-------
and general findings are discussed.
Profit maximizing solutions without cost sharing included
primarily row crops or permanent hayland grown under no-till
resulting in estimated erosion levels far below those of the
baseline or preproject conditions (Table 14). For most typical
farms, these solutions did not exceed Illinois' allowable erosion
limits. These profit maximizing activities involve a greater use
of no-till and reduced-till systems with increased acreages de-
voted to pasture and hayland. According'to analyses of crop
budgets, these activities were more profitable in both the short
and long run.
Availability of ^ost share funds would have little impact on
land use and treatment. ' Cost sharing would induce previously
profit Bjaxisizing operators to make only minor adjustments in
cropping activities during the ten years of project life. These
adjustments would aainly be shifts to no-till from reduced-till
and from permanent pasture to rotations including row crops and
multiple hay crops. These changes found in the first 10 year
period would revert back in subsequent periods when cost share
payments were no longer available.
The University of Illinois SOILEC model simulated erosion
impacts of a 50 year planning horizon (Eleveld and Starr, 1983).
Average erosion rates were virtually identical with and without
cost sharing (a difference of .11 tons/acre). The reason is that
less profitable activities, which are also slightly more erosive,
become more profitable with the addition of cost share payments.
The typical farm analytical models incorporated productivity
impacts of soil erosion on yields. The SOILEC model estimated
crop yields by soil for crops and BMPs allowed in the farm
analyses. The lower sloping soils of primary concern in this
project are the most productive soils in the watershed. The
erosion rates for these soils for a CSW/S rotation were estimated
to be very low for all management alternatives considered.
Related productivity impacts were also low enough to be
negligible.
In several instances, the availability of RCWP cost share
paytneni-s created a different allocation of land use and treatment
>I;.T, ,, -) s&d to that created without such funds (Eleveld and Starr).
This .nJicates a dilution of the impact of transfer payments.
That i.s> when a lar.d use and/or SMF is selected as part of an
"ff->-.ant resource allocation when cost sharing is available but
ib .i j t selected when funds are not available, the farm model
Selected a crop management alternative having a lower per acre
Tot return without cost share payments. Therefore, some of the
^ r;>:••; fee payment is being used to compensate for a somewhai, less
;>(ufi table crop management system. The iiepl i- ) ti on is that de-
sicable conservation impacts might be obtained with lower total
tf•••'.lifer (cost share) payments. This might be possible if opera-
tors could be convinced to change to profit maximizing .aanagement
activities suggested by analyses wh^n cost sharing wa? not
71
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available .rather than those suggested when such funds were avail-
able.
Cost share payments affect net income only during the first
10 year period in the typical farm analyses. The average annual
returns for the 416 acre farm illustrated in Table 14 in the 10
year analysis suggests a sizeable impact of $13.28 per acre per
year for production under cost sharing.
Terracing and contouring although included in the farm model
alternatives were not selected as part of any solution. This was
in part due to the expense of these practices and in part due to
the relatively low levels of erosion inherent in both of the
alternative future conditions under the profit maximizing assump-
tion.
None of the results of these analyses suggests differential
economic impacts due to farm size. Identifiable differences seem
more related to the quality of the resource endowment of the
typical farms analyzed.
WATER QUALITY DATA ANALYSIS
Summary of Project Results
Extensive analyses of the Illinois RCWP data performed
by project staff have been reported in the 1984 annual report and
previous reports. The project should be commended for its
efforts in data analysis and also for its clarity in reporting
the results of these analyses.
For most analyses performed by the project, the data were
stratified by two different factors, time and flow. The yearly
data were divided into 3 periods based on agricultural activities
and condition of the land surface:
period 1 (Pi) April to June: fertilizer, seed bed prepara-
tion, and crop establishment
period 2 (P2) July to November: reproduction and maturation
of crop
period 3 (P3) December to May: residue.
Clio flow was classified by bassflow and event flow for data
in ""-.is purposes.
The data analysis in the 1984 annual report Included 2.25
/V-JA'-S of small watershed study data and 3 years of lake water
jualily data. The standard deviations of the concentrations for
stream baseflow and event flow are quite high, sometimes
exceeding the means. This high variation makes it difficult to
document significant water quality changes over a short period of
t. I..UIP However, a few significant changes were reported. Total
72
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suspended solids (TSS) and total phosphorus concentration at the
spillway were found to be significantly less than that at gage
site 1, located immediately above the lake. This suggests that
the lake acts as a trap for TSS and phosphorus. TSS concentra-
tions during events in periods P3 and Pi were generally higher
than those during P2 , this may be related to precipitation and
land use activities. No significant differences were found among
stream stations for concentrations of TSS or turbidity. Event
concentrations were found to be significantly higher than base-
flow concentrations for both these parameters.
Several observations from the field site data indicated
that, TSS yields from 7 of the 8 fields were composed mostly of
inorganic soil particles, and phosphorus concentrations were
highly correlated with TSS concentrations during PI, less
correlated during P2, and least correlated during P3. Nutrient
concentrations from- feedlot runoff were also reported to be
significantly higher than from croplands.
The monthly loads measured at the stream and spillway
stations also had a high amount of variation. Loadings during P3
were generally highest; probably due to snowmelt and spring
runoff. Unit area loadings of TSS from stream gage site 3, the
smaller watershed, were about twice as high as at sites 2, except
during P3-1981. This disproportionately high unit area load from
stream site 3 suggests that this subbasin may contain an
important untreated source.
Two levels of- modeling are planned for this project: field
scale and watershed. • -Different land use practices were modeled
on the field scale using CREAMS. To summarize the results, (1)
the most effective practice was no-till with 80 percent residue,
(2) spring moldboard and fall chisel plowing were found to
produce approximately the same change in water quality, (3) grass
waterways reduced concentrated flow erosion, and (4) sediment
loadings were reduced by dry dams. CREAMS is also being used to
model two field sites which are also monitored. The results of
comparisons between simulated and observed data for the 2 sites
is planned for the 1985 Annual Report. Results from watershed
modeling, performed with the AGNPS model, has not yet been
reported.
Several regression analyses were performed and reported in
attempts to establish the relationship between different
var i -I'nl.is . Land use (i.e. type of crop) was not found to be
aigni t'iuantly related to sedioienl and nutrient yields on the
watershed-scale. However, this comparison lid not consider other
'^oportant characteristics such as dinnagement practices, soil
',ype, slope of field, farm location, etc,
on of nutrient and jodiment yields vs, rainfall
energy and rainfall/runoff ratios indicated that rainfall energy
ind the amount of runoff were related to nutrient yields at the
throe stream sites, but rainfall energy and runoff were related
'••o suspended solids at only site 3.
73
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To document I ; h* relationship bet**^**ii *»ater quality of the
stream (site 1) «o4 J«ke, regression analysis was used. No
significant correlation was found. However, only baseflow data
that were not stratified into periods (due to small sample size)
were examined. Perhaps after additional data are collected, a
relationship between stream and lake water quality will be more
apparent .
Duncan's multiple range test was used to compare the means
of the lake water quality data. The variation in the lake data
was high, but not as high as the stream data. Generally,
however, Secchi transparency- improved in the summer (P2) probably
due to stratification of the lake. Approximately 70 percent of
TSS is non-volatile. TSS is correlated to turbidity, with a
better correlation found in main lake samples than in bay
samples, however, neither the significance level nor the
regression coefficients were reported. Nutrient levels in the
lake were high, especially during PI. Chlorophyll a concentra-
tions were low, probably due to limited light penetration.
The following spatial trends in the lake data were observed,
although they were not significant at 95 percent confidence. In
a direction going toward the dam, Secchi transparency and
dissolved oxygen increased and total suspended solids, non-
volatile solids, and alkalinity decreased.
Simple regression of lake water quality parameters against
time indicated significant increases in inorganic nitrogen,
dissolved phosphorus, and Secchi over the three ye'ar period.
However, upon brief inspection of the reported Secchi data, it
appe'ars that Secchi transparencies in the. lake were decreasing
over time. Further analysis of these data, with stratification
of data by time period, may clarify this apparent discrepancy.
Analysis §od isi§r.p.r.etations
Additional data were presented after the 1984 Annual Report
in a report from the Illinois State Water Survey (Report No. 357,
February 1985). We examined these data to determine if the
differences in water quality at gage sites 2 and 3 were indeed
significant. Although the report covers the period from February
1982 to April 1985, it included only 8 storms where loads were
estimated at both gage sites 2 and 3. Total storm runoff and
runoff ratios were estimated for 32 events. Additional storm
•-infrfl orobnbly exist but were not reported.
#e examined the data by regression analysis. Storm loads of
't-Si ;>nd event mean concentrations of TSS and turbidity were
t ra.\ s f vrmed to their logarithms. Paired observations from the
two subbasins were then regressed by linear least squares, and
the simultaneous hypotheses that the intercept is equal to zero
*nd slope is equal to one were tested.
Results from the regiession analysis are sho*n in Table 15.
.1 .lear indication of differences in water quality between the
74
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two subbasins was observed. At 90 percent confidence, we found
that TSS concentration and TSS unit area loading rates were
higher in subbasin 3, the smaller basin, than in subbasin 2.
Turbidity was not significantly different at the 90 percent
confidence level.
Because both loading and concentration were found to be
significantly different, we considered whether storm runoff
volume and rainfall/runoff ratio might also be different.
Results are shown in Table 15. A higher level of confidence was
possible in this analysis because there were more stormflow
observations that could be paired between gages than there were
water quality observations that could be paired. The runoff
ratio was not transformed to its log. The analysis indicated
that runoff volume froa the two sites were not significantly
different, but the rainfall/runoff ratio in subbasin 3 was
significantly higher than that of subbasin 2 (p=.95).
These results suggest that the runoff response and the
concentration of sediment in stormflow from subbasin 3 is greater
than that of the larger subbasin. Subbasin 3 is generally not
included in the designated critical area of the project. These
observations suggest that the water quality data should be
considered in a reevaluation of critical areas. Specifically,
subbasin 3 should be examined for unique characteristics that
make it contribute more than is expected.
Table 15. Regression analysis to test for differences between
water quality at Gage Site 2 and Gage Site 3*
(Illinois RCWP)
Parameter
N
Conclusion Confidence
TSS EMC**
TSS Load
Turbidity
Runoff
Runoff/Rainfall
8
8
8
32
32
S3
S3
S3
S3
S3
> S2
> S2
= S2
= S2
> S2
90*
90*
95*
Data from Sta'e Water Survey Report 357.
*SM!' is Event faean Concentrations.
Other analyses froai the available data may be useful in
.i-lading the project and producing early projections of the
results. Sepa at.ing the bay water quality data from the mean
lakr- water quality data would allow analyses of each data set,
The Says may respond to land treatment at a different rate than
the main lake. Since all of the Innd around the bays is
designated as critical, data from the bay stations may indicate
other sources of loading, Mso, a
the
may
relationship
between
75
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concentration in •torn samples and discharge rate can be
developed and applied to storms with incomplete records to
utilize more of the information in the monitoring data.
Many of the water quality projections and analyses of the
project are based on a delivery ratio developed from analysis of
soils, slopes, and.distance to stream network (Davenport, 1984).
Delivery ratios from this analysis varied from 22 percent to 100
percent for one field site. In general, they concluded that the
site specific delivery ratio was even higher than 47 percent, the
previously estimated overall delivery ratio.
To consider the validity of a delivery ratio of 47 percent
or more, we compared an estimate of annual TSS load from gaging
sites 1, 2, and 3 with an estimate of gross erosion. Results are
shown in Table 16, This is a rough estimate, because the actual
gross erosion for the period of study *ay be different from the
average annual gross erosion eatianated by the USLE. The observed
sediment delivery ratio was about one-half of that used by the
project. It seems likely that the delivery ratio for larger
particles may be low, while the ratio for fine particles may
approach 100 percent. An accurate delivery ratio is extremely
important in getting a correct projection of water quality re-
sults from this project.
Table 16. The Relationship of Average Annual Gross Erosion to
Observed Total Suspended Solids Yield. (Illinois RCWP)
Land Use/Cover Percent of Area Average Erosion
Rate (t/acre/yr)
Cropland 82.3* 3.8**
Pasture/Hayland 5.4 0.9
Woodland , 4.1 0.2
Urban 0.7 0.7
Feedlots 0.3 17.4
Other 7.2 1.6
Overall 100.0 3.30
***
Site Months* Average TSS load Deliv. Ratio
t/acre/yr percent
23
14
21
* data
** data
***only
GS 1
GS 2
OS 3
from
from
mon t
22
20
19
0.
0.
0.
779
452
707
Davenport, 1984
1982 Annual Report
hs with complete records
used
76
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PROJECTIONS
The absence of significant water quality improvement could
be due to any single factor or combination of factors such as the
following:
1. The period of record is still too short.
2. There is not enough BMP implementation to cause a
detectable change in water quality.
3. BMPs are not adequate to reduce these water quality
problems.
4. Critical areas may not be correctly defined.
5. Other phenomena are masking the ef %«5cts of BMPs.
The water quality data collected thus far have relatively
high variation and represent a relatively short period of time.
Thus far, only 37 percent of the critical area is under contract,
and roughly 10 to 20 percent of the critical area has implementa-
tion of BMPs. A change in water quality might be detected when
there are higher levels of BMP implementation. The fine
particles that are responsible for the high turbidity in the lake
and • the natric (sodium) nature of the soil may not be
appropriately addressed by the BMPs that have been used. These
BMPs may have the potential of reducing erosion, but may not
substantially reduce the fine particles concentration in runoff
water. «In the unique case of natrijc soils, practices designed
specifically to reduce the volume of runoff may be more- effective
than those which have primary effectiveness for erosion control.
Other phenomena, such as lake turnover, may also mask the
effects of the BMPs. Lake turnover causes resuspension of fine
particles from the bottom sediments, but this process also helps
purge the lake of sediment build up. At this time, it is
difficult to determine exactly which factor or combination of
factors is predominant, but it is clear that considering the low
level of BMP-implementation and the short period of monitoring
record, we would not expect to observe a water quality effect in
the lake.
The 1984 Annual Report projected a 67 ->ercent reduction of
;*> upended solids load at gage site I inder the following
."xiremely optimistic conditions: (1) all cropland is managed
•rii'-h conservation tillage, (2) pastures ard woodlands are well
managed, (3) waterways and structures are implemented where needs
indicate, (4) rainfall runoff is reduced by 50 percent, and (5)
rainfall energy is reduced by 45 percent, No projections of
changes in lake water quality w?re attempted. The complexity of
th*' ^y«?t. em makes all of these projections rather tenuous.
77
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IMPLICATIONS
The Highland Silver Lake project had much advance planning.
Critical areas were defined and a sound monitoring approach was
developed. Yet there is no certainty at this time whether or not
the water quality impairment can be reversed. The main question
remaining to be answered is: "Can BMPs effectively reduce the
erosion of fine particles of sediment from natric soils suffi-
ciently to reverse the impairment of Highland Silver Lake?"
The field study data should contribute substantially to the
answer to this question. These data should be analyzed to deter-
mine which BMPs are best for treating natric soils. With this
information, the more effective BMPs could be promoted for im-
plementation. The water quality data should .be used to
reevaluate where critical areas and important sources of pollu-
tants are located. Th- relationship between stream and lake
water quality needs to be well established. Characteristics of
the lake (i.e. hydraulic retention time and the rates of sediment
settling and resuspension) would help to estimate the potential
effects that the recommended land treatment would have on
Highland Silver Lake.
78
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St. Albans Bay, Vermont
RCWP 12
INTRODUCTION
The St. Albans Bay Project is located in northwest Vermont on
Lake Champlain. Agricultural activity in the 33,344 acre project
area consists primarily of dairy operations with an average of
330 acres and about 100 dairy cows.
The water resources use impairments are related to eutrophic
conditions in the Bay. Excessive macrophytic plant growth
.npairs boating; algal conditions impair swimming, fishing, aes-
thetic enjoyment, and shore-line property values. Phosphorus,
contributed from the sewage treatment plant (76%) and from non-
point sources (24%), is believed to be the limiting nutrient.
Bacteria from these same two sources impair use of waters for
swimming.
E§r§B§£:tiyes of the Project
The following questions related to agricultural management
and water quality are relevant to the project situation.
1. What degree of phosphorus, nitrogen and sediment loading
reductions can be accomplished through treatment of 80 per-
cent of the critical areas and sources in an intensive
dairy farming area?
2. What are the most effective manure management practices for
reducing phosphorus loading in northern U.S. climates?
3. What is the relationship between total phosphorus loading
reductions and orthophosphate reductions from improved
animal waste management?
4. To what extent and how quickly will a lentic water body
respond to significant pollution loading reductions from
both point and non-point sources?
o. What will be the effect on stream nutrient loading of elimi-
nating the application of manure to frozen ground in
northern U.S. cLiraates?
6, How well does the CREAMS model predict actual pollutant
losses from various agricultural management systems in
northern U.S. climates?
7 What is the minimum water quality change which can
be detected by a well-designed, comprehensive monitoring
program?
79
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What role do?»3 *«diment-bound phosphorus play in improving
the trophic status of a phosphorus-limited lentic water
body?
Strategy.
All RCWP BMPs except BMP 13 and BMP 16 have been approved
for the project. The emphasis has been on BMP 1 (permanent
vegetative cover), BMP 2 (animal waste management), BMP 8 (crop-
land protective system), and BMP 15 (fertilizer management).
The greatest need has been for BMP 2 which has been part of every
RCWP water quality plan written in the project.
The project has developed a relatively rigorous method for
selecting critical areas. The criteria include present manure
management practices, water resource accessibility, on-site
evaluation, and water quality monitoring needs. A total of
15,257 acres or 45.8 percent of the total project area has been
designated as critical.
Information/Education efforts in the project have
been extensive. Information about the project has reached every
resident within the watershed, and the effectiveness of these
activities is evidenced by the fact that nearly every landowner
in the critical area has signed up for the program.
Water "Quality. Monitoring Strategy
A thorough and complex water quality monitoring (WQM) pro-
gram is an integral part of the project. The design can be
briefly summarized as follows:
1. monitoring of St. Albans Bay. (This includes special
studies such as bay circulation patterns and phos-
phorus remobilizat ion from bay sediments.)
2. automated sampling of streams to determine pollutant
loading trends.
3. randoa? grab sampling of streams to determine concentra-
tion trends.
•1 . monitoring at the edges of t'.co smaH paired watershed
sites.
5. monitoring of the St. Albans Bay sewage treatment plant
effluent.
BMP IMPLEMENTATION ACHIEVEMENTS
The project has been quite successful in attaining its
implementat ion goals. Credit for this achievement belongs to
80
BMP
all
-------
of the agricultural Bgc/*vy personnel involved who have created a
high level of farmer awareness of both the water quality and
economic benefits of participation in the project.
BMP implementation is occurring under both RCWP and ACP
contracts. Of 85 dairies and 15,257 acres identified as needing
treatment, 69 dairies (56 - RCWP, 13 - ACP) and 12,762 acres
(10,330 - RCWP, 2392 - ACP) were under contract as of September
1984. The project estimates that 13,442 acres and 74 dairies
will eventually receive treatment. This represents 87 percent of
the critical dairies and 88 percent of the critical acreage.
Project personnel believe that the awareness brought about
by the RCWP project has contributed an impetus to other dairy
operations for initiating barnyard improvements under ACP and for
achieving a general reduction in fertilizer usage as farmers
understand better the nutrient values of manure. Of the 56 far.;s
under RCWP contract as of September 1984, treatment had been com-
pleted on 29. Almost exactly half of the animal manure produced
in the project was under best management as of this date. This
percentage is much higher if only the critical area is con-
sidered. Nearly all cost-share funds (96*) have gone for
managing animal waste. This includes cost-sharing directly for
BMP 2 (86%) and also for BMP 12 (10*) which has actually involved
barnyard runoff improvements.
Overall the project personnel estimate that 74 percent of
all BMPs contracted have been completed. This indicates clearly
the farmer enthusiasm for the project.
•
The project requested and received'supplemental funding for
FY 1985 to cost-share additional requests and to modify existing
contracts. In addition to these pending applications, howeve ,
there remain several dairy operations in the critical area which
have not applied for RCWP. It is somewhat unclear whether these
farms could be persuaded to participate if cost-sharing were
available.
ANALYSIS OF FARM LEVEL COSTS
Impacts at the individual farm level are illustrated in
Table 17, which shows the relevant financial and physical impacts
associated with BMP adoption. Two representative farms, a medium
ind l-^rge size, are depicted in the table. In each instance the
daily spreading' situation is presented which reflects the pre
projet. l condition. The project effects can be determined cy
•roaipar I ?ig the various manure storage alternatives with the daily
3prea
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Table 17. Annual Impacts of BMP Adoption for Two Typical Dairy Farms in the Jewett
Brook Subwatershed of the St. Albans Bay RCWP Project.
•
*
Impacts "
FinnncJnl F.ffects
Cross Revenue * i
Vre-tax Met, Income-
Cost Share (Covrt)
Cost Share (Farmer)
Environmental Effect
Cross Erosion (Tons)
Delivered Sediment (Tons)
K Loss
Adsorbed (Ibs)
Dissolved (Ibs)
Total
P Loss
Adsorbed (Ibs)
Dissolved (Ibs)
Bionvailable
«
Farm Operations
Cows Milked '
Replacement: Bought
Raised
Crops
Corn (Acres
Alfalfa (Acres)
Manure Spread (Tons)
Spring
Summer
Fall
Vintcr
frV-rrUiz-i- Purchased (Tons
«-abor Hired ^Hrs)
Spring
Sunncr
Fall
Win?. .;;'
Total
w/o RCVP
Daily
Spread
109,470
27,427
0
0
102.6
40.0
554
171
725
30.8
141.0
171.8
58
32
9
48.0
60.4
450
450
450
450
20.5
290
276
214
780
Medium Fam
\ W/
^Semi-Solid
* A-Frame
•
•
107,619
29,785
27,862
8,966
68.0
26.7
407
93
500
22.6
23.0
45.6 .
58
20
21
53.1
60.4
915
'915
9.04
228
194
138
560
n
P.C'-f?
Liquid
' (Earthen
! Pit)
•
108,948
28,752
11,312
17,783
68.2
26.7
407
126
633
22.6
72.0
94.6
* „
58
29
12
53.1
60.4
-
904
904
9.7
224
190
129
543
•
Large
7 w/o RCWP :
; Daily
• •
• *
• •
191,500
42,675
0
0
171.0
66.6
9-41
302
1243
51,6
239! 0
. 290,6
100
70
0
87.4
114.0
761
761
761
761
39.8
414
108
383
303
1208
Farn ^P
w/ RCVP
Liquid
(Earthen
Pit)
191,500 ,
45,800
16,005
22,633
114.3
44.8
699-
226
925
38,0
123.0
161%0 ^
m
V
100
70
0
87.4
114.0
1522
1522
22.0
304
240
167
TiT
net income to land, management, and owner labor. Value, are adjusted aftc_,
years when the facility is totally amortized and repair and replacement 'costs arc
j to be 50 percent of original costs.
-------
Pre-tax net fara income is used «s a measure of project
efficiency since taxes tend to mask what is occurring with re-
spect to the allocation of resources. For example, rapid depre-
ciation schedules do not provide a realistic measure of equipment
life. Also, consider two pre-tax situations that are identical,
but because of different exemptions the net incomes can be mark-
edly different. Consequently, pre-tax net farm income is used
when examining economic efficiency.
Examination of Table 17 reveals that in each case the in-
stallation of a nanure storage facility with a 75 percent RCWP
cost sharing of eligible costs results in an increase in pre-tax
net farm income when compared with the pre-BMP state of daily
spreading. In the case of the medium size farm, the semi-solid
and liquid storage facilities provide increases in pre-tax net
farm income of $2,358 and $1,325, respectively. The; adoption of
a liquid manure pit yields an increase in pre-tax income of
$3,125 in the large farm setting. After 20 years these values
increase somewhat as the structures are assumed to be fully
amortized at that time. However, it is further assumed that
repair and replacement will be 50 percent of the original cost.
Thus, the annual pre-tax net farm income figures for the medium
size farm after 20 years will be $2,887 and $2,355 respectively,
and $4,435 for the large farm liquid pit. Although there exists
an increase in current income it must be recognized that the
simulation performed by the IP model accounted only for the farms
financial commitment, i.e., 25 percent of eligible RCWP costs
plus some noneligible costs, not the government's cost share.
After tax income was not used to evaluate project efficiency
because it does not properly account for resource use, but also
because the number of possible tax scenarios was too many to
incorporate into the analysis. However, the reality of every day
decision making dictates their consideration. Although it is
difficult to make a specific statement about the tax implications
it can be generalized that the Federal and Vermont state tax laws
are such that they will reduce the negative impacts of BMP adop-
tion. The farmer has several tax incentives applicable to the 25
percent fans cost share and other RCWP associated expenditures.
An investment tax credit can be claimed on the manure storage
facility if it is more than an earthen structure. This of course
would apply to additional spreaders, tractors, and pump invest-
ments. Further, manure pits that do not qualify as soil and
wa^er conservation expense and can therefore be deducted from
>• -».xah 1 e income ,
Vermont's income, property, and sales taxes also have provi-
that can affect conservation and environmental programs.
t' s income tax schedule in based on a straight percentage
,2P percent) of the federal tax. As such, all tax considerations
jpp] xr-^ble to BMPs for federal tax purposes also apply to Ver-
mont In addition, manure storage facilities are also exempted
from property taxes.
83
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WAfiSt DUALITY DATA ANALYSIS
Summary of Project Results
§1.1 Albans Bay The Bay monitoring program consists of:
1. periodic (approx. 20/year) grab sampling at four sites.
2. some biological monitoring at these four sites.
3. sediment phosphorus release studies.
4. a study of bay circulation which"involves using wind,
water, current and concentration data to determine the
effect of bay circulation on water quality.
The bay concentration data show no obvious trends over the
1982-1984 period. Mean concentrations of total suspended solids,
total P, and TKN were slightly higher in *83-'84 than '82-'83.
This may be associated with higher than normal precipitation
during '83-'84, although it must be remembered that most of the
nutrients in the bay itself come from the sewage treatment plant.
Ortho-P concentrations were about the same both years.
No biological monitoring results from the bay were included
in the 1984 report materials. However, extensive biomonitoring
information from the five tributary sites was reported.
The sediment phosphorus release studies appear to have been
completed. The following results are evident from this study:
1. Phosphorus is released from bay sediments under both
aerobic and anaerobic conditions; however, release is
.more rapid under anaerobic conditions.
2. Phosphorus release rates increase with both temperature
and flow rate at the sediment-water interface.
3. Over extended periods of time phosphorus can be re-
leased frost deeper sediments as well as the upper
several centimeters.
4. The sediment column contains sufficient phosphorus to
be a long-term source for continued supply.
These results have 'several possible implications relating to
t->otenH"l water quality improvement in the bay. Most importantly
they j-'j'gest that improvement of the bay's trophic status may lag
behind anticipated reductions in phosphorus input. It is not
• •1..MC iYom information contained in project Annual Reports, just
hov? large a sediment phosphorus reservoir exists.
Another implication is that, as volatile suspended solids,
fluttients, and oxygen-demanding dissolved organic loads are sub-
§t-antin]ly reduced, the incidence of bay sediment conditions
-------
becoming anoxic may tv rr^luced. In this case flushing of sedi-
ment phosphorus may t*k« longer, but the bay may exhibit improved
trophic conditions in the meantime.
S§Y. Circulation Studies No results of the bay circulation
studies were included in the 1984 annual progress reports.
Earlier reports indicated that detailed computer models of bay
circulation patterns have been developed and are ready for use.
Tributaries The tributary (level 2) studies include:
1. automated stream sampling to determine loading and
concentration trends in the four main tributaries.
2. biological monitoring of fish species, benthos, other
invertebrates, and periphyton.
3. meteorological monitoring to relate .tributar • water
quality changes to meteorological variables.
4. detailed land use monitoring (manure spreading logs,
dates of field operations, etc.) to relate tributary
water quality observations to land use activity.
Only two full years of tributary monitoring had been com-
pleted, analyzed and reported as of September 1984. The WON
personnel .are, thus, reluctant to project any water quality
trends based on this short period of record. Also, BMP implemen-
tation was in progress throughout this period, although completed
impleme.ntation was significantly higher during .the second year.
, * •
f ,
The analysis conducted by the project shows several 'note-
worthy spatial .trends. The subwatershed (Jewett Brook) with the
greatest intensity of agricultural activity shows the highest
concentrations and loads of agricultural NFS pollutants. Phos-
phorus loads are about 20 times the average for U.S. agricultural
watersheds. It is this subwatershed which receives the greatest
BMP coverage, and thus, has the most potential to show water
quality improvement during the RCWP timeframe.
Although the WQM personnel are hesitant to claim a water
quality improvement in Jewett Brook, we believe that there are
already some good indications of a significant reduction in
nutrient concentrations. Referring to Figure 16, large (approx.
50%) reductions in mean orthophosphate and total Kjeldahl nitro-
gen concentrations are evident between Year 1 and Yeai 2 of
lonitoring. As noted above, there were substantially more manure
nt systems completed in Year1 2. The observed reduction
orthophosphate concentration occurred even though precipita-
was 30 percent greater in Yeai 2 which would tend to in-
se NPS nutrient concentrations. This gives further support
the suggestion that the manure management BMPs are having a
positive effect. It is anticipated that these trends will become
given a longer monitoring period and the high level of
85
o
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75T
TRIBUTARY STATION
21 22 23 24
JEWETT STEVENS RUGG MILL
1.0-r
75
S,P
6.24.8
4.44.8
BAY STATION
12
OUTER INNER
11
0.1-r
12
24
25
11
12
,-T 10-T
18.317.1
21 22 23
JEWETT STEVENS PUGG
24
MILL
"5
STP
II
OUTER
12
INNER
Figure 16. Mean Concentrations of Solids, Phosphorus and Nitrogen at
the Tributary and St. Albans Bay Trend Stations for Two
Years. (From VT 1984 Summary Report, page V-2.)
86
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BMP implementation \%Q -30*) projected. Based on the percentage
of manure brought uttder best management, the project has
developed models which estimate that total P runoff losses have
been reduced about 21 percent and dissolved P runoff losses by
about 57 percent in the Jewett Brook drainage (Figure 17). Reduc-
tions by 1990 are projected to be 30 percent and 86 percent
respectively. The 1984 report suggests that the large majority of
P inputs after bringing manure under BMP is from soil erosion.
It would appear, therefore, that a large excess of P has built
up in some project soils. These results emphasize again the need
for good fertilizer nutrient management to achieve maximum reduc-
tion in P loadings. The project has noted that further refine-
ments of these models are underway and should improve the
accuracy of the projections.
Figure 16 also provides a graphic portrayal of the magnitude
of the nutr ent inputs from the sewage treatment plant. (STP)
Plants constructed or up-graded in the past ten years are expect-
ed to produce final effluent with total P concentrations of less
than 1 mg/1. This illustrates once again the importance of the
STP upgrading to obtaining improvement in the Bay itself.
The biological monitoring information presented in the 1984
Report reflects essentially pre-BMP or baseline conditions. The
tributaries were found to have basically the fauna expected of
small Vermont warm-water streams moderately impacted by NPS.
Jewett Brook exhibited a unique fish species composition and
distribution which may change significantly as NPS loads are
reduced.
Watershed" Field Sites The objective of a "paired
watershed" experiment was to show the effects of land management
on water quality by effectively controlling for meteorological
and other tim,. - related variation. The paired watershed design
conducted by the project is shown in Figure 18.
Essentially the design involved doing the opposite of the
RCWP BMP implementation: (1) two corn fields initially were
cropped under best manure spreading practices during the calibra-
tion period; (2) management on one field reverted to the pre-
RCWP practice of field spreading manure through the winter. Thus,
the expected result from comparison between fields was an in-
crease in pollutant losses from the winter spread field that
should be approximately equal to the reductions accomplished by
installing animal waste BMPs on poorly managed fields.
87
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L
JO
-------
Paired Watershed Treatment Schedule
PHASE:
Calibration Treatment
Watershed:
Control
Treatment
Best
Manure
Management
Best
Manure
Management
Best
Manure
Management
Winter
Spreading
Figure 18.
Paired watershed treatment schedule
Summary Report V-3, 1984)
(from Vermont
Analysis and Interpretations
The project monitoring personnel have conducted extensive
analysis of tfee paired watershed experiment. A somewhat
surprising result was that wint.er manure spreading actually
decreased runoff concentrations and mass export of total
suspended solids (TSS) by 68 percent and 50 percent, respectively
(Figures 19 and 20). The reduction in TSS was attributed to a
"mulching effect" of the winter-applied manure. Volatile
suspended solids (VSS) concentrations were al'so reduced by winter
spreading. Our analysis of the TSS and VSS data confirmed these
results. The divergence of the regression lines in Figure 20
suggests that the mulching effect is most pronounced at high TSS
concentrations.
In contrast to TSS and VSS, concentration increases of total
phosphorus, ortho-phosphate, total Kjeldahl N and ammonia N have
been observed as a result of winter spreading (See Figures 19,
21, and 22). In general, the elimination of winter spreading
reduced concentrations more than mass export because the winter
manure application reduced runoff volume from the treatment site
by 78 percent. This is presumably due to improved infiltration
conditions.
The project, found that total mass export increased from the
winter ?pread field of ortho-P, 1500 percent, total P, 11 per-
ceril, TKN, 148 percent, and annnonia N, 618 percent, even though
th -us,*,jit of runoff decreased (Figure 23), This gives a direct
inul cation of the probable effectiveness of eliminating the prac-
»-ice v f winter spreading. It should be note--!, that BMP 2 in this
project also reduced manure-derived stream inputs by eliminating
losses from stacked manure ami by improving barnyard and
•ailkhouse manure conditions. Thus, the expected improvements
from treatment of a farm with BMP 2 might be different from what
.<>as indicated by the paired watershed experiment
89
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g 40-r CALIBRATION
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Mean concentrations in runoff froa the LaRose farm
paired watersheds. (Fron VT 1984 Summary Report, pg,
90
-------
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TOTAL SUSPENDED SOLIDS CONCENTRATIONS (Control Watershed)
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rc 20. Regression analysis of paired observations of total suspended solids
concentrations, treatment vs. control watersheds, 1983-1984. (VT RCWP)
91
-------
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Regression analysis jf paired observations of total phosphorus
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ORTHO HHOSPH/JL CONCENTRATIONS (Control Watershed)
Figure 22. Regression analysis of paired observations of ortho phosphate
concentrations, treatment vs, control watershed, 19G3~1984.(V7 RCWP)
93
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IMPLICATIONS
This project is making several important contributions to
our knowledge of agricultural NFS control. These are briefly
summarized below:
1. A properly conducted paired watershed experimental
design can document water quality effects of specific
BMPs within a two year timeframe.
2. A very detailed land use information base is necessary
to attribute water quality changes to specific land
management activities.
3. Eliminating the practice of winter manure spreading in
northern U.S. climates would have the effect of
^creasing suspended sediment losses but would reduce
surface losses of total phosphorus, orthophosphorus,
and total nitrogen.
4. The major portion of surface pollutant transport in
northern dairy areas is associated with winter thaw,
spring snow-melt or spring precipitation events.
5. Some modification of the CREAMS model is needed to
describe field losses of agricultural pollutants in
northern U.S climates.
94
-------
CALIBRATION
TREATMENT
iS 0.54-
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LOWER UPPER
0.1 -p
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LOWER UPPER
+618%
LOWPR UPPER
Figure 23. Mass export of phosphorus and nitrogen from the LaRose
Paired watersheds. (Frow \T 1£84 Summary Report, pg. V-7)
95
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Conesioga Headwaters, Pennsylvania
RCWP 19
INTRODUCTION
Background
The Conestoga Headwaters project is located in Lancaster
County, which is acknowledged to be the most intensive non-
irrigated agricultural county in the U.S. The intensity of
agricultural production in the project area is even greater than
for the county as a whole. This production takes the form of row
cropping as well as intensive animal production (approx. two
animal units (a.u.) per acre). As a result severe groundwate.
(bacteria, nitrates) and surface water impairments (sediment,
phosphorus, nitrogen, bacteria) have been documented. From among
the multitude of agriculture-related impairments(fishery, water
supply, contact recreation, aesthetics and downstream eutrophica-
tion) the project has chosen to focus increasingly on the
drinking water impairment caused by excessive nitrates in
groundwater. In the opinion of NWQEP, this is the most serious
water resource impairment because it impairs the drinking water
supply for 175,000 people both within and outside the project
area. Several cases of methemoglobinemia have been reported by
the project for infants in the project area. There has also been
increasing concern about surface transport of nitrogen forms and
herbicides in the context of the Chesapeake Bay studies.
Perspectives of the Project
The following questions related to agricultural management
and water quality are relevant to the project situation.
1. Can animal manure be managed sufficiently to protect water
quality in an area where the nutrient content of this manure
exceeds crop needs?
2. Is there an inherent trade-off between practices designed to
reduce surface transport of nitrogen and those designed to
minimize nitrogen transport to groundwater?
.:; 5-; groundwater resources in karst areas respond rapidly
;'-,ough to reflect changes in land management within a ten
year tiraeframe?
'\ Can groundwater nitrate levels be reduced below lOag/1 in an
area with an animal density of 2 a.u./acre with a public
investment of approximately $60/acre of agricultural land?
How will groundwater nitrate levels change- in response to
the construction of manure storage facilities which permit
96
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better timing of nanure application?
6. Do herbicides impair groundwater in a karst area with
intensive row cropping?
7. What BMPs are the most cost-effective for reducing ground-
water impairments caused by agricultural activity?
L§Qd Treatment Strategy
All HCWP BMPs except BMP 13 have been approved for the
project. The emphasis has been on BMP 2 (animal waste manage-
ment), BMP 4 (terraces), BMP 7 (grassed waterways), BMP 9 (con-
servation tillage) and BMP 15 (fertilizer management).
Targeting of cost-sharing to critical arpis has been under-
mined greatly by lack of farmer participation. The project has
established three priority areas based on water quality moni-
toring needs and groundwater nitrate levels.
Priority 1 - The Little Conestoga watershed (3700 acres)
Priority 2 - Other lands within the carbonate area (areas
with highly permeable soils).
Priority 3 - Non-carbonate area.
.Information/Education efforts during FY84 'included a news-
letter sent to 25 percent of farms, visits to 12 percent o'f farms
by SCS and ASCS, availability of two no-till corn planters, fifty
RCWP posters, 1500 pamphlets, public meetings, and meetings with
Amish church leaders.
W§t§r Quality. Monitoring IWQM^ Strategy.
There are three levels of WQM being performed. The first
level is a regional network which monitors ground and surface
waters in the entire project area. The network includes 2 stream
gauges which monitor major storms, four baseflow sites sampled
monthly, and 43 groundwater sites sampled quarterly.
The second level involves more detailed monitoring of the
Little Conestoga watershed. (2 stream gauges - major storms; 7
base f*iow sites - 17 times/year; 5-10 grorndwater sites
quarterly). The watershed has two paired watersheds within it,
one designated for a high level of BMP implenjentat ion (nutrient
. ) and the other to serve as a control.
The third level is the two 25 acre field sites which have
-.nterisive monitoring of surface and grounawater pollutant
transport:. These sites are scheduled to have nutrient management
and/or erosion control BMPs installed after a suitable background
•nonitoring period. One site is presently in the BMP
implementation phase while the other is still in the pre-BMP
<. • h f\ s e .
-------
BMP IMPLEMENTATION ACHIEVEMENTS
The actual implementation of BMPs through the RCWP program
has been far below anticipated levels. Out of 1250 farms in the
project area only 96 have filed an RCWP-1 application through
9/30/84. During this same period 51 contracts have been signed
which cover less than 4 percent of the project area. Only ten
contracts were signed dmring FY84. * The original project goal was
to obtain contracts on 300 farms; however, this has been revised
to 90 farms in the face of low farmer participation.
The reasons for the lack of participation are numerous and
complex. The Economic Research Service (ERS) reported a 40 page,
indepth analysis of the situation in the 1984 Progress Report.
In the opinion of NWQEP, the Tsic problems are that:
1. Animal production is so intensive that manure nutrients
exceed crop utilization potential, and thus the economic
incentive to properly manage animal waste is lost.
2. The BMPs which potentially benefit the farmers by protecting
their soil resource base are not the same BMPs which are
needed to address the groundwater nitrate problem.
3. The cost-share rates for several key BMPs have been set too
low to expect significant participation.
4. Farmers have had inadequate access to soil nitrogen* cont&nt
information to make cost-efficient judgments on fertilizer
usage.
5. Over 50 percent of tht farmers are Atnish with a strong
Over 50 percent of tnt farmers are
cultural history of self-sufficiency.
The underlying assumption throughout the RCWP program has
been that farmers will have inherent economic interest in
utilizing animal waste to its fullest potential in meeting crop
nutrient requirements. Hence cost-sharing BMP 2 was intended to
assist with the relatively large initial capital outlay for
constructing a storage and application system. However, when
manure nutrients exceed crop needs, there is no longer an
economic incentive to efficiently store and apply manure. From
this p'.-rspect ive it is not surprising that there has been little
fg-roer interest in constructing manure management systems at a
30 percent cost-share rale. Even in RCWP projecfs where crop
lull-lent requirements exceed manure nutrients, and manure storage
has greater value, a 75 percent cost-share rate has often not
insured the desired level of Dinner participation.
For farmers with an excess of manure nitrogen, manure
.fcorage systems should be designed to allow maximum ammonia
volatilization and denitrification. The ERS report states that
in uncovered, 6-month storage systeru is optimal for this purpose.
98
-------
These systems are now ter'isg emphasized in the project. It should
be noted that maximua {nitrogen volatilization takes place under
conditions of daily spreading. Manure storage systems partially
compensate for this disadvantage by enabling the farmer to
refrain from spreading on frozen ground and immediately
preceding storm conditions which increase nitrogen transport to
ground or surface water resources. The net result is that some-
what more nitrogen is percolated to groundwater under the
storage-application system than under the daily spreading system
when manure is applied at the nutrient-excessive rate of 40
tons/acre. When manure is applied at 20 tons/acre (i.e. an
amount better Batched to crop needs) storage systems are predic-
ted to reduce losses to groundwater because of the improved
application timing options.
The previous discussion eepbasizes the importance of
nutrient management to address the groundwater nitrate impair-
ments in the project area. The typical situation at the
beginning of the project was that excess manure nutrients were
being applied to cropland and then chemical fertilizer was used
in addition. The economic analysis of BMPs performed by the BRS
shows clearly that BMP 15 (fertilizer management) is the most
cost-effective BMP for reducing losses of nitrate to groundwater.
Considerable progress has been made toward reducing unnecessary
chemical fertilizer usage primarily through: educational efforts,
obtaining a 50 percent cost-share for BMP 15, requiring BMP 15 in
all contracts with an animal density of 1.5 animal units per acre
or greater, and increasing the accessibility to nitrogen soil and
manure tests.
Even with these efforts, however, only $16,185 (7.5*) of
RCWP cost-share funds have been contracted for BMP 15. The
proj ct personnel estimate that BMP 15 has reduced edge of field
nitrogen loss by 38,880 pounds which is 56 percent of the total N
reduction. At the other extreme 49- percent of cost-share funds
have gone for terraces which have been responsible for only 6
percent of nitrogen loss reductions. If the primary goal of the
project is to cost-effectively address the groundwater nitrate
impairment, it is clear that an increasing emphasis on nutrient
management and a decreasing emphasis on expensive erosion control
practices is needed.
It should be noted that the project estimates that more BMPs
have he^n implemented exclusive of the RCWP program than under
?OWP > v.ract since the project began. This phenomenon has been
j i. tr lo-• ted to tho restrictions built into the RCWP contracts
vn '. •• ?-j.sentially require that any land under contract must hnve
,'• -• ' "as which reduce erosion down to "T". The ERS analysis
5h-;.» clearly that the most cost-efficient surface transport
.T:duo i, 1 ons of nitrogen, phosphorus and sediment are accomplished
by practices which are not sufficient to reduce erosion to "T",
but '-^her reduce erosion by 30-60 percent at very low per-acre
'^osfc. The adoption of these practices, including contour strip--
cropping, cover crops, reduced tillage, diversions, and grassed
through ACP and without cost-sharing indicates the
99
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increased acceptability of these practices to farmers relative to
the RCWP contracts being developed.
The total nutrient losses to project surface and groundwater
resources can only be reduced to a somewhat limited extent
(approx. 30-35*) through optimal management of nutrients in the
watershed and traditional soil and water conservation practices.
It is recognized that further reductions can be achieved only by
either:
1. reducing the cumber of livestock
2. exporting nutrients from the project area.
The project is continuing to explore possibilities for exporting
nutrients. These include hauling manure to be used on cropland
outside the project area and drying/comporting and bagging manure
for retail sale. The 1984 Annual Report stated that at least one
such facility has begun operation in the project area.
Another aspect of the manure management situation which has
been overlooked involves poultry manure. While poultry accounts
for only about 13 percent of total manure production its nitrogen
content is such that it accounts for approximately 40 percent of
manurial nitrogen in the project. Thus 40 percent of the
manurial nitrogen could be removed by exporting poultry manure
with minimal transport costs, compared to costs of hog or cattle
manure export. The poultry manure also has the highest market
value as fertilizer. Thus, although the ERS analysis showed that
cow manure hauling would be very expensive per pound of nitrogen
removed, the analysis should be about three times more favorable
for poultry manure.
ANALYSIS OF FARM LEVEL COSTS
Two approaches were used to model the farm level impacts of
participation in the Conestoga Headwaters RCWP project. A
representative farm linear programming model was used to assess
the impacts of alternative manure storage and handling systems.
The impacts of field level BMPs were evaluated using budgets.
Environmental effects were modeled using the CREAMS model in both
approaches.
l:j
-------
storage were the ao%t n^-.i. -effective sys.?e«.j» for preventing field
losses of nitrogen, lj.o*h because of lo**»»r capital outlays for
these two systems - and the lesser amount of plant nutrients
available compared to other types of storage, particularly the 6-
month uncovered solid storage (Table 18). A "typical" Lancaster
County farmer can reduce nitrogen losses by 10 percent with no
loss in income by applying manure evenly on all farm fields in an
environmentally sound manner for a given crop and by reducing the
rotation intensity of some land—a clear indication of the
utility of the fertilizer management BMP.
Cost information is combined with field losses of soil and
plant nutrients in Table 19 to illustrate the cost effectiveness
of field BMPs for reducing losses. Costs shown are total costs,
with the life span of nonstructural practices being 5 years and
structural practices requiring maintenance for 10 years as part
of RCWP contract requirements by farmers. The costs shown are
estimated average costs and do not include cost sharing to
farmers or other considerations (such as tax incentives).
Among the nonstructural practices, conservation tillage—
reduced tillage and no-till—are effective in reducing pollutant
losses at a cost assumed to be zero for purposes of RCWP cost
sharing. Other benefits such as reduced soil compaction and
increased moisture-holding capacity make this BMP a critical
element in any economically sound nutrient and soil management
program. The deep, well-drained soils typical in the project
area should provide equal crop yields compared with conventional
tillage in normal years (Bepper, et al., 1981). Crop yields may
actually, be better for conservation-tilled land relative to
conventionally tilled land in those years when rainfall is
significantly below average. The only clear disadvantages are:
1) the capital outlays required to convert tillage equipment; 2)
the possibility of increased reliance on herbicides to control
weed problems normally controlled by deep tillage; 3) conserva-
tion tillage, especially no-till, has been found to require
greater fertilization to attain equal yields (although this may
not be a major concern for many farmers who have considered or
are using conservation tillage. The use of herbicides that are
incorporated into the soil during tillage or planting, combined
with the reduced runoff associated with conservation tillage.
The use of herbicides that are incorporated into the soil during
tillage or planting, combined with the reduced runoff associated
with conservation tillage, may help to alleviate the latter
o r • •!< 1 em .
Permanent vegetative cover will obviously control a number
of pollutant problems, but should only be considered in critical
areas due to its high cost to both farmers and government (50
percent cost sharing is provided). Other nonstructural practices
include residue management( stripcropping, and contouring. It
has been assumed in the RCWP project area that farmers' costs are
Iho same with contouring and stripcropping (largely due to
protection of agricultural productivity) as they are for
conventional practices once the strips and contours have been
101
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103
-------
established. Inasmuch as farmers, who have signed contracts with
no cost sharing, have adopted these two practices, they are both
cost effective since thftir assumed annual cost is zero; i.e.
benefits to farmers are perceived as matching the costs.
Structural practices are not applied on a "per acre" basis
and are slightly more difficult to evaluate. However, they are
more expensive than nonstructural practices, with the exception
of permanent vegetative cover. The stream protection system, or
livestock fence, is designed to keep livestock out of the stream
and thus from adding nutrients directly to waterway. Savings of
nitrogen, phosphorus, and fecal coliform bacteria from fences
would depend on the number of animals and could be substantial.
Other practices include terraces, diversions, and sod
waterways. Examining the costs of the three systems, it is
evident ,at terraces are much more expensive. Estimated costs
per acre for terraces are based on examination of contracts in
the project . However, terraces do retain nutrients and soil
more uniformly throughout the field, and are effective in those
cases where a great deal of control is needed in addition to
those obtained through nonstructural practices.
Practices which reduce runoff on the field also conserve
valuable nutrients for crop production. For example, looking at
Table 19, the full set of BMPs modeled for continuous corn silage
can be installed at a one time cost of $425 per acre (which has a.
life of 10 years with proper maintenance). At 20 tons of manure
per acre per year, 36 pounds of nitrogen per acre could be saved
"each year at a value of $10.00 ($0.28/lb. • N), plus the savings of
phosphorus, potash, and organic matter. Without the cost of
expensive structural practices, particularly terraces, the bene-
fits of nutrient and organic matter retention on the field may
outweigh the costs of the practices. Reduced tillage, for
example, saves 23 pounds total nitrogen and 11 pounds phosphorus
per acre per year when manure is applied at 30 tons per acre.
WATER QUALITY DATA ANALYSIS
,i..\
The water quality results from the project to date have come
\ r 'i y from the Zimmerman farm, 22 acre experimental site with
additional results from the little Conestoga 3700 acre
r- l .-»r-s ' i1. All of the water quality results should be considered
» '.: :^MP implementation, However, the documentation of spatial
i'i leiaporal trends as woll as thr- coincidence of land activities
i t '- ob' erved water quality suspenses lend considerable insight
ot<- • h? potential effects of BMPs in the watershed.
C;.sted below are some of the major observations that the
t •. ,}pf;!. monitoring personnel have reported. These observations
O ^he'i discussed in more detail in relation to interpretation
104
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and implications for R-.'^j-' program goals. &** also present som« of
our.own analysis and i«t?rpretation of the water quality data.
1. Of the 43 wells in the regional network 67 percent in the
carbonate areas exceeded 10mg/l. nitrate, while 27 percent
in non-carbonate area exceeded the standard. This trend
persisted throughout the year with somewhat higher mean
concentrations during the summer.
2. Most of the nitrogen transported in surface waters is in the
nitrate form during baseflow periods but organic nitrogen
predominates during storm flow.
3. The water levels in field site monitoring wells
(carbonate area) respond quickly (i.e. days) to major
precipitation events.
4. Suspended sediment runoff concentrations were lowest during
frozen ground and maximum crop cover conditions.
5. The highest surface runoff nitrogen concentrations were
observed during snowmelt where the water-manure contact time
was longer.
6. Groundwater nitrate levels at the field site respond rapidly
to the combination of manure application and precipitation.
Our own analyses of the project's raw data corroborate
these findings. As will be discussed subsequently each of these
results has important implications relating to the effects of
BMPs and the potential for the project to address its water
resource impairments. Our analysis of the water quality data
indicates some qualification of results #3, #5 and #6. In
regard to # 3 it should be noted that the field site wells not
only respond quickly to precipitation events but also show large
rises in water table levels relative to the amount of precipita-
tion. For instance, a one-inch infiltration appears to raise the
water table by about a foot. This indicates a porosity of the
groundwater aquifer of less than 0.1. This would be a common
value in many areas but is significantly lower than we would have
expected for this karst topography which clearly has a
preponderance of direct infiltration routes.
The projects' analysis and interpretation of results #5 and
:*C, while correctly indentifying trends and causal factors
ro'.;l:?d to groundwater nitrate levels, give the somewhat
misleading impression that groundwater nitrate levels show a
i»r£e response to precipitation, snow-melt and manure application
p.-^ terns. While the trends summarized in # 5 and # 6 are evi-
dent, these results should be placed into the context that the
groundwater nitrate concentrations at the field site are actu.illy
fairly constant, and the responses to precipitation and manure
spreading are relatively smnll. For the site analyzed most
thoroughly the total range of nitrate concentrations was only 5-
1R mg/1 and 80 percent of the observations fell between 10.0 and
105
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16.0 mg/1. It would h>sve been easy for the project to have
dismissed this data »« showing no trends or causal relationships,-
so it is to their creUit that they performed the level of analy-
sis needed to show that concentrations increased following manure
spreading combined with precipitation events. However, the im-
plication of our analysis is that a substantial period with no
additional manure application would probably be required for
nitrate levels to flush to a significantly lower level.
The project. has also attempted to develop a regression
equation which relates nitrate concentration to manure applica-
tion and precipitation. The purpose of the equation is to enable
prediction of future (post-BMP) nitrate concentrations. The
regression equation developed: N03 = 0.035 Manure Load - 0.073
water level rise + 9.995, while generating results of the same
general trend as observed results, is probably not the best
regression equation to explain the effects of these two variables
on nitrate levels. First, the statistical equation indicates
that water level change has a negligible effect. Second, the
effect of recent manure applications appears to be underesti-
mated. One reason for this may be the use of the previous 120
day period for calculating manure application. A shorter period
would probably provide a better predictive equation. Also, a
temporal staggering of water level and nitrate level would appear
to explain better the relationship of these two variables.
PROJECTIONS
*
A number of interpretations of the present water ' quality
data and projections to the future effects of BMPs can be made.
Some of these have already been postulated by the project water
quality monitoring personnel. The following includes some speci-
fic BMP projections based on the observed water qualit., results
to date. For the most part these are fairly similar to the
projections developed by ERS through the use of the CREAMS model.
1) Terraces
Terracing will greatly increase the time of contact between
applied manure and precipitation which infiltrates the soil.
This will increase the nitrate concentrations of infiltra-
ting water. In addition a slightly larger percentage of
precipitation will reach groundwater. The combined effect is
an increase on groundwater nitrate concentratiins, The
terraces would be expected to increase dissolved nutrient
concentrations in surface runoff but somewhat decrease total
surface nutrient losses. Sedimenf loads would be reduced
-significantly (70-80%).
2) Animal Waste Management
The pre-BMP management strategy is to spread manure
daily when field conditions permit. Generally this
means that no spreading is done during June, July and
106
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August when e*»rfl is in the field. The animal waste BMP
involves 6 month open storage so that manure is applied when
crops can make maximum use of the nutrient (i.e. May for
field crops and September for cover crops).
The projected effect is that ground and surface water
nitrate concentrations would increase over present values
for the periods following application and would be lower the
rest of the year. Hence, it is probably the range of values
which will be most affected. The loss of nutrients to water
sources would be reduced by more timely plant uptake, but
this would be counteracted by the increased nutrient content
of stored versus daily-spread manure.
3) Nutrient Management
We see nutrient manag. "ent in this project as having four
basic components:
a) Soil and manure testing to insure that no unnecessary
chemical fertilizer is used.
b) Growing crops which use rather than fix nitrogen (i.e.
corn) .
c) Applying manure nutrients when they can best be used
by the crop.
d) Exjporti-ng manure where nutrient supply greatly exceeds
» . crop needs.
The nutrient management BMP is projected to greatly reduce
both surface and groundwater nutrient concentrations. Fluctua-
tions wo.uld still be observed as a function of application dates
and precipitation events. However, the mean concentration and
the frequency of nitrate values greater than 10mg/l would be
reduced. We estimate that the reduction would be greater than
the percentage reduction in nutrients applied because of a closer
match of application and plant usage rates.
Considerable monitoring for herbicides in surface and
groundwater is being conducted in the project. Some analysis and
interpretation of this data has been done by the project
including tabular and graph4 ? presentations of the concentration
la»:a.
Our inspections and analysis of the data reveal the following
i nf ornnn t i on relevant to pesticide surface and groundwater
tin "sport in the project area.
1. Herbicide concentrations in groundwater at the field sites
rise to barely above detectable levels following
appl icat ion .
2. Herbicide concentrations in groundwater throughout the pro-
107
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ject area are surprisingly low (generally less than 1 ug/1)
given the amount of usage and the karst topography.
3. Herbicide concentrations in stream baseflow are also very
low (less than 1 ug/1) but show small though clear increases
during the summer months.
4. Moderate concentrations of alachlor (2-5 ug/1), atrazine(7-
17 ug/1), cyanazine (7-16ug/l) and metolachlor (l-18ug/l)
were observed during a storm event in the Little Conestoga
basin following spring herbicide application.
5. High concentrations (greater than 50 ug/1) were observed in
surface runoff from the field site during first runoff event
following application. Elevated concentrations appear to
persist for about 2-3 months following application.
6. The surface water pesticide data from the Little Conestoga
Basin strongly suggest that there is another source of
herbicide input beside field application (elevated concen-
trations yeai—round and consistent observation of elevated
levels of herbicides no longer in common use). Further
investigation revealed the presence of a pesticide disposal
area in the upper part of the watershed. Further investiga-
tion of the impacts of this source are underway.
IMPLICATIONS
It is possible, although unlikely, that nutrient management
and- other BMPs will be implemented to an extent sufficient to
significantly reduce area-wide surface and groundwater pollutant
loads within the project timeframe. However, since it has been
shown that shallow groundwater is recharged by the land area
immediately (with a few hundred feet) up-gradient, BMP ground-
water relationships for the project can be established with
relative accuracy from the field sites.
Thus, at this point it appears that the projects' primary
contributions to overall BMP water quality understanding will
come from the field sites and possibly from the 3700 acre small
watershed site. Relevant information from the overall project
will probably relate primarily to economic, social and institu-
tional factors which affect the success of the voluntary project
Approach. These contributions are summarized below:
1. To gain farmer participation and to select appropriate
BMPs and critical areas a project needs to decide early on
which water resource impairment is to be given top priority.
This is particularly true when both groundwater and surface
water impairments exist. All subsequent project activities
need to be consistent with this decision.
.2 A 50 percent cost-share rate for animal waste management
structures will probably be inadequate to gain farmer parti-
cipation in areas with excess manuria? nutrients.
108
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3. Land conservation contracts which are developed to meet 'T'
may not ke a cost-efficient method of meeting surface or
groundwater quality goals.
4. There may be inherent trade-offs between BMPs designed to
improve surface water and groundwater quality.
5. In an area where subsurface flow re-emerges as stream
baseflow, BMPs which reduce surface runoff losses of nitro-
.gen will generally increase stream baseflow nitrogen loads
proportionately.
6. The project illustrates what may be a very common situation
which is that pesticide disposal practices and sites consti-
tute at least as great a source of pesticides as field
applications.
7. The application timing advantages provided by manure storage
versus daily spreading are partially or completely nullified
by increased manurial nutrient availability.
8. Groundwater nitrate concentrations from the field site
increased significantly in response to periodic manure
applications.
9. Precipitation infiltration, which raises the water table,
can have either an increasing or decreasing effect on
groundwater nitrate concentrations depending on the time
interval since manure application and on the quantity of
manure applied. A common situation observed at the field
site is that precipitation first has a diluting effect on
nitrates. However, as slower percolating water, which has
had longer soil nutrient contact time, reaches the water
table, nitrate concentrations increase.
10. Used properly as a BMP, nutrient management reduces nitrogen
inputs to both surface and groundwater.
.109
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Oakwood Lakes - Poinsett, South Dakota
RCWP 20
INTRODUCTION
The Oakwood Lakes - Poinsett RCWP is a 106,000-acre project
located in the glacial lakes region of east .central South Dakota.
The project area includes about 80 percent crop and grass land
with the balance state/federal lands or lakes. Area soils are a
mix of relatively impermeable till and less interspersed with
highly permeable areas of sand and grav 1 outwash. Use impair-
ments have been documented for groundwater affected by excessive
nitrate levels and for eutrophic recreational lakes that receive
excessive plant nutrients and sediment. Both impairments have
been attributed to loss of soil and fertilizer nutrients, from
cropland and grasslands.
The impaired surface waters of the project include three
large lakes and a number of smaller lakes. The lakes are gener-
ally shallow, average depth from 4 to 10 feet. The three largest
lakes are Lake Poinsett, 7,868 acres draining 32,452 acres (83
percent cropland), Oakwood Lake, 2,184 acres draining 52,856
acres (5Q% cropland), and Lake Albert, 2400 acres, within the
drainage of Lake Poinsett. ' Average depth of Lake Albert is only
4 feet. These lakes have very high recreational value which is
impaired primarily by eutrophication.
Perspectives of the Project
Because this project has both documented groundwater and
surface water impairments, there are four general questions to be
answered analytically:
1. What BMPs are most cost-effective for reducing the impair-
ment of groundwater by agricultural activity?
2. What BMPs are most cost-effective for reducing the impair-
ment of surface water by agricultu %al activity?
To what extent do BMPs designed to protect
exacerbate groundwater impairments0
4-
What will be the
quality impairment
efficiently?
economic benefits from
and how can *;hese be
surface water
reduced water-
achieved most
fc date, the project has developed a monitoring program to
investigate the impact of agricultural management on groumhv >' er
but" -as not monitored surface water Therefore, there has 'oecn
110
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no contribution from tJ-;i.^ &>o ject toward the answers to questions
2 or 3. A monitoring effort to evaluate the overall effective-
ness of the RCWP in reducing the impairment of the water
resources has not been attempted because there are no continuous
streams in the project area, and the subsurface hydrology is very
complex. Specifically, the interconnections of the surficial
sand and gravel aquifers with the major groundwater resource
of the area, the Big Soux aquifer, or with the lakes, are
generally unknown.
Project monitoring efforts have concentrated on evaluating
the relative effectiveness of management practices in reducing
nitrate and pesticide leaching.
Specific questions addressed by monitoring include:
1. Do conservation t;llage (no till or chisel plowing) reduce
the downward flux of nitrate-N?
2. Does residue management affect the nitrogen content of the
soil profile through denitrification, leaching, or crop
uptake?
3. Does the quality of groundwater beneath agricultural lands
with conservation tillage or fertilizer and pesticide
management differ from that of areas with conventional farm-
ing practices?
4- What is the relationship between soil characteristics (gla-
cial till or' sand and gravel 'outwash) . and groundwater
quality under alternative agricultural management practices?
5. Is the quality of groundwater beneath agricultural land
different from t..iat of a control area where there has never
been any agricultural activity?
Operationally, the monitoring component of the project is
investigating whether or not agricultural BMPs can prevent ni-
trate and pesticide contamination of groundwater. Plans have
been developed to instal.1 runoff gaging and sampling devices at
each groundwater monitoring site to look at trade-offs between
protection of surface and subsurface waters, but these plans have
not been implemented. Although the land treatment component of
f:h.^ project is concerned with reducing sediment and nutrient
-:. • inGport to the lakes, no clear experiment has been developed to
> I-rat e this type of effect.
Treatment Strategy
before the project was initiated, 52 percent of the crop and
lind was considered adequately treated for erosion. There-
fore, the focus of the RCWP land treatment effort has been on
reducing the contamination of ^roundwater by fertilizer nitrogen
and preventing their contamination by pesticides. Because the
'»ii<~facial aquifer occurs irregularly throughout the project area,
111
-------
no contribution fro* ti>i< project toward the answers to questions
2 or 3 . A monitoring effort to evaluate the overall effective-
ness of the RCWP in reducing the impairment of the water
resources has not been attempted because there are no continuous
streams in the project area, and the subsurface hydrology is very
complex. Specifically, the interconnections of the surficial
sand and gravel aquifers with the major groundwater resource
of the area, the Big Soux aquifer, or with the lakes, are
generally unknown.
Project monitoring efforts have concentrated on evaluating
the relative effectiveness of management practices in reducing
nitrate and pesticide leaching.
Specific questions addressed by monitoring include:
1. Do conservation t'llage (no till or chisel plowing) reduce
the downward flux of nitrate-N?
2. Does residue management affect the nitrogen content of the
soil profile through denitrif ication , leaching, or crop
uptake?
3. Does the quality of groundwater beneath agricultural lands
with conservation tillage or fertilizer and pesticide
management differ from that of areas with conventional farm-
ing practices?
4. What is the relationship between soil characteristics (gla-
cial till or sand and gravel outwash) and groundwater
"quality under alternative agricultural management practices?
* •
5. Is the quality of groundwater beneath agricultural land
different from t-iat of a control area where there has never
been any agricultural activity?
Operationally, the monitoring component of the project is
investigating whether or not agricultural BMPs can prevent ni-
trate and pesticide contamination of groundwater. Plans have
been developed to install runoff gaging and sampling devices at
each groundwater monitoring site to look at trade-offs between
protection of surface and subsurface waters, but these plans have
not been implemented. Although the land treatment component of
bh^ project is concerned with reducing sediment and nutrient
I; Disport to the lakes, no clear experiment has been developed to
t- rat e this type of effect.
Strategy
before the project was initiated, 52 percent of the crop and
land was considered adequately treated for erosion. There-
fore, the focus of the RCWP land treatment effort has been on
ing the contamination of groundwater by fertilizer nitrogen
preventing their contamination by pesticides. Because the
.•snrficial aquifer occurs irregularly throughout: the project area,
111
-------
no contribution from thi* {••• oject toward ihe answers to questions
2 or 3. A monitoring effort to evaluate the overall effective-
ness of the RCWP in reducing the impairment of the water
resources has not been attempted because there are no continuous
streams in the project area, and the subsurface hydrology is very
complex. Specifically, the interconnections of the surficial
sand and gravel aquifers with the major groundwater resource
of the area, the Big Soux aquifer, or with the lakes, are
generally unknown.
Project monitoring efforts have concentrated on evaluating
the relative effectiveness of management practices in reducing
nitrate and pesticide leaching.
Specific questions addressed by monitoring include:
1. Do conservation tillage (no till or chisel plowing) reduce
the downward flux of nitrate-N?
2. Does residue management affect the nitrogen content of the
soil profile through denitrif ication , leaching, or crop
uptake?
3. Does the quality of groundwater beneath agricultural lands
with conservation tillage or fertilizer and pesticide
management differ from that of areas with conventional farm-
ing practices?
4.' What is the relationship' between soil characteristics (gla-
cial till or sand and 'gravel outwash) and groundwater
quality under alternative agricultural . management practices?
5. Is the quality of groundwater beneath agricultural land
different from t.iat of a control area where there has never
been any agricultural activity?
Operationally, the monitoring component of the project is
investigating whether or not agricultural BMPs can prevent ni-
trate and pesticide contamination of groundwater. Plans have
been developed to install runoff gaging and sampling devices at
each groundwater monitoring site to look at trade-offs between
protection of surface and subsurface waters, but these plans have
not been implemented. Although the land treatment component of
thf project is concerned with reducing sediment and nutrient
'•, •. t.jsport to the lakes no clear experiment has been developed to
this type of effect.
Treatment Strategy
•Jefore the project was initiated, 52 percent of the crop and
land was considered adequately treated for erosion. There-
fore, the focus of the RCWP land treatment effort has been on
rednr.ug the contamination of groundwater by fertilizer nitrogen
and preventing their contamination by pesticides. Because the
aquifer occurs irregularly throughout the project area,
111
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no contribution from thi* f-foject toward the answers to questions
2 or 3. A monitoring effort to evaluate the overall effective-
ness of the RCWP in reducing the impairment of the water
resources has not been attempted because there are no continuous
streams in the project area, and the subsurface hydrology is very
complex. Specifically, the interconnections of the surficial
sand and gravel aquifers with the major groundwater resource
of the area, the Big Soux aquifer, or with the lakes, are
generally unknown.
Project monitoring efforts have concentrated on evaluating
the relative effectiveness of management practices in reducing
nitrate and pesticide leaching.
Specific questions addressed by monitoring include:
1. Do conservation tillage (no till or chisel plowing) reduce
the downward flux of nitrate-N?
2. Does residue management affect the nitrogen content of the
soil profile through denitrification, leaching, or crop
uptake?
3. Does the quality of groundwater beneath agricultural lands
with conservation tillage or fertilizer and pesticide
management differ from that of areas with conventional farm-
ing practices?
4. What is the relationship between soil characteristics (gla-
cial till or sand and gravel outwash) and groundwater
quality und*er alternative agricultural management practices?
5. Is the quality of groundwater beneath agricultural land
different from t.iat of a control area where there has never
been any agricultural activity?
Operationally, the monitoring component of the project is
investigating whether or not agricultural BMPs can prevent ni-
trate and pesticide contamination of groundwater. Plans have
been developed to install runoff gaging and sampling devices at
each groundwater monitoring site to look at trade-offs between
protection of surface and subsurface waters, but these plans have
not been implemented. Although the land treatment component of
thr> project is concerned with reducing sediment and nutrient
•!. •: lusport to the lakes no clear experiment has been developed to
lomo-strate this type of effect.
Oanci Treatment Strategy
Before the project was initiated, 52 percent of the crop and
a'ra»s"iind was considered adequately treated for erosion. There-
fore, the focus of the RCWP land treatment effort has been on
reducing the contamination of groundwater by fertilizer nitrogen
*nd preventing their contamination by pesticides. Because the
-."rficial aquifer occurs irregularly throughout the project area,
111
-------
no contribution from t Js i ?•- /-s eject toward the answers to questions
2 or 3. A monitoring effort to evaluate the overall effective-
ness of the RCWP i t» reducing the impairment of the water
resources has not been attempted because there are no continuous
streams in the project area, and the subsurface hydrology is very
complex. Specifically, the interconnections of the surficial
sand and gravel aquifers with the major groundwater resource
of the area, the Big Soux aquifer, or with the lakes, are
generally unknown.
Project monitoring efforts have concentrated on evaluating
the relative effectiveness of management practices in reducing
nitrate and pesticide leaching.
Specific questions addressed by monitoring include:
1. Do conservation t;llage (no till or chisel plowing) reduce
the downward flux of nitrate-N?
2. Does residue management affect the nitrogen content of the
soil profile through denitrification, leaching, or crop
uptake?
3. Does the quality of groundwater beneath agricultural lands
with conservation tillage or fertilizer and pesticide
management differ from that of areas with conventional farm-
ing practices?
4- What is the relation-ship between soil characteristics (gla-
cial till or sand and gravel outwash) and groundwater
quality under alternative agricultural management practices?
5. Is the quality of groundwater beneath agricultural land
different from t-iat of a control area where there has never
been any agricultural activity?
Operationally, the monitoring component of the project is
investigating whether or not agricultural BMPs can prevent ni-
trate and pesticide contamination of groundwater. Plans have
been developed to install runoff gaging and sampling devices at
each groundwater monitoring site to look at trade-offs between
protection of surface and subsurface waters, but these plans have
not been implemented. Although the land treatment component of
thp project is concerned with reducing sediment and nutrient
;. i lusport to the lakes, no clear experiment has been developed to
•> t rate this type of effect.
Treatment Strategy
Before the project was initiated, 52 percent of the crop and
land was considered adequately • trea ted for erosion. There-
fore, the focus of the RCWP land treatment effort has been on
reducing the contamination of groundwater by fertilizer nitrogen
ami preventing their contamination by pesticides. Becausfe the
-,"rficial aquifer occurs irregularly throughout the project area,
111
-------