[From the U.S. Government Printing Office, www.gpo.gov]

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                 MITIGATION OF AGRICULTURAL CONTAMINANTS OF ESTUARINE
                             WATER USING CONSTRUCTED WETLAN@V



   Ln                    A final report submitted to the New Hampshire Coastal Program
                                       NH Office of State Planning





    '25

                                                 by


                                    Stephen H. Jones and Richard Langan
                                       Jackson Estuarine Laboratory
                                       University of New Hampshire







                   QH
                   91.57
                   -B5
                   J664





              This report was funded in part by a grant from the Office of State
              Planning, New Hampshire Coastal Program, under the auspices of the
              National Oceanic and Atmospheric Administration (NOAA), Award
              Number NA370ZO277-01.                                           A

                                                                               mew




















                         MITIGATION OF AGRICULTURAL CONTAMINANTS OF ESTUARINE
                                          WATER USING CONSTRUCTED WETLANDS




                                                              INTRODUCTION


                         The Squamscott River has historically been a significant source of bacterial contaminants
                and nutrients to Great Bay, due in large part to two POTW's that discharge directly into the tidal
                portion of the river. Recent improvements in wastewater treatment processes have decreased
                contamination from these sources, resulting in some improvement in water quality in the river.
                However, the river still has elevated levels of fecal-bome microbial contaminants and dissolved
                nitrogen and phosphorus. Much of this contamination comes from nonpoint sources, including
                agricultural areas like the Stuart Farm in Stratham. This site is of particular interest because the
                farm's animal waste storage area is located at the head of a ditch that drains into the Squamscott
                River. Assessment of the fate of nutrients and microbial contaminants from the animal waste
                storage area was initiated by NH DES in 1992 and continued by UNHIJEL in 1992-1993. In the
                fall of 1993, the drainage ditch was altered by creating two impoundments to promote longer
                detention times for water-bome contaminants and to allow for growth of wetlands plants that
                should serve as sinks for nutrients. The purpose of this project was to evaluate the effectiveness of
                these management practices in reducing the impact of agricultural contamination of tidal waters.


                                                      MATERIALS AND METHODS


                         Five sites were chosen on a transect extending from the manure storage area through the
                drainage ditch and impoundments and ending in the Squamscott River (Figure 1). The locations of
                the sites were as follows:


                Site 1. The ditch just below the manure pile/picket dam;
                Site 2.  The effluent from the first new impoundment pond/solids settling basin;
                Site 3.  The effluent from the second, larger pond;
                Site 4.  The small pond at the end of the ditch just upstream of the tidal dam;
                Site 5.  The mouth of the tidal portion of the ditch/stream where it meets the Squamscott River.

                         Samples were collected on six dates, which included dry periods as well as
                rainfall/snowmelt runoff events. The six sample dates were November 30, 1993 (wet), March 30,








              1994 (wet), May 13, 1994 (dry), June 2, 1994 (relatively dry), June 15, 1994 (wet), and June 27,
              1994 (dry). Sample analysis included the microbial indicators fecal colifoims, Escherichia coli,
              Clostridiwn perfringens and enterococci; the inorganic nutrients ammonium, nitrate/nitrite and
              orthophosphate. Measurements were made of temperature, salinity, conductivity and pH at the
              time of sampling. Analytical methods used were standard multiple tube fermentation MPN
              analyses or EPA-recommended and other standard membrane filtration methods for
              microorganisms, the appropriate LACHAT "Quik-Chem" methods for nutrients, and standard
              procedures for all other parameters. Data from this study was compared to the assessment data
              collected before the alteration of the drainage ditch and creation of impoundments.


                                              RESULTS AND DISCUSSION

              Bacteria
                     The spatial trend for concentrations of bacterial indicators was relatively clear throughout
              the year. Concentrations of bacterial contaminants were always higher at the manure pile source
              (Site 1) than downstream at Site 5 in the Squamscott River (Figures 2-4). The greatest drop in
              levels was between the second pond (Site 3) and the tidal dam pond (Site 4) for all three indicators,
              especially for C. per                                              tr         oc:
                                 firingens (Figure 4). C. perfringens tends to be s ongly ass iated with
              surfaces and suspended solids, and the cleansing of particulate matter that occurs from the second
              pond to the tidal dam pond probably takes the C. per
                                                                 firingens with it. The levels of bacteria were
              similar in the first three sites except for fecal coliforms (Figure 2) and enterococci (Figure 3) during
              the spring and summer of 1994. During this time, there was an apparent die off of these indicators
              from the first pond effluent to the second pond effluent. This may be attributed to the higher
              temperatures during this time compared to the two previous sample dates (Table 1). In fact, the
              levels of enterococci and fecal coliforms were also relatively high at Sites 4 and 5 on the colder,
              first two sample dates. The same was not observed for C. perfringens, which survives in spore
              form and is better able to survive over wide temperature ranges. Both fecal coliforms and
              enterococci were present at very low levels on November 30 at Site 1. The pH was relatively
              alkaline (>10x [H+1 at downstream sites) and may reflect the presence of inhibitory substances
              (i.e. bleach, disinfectant, etc.) from the milk house effluent that mixes into the manure pile runoff
              just above Site 1.
                     Samples were collected during dry and after rainy periods. No consistent trends were
              observed that reflected any influence of rainfall-associated runoff on bacterial indicators. This is
              not surprising because of the infrequency of sampling and because comparisons are made for
              different seasons. The only potential trend was for fecal coliforms at Sites 1, 2, 4 and 5 during
              June, 1994. During this time, fecal coliform levels were higher for samples collected after dry
              periods than for the rainy sample at these sites, potentially reflecting some dilution effect from
              rainfall runoff. However, this was not observed consistently for the other bacteria. As previously
              mentioned, temperature seems to influence levels of the non-spore forming bacteria, so season
              does have an influence on bacteria.












               Nutrients
                      Though the general trend for nutrient concentration was that the levels decreased along the
               transect, there was a great deal of variation in concentration between sample dates, as well as
               variation in the location (site) of reduction for a particular nutrient (Table 1; Figs. 5, 6, 7). In the
               November 30 samples, both ammonium and nitrate increased from Site 1 through Sites 2 and 3
               before sharp reductions occurred in the tidal dam pond. This was not the case for phosphate,
               which showed reduced concentration at each site. Since the pH was relatively high and bacterial
               levels were so low, it may be that the effluent at Site 1 was diluted by runoff with lower nutrient
               concentrations from the milkhouse or other source.
                       Although the initial concentrations of all the nutrients were lower than several other dates in
               the March 30 samples, the poorest reduction in concentration was observed in these samples. This
               sample date was during the time of spring snowmelt and high runoff, therefore the reduced initial
               concentrations were probably due to dilution, and the high concentrations in the Squarnscott River
               reflect the influence of innumerable pollution sources in addition to Stuart Farm. Wetland plant
               growth was also minimal at this time as well. The May 13 samples, which were preceded by a
               period of dry weather, had the highest concentrations of ammonium and phosphate at site 1.
               Effective reductions in concentrations were observed at each site for all three nutrients, and the
               concentrations in the river samples were all low.
                       In the June 2 samples, nitrate concentration at Site 1 was relatively low, and effective
               reduction at each subsequent site was observed. The river sample, however, was higher than the
               tidal dam pond sample. Ammonium concentrations increased at Sites 2 and 3, were much lower in
               the tidal darn pond, and higher in the river sample, while phosphate concentration increased
               between Sites 2 and 3 before dramatic reduction occurred in the tidal dam pond. Though there was
               no observed increase in phosphate concentration in the river sample as there was with ammonium
               and nitrate, the river sample sample concentration was high relative to the other sample dates. On
               June 15, both ammonium and nitrate concentrations were higher at Site 3 than Site 2, however
               effective reductions were observed at Site 4 for both nitrogen compounds. Phosphate
               concentration was reduced at each site along the transect. In the June 27 samples, both ammonium
               and nitrate concentrations showed sharp reductions between Sites 1 and 2, and consistent reduction
               through the rest of the transect. Phosphate was slightly higher at site two than at Site 1, and the
               greatest change was observed between the second impoundment and the tidal dam sample.
                       More effective reductions in nutrient levels were observed in the late spring samples than in
               either the fall or early spring. This was probably due to the warmer temperatures stimulating
               greater microbiological activity, longer detention times resulting from plugging a leak in the second
               pond dam, or a more established plant community along the transect. Additional sampling as the
               vegetation becomes more established would probably be needed to document the success of the
               mitigation effort.









              Interannual Comparisons and Conclusions
                       These results do not indicate any favorable effect of the construction on bacterial levels.
              Greater reductions in bacterial levels within the first three sites would be expected on any given
              sample date. The obvious reason for this conclusion is that it takes time for the wetland plants to
              grow and initiate processes that would decrease contaminant levels through uptake or longer
              detention times. Because of delays in construction, no plant growth was possible during the fall of
              1993, so the wetland would not be expected to function until plants began growing in the late
              spring of 1994. In fact, we did observe some decreases in levels of two of the three bacterial
              indicators during June, 1994, in the effluent from the second pond. However, because we did not
              see reductions in levels of the spore-forming C. perfringens, we concluded that the reductions
              were a function of increased temperature, and probably not from natural treatment processes that
              may have occurred within the constructed wedand area. Additional analysis of data comparing
              before- to post-construction data supports this conclusion.
                      A comparison of data from before and after construction was made for the fecal coliforms,
              enterococci, and dissolved nutrients using geometric mean values for bacteria and arithmetic mean
              values for nutrients (Table 2). Since the sites were slightly different as a result of pond
              construction, only four sites common to both years could be compared. The small database cannot
              support rigorous statistical evaluation, so simple ratios were used to determine if there were
              obvious trends for contaminants at the different sites between years. Ratio values <1 indicated
              lower levels after construction and values >1 indicated lower levels before construction. To assess
              the impact of the construction, consideration was given to source concentrations, concentrations in
              the river, and the effect of passage through the ditch ending in the tidal dam pond. Ammonium and
              phosphate concentrations from the manure pile source (Site 1) were much greater, while fecal
              coliform concentrations were much less after construction. Enterococci, ammonium and phosphate
              concentrations were much greater in the Squamscott River in the second year. Thus, we could
              expect to see less of an apparent 'treatment' of contaminants through the ditch because some source
              and endpoint levels were elevated in the second year. There was no second pond before
              construction, so data for the tidal dam pond would best reflect any construction-related differences
              in the efficiency of treatment of contaminants in the whole ditch. The data for the tidal dam poznd
              (Site 4, 1993-94) do not indicate any major potential affects of construction, although enterococci
              and ammonium levels were -7x and -5x higher, respectively. However, enterococci and
              ammonium levels were higher in the first pond effluent and the river the second year as well.
              Thus, the impact of construction does not appear to have either negatively or positively affected
              contaminant levels. As the vegetation become established in the constructed wetland and detention
              time for runoff is increased, more effective reductions in contaminant levels should occur. Future
              sampling of the area after establishment of a stable wetland and functioning water level controls
              would be useful to document the success of this management practice.






                Table 1. Summary of data for Stuart farm study: 8/93-6/94.


                                    SITES/# Ditch below         1 st pond    2nd pond Tidal dam Squamscott                           SITES/# Ditchbelow lstpond 2ndpond Tidaldam Squamscott
                                                manure pile     effluent       effluent     pond          River                                  manurepile effluent effluent                pond          River
                    Parameter         Date            1             2            3             4             5         Parameter       Date            1            2            3           4             5
                  Fecal coliform      30-Nov          1         1.18E+05     6.60E+05     4.70E+04      2.OOE+02           N03         30-Nov          187          815          827         18.4          16.2
                    per 100 ml        30-Mar     9.90E+05       7.80E+05     3.50E+05     3.40E+03      4.10E+03           @OM         30-Mar          1407         689          351         9.1           67.7
                                      13-May     8.60E+05       3.40E+05     4,40E+04     1. 12E+03     1.20E+02                       13-May          1939         1060         918         7.9           3.3
                                      2-Jun      5.60E+05       1.22E+06     3.50E+04     5.90E+02      4.OOE+01                       2-Jun           3858         838          105         2.7           0.6
                                      15-Jun     4.OOE+04       1.40E+05     4.OOE+03     1.OOE+01      4.OOE+00                       15-Jun          477          343          787         7.3           9.5
                                      27-Jun     6.10E+05       1.04E+06     2.30E+03     2.70E+02      1.94E+02                       27-Jun          1807         142          11          7.2           7.4


                      E. coli         30-Nov         <1         1.15E+05     6.OOE+05     4.40E+04      1.75E+02           NH4         30-Nov          1320         7070         34230       2775          11.3
                    per 100 nil       30-Mar     9.70E+05       7.40E+05     3,50E+05     3.40E+03      4.IOE+03           @LM         30-Mar          31180        26455        19845       624.3         502.3
                                      13-May     8.60E+05       3.30E+05     4.40E+04     9.80E+02      8.80E+01                       13-May          508346       75893        53474       418.4         7.2
                                      2-Jun      2.OOE+04       3.80E+05     1.90E+04     2.20E+02      4.OOE+01                       2-Jun           4052         4262         7556        43.1          81.9
                                      15-Jun     4.00E+04       1.30E+05     4,OOE+03     1.00E+01      4.OOE+00                       15-Jun          22886        1724         3942        18.8          13.0
                                      27-Jun     5.80E+05       9.50E+05     1,33E+03     1.60E+02      1.50E+02                       27-Jun          10174        2475         1858        35.6          15.3


                    Enterococci       30-Nov        <10         9.90E+05     4.21E+06     1.47E+05      4.60E+02           P04         18-Aug          1289         877          780         85.7          1.6
                    per 100 ml        30-Mar     1.54E+06       1.41E+06     4.OOE+05     1.22E+04      1. 19E+04          pM          30-Mar          609          661          284         24.9          16.8
                                      13-May     1.17E+06       6.60E+05     5.OOE+04        <100       2.67E+03                       13-May          14239        4681         3597        18.5          1.4
                                      2-Jun      3.47E+05       3.40E+05     3.OOE+03     7.50E+01      2.50E+00                       2-Jun           347          293          805         7.1           6.5
                                      15-Jun     1.05E+06       5.OOE+04     2.OOE+03     4.06E+02      1.60E+01                       15-Jun          2937         1716         1001        1.0           0.8
                                      27-Jun     3.50E+05       1.31E+05     3.20E+03     3.10E+02      5.30E+01                       27-Jun          1260.0       1529A        939.9       5.3           1.3-
                                                                                                                      Temperature      30-Nov          16           6            2           0             4
                  C. perfringens      30-Nov        ND             ND           ND        4.40E+02      6.40E+01           0C          30-Mar          9            12           14          3             3
                    per 100 ml        30-Mar     5.80E+03       1.51E+04     3.OOE+03     6.50E+01      5.60E+01                       13-May          16           18           18          18            15
                                      13-May     8.80E+04       2.60E+04     4.10E+04     1.55E+02      1.25E+02                       2-Jun                                                 19            20
                                      2-Jun      1.20E+04       2.10E+04     5.OOE+03     2.50E+01      2.OOE+01                       15-Jun          29           26           23          25            24
                                      15-Jun     2.64E+05       6.OOE+03     4.OOE+03     5.0011+00     8.OOE+00                       27-Jun          30           30           29                        24
                                      27-Jun     1. 14E+05      6.50E+03     2.37E+04     1.65E+01      4.65E+01           pH          30-Nov          9.05         7.95         7.86        7.45          7.36
                                                                                                                                       30-Mar          8.32         8.53         8.31        7.53          7.67
                                                                                                                                       13-May          7.57         7.34         7.81        7.30          7.25
                                                                                                                                       2-Jun           8.56         7.37         9.04        7.57          7.60






             Table 2. Annual average and interannual comparisons on bacterial and nutrient concentrations at
             Stuart Farm: 1992-94.



             Geometric average concentrations of bacteria and arithmetic means for nutrients at Stuart Farm:8/93-6/94.
             Parameter           units        Below manure pile      I st pond effluent Tidal dam pond Squarnscott River
             Fecal coliforms     cfu/100 ml                   28581             351228                 1011                 110
             Enterococci         cfu/100 MI                   80012             435481                 1222                 226
             Nitrate             PM                            1574                 749                  9                  19
             Ammonium            PM                          113557              23081                 776                  12
             Phosphate           PM                            3884                1645                27                      5



             Geometric average concentrations of bacteria and arithmetic means for nutrients at Stuart Fann:8/92-6/93.
             Parameter           units         Below manure pile     Ist pond effluent  Tidal dam pond Squarnscott River
             Fecal coliform      cfu/100 ml                1367387              232499                 1651                 62
             Enterococci         cfu/100 ml                 365021                 4858                166                     7
             Nitrate             PM                            443                  194                21                   11
             Ammonium            9M                            5362                2262                161                     9
             Phosphate           11M                           435                  325                22                      1



             Ratio of FY94 average values to FY93 values.
                                               Below manure pile     I st. pond effluent Tidal dam pond    Squamscott River
             Fecal coliforms                                   0.02                 1.51               0.61                 1.78
             Enterococci                                       0.22                  90                7.4                  34
             Nitrate                                             3.6                 3.9               0.44                 1.83
             Ammonium                                             21                  10               4.8                  13
             ,Phosphate                                          8.9                 5.1               1.23                 6.31






                                                                              STUART FARM


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                                                        Figure 2. Fecal coliform concentrations in Stuart farm constructed wetland, ditch and Squamscott
                                                                                                                             River: 11/93-6/94.


                                                                                            30-Nov            30-Mar             13-May             2-Jun             15-Jun             27-Jun



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                                                     Below manure pile                      lst pond effluent                    2nd pond effluent                      Tidal dam pond                      Squamscott River
                                                                                                                                          Site











                                                Figure 3. Enterococci concentrations in Stuart farm constructed wetland, ditch and Squamscott
                                                                                                        River: 11/93-6/94.


                                                                            30-Nov          30-Mar         13-May         2-Jun           15-Jun         27-Jun



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                                            Below manure pile               lst pond effluent              2nd pond effluent               Tidal dam pond                Squarnscou River
                                                                                                                  Site











                                                                                               Figure 4. Clostridium perfringens concentrations in Stuart farm constructed wetland, ditch and
                                                                                                                                                                                             Squamscott River: 11/93-6/94.


                                                                                                                                                       30-Nov                        30-Mar                          13-May                        2-Jun                           15-Jun                         27-Jun



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                                                                                     Below manure pile                                                 Ist pond effluent                                             2nd pond effluent                                                Tidal dam pond                                              Squamscott River
                                                                                                                                                                                                                                   Site











                                             Figure 5. Nitrate concentrations in Stuart farm constructed wetland, ditch and Squamscott River:
                                                                                                            11/93-6/94.


                                                                      M 3o-Nov F-I 30-Mar                 13-May         2-Jun           15-Jun         27-Jun


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                                                         Figure 6. Ammonium concentrations in Stuart Farm constructed wetland, ditch and Squamscott
                                                                                                                            River: 11/93-6/94.


                                                                                      N 3o-Nov El 30-Mar E 13-May 0 2-Jun                                       M 15-Jun 0 27-Jun


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                                                    Below manure pile                      lst pond effluent                    2nd pond effluent                      Tidal dam pond                      Squamscott River
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                                       Figure 7. Orthophosphate concentrations in Stuart Farm constructed wetland, ditch and
                                                                      Squamscott River: 11/93-6/94.

                                                     0 30-Nov D 30-Mar M 13-May 0 2-Jun            M 15-Jun El 27-Jun


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                                                                                                                                       @ 3 6668 14109 2603