Illinois Highland Silver Lake (RCWP 4)

Critical areas were composed of crop and pasture lands characterized by fine-particle-size natric soils, high erodibility, and slopes greater than two percent. Also critical were crop and pasture lands of non-natric soils with slopes greater than five percent with high erodibility and close proximity to the water course. Feedlots were designated as critical based on animal units and distance to streams.

The water quality objectives of the Rural Clean Water Program (RCWP) project were to: 1) increase the useful life of the reservoir as a public water supply; 2) reduce water treatment costs and taste and odor problems; 3) improve habitat for sport fish by increasing water transparency; and 4) provide better boating, fishing, hunting and other recreational opportunities for users of Highland Silver Lake.

Best management practices (BMPs) emphasized in the project were conservation tillage, sediment retention basins, grassed waterways, animal waste management, and permanent vegetative cover. The land treatment teams were very effective in contracting and implementing BMPs; 83% of the cropland treatment goal was implemented and even a higher percentage was achieved for animal waste implementation. Contracting reached 118% of the goal.

Comprehensive monitoring and evaluation were conducted at the lake, tributary, and field levels. Tributary and field level water quality monitoring was conducted for less than three years and was essentially ineffective for assessing project or BMP effectiveness. However, lake monitoring showed that resuspension of particles was partly responsible for turbidity and that turbidity, not nutrients, was most important for limiting algae production. CREAMS modeling showed that no-till operations reduced sediment yield. AGNPS modeling helped to verify critical areas and to assess relative effectiveness of structural versus management BMPs.

Project management and administration were effective. A high level of land treatment was achieved because the information and education and land treatment teams worked together in reaching farm community leaders and tailoring technical services to match production, land resource protection, and water quality needs. Initially, the water quality problem was not clearly defined, nor was the critical area, creating difficulties for the project team in formulating effective project goals. Monitoring agencies were unable to design the program and organize resources to achieve meaningful experimental results.

4.2 Project Findings, Recommendations, and Successes

4.2.1 Definition of Project Objectives and Goals

4.2.1.1 Findings and Successes

The project had a good set of overall objectives that were comprehensive and reflected the desired state for the designated use of Highland Silver Lake.

Initial project goals were not well formulated because they were based on the incorrect assumption that sedimentation and nutrient delivery had a significant effect on the impairment.

The pre-project sediment delivery ratio was determined to be 25%; however, further investigation revealed that the sediment delivery ratio is closer to 47%. The new ratio may be used to set land treatment goals.

4.2.1.2 Recommendations

Detailed water quality problem analysis should be the first step toward the development of effective goals.

If sedimentation is suspected as a problem, it should be quantified by using a sedimentation survey. This information can then be used to develop a goal of reducing sediment delivery.

If turbidity is the problem, then a detailed analysis of the sources (watershed, resuspension) of the turbidity is needed. This information, along with lake modeling, can be used to determine if setting a turbidity goal is reasonable. If turbidity can be reduced, then a quantitative reduction goal can be set.

A spatially distributed pollutant runoff model should be used to identify critical areas contributing to the sedimentation and/or turbidity problem. The model may also be used to set treatment goals.

Monitoring below suspected critical areas should be used to verify modeling results and should be used to characterize the water quality problem, which in turn makes setting goals more effective.

4.2.2 Project Management and Administration

4.2.2.1 Findings and Successes

The local project staff were successful in gaining participation, providing information and education, and installing BMPs. There was very good coordination of activities related to implementing practices. The local land treatment staff provided valuable land use and land treatment survey data to the water quality monitoring group. The Soil Conservation Service (SCS) and the Soil and Water Conservation District (SWCD) worked well together to complete farm plans, develop practice designs, and install BMPs. Coordination and planning was improved by the participation of the agency responsible for section 208 planning, the S.W. Illinois Metro-Area Planning Commission (SWIMPC).

The project suffered from an inadequate definition of the water quality problem and the critical area. A more complete analysis of lake algal production, nutrient dynamics, and factors affecting turbidity would have helped the project target specific pollutants and their sources in the watershed.

The project team met annually in early years with the State Coordinating Committee (SCC) but needed more meetings and feedback. The project would have benefited from SCC leadership on project direction. The SCC supported the project by requesting cost share for additional BMPs.

The SCC should have devised a land use / land treatment tracking system for use and by all agencies and for input into a geographic information system (GIS).

The project would have benefited from more guidance on reporting. In some cases, the local project personnel were unaware of the intended audience for a report or how the information would be used.

The content of the conservation plan and the requirement to complete the plan as determined by the county Agricultural Stabilization and Conservation (ASC) Committee is critical to the overall success of the land treatment program. Some farmers were very interested in treating gullies with grassed waterways, but were reluctant to implement conservation tillage to reduce sheet and rill erosion. Project administration would therefore determine if producers were required to complete the plan or if a change would be made to accommodate the wishes of the farmer and avoid the reduced tillage treatment.

The project was expected to accelerate the adoption of practices prior to having an adequate definition of the water quality problem and the critical area. The pressure to accelerate the adoption of practices meant less effort was spent on setting priorities. Loss of early planning opportunities diminished the project's effectiveness in targeting resources to the greatest need.

Water quality monitoring at field and stream sites was not synchronized with land treatment, providing little feedback to project staff on problem areas. Ninety percent of the contracts were written before there were any useful monitoring results on problem area runoff and the effectiveness of BMPs. Improved management of the water quality monitoring program, including continuation of the tributary and field site monitoring, would have supported critical area redefinition and strengthened the project.

Early in the project, there were some difficulties in selecting construction materials for some BMP components. Problems determining cost share rates on materials and labor were resolved through agency cooperation and communication with producers. Once procedures were established, the cost share payment system functioned smoothly.

4.2.2.2 Recommendations

The SCC should provide technical leadership in the definition of the water quality problem and the critical area before BMPs are adopted. Projects always benefit from a carefully developed problem statement.

The SCC should provide technical leadership in the timing and intensity of water quality monitoring to match the goals of the project. Projects should make individuals accountable for successful implementation of a monitoring program.

Projects should have an overall coordinator with some authority to develop a timetable for land treatment and water quality monitoring consistent with trend detection.

4.2.3 Information and Education

4.2.4 Producer Participation

4.2.4.1 Findings and Successes

Producer participation was very good to excellent. More pre-project I&E would have reduced the contract period, but might not have increased the total number of participants or practices installed.

Factors that motivated producers' adoption of practices included cost sharing, seeing conservation and aesthetic improvements on a neighbor's farm, and interest in natural resource conservation and water quality improvements in the lake.

Economics was the primary barrier to participation. Many farmers waited to see how new practices would affect production and labor before adopting them. Some farmers resented the City of Highland for condemning farmland in 1962 to create the lake and, for this reason, refused to participate in the project. The project also lacked technical assistance in the form of soil conservationists for I&E, which decreased effectiveness of I&E efforts.

The chances of continued maintenance and adoption of practices seems to be good, but they are dependent upon the practice. Structural practices will most likely be maintained. Continued tillage and residue management is less likely due to poorly drained soils. No-till, reduced tillage, and sufficient residue levels may not be maintained. There is also a question as to whether nutrient management will be maintained.

4.2.4.2 Recommendations

This project serves as a model for producer participation. The U.S. Department of Agriculture (USDA) agencies, SWIMPC, and local agencies worked well together and achieved a high rate of contracting and implementation.

4.2.5 Land Treatment Implementation, Tracking, and Evaluation

4.2.5.1 Findings and Successes

The project team had difficulty defining the critical area because the water quality problem and impairment of designated use were not clearly identified at the start of the project. Project personnel determined implementation goals to treat the lake sedimentation and turbidity problem and the original critical area was selected to target erosion and runoff from cropland. The use of soil maps that did not indicate areas where slopes were less than 2% resulted in overestimation of the actual critical area. Field investigations were used to delineate a revised critical area based on both soils and slope.

Watershed monitoring studies indicated that suspended sediments were from natric soils with slope less than 2%. If the project team had had access to this information at the beginning of the project, the critical area would have been more narrowly defined based on treatment of natric soils. There are some natric soils in the watershed that are not currently in the critical area that should be considered if a new critical area was developed.

Many farm fields contained both natric and non-natric soils. Although the land treatment goal was to treat natric soils, farm fields were treated as single units for practical reasons. The result was lower crop productivity on non-natric soils treated with conservation tillage. Management was a key factor in the success of no-till and reduced till for fields where only part was poorly drained.

Farmers should have received more follow-up assistance from the technical agencies on the proper implementation of cost shared fertilizer management. Once a soil test was taken, farmers needed assistance to assure that proper levels of nutrients were being applied to minimize losses. The Extension Service had the responsibility as the technical agency for nutrient management but may not have had the staff to follow up and monitor implementation.

The SCS did a good job of follow-up with assistance to farmers on conservation tillage in order to ensure that farmers continued the practice after the three-year cost sharing period expired.

4.2.5.2 Recommendations

Water quality monitoring should be timed so that results may be used to refine the problem statement or critical area definition. The design of land treatment and water quality monitoring programs should reflect the need for on-going feedback and refinements in both areas.

4.2.6 Water Quality Monitoring and Evaluation

4.2.6.1 Findings and Successes

The monitoring strategy was developed to quantify important hydrologic factors affecting water quality. The overall design of lake, stream, and field monitoring was appropriate and well supported for comprehensive monitoring. The primary difficulty was too much concentrated monitoring at the start of the project, which exhausted funds for much further work.

The primary impairment of designated uses was turbidity. The respective contributions of algal and nonalgal turbidity to the water quality problem were not known. The Illinois Environmental Protection Agency (ILEPA) indicated that lake productivity is light limited and not nutrient limited, and that the current ratio of nitrogen to phosphorus in the water column may encourage the production of bluegreen algae if transparency improves.

One of the most common mistakes made in monitoring programs is the sampling of many variables (similar to ambient monitoring strategies) Trend detection is very specific and the number of variables monitored is much lower than in monitoring programs designed to assess overall conditions.

Field sampling requires carefully controlled conditions and is essentially research on the effectiveness of individual BMPs or BMP systems.

4.2.6.2 Recommendations

Stream sampling should be implemented for the duration of nonpoint source (NPS) projects, reflecting pre- during- and post- implementation periods. The paired watershed design or the upstream-downstream design is preferred. Stream sampling protocols should follow the USEPA 319 National Monitoring Protocol. Water quality variables and covariates measured should reflect the impairment and should avoid typical ancillary variables that do not support trend detections goals.

Future monitoring of the Highland Silver Lake project should be directed toward trend detection with a smaller number of variables sampled at a greater frequency. Variables measured should be more directly related to characterizing the nonalgal and algal portions of the turbidity problem. The nutrient series does not need to be measured as often and can be reduced to spring turnover, and once during the peak growing season. Sampling at the three stations should be more frequent (e.g. weekly or biweekly) during high precipitation seasons to reflect storm event effects on turbidity.

Water supply reservoir sampling for trend detection should be reduced to three main stem stations: 1) near the water supply intake, 2) mid- lake, and 3) one lake station near the tributary receiving the bulk of turbid inflow. The mid-lake and tributary stations are less important, but can help in analyzing relative contributions of inflows and resuspension to turbidity.

4.2.7 Linkage of Land Treatment and Water Quality

4.3 Project Description

4.3.1 Project Type and Time Frame

4.3.2 Water Resource and Watershed Descriptions

4.3.2.1 Water Resource and Water Quality

4.3.2.1.1 Water Resource Type and Size

Highland Silver Lake (600-acre impoundment) and tributaries

4.3.2.1.2 Water Uses and Impairments

Highland Silver Lake provides a public water supply for about 8,500 residents in the county. Several industrial firms located in the city of Highland also use the lake for water supply. Non-contact recreational use of the lake includes boating, fishing, and waterfowl hunting.

Use of the lake is impaired by suspended sediments, and, potentially, nutrients and contaminants in fish. High turbidity levels are caused by suspension and resuspension of fine natric soil particles. Excessive nutrient concentrations contribute to eutrophic conditions. Agricultural chemicals in surface runoff entering the lake may be a public health concern (Madison County Soil and Water Conservation District, 1979).

4.3.2.1.3 Water Quality Problem Statement & Status

Sedimentation, high turbidity, and eutrophication impair non-contact recreational uses of the lake. High turbidity levels are caused by sediment delivered to the lake and in-lake resuspension of fine natric soil particles. Erosion and runoff from croplands are the primary sources of pollutants.

4.3.2.1.4 Water Quality Objectives and Goals

Water quality objectives for the project include:

Increase the useful life of the reservoir as a public water supply
Reduce water treatment costs and taste and odor problems
Improve habitat for sport fish by increasing water transparency
Provide better boating, fishing, hunting, and other recreational opportunities for users of the Highland Silver Lake resource.

Water quality goals include:

Reduce sediment delivered to the lake by 60% (with parallel reductions in phosphorus and organic nitrogen)
Increase lake transparency to greater than 2 feet and reduce suspended solids to less than an average of 25 milligrams per liter (mg/l)

4.3.2.2 Watershed Characteristics

4.3.2.2.1

Watershed Area: 30,946 acres
Project Area: 30,348 acres
Critical Area: 6,525 acres

4.3.2.2.2 Relevant Hydrologic, Geologic, and Meteorologic Factors

Precipitation: annual = 43 inches

Geologic Factors: Soils in the project area are almost entirely glacial in origin. Topography ranges from nearly level to very gently sloping.

4.3.2.2.3 Project Area Agriculture

Major crops grown in the watershed include corn, soybeans, and wheat. Beef cattle, dairy cows, and hogs are also raised.

4.3.2.2.4 Land Use

Use      % of Project Area % of Critical Area

Cropland    82       100
Pasture/range     5        -
Woodland    4        -
Urban/roads    2        -
Other       7        -

4.3.2.2.5 Animal Operations

Operation # Farms Total # Total Animal Animals Units Beef NA NA 944 Dairy NA NA 760 Hogs NA NA 1,178 The project area has 20 animal operations.

4.3.3 Total Project Budget

Cost Share 1,502,372 5,000 466,990 0 1,974,362 Info. & Ed. 47,738 0 0 0 47,738 Tech. Asst. 462,560 0 0 109,427 571,987 Water Quality 1,479,483 3,846 0 245,963 1,729,292 Monitoring SUM 3,492,153 8,846 466,990 355,390 $4,323,379 Source: Illinois State Coordinating Committee, 1986

4.3.4 Information and Education

4.3.4.1 Strategy

Control livestock waste through prevention of runoff from livestock operations

Erosion and sediment control to reduce sediment delivery

Nutrient management through fertility programs

Pesticide management through proper application

4.3.4.2 Objectives and Goals

Help people in the watershed area understand the water quality problem

Help people in the watershed understand the impact soil erosion has on water quality

Assist landowners and operators in using plant nutrients in such a way that good water quality can be maintained.

Help landowners and operators use pesticides in a manner that contributes to the maintenance of good water quality

Help livestock operators understand the best methods of handling livestock waste to maintain good water quality

Help landowners learn how to estimate soil losses

Help landowners and operators understand the cost and benefit of the various soil and water quality management practices on their farm operation

Help landowners and operators understand the principles of good soil conservation

4.3.4.3 Program Components

Letters to producers about the RCWP project

Meetings with potential participants about the RCWP project

Field demonstrations of BMPs

Tours of demonstration farms

Field spot checks related to RCWP contracts

4.3.5 Producer Participation

4.3.6 Land Treatment

4.3.6.1 Strategy and Design

The land treatment strategy was to increase ground cover, decrease velocity of surface runoff, and improve management of livestock waste.

4.3.6.2 Objectives and Goals

Reduce the amount of animal waste entering the water by applying waste management systems on 10 swine, five beef, and five dairy operations

Reduce the amount of sediment and sediment related pollutants entering the lake by applying BMPs on 10,500 acres through 85 RCWP contracts

Reduce sediment delivered to the lake by 60%

4.3.6.3 Critical Area Criteria and Application

Criteria:

Crop and pasture lands composed of natric soils with fine particle size and high erodibility and slopes greater than 2%

Crop and pasture lands of non-natric soils with slopes greater than 5% with high erodibility and close proximity to water courses

Animal operations were prioritized according to the number of animal units and distance to stream.

These criteria were found to be a fairly accurate assessment of high pollutant source areas according to the AGNPS modeling results.

Application of Criteria: The criteria were followed carefully in selection of farm fields for contract.

4.3.6.4 Best Management Practices Used

The project used practices designed to increase ground cover, decrease the velocity of surface runoff, and improve the management of livestock waste.

BMPs Utilized in the Project*:

Permanent vegetative cover (BMP 1)
Animal waste management system (BMP 2)
Terrace system (BMP 4)
Diversion system (BMP 5)
Waterway system (BMP 7)
Cropland protection system (BMP 8)
Conservation tillage systems (BMP 9)
Stream protection system (BMP 10)
Permanent vegetative cover on critical areas (BMP 11)
Sediment retention, erosion, or water control structures (BMP 12)
Tree planting (BMP 14)
Fertilizer management (BMP 15)

*Please refer to Appendix I for description/purpose of BMPs.

Quantified Project Achievements:

Pollutant      Critical Area                Treatment  Goals 
Source   Units Total % Contracted   Total % Implemented
Acres      #   6,525      82% 4,894         83%
Cattle farms     #     695     119%   521        143%
Dairy farms   #     727      80%   545         84%
Hog farms     #   1,116        23%          837        138%
Contracts     #     125        89%           94        118%

4.3.6.5 Land Treatment and Use Monitoring & Tracking Program

4.3.6.5.1 Description

BMP implementation was reported by units applied (acres, systems, feet). Data on animal units, tons of manure, and tons of phosphorus and nitrogen from manure treated by BMPs were recorded. Conservation Reserve Program (CRP) enrollment within the project area was also reported.

4.3.6.5.2 Data Management

Land use monitoring data were collected at the field, subwatershed, and watershed levels for analysis with water quality data.

The project had two detailed land use / land treatment surveys early in the project. Illinois State Water Survey had a GIS system and some watershed data was used in the system.

4.3.6.5.3 Data Analysis and Results

Not available

4.3.7 Water Quality Monitoring and Evaluation

4.3.7.1 Strategy and Design

Conducted by the Illinois Environmental Protection Agency and Illinois State Water Survey.

The monitoring approach was designed to consider event and non-event sediment loadings and to measure BMP effectiveness at the field, stream, and lake levels.

4.3.7.2 Objectives and Goals

Determine if BMP application reduces sediment and nutrient loads sufficiently to achieve the following four goals:

Improve recreational potential by increasing aesthetic appeal
Improve sport fishing and aquatic habitat
Increase "useful life" of the reservoir
Minimize water treatment costs and taste and odor problems

4.3.7.3 Time Frame

Intensive monitoring supported by CM&E funding from December 1981-October 1985

Ambient lake monitoring continued from 1986 through 1990

Lake stations: May 1981 - 1990

Stream stations: January 1982 - October 1984

Field sites: spring 1982 - October 1984

4.3.7.4 Sampling Scheme

4.3.7.4.1 Monitoring Stations

9 lake sites and 1 lake outflow site
3 stream sites
8 field sites (7 cropland sites from 29 to 332 acres; 1 livestock waste management system)

4.3.7.4.2 Sample Type

Lake sites: grab (automatic at spillway)
Stream sites: automatic
Field sites: automatic

4.3.7.4.3 Sampling Frequency

See sections 4.3.7.4.4 and 4.3.7.4.7 below

4.3.7.4.4 Variables Analyzed

Lake: Total suspended solids (TSS), total volatile solids (TVS), turbidity, total phosphorus (TP), dissolved phosphorus (DP), nitrate and nitrite nitrogen (NO2-N+NO3-N), ammonia nitrogen (NH3-N), total kjeldahl nitrogen (TKN), temperature, dissolved oxygen (DO), pH, conductivity, total alkalinity, chlorophyll a, and metals (monthly)

Stream and lake spillway: TSS, TVS, turbidity, temperature, DO, pH, and conductivity (three times per week)

TP, DP, TKN, NO2+NO3-N, NH3-N (twice a month)

Total alkalinity, chlorophyll a, and metals (monthly)

Field: TSS, TVS, turbidity, TKN, TP, chemical oxygen demand (COD) (event-based)

4.3.7.4.5 Flow Measurement

Spillway: daily
Streams: continuous
Field Sites: H-flumes for continuous stage records during runoff events

4.3.7.4.6 Meteorologic Measurements

Precipitation: 3 sites in watershed

4.3.7.4.7 Other Important Water Quality Monitoring and Evaluation Information

Biomonitoring: macroinvertebrates monitored near stream sampling sites twice per year
Channel & streambed surveys: December 1981 & November 1984
Sedimentation surveys: lake and bay - July 1981 / lake - September 1984

4.3.7.5 Data Management

Data from lake stations are in STORET. Other data are managed locally and by the Illinois State Water Survey.

STORET            STORET            PROFILE / STATION
AGENCY CODE STATION NO.     MAP / NO. 

21ILLAKE RO-A04ZA-1  IL-1 / 1
      RO-A04ZA-2  IL-1 / 2
      RO-A04ZA-3  IL-1 / 3
      RO-A04ZA-4  IL-1 / 4
      RO-A04ZA-5  IL-1 / 5
      RO-A04ZA-6  IL-1 / 6
      RO-A04ZA- 7 IL-1 / 7
      RO-A04ZA-9  IL-1 / 9
      RO-A04ZA-10 IL-1 / 10

4.3.7.6 Data Analysis and Results

Analysis:

For field sites, pollutant runoff data was summarized by event into an event mean concentration (EMC). Trends in EMCs for total suspended solids, total volatile solids, and turbidity were analyzed. Multivariate analysis was used to determine variables that would effect loading rates.

Trend analysis of EMCs and multivariate analysis of loads were both inconclusive. Each type of analysis suffered from lack of good experimental design and control of important factors such as land use. The length of the study was also a major factor, because only a few events were measured.

To assess temporal and spatial trends of tributary sites, the data were stratified by periods conforming to typical agricultural patterns in the watershed (Kelly and Davenport, 1986). Periods were defined as follows:
Period 1 (P1): fertilizer, seedbed and establishment (April-June)
Period 2 (P2): reproduction and maturation (July-November)
Period 3 (P3): residue (December-March)

Data were routinely analyzed by site, sampling year, period, and by period-sampling year. Multiple comparison of means was accomplished using Tukey's studentized multiple range test. Pearson's product moment correlation coefficients were routinely calculated for various stratifications of data (temporal and spatial) and resultant matrices examined for significant correlations. If significant correlations were found, they were examined by scattergrams to insure that a significant relationship did exist. When appropriate, multiple linear regression analysis was used. Cluster analysis followed by canonical discriminant analysis was also used on field site event data to determine which variables were most important in accounting for variance in runoff water quality.

Lake water quality data were analyzed graphically and using regression analysis.

Results:

Lake data from 1980-1990 showed limited improvements. Average annual Secchi transparency increased from 10 inches in early project years to 12 inches from 1985-1990. The project goal was to increase Secchi transparency to 24 inches. Total suspended solids also improved with an early project mean of 40 milligrams per liter (mg/l) and a reduction to an average of 33 mg/l in latter years. The project goal was 25 mg/l (Hite and Bickers, 1991).

Annual weighted lake means for turbidity, volatile suspended solids, and total ammonia showed limited reductions in later project years. Chlorophyll a concentrations increased significantly when regressed with BMP implementation (Hite and Bickers, 1991).

Analysis of changes in lake quality due to BMP implementation was confounded by resuspension of fine natric soil particles from the sediment, low particle settling velocity, lake turnover, and wind action. These factors are difficult to distinguish from the effects of reduced watershed loadings.

A sedimentation survey indicated an average annual capacity decrease by 0.67 %. This rate does not pose a threat to use of the lake for municipal water supply.

Generally dry conditions with few rainfall events resulted in a small, sporadic, stratified data set from the field monitoring sites (Makowski et al., 1986). The data were used to calibrate the CREAMS model. CREAMS results indicated that no-till is effective in reducing sediment yield. Results also indicated that contouring, grassed waterways, and grade stabilization structures are effective in reducing sediment yield (Davenport, 1984).

4.3.8 Linkage of Land Treatment and Water Quality

4.3.9 Impact of Other Federal and State Programs on the Project

4.3.10 Other Pertinent Information

4.3.11 References

Davenport, T.E. 1984. Field Modelling in the Highland Silver Lake Watershed: Interim Report. IEPA/WPC/84-026. IL EPA, Div. of Water Pollution Control, Springfield, IL.

Hite, R.L. and C. Bickers. 1991. Highland Silver Lake RCWP Water Quality Monitoring Report. Illinois Environmental Protection Agency, Marion, IL. 56 p.

Illinois State Coordinating Committee. 1986. Highland Silver Lake Watershed RCWP: Summary Report Fiscal Year 1986. Springfield, IL.

Kelly, M.H., and T.E. Davenport. 1986. Water Resource Data and Trend Analysis for the Highland Silver Lake Comprehensive Monitoring and Evaluation Project, Madison County, Illinois, Phase IV. Planning Section, Div. of Water Pollution Control, Illinois Environmental Protection Agency, 2200 Churchill Rd., Springfield, IL 62706.

Madison County Soil and Water Conservation District, 1979. Highland Silver Lake: Application for Rural Clean Water Program. Madison County, Illinois.

Makowski, P.B., M.T. Lee, and M. Grinter. 1986. Hydrologic Investigation of the Highland Silver Lake Watershed: 1985 Progress Report. SWS Contract Report 380. Illinois Dept. of Energy and Natural Resources, State Water Survey Div., Surface Water Section at the University of Illinois, Champaign, IL.