Years (ton/ac) |
| Logan Branch | 0.11 | 0.14 |
| Buffalo Run | 0.06 | 0.07 |
| Cedar Run | 0.17 | 0.22 |
| Slab Cabin Run | 0.05 | 0.07 |
Notice that the dissolved nitrogen exceeds the sediment-bound nitrogen, as expected. However, the dissolved phosphorus also exceeds the sediment-bound phosphorus. Usually, the sediment-bound phosphorus will exceed the dissolved phosphorus, since dissolved phosphorus is very reactive with sediment. GWLF does not contain complex chemical balancing, so it does not account for dissolved phosphorus going to sediment-bound phosphorus. As shown earlier, phosphorus monitoring usually looks at the total phosphorus.
Below are buttons to bring up all four nutrient calculators.
Click the button below to load the Dissolved Nitrogen Calculator.
Click the button below to load the Dissolved Phosphorus Calculator.
Click the button below to load the Sediment-Bound Nitrogen Calculator.
Click the button below to load the Sediment-Bound Phosphorus Calculator.
Source Data for map: Environmental
Resources Research Institute at The Pennsylvania State University.
The output from each calculator reflects the mean annual change of the nutrient caused by a particular set of policies. The nutrient calculators only display change in the 8 categories listed in the table below, due to the complexity of the modeling.
Percent Change Categories
| Category | Percent Change Range |
| Large Decrease | X<-50 |
| Medium Decrease | -50<=X<-25 |
| Slight Decrease | -25<=X<-10 |
| No Change | -10<=X<+10 |
| Slight Increase | +10<=X<+25 |
| Medium Increase | +25<=X<+50 |
| Large Increase | +50<=X<+100 |
| Very Large Increase | +100<=X |
First, using the two dissolved nutrient calculators, experiment with the policies and see how each kind of policy affects the dissolved nutrients. Notice that dissolved nutrients are affected by all policies, except riparian policies which only affect sediment. Also notice the impact of the different waste water policies. For policies using sewage treatment, it is assumed that all Centre Region sewage goes to the UAJA sewage treatment plant (STP) and all other sewage goes to the Bellefonte STP. These STP's are shown on the previous map.
Now experiment with the sediment-bound nutrient calculators. Note that these nutrients are affected by all policies except the waste water treatment policies, which only impact dissolved nutrient. The response of the dissolved and the sediment-bound nutrient to changing policies corresponds to the factors shown on the nutrients from the researcher perspective web page.
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Questions or Problems? Let me know at parson@andassoc.com.