December 2, 2005
Mr. Jeffrey Boring
Big Thompson Watershed Forum
800 South Taft Avenue
Loveland, CO 80537
Dear Jeffrey:
We are pleased to submit the deliverables for Task 1 of the Mariano Exchange Ditch System
Assessment Project. The deliverables are organized according to subtask, as described in the
Statement of Work. Photographs taken during the site visits are also provided separately in
four .zip files.
We look forward to meeting with you and the planning committee on December 15th or 16th
where we plan on discussing our findings and making recommendations. Please let me know if
you have any questions or concerns that you would like to discuss prior to the meeting. I will
send out an agenda after we settle on a final date and time.
Sincerely,
Hydrosphere Resource Consultants, Inc.
by:
Jean Marie Boyer, Ph.D., P.E.
EXHIBIT A
Mariano Exchange Ditch System Assessment Project
Scope of Work
Hydrosphere Resource Consultants
September 7, 2005
PROJECT OBJECTIVES
The objective of this project is to:
1.
Conduct a n assessment of the Mariano Exchange Ditch System (MEDS)
resulting in a preliminary description of water quality impacts from the
MEDS to the Big Thompson River and the source(s) of these impacts.
Task 1 - Establish Existing Conditions
The purpose of this task is to identify, from existing information, site visits and
initial sampling, 1) water quality impacts, 2) sources of water quality impacts, and
3) relative contribution of each source to the Big Thompson River. The
operational schedule and current water rights context of the MED will be provided
through interviews.
During this task, Hydrosphere will:
1.1
Collect and analyze grab water-quality samples at five sites. Data will be
collected the week of September 12, 2005. The five sites include: 1)
immediately below the reservoir outlet, 2) upstream of the most incised
section of the MED, approximately 2000 feet below the reservoir outlet, 3)
directly below the most incised section of the MED, 4) above the Wilson
Avenue bridge (near SW 9 th Place), and, 5) in the MED at the confluence
with the Big Thompson River. GPS readings of these sites will be
documented. Water samples will be analyzed for non-volatile suspended
solids, total suspended solids, turbidity, temperature, tota l phosphorus and
total nitrogen. Discharge will be calculated based on readings at the
gaging station located on the MED. These flows will be used to calculate
total suspended solids, total phosphorus and total nitrogen loads at the
time of sample collection. BTWF will provide 2005 MED flow data, if
available. Hydrosphere will use these data to estimate total suspended
solids, total phosphorus and total nitrogen loads for the 2005 flow season;
1.2
Gather background data including water quality data provided by the
BTWF and the following reports/items from the City of Loveland: 1)
Loveland stormwater map identifying each stormwater discharge into the
MED, 2) as-built construction drawings for all capital improvement projects
affecting the MED, 3) system drainage map including subbasin drainage
areas, and 4) MS4 information including the stormwater system map and
attribute tables and Illicit Discharge Detection and Elimination Plan (in
progress);
1.3
Conduct a water rights review to ascertain the current operational and
water rights context of the MEDS. This review will be based on
documents publicly available online from the State Engineer’s Office web
site and interviews with the water commissioner for District 4, staff from
the Consolidated Home Supply Ditch Company & Reservoir Company
(Company) , and staff from the City of Loveland.
Based on information from the State’s water rights online database,
Hydrosphere will identify the water rights associated with the Geroge Rist
Ditch and Mariano (Boedecker) Reservoir and the Mariano Exchange
Ditch, including each right’s appropriation date, adjudication date,
instantaneous rate and volumetric limits. Hydrosphere will also tabulate
the historical diversions by the George Rist Ditch, the Mariano Reservoir
diversion, and the exchanges made from the outfall of Mariano Exchange
Ditch to the George Rist headgate from records available electronically.
In the interview of the water commissioner, Hydrosphere will discuss the
current operation of the MEDS, and any concerns or problems with the
exchange that the commissioner may be aware of. To the extent allowed
by electronically available water use records, Hydrosphere will identify
which downstream water users are potentially affected by the operation of
the exchange, where they are located, and what their water right(s) priority
date(s) are.
Based on i nformation from the water commissioner, Hydrosphere will
generate a schematic (line diagram) of the river from the headgate of the
George Rist Ditch down to the outfall of the Mariano Exchange Ditch,
including the intervening water rights that actively divert water from the
river. In addition, Hydrosphere will identify the junior water user(s) who
most commonly divert the water supplied to the river by the Mariano
Exchange Ditch, and the ditches within District 4 that historically received
water from the e xchange ditch, based on priority date. Ditches receiving
water from the exchange ditch downstream of Division 4 will not be
individually identified.
1.4
Conduct site visits of the MEDS. Hydrosphere will inventory and locate
potential non-point sources of pollution and to field verify point-source
discharges identified in the reports/items provided by the City of Loveland.
GPS coordinates will be provided for all point-sources and potential nonpoint sources of pollution identified and other relevant features of the
MED. In addition, one site visit will occur during stormwater conditions
(weather permitting) to conduct visual inspections of stormwater
contributions from the ditch to the Big Thompson River;
1.5
Collect five samples of soil from the MEDS (two from the ditch side walls ,
two from the bed in the incised reach, and one from the reservoir). The
most representative samples from each location (one side wall sample ,
one bed sample, and one reservoir sample) will be evaluated to determine
the classification and settling characteristics of the suspended sediment.
Gradation and hydrometer tests will be conducted for these two samples
to identify the fine sand component and to distinguish between silt and
clay material. Sample settling rates will be compared with theoretical
information for the classified material to define settling rates needed for
the evaluation stage of work. Soil types will be defined for all soils tested
for analysis in accordance with the United Soil Classification System;
1.6
Conduct topographic surveying to supplement the information provided to
Hydrosphere by the City of Loveland (described in Task 1.2). The
surveying information required for this sub-task includes 1) field surveying
for up to four representative cross-sections at representative locations
(sites to be determined by Hydrosphere based on site inspections) and 2)
longitudinal profiles approximately 200 feet upstream and 200 feet
downstream of the cross-section locations ;
1.7
Analyze and document the above information. The BTWF will be provided
with a document that will include the raw data collected, calculations
made, methodologies, and a text description of the water rights review.
This document will be provided to the BTWF Project Manager
electronically in Microsoft Word by 5 PM on December 2, 2005; and
1.8
Hold a meeting at the completion of this task to discuss the study results,
additional sampling recommendations for the 2006 exchange water
delivery season, and recommendations for subsequent tasks. The
meeting will involve the BTWF Planning Committee and Hydrosphere.
Hydrosphere will develop an agenda and presentation for this meeting that
will be held in Hydrosphere’s Boulder office. The BTWF Project Manager
will take minutes and distribute to the MEDS Planning Committee as
requested.
BUDGET
The budget to conduct this work is $17,404. The breakdown by task is shown on
the attached budget. Hydrosphere will not exceed this budgeted amount without
written permission from BTWF. Hydrosphere will notify BTWF if work is
requested outside this scope of work.
SCHEDULE
The project will be completed by January 31, 2006.
STAFFING AND SUPPORT
Hydrosphere commits the following staff to this project: Jean Marie Boyer, Doug
Laiho, John Winchester, Laura Belanger and / or Kevin Wheeler and
miscellaneous AutoCAD, GIS and administrative staff. All water quality samples
will be analyzed at University of Colorado Center for Limnology Lab. Soil
analyses will be conducted by the laboratory at Terracon Consultants. Ayres &
Associates will conduct the topographic surveying tasks, as required. No
changes regarding staff, sub-consultants, labs and analysis measures will be
made without prior written consent of the BTWF Project Manager, which consent
shall not be unreasonably withheld.
PROJECT MANAGEMENT AND COMMUNICATION
For purposes of this project, Mr. Jeffrey Boring is the BTWF Project Manager.
Dr. Jean Marie Boyer is the Project Manager for the Consultant Team. Any
formal notice or communication between the Consultant Team and the BTWF will
be between the two Project Managers.
Note that if any item in this scope of work is in conflict with the main contract, this
scope of work takes precedence.
Task 1.1: September Sampling
Mariano Exchange Ditch (MED) System Assessment Project
Task 1.1 - Collect and Analyze Grab Water-Quality Samples at Five Sites
September 12, 2005 Field Visit
The purpose of this field visit was to quantify sediment loading by collecting water
quality and field data at five sampling sites as described in the Scope of Work. The
following were collected at each site: surface water samples; turbidimeter readings; air
and water temperatures; GPS coordinates; photographs; and visual observations. In
addition, a staff gage reading was made at the flume on the MED located just north of
West 1st Street. Surface water samples were analyzed for total suspended solids, nonvolatile suspended solids, total nitrogen, and total phosphorus.
The water in the MED was cloudy at all sampling locations and the sampler (Laura
Belanger) was unable to discern a visible difference in turbidity between sites. Water in
Boedecker Reservoir at the outfall to the MED was sediment- laden and at the
downstream end of the ditch a visible plume of sediment- laden water was apparent in the
Big Thompson River originating at the MED.
Pictures from this field visit can be found in the attached file:
MEDPhotos - Site Visit 091205.zip
Mariano Exchange Ditch (MED) Site Visit
September 12, 2005
Laura Belanger
Field measurements are followed by Site Descriptions
Field Measurements
Flow in the Big Thompson River just above the MED inflow per Fred Ritter at Loveland (estimation based
on upstream gaged data and ditch/diversion data)
1
Site
Time
Gage
Reading
Staff Gage
9:09
6 2/5"
Weather
Flow per Fred
Ritter
sunny, ~75°C, slight wind
17.00
= 42 cfs
Flow in Ditch
per Delbert1
18 second feet
(i.e. cfs)
Latitude
(N)
Longitude
(W)
40.3932
-105.11094
Delbert gives the flow in the MED on 9/12/2005 (presumably at the reservoir outfall, could check on this) at 18.00 cfs
Site
Time
Site 1
9:47
Site 2
10:35
Site 3
11:25
Site 4
12:20
Site 5
12:50
2
Average of three readings
Readings
1
1
2
3
Average2
Turbidity
(NTU)
58
53
46
41
79
Turbidity Readings
Site
3
2
58.4
57.2
57.6
Weather
sunny, slight breeze
sunny, slight breeze
sunny, warm, slightly windy @ times
sunny, more wind than @ downstream sites
sunny, windy
54.7
52.5
52.6
Air Temp (°C)
22
28
30
25.5
25
4
46.7
46.6
46.1
Latitude
(N)
Water Temp (°C)
19
40.39804
19
40.38236
20
40.38212
20
40.38446
21
40.38463
5
40.5
41.7
39.7
79.0
79.0
78.5
Longitude Water Visual
(W)
Description
-105.11155
Cloudy
-105.11640
Cloudy
-105.11850
Cloudy
-105.12678
Cloudy
-105.12960
Cloudy
Site Descriptions
Staff Gage
Located at flume (a 10 foot Parshall flume according to Delbert) just to north (downstream) of 1st Avenue. Gage is between Sites 1 and 2.
Site 1
MED approximately 50 feet upstream of confluence with the Big Thompson River (BT) Ditch is shaded and narrow then opens up for about 50 ft before
entering the BT. The stream was cloudy and there was a very obvious plume entering the BT. The ditch bottom became very muddy as it narrowed.
Sampled at spot where ditch just started to get wider. Ditch bank was well vegetated w/tall grasses, There was a red stringy algae (?) occupying the last foot
of bank above the water line.
Site 2
MED approximately 200 feet west (upstream) of the Wilson Avenue bridge. Bordered on south by open meadows and on north by older development. New
development going on to NW of site. Some cattails and grasses, minimal riprap, some exposed soil. Stream was cloudy. Water from one of the Cattails
reservoir (clear) enters the MED between Sites 2 and 3.
Site 3
MED approximately 1/5 mile west (upstream) of Wilson Avenue bridge. Just at a bend below area with trees. Slightly less eroded as upstream area, banks
are not as steep. Across for Ivy (St. or Ave) cul de sac. Location chosen to represent area just below most impacted (eroded) section of ditch. water is
cloudy, grassy banks, visible erosion in places.
Site 4
MED approximately 1/5 mile east (downstream) of Boedecker Reservoir. Banks are ~10 feet high. Site is located where MED starts to really become
impacted (eroded). Was chosen to represent ares just above most impacted section of ditch. Grassy banks and along waters edge. Water is cloudy. Salt
(?) line along northern bank. Marshy, muddy bottom.
Site 5
MED at upstream end near Boedecker Reservoir outfall. Site located at downstream end (east) of culvert (~4 ft in diameter) under Crestone Drive. Large
riprap covering banks and ditch bottom extending approximately 50 feet downstream. Water is cloudy.
DON'T USE THE 1.40 cfs value (see note below)
From "Isco Open Channel Flow Measurement Handbook" 3rd edition by Douglas M. Grant
10 ft Parshall Flume
CFS = 39.38H1.6
H = feet
9/12/05 staff gage reading =
CFS =
6 2/5 inches
=
0.533333 feet
14.40
11/17/2005
Laura spoke to Fred Ritter at Jeffrey Boring's suggestions. He said it's hard to read that outside staff gage at the flume and that there's
a stilling point inside the gage house at the point. Using that reading he said the flow was 17 cfs (which better matches Delbert's 18 cfs).
To confirm, the water was moving up and down at the gage on when the reading was taken so it was difficult to get a value.
Flow at flume on 9/12/2005 per Fred Ritter =
17 cfs
Flow just above the MED on 9/12/2004 in the Big Thompson per Fred Ritter is estimated to be approximately =
42 cfs
Hydrosphere summary
12-Sep-05
SITE
TIME TDP, ppb
#1
9:47
#2
10:35
#3
11:25
#4
12:20
#5
12:50
10.84
10.84
10.19
10.19
9.53
TPP, ppb
18.60
18.34
16.96
17.27
26.64
TP, ppb
Dry mass
Ash mass
Total N, ppb (TSS), mg/L (NVSS), mg/L AFDM, mg/L
29.45
337
92.7
84.5
8.2
29.18
384
46.9
40.7
6.2
27.15
297
43.6
38.3
5.4
27.46
313
47.9
42.0
5.9
36.17
361
53.2
46.6
6.6
University of Colorado at Boulder
Cooperative Institute for Research in Environmental Sciences
Center for Limnology
216 UCB
Boulder, Colorado 80309-0216
303-492-5191
Fax: 303-492-0928
23 November 2005
Dr. Jean Marie Boyer
Hydrosphere Resource Consultants
1002 Walnut, Suite 200
Boulder, CO 80302
Dear Jean Marie:
Information on the following pages describes the analytical methods used in our laboratory and
outlines QA/QC procedures associated with these analyses. Also, I am including information
on the analytical performance (duplication) associated with selected tests. Performance data are
included for samples analyzed for Hydrosphere and also for additional samples that were analyzed
recently in our laboratory.
Sincerely,
James H. McCutchan, Jr.
Associate Director
Center for Limnology
Quality Assurance and Quality Control Procedures
Analytical methods used by the Center for Limnology are listed below (Table 1); original
references describing the methods are given, along with reporting limits. Specific information on
quality-assurance and quality-control procedures associated with the analyses are described below.
Sample handling
Handling of samples follows a standardized protocol. For samples collected by the Center
for Limnology, a record of sample collection is maintained in a field notebook. Samples for nutrient analyses are kept in a dark cooler until they reach the laboratory, where they are stored under
refrigeration for 2 hours or less, at which time they are filtered (Whatman GF/C glass-fiber filters).
Prior to use, all laboratory glassware and sample containers provided by the Center for Limnology
are washed 5x with tap water and 5x with deionized water. Dedicated glassware is maintained for
individual analytical tests (e.g., SRP, TDP, TPP, ammonia-N) and for individual standards.
For phosphorus analyses, the particulate component iss stored under desiccation pending
digestion and analysis. A portion of the filtrate is analyzed immediately for SRP and TDP. The
remaining filtrate is frozen at –20°C for subsequent batch analysis of ammonia, nitrate, and TDN.
Samples for TN analysis are frozen separately at –20°C.
Phosphorus
For phosphorus analyses (SRP, TDP, and TPP), randomly selected samples (10%) are run in
duplicate. Also, randomly selected samples (10%) are run with a spike of known quantity. If the
variation between duplicates exceeds 10% or if spike recovery is less than 90% (or greater than
110%), the samples are re-analyzed. Three-halves blanks are run with ordinary blanks to correct
for reagent effects. Spikes and standards for phosphorus analyses are as follows: 19.5 µg/L for
SRP, 22.2 µg/L (inorganic and organic) for TDP, and 20 µg/L for TPP. Any sample with an absorbance > 0.8 is diluted and re-analyzed.
Ammonia
For ammonia analyses, samples are run in triplicate. If absorbance values for a sample differ
from one another by more than 10%, the sample is reanalyzed. Randomly selected samples (10%)
are analyzed in duplicate; 10% of samples also are analyzed with a spike of known quantity. If the
variation between duplicates exceeds 10%, the samples are re-analyzed. If spike recovery is less
than 90% or greater than 110%, the samples are re-analyzed. Standards for ammonia analyses are
as follows: 20, 50, and 100 µg/L. Spikes are 50 µg/L. Any sample with an absorbance > 0.8 is
diluted and re-analyzed.
Ion Chromatography (nitrate, total dissolved nitrogen, total nitrogen)
Randomly selected samples (10%) are analyzed in duplicate; 10% of samples also are
analyzed with a spike of known quantity. If the variation between duplicates exceeds 10%, the
samples are re-analyzed. If spike recovery is less than 90% or greater than 110%, the samples are
re-analyzed. Nitrate standards for all analyses are as follows: 10, 25, 50, 100, 200, 500, 1000, and
2000 µg/L. For TDN and TN analyses, additional organic standards are as follows: 187 and 374
µg/L. Spikes for nitrate analyses are 200 µg/L and spikes for TDN and TN analyses are 187 µg/L.
Any sample with a concentration > 2000 µg/L is diluted and reanalyzed.
Chlorophyll
Randomly selected samples (10%) are analyzed in duplicate. If the variation between duplicates exceeds 10%, the samples are re-analyzed. Any sample with an absorbance > 0.8 is diluted
and re-analyzed.
Test
Nutrient analyses
Nitrogen series
Ammonia-N
Nitrate-N, Nitrite-N
Total dissolved N or
total N
Method
References
Reporting limit
Modified Solarzano method Grashoff 1976
Ion chromatography
Oxidation with potassium
Valderrama
persulfate followed by IC
1981; Davi et al.
1993
0.1 µg/L
0.3 µg/L
0.3 µg/L
0.3 µg/L
Total dissolved P,
Total particulate P
Ascorbic acid-molybdate
method
Oxidation followed by
ascorbic acid-molybdate
Total P
Sum of TDP and TPP
0.6 µg/L
Hot ethanol extraction fol- Marker et al.
lowed by spectrophotom1980; Nusch
etry
1980
Filtration (Whatman GF/C),
gravimetric analysis
0.3 µg/L
Phosphorus series
Soluble reactive P
Other analyses
Chlorophyll-a
Total suspended solids,
AFDM, NVSS
Murphey and
Riley 1962
Lagler and
Hendrix 1982;
Valderrama
1981; Murphey
and Riley 1962
0.3 µg/L
0.01 mg/L
Table 1. Summary of analytical methods. References are given below.
References
Davi, M.L., S. Bignami, C. Milan, M. Liboni, and M.G. Malfatto. 1993. Determination of nitrate in surface
waters by ion-exchange chromatography after oxidation of total organic nitrogen to nitrate. Journal of
Chromatography 644: 345-348.
Grashoff K. 1976. Methods of seawater analysis. Verlag Chmimie, Weinheim, pp 126-137
Lagler, C.L., and P.F. Hendrix. 1982. Evaluation of persulfate digestion method for particulate nitrogen and
phosphorus. Water Research 16: 1451-1454.
Marker, A.F.H., E. A. Nusch, H. Rai, and B. Riemann, 1980. The measurement of photosynthetic pigments
in freshwaters and standardization of methods: conclusions and recommendations. Archiv. fur Hydrobiologie, Beihefte, Ergebnisse der Limnologie 14: 91-106
Murphy, J., and J.P. Riley. 1962. A modified single solution method for the determination of phosphate in
natural waters. Anal. Chim. Acta 27: 31-36
Nusch, E. A. 1980. Comparison of different methods for chlorophyll and phaeopigment determination. Archiv. fur Hydrobiologie, Beihefte, Ergebnisse der Limnologie 14: 14-36.
Valderrama, J. C. 1981. The simultaneous analysis of total nitrogen and phosphorus in natural waters. Marine Chem. 10: 109-122.
Performance data
Soluble reactive P (duplicate), ug/L
Performance data (duplication) for nitrogen and phosphorus analyses are given below (Figures 1 and 2).
Data included in these figures are for samples analyzed for Hydrosphere and for additional samples that were
analyzed recently in our laboratory.
30
Log10(Dup) = 0.0932 + 0.895 Log10(Conc)
r2 = 0.978, p < 0.0001
20
10
5
3
2
1
0.5
0.5
2
1
3
4
5
10
20
30
Total dissolved P (duplicate), ug/L
Soluble reactive P, ug/L
Log10(Dup) = 0.00442 + 0.995 Log10(Conc)
r2 = 0.977, p <0.0001
20
10
5
4
3
2
1
1
2
3
4
5
10
20
Total dissolved P, ug/L
Figure 1. Duplication for soluble reactive P (SRP) and total dissolved P (TDP).
100000
Log10(Dup) = -0.0183 +1.00 Log10(Conc)
r2 = 0.999, p < 0.0001
Nitrate-N (duplicate), ug/L
40000
10000
4000
1000
400
100
40
10
4
1
2
1
5
40
10
100
1000
10000
100000
Nitrate-N, ug/L
Total dissolved N (duplicate), ug/L
10000
Log10(Dup) = -0.0171 + 0.999 Log10(Conc)
r2= 0.970, p < 0.0001
5000
3000
2000
1000
500
300
200
100
300
100
500
1000
2000
4000
10000
Total dissolved N, ug/L
100000
Log10(Dup) = -0.0253 + 1.007 Log10(Conc)
r2= 0.999, p < 0.0001
Total N (duplicate), ug/L
50000
30000
20000
10000
5000
3000
2000
1000
500
300
200
100
100
200
400
1000
4000
10000
Total N, ug/L
Figure 2. Performance data (duplication) for nitrogen analyses
100000
Mariano Exchange Ditch Monitoring -- September 12, 2005
Summary of Results
40.00
TDP
TPP
35.00
Date of Sampling:
9/12/2005
Ditch Flow:
17 cfs
BT Flow:
42 cfs
Sampler:
Laura Belanger, Hydrosphere
Laboratory:
Center for Limnology, University of Colorado
Field Parameters:
Water Temperature, Turbidity, Air Temperature
Lab Parameters:
TDP, TPP, TN, TSS, VSS
See Field Data Description for more details
TP
30.00
25.00
20.00
15.00
10.00
5.00
0.00
Results:
Phosphorus (ug/l)
A
B
C
D
E
A
Site
5
4
3
2
1
Nitrogen (ug/l)
A
B
C
D
E
Site
Sediment (mg/l)
A
B
C
D
E
Site
Field Data
A
B
C
D
E
Site
TDP
9.53
10.19
10.19
10.84
10.84
TPP
26.64
17.27
16.96
18.34
18.60
TP
36.17
27.46
27.15
29.18
29.45
B
C
D
E
450
400
350
300
250
200
TN
150
5
4
3
2
1
361
313
297
384
337
5
4
3
2
1
TSS
53.2
47.9
43.6
46.9
92.7
100
TN
50
0
A
VSS
6.6
5.9
5.4
6.2
8.2
% org
12%
12%
12%
13%
9%
?
Turb (NTU) Tw ( C)
79
21
41
20
46
20
53
19
58
19
Ta (?C)
25
25.5
30
28
22
B
C
D
E
100
90
80
70
60
50
40
5
4
3
2
1
30
TSS
20
Turb
10
0
A
B
C
D
E
Flow on Graphs - upstream to downstream along ditch
See map for site locations
Task 1.1 Loading Analysis
1 Estimated Loads from the MED to the Big Thompson River on September 12, 2005
TSS
TN
TP
Concentration* MED Flow**
Conversion Factor
Load to BT
mg/l
cfs
(sec/day)*(liters/ft3)*(lb/mg)
lb/day
92.7
17
5.39382228
8,500
0.337
17
5.39382228
30.9
0.02945
17
5.39382228
2.7
*Lab results from 9/12/05 sampling
**From gage reading on 9/12/05 and verified by Fred Renner
2 Estimated Loads from the MED to the Big Thompson River for the 2005 Flow Season
TSS
TN
TP
Concentration* MED Flow**
Conversion Factor
Load to BT Load to BT***
mg/l
cfs
(sec/day)*(liters/ft3)*(lb/mg)
lb/day
lb/year
92.7
43.5
5.39382228
21,773
1,371,719
0.337
43.5
5.39382228
79
4,987
0.02945
43.5
5.39382228
7
436
* Assume TSS, TN, and TP concentrations measured on 9/12/05 apply for the 2005 flow season
(This assumption may not apply because the concentration may vary with flow and operations.
Additional data collection is needed to better estimate concentrations over the flow season.)
** Average daily flow for 2005 (per Fred Renner spreadsheet)
*** Ditch ran 63 days in 2005 (per Fred Renner spreadsheet)
Task 1.2: Gather Background Data
Data Collected
Mariano Exchange Ditch (MED) System Assessment Project
Task 1.2 - Gather Background Data to Establish Existing Conditions
Data in Scope of Work
Item
1) Stormwater map
2) As-built construction drawings
3) System drainage map
4) MS4 information
1
Received?
Description
Yes
Stormwater map identifying each stormwater
discharge into the MED
No
As build construction drawings for all capital
improvement projects affecting the MED
Partial
No
System drainage map including subbasin drainage
areas
MS4 information including the stormwater system map
and attribute tables and Illicit Discharge and
Elimination Plan
Source1
1
1
1, 2
1
See attached Source key
Additional Data Collected
MED HEC-RAS Model
Yes
Wind and precipitation data
Wilson Avenue Mariano Exchange
Ditch Culvert Replacement Design
Report
Mariano Reservoir Dam
Rehabilitation Report and
photographs
Larimer County soils report
MED area soils map
Boedecker Reservoir observation
forms
Yes
Description
HEC-RAS surface water model of Mariano Exchange
Ditch
Daily (Olde Golf Course) and 10 minute interval (1st
and Taft) weather data
Yes
Report on 2004 Wilson Avenue culvert replacement,
includes detailed MED data
Item
Received?
Yes
Yes
Yes
Pending
MED related water quality data
Yes
General background information
USGS topographical maps
Yes
Yes
Aerial photo of Boedecker Reservoir
Yes
2000 - 2005 Daily MED flows
Yes
1
See attached Source key
Report on Boedecker Reservoir dam work completed
in 2003 and related photographs
1980 soils survey report of Larimer County
MED area soils map
Site observations of the reservoir being made by
Delbert Helzer
Water quality data for the MED and Big Thompson
River in the vicinity of the MED
General background data regarding Boedecker
reservoir and the MED gathered during multiple
conversations with Delbert Helzer
Topographical maps of the Loveland area
Aerial photo of Boedecker Reservoir during draw
down for dam work
Average daily flows for water years 2000 through 2005
for the MED at the 1st Street flume
Source1
1
3, 4
2
5
6
7
8
9
10
11
12
13
Comment
Aerial photo with known stormwater system structures
identified.
Per Joe Chaplin (City of Loveland), without a specific
request, it would be difficult to gather this information. No
drawing were requested, though some may be at later date.
A map covering the MED from Boedecker Reservoir to
Wilson Avenue was provided in the Ayres Report. Per Joe
Chaplin, drainage area information on the rest of the ditch
was unavailable.
Per Joe Chaplin, these documents are still being
written/revised so are currently unavailable.
Task 1.3: Water Rights Review
A Water Rights and Operations Review
of Mariano Reservoir and Exchange Ditch
1.0 Background
The Home Supply Ditch diverts water from the Big Thompson River at the mouth of the
Big Thompson Canyon, near Loveland, Colorado, and supplies water to agricultural
users. To increase the reliability of the ditch’s water supply, the ditch can store water in
three reservoirs, Lon Hagler Reservoir, Lonetree Reservoir, and Mariano Reservoir.
All three reservoirs store water during the snowmelt runoff season. Unlike the Lonetree
Reservoir, Mariano and Lon Hagler reservoirs do not deliver water directly to the
irrigated lands, but release water to the Big Thompson River. As water is released to the
river, a like amount is diverted at the Home Supply Ditch via a rive r exchange, which is
operated so as not to injure senior water rights holders. Lon Hagler Reservoir delivers
water to Mariano Reservoir via pipeline, which in turn releases the water to the river.
The exchange of water between the Mariano Exchange Ditch and the Home Supply
headgate is decreed in water court, and administered in priority with the other water
rights on the Big Thompson River. 1
When releases are made from Mariano Reservoir to the Big Thompson, the water coming
from the Mariano Exchange Ditch is typically cloudy with fine silt. Where the exchange
ditch meets the Big Thompson River, the difference in water quality commonly
pronounced.
This document provides a review of the water rights associated with the Home Supply
Ditch, Mariano Reservoir and the other water rights on the Big Thompson, to determine
if opportunities exist whereby operation of the Mariano exchange could be modified to
improve water quality, without injuring senior water rights. This effort involved the
development of a straight line diagram which includes water transfers (HRC Straight
Line Diagram.ppt). The State’s Division 1, District 4 straight line diagram, which
describes original water rights and was needed to develop the straight line diagram
including water transfers, is also provided (District4_StraightLine_20050719.pdf).
2.0 Area Water Rights
Water rights in Colorado are administered under the prior appropriation system, which
gives “the party who first puts water to a beneficial use the right to use the water to the
exclusion of others.”2
1
Telephone conversation with Delbert Helzer, general manager of the Home Supply Ditch, on Oct 24,
2005.
2
Sandra H. Johnson ET AL., Property Law: Cases, Materials and Problems 28-29 (2nd ed. 1998).
Hydrosphere Resource Consultants, Inc.
Boulder CO – Socorro, NM
303-443-7839 505-835-2569
Mariano Exchange Ditch Water Operations and Water Rights
Page 2 of 9
October 25 2005
In order to acquire a water right with a legally enforceable priority under Colorado law, a
water user must put the water to a beneficial use and have that appropriation adjudicated
in water court. The court issues a decree for the water right that states the priority for
right, the specific uses the right may be used for, and the amount of water that may be
used. The priority date is based on a combination of the adjudication and appropriation
dates. 3
Home Supply Ditch
The Home Supply Ditch has nine direct flow water rights, plus is listed as the terminus
for fifteen alternate points of diversion. The ditches direct flow rights have a cumulative
capacity of 903.96 cfs, with adjudication dates between 1883 and 1987, and appropriation
dates between 1861 and 1907. Including the alternate points of diversion, the ditch has a
total decreed capacity of 1570.71 cfs. The ditch has an estimated capacity of 325 cfs. 4
Mariano Reservoir
In addition to the rights decreed for the Home Supply Ditch, the ditch also carries water
to Mariano Reservoir. The reservoir has two decrees, the more senior for 11,141.4 acrefeet with an adjudication date of 1883 and the junior for 5,507.7 acre- feet with an
adjudication date of 1939.
Lon Hagler Reservoir
The Home Supply Ditch also carries water to Lon Hagler Reservoir, which releases
exchange water via Mariano Reservoir. Lon Hagler is a comparatively junior right, with
two rights, an absolute right for 5,307 acre-feet with an adjudication date of 1970, and a
conditional right for 3,529 acre-feet with an adjudication right of 1980.
Mariano Exchange Ditch
The Home Supply Ditch Company holds a decree for exchanging water from the outfall
of the Mariano Exchange Ditch to the headgate of the Home Supply Ditch. The
adjudication and appropriation dates for the exchange decree were not available on- line.
Three other ditches on this reach of the Big Thompson exchange water from reservoirs to
headgates, the most frequent being from the outlet of Ryan Gulch Lake to the headgate of
the South Side Ditch. 5
3
Lawrence J. MacDonnell, Five Principals that Define Colorado Water Law, 26 Colo. Law. 165, 165-167
(1997).
4
Hydrobase, database for the Colorado Decision Support Systems.
http://cdss.state.co.us/DNN/WaterRights/tabid/76/Default.aspx
5
Telephone conversation with Les Dalby, Colorado State Engineer’s Office, Division 2, Greeley Colorado,
on Oct 25, 2005.
Hydrosphere Resource Consultants, Inc.
Boulder CO – Socorro, NM
303-443-7839 505-835-2569
Mariano Exchange Ditch Water Operations and Water Rights
Page 3 of 9
October 25 2005
3.0 Typical Operations
The Home Supply Ditch is used to convey water to irrigated agricultural lands. The ditch
diverts water year-round, delivering water to the fields during the growing season, and to
the reservoirs during the non- irrigation season.
Home Supply Ditch
The Home Supply Ditch physically diverts water from the Big Thompson year-round. As
shown in Table 1, prior to 1971 the ditch diverted direct flow rights for use during the
irrigation season. For the past 35 years, the ditch has diverted water throughout the year,
for direct use during the summer and reservoir storage during the winter.
The values in Table 1 include diversions under the ditch’s water rights, diversions of
exchanged water, and diversions of water leased from other entities, such as the Colorado
Big-Thompson Project.
Hydrosphere Resource Consultants, Inc.
Boulder CO – Socorro, NM
303-443-7839 505-835-2569
Mariano Exchange Ditch Water Operations and Water Rights
Table 1. Home Supply Ditch Historical Diversions 6
6
Hydrobase, database for the Colorado Decision Support Systems.
http://cdss.state.co.us/DNN/Structures/tabid/75/Default.aspx
Hydrosphere Resource Consultants, Inc.
Boulder CO – Socorro, NM
303-443-7839 505-835-2569
Page 4 of 9
October 25 2005
Mariano Exchange Ditch Water Operations and Water Rights
Page 5 of 9
October 25 2005
Mariano Reservoir
Because water from Lon Hagler Reservoir can only be released to Mariano Reservoir and
exchanged back to the Home Supply headgate, Mariano and Lon Hagler reservoirs
operationally act as one reservoir. The reservoirs are filled as early as possible during the
fall and winter, and release water predominantly during July and Augus t. Table 2 and
Table 3 show the diversions to storage in Mariano and Lon Hagler reservoirs,
respectively, for the period of record publicly available on- line. Records of Mariano
Reservoir and Lon Hagle r Reservoir contents were not available on-line.
Table 2. Mariano Reservoir Diversions (af/mo)
Table 3. Lon Hagler Reservoir Diversions (af/m0)
Mariano Exchange
The Home Supply Ditch diverts part of its water from water rights that were transferred
to the Home Supply from other ditches. One of the transfer decrees specifies that the
Home Supply Ditch can only divert transferred water through July 14. Consequently, the
Mariano Exchange typically begins in the middle of July and runs until the reservoir is
drawn down, or until the demand for irrigation water ends. 7 Table 4 shows the recorded
exchanges by month for the last 55 years.
The Mariano Exchange is typically begun at 50 cfs, and is occasionally run as high as 60
or 70 cfs. The exchange is estimated to be physically limited to 90 cfs, due to a
restriction at the box culvert that carries the ditch under Wilson Avenue.
The water released by the exchange physically satisfies the ditches just downstream of
the exchange ditch, including the Loveland and Greeley Ditch, the Big Thompson Ditch
Co., and the Farmers Irrigation Canal. 8
7
8
Telephone conversation with Delbert Helzer, manager of the Home Supply Ditch, Oct 24, 2005.
Telephone conversation with Fred Renner, District 4 Water Commissioner, Oct 20, 2005.
Hydrosphere Resource Consultants, Inc.
Boulder CO – Socorro, NM
303-443-7839 505-835-2569
Mariano Exchange Ditch Water Operations and Water Rights
Page 6 of 9
October 25 2005
Table 4. Mariano Reservoir Exchanges to Home Supply Headgate (af/mo) 9
River Call
The call record for the Big Thompson was obtained from the Colorado Department of
Water Resources’ web site, which was available electronically for the period July 1997
through September 2005. Table 5 shows summarizes the most frequently calling
structure by month and year.
9
Provided by Les Dalby, Colorado State Engineer’s Office, Division 2, Greeley, Colorado.
Hydrosphere Resource Consultants, Inc.
Boulder CO – Socorro, NM
303-443-7839 505-835-2569
Mariano Exchange Ditch Water Operations and Water Rights
Page 7 of 9
October 25 2005
Table 5. ID of most Frequently Calling Ditch
The table shows that during July and August, the months the Mariano Exchange Ditch
supplies replacement to the Big Tho mpson, the Loveland Greeley Canal is most
frequently the calling right on the river. The Loveland Greeley is the second diversion
downstream from the Mariano Exchange Ditch.
4.0 Potential Changes in Operations
The purpose of this water rights and operations review is to determine what changes, if
any, can be made in the operation of the Mariano Exchange to improve the water quality
of water coming from the exchange ditch. The following sections examine three
potential modifications to operations that could be employed to improve water quality.
Store and Release at Different Times
There are ditch systems in Colorado that have modified their operations by changing
which rights they diverted at particular times of the year, using junior rights during times
of high flows to fill reservoirs, and then using their senior rights during periods of lower
flows. These changes in accounting allowed the ditches to continue to divert year-round
without having to augment their use.
Mariano Reservoir and the Mariano Exc hange were built and decreed to store water
during one season for use in another. Because streamflows generally decline in July and
August, rearranging the diversion pattern from the river is unlikely to be possible without
injuring senior rights. Thoroughly researching the possibility of reoperating multiple
ditches is beyond the resources available under this contract.
Store in Different Reservoir
Storing water in a reservoir other than Mariano Reservoir would reduce or eliminate the
releases made down the Exchange Ditch, which in turn would reduce the amount of
cloudy water released to the Big Thompson River. Water could be stored in a reservoir
under the Home Supply Ditch or under another ditch.
Hydrosphere Resource Consultants, Inc.
Boulder CO – Socorro, NM
303-443-7839 505-835-2569
Mariano Exchange Ditch Water Operations and Water Rights
Page 8 of 9
October 25 2005
The Home Supply Ditch operates three reservoirs, Lon Hagler, Mariano and Lonetree.
Because both Lon Hagler and Mariano reservoirs are used as exchange reservoirs, their
combined space of 21,957 acre-feet would have to be replaced in Lonetree reservoir.
Because the current size of Lonetree reservoir is 9,211 acre-feet, replacing the storage in
Lon Hagler and Mariano would require a significant enlargement of Lonetree Reservoir
or construction of a new reservoir, which may or may not be physically or economically
feasible.
Based on records from the State Engineer’s Office, only one reservoir between the mouth
of the Big Thompson Canyon and the confluence with the South Platte River has a
capacity of 22,000 acre- feet or more of water. Boyd Reservoir, an existing reservoir
north of the river, has a capacity of 92,600 acre-feet. According to the Colorado Division
of Water Resources ditch map for District 4 10 , Boyd Lake can supply water to the
Loveland Greeley Canal. Assuming there is space in Boyd Lake to store the water
currently stored in Mariano Reservoir, and assuming the facilities to release the water
from Boyd Lake to the Loveland Greeley Canal are in place, one alternative would be to
store water from Mariano Reservoir in Boyd Lake, which would preclude the release of
water down the Mariano Exchange Ditch.
While it may be possible to assemble the required storage in multiple reservoirs, such an
arrangement would be complicated by two factors: first, the accounting for the Home
Supply Ditch water in other reservoirs would be directly proportional to the number of
cooperating water users, and second, because of their senior water rights, the other
reservoirs on the river usually fill under their own rights, and as such, don’t have empty
space to allocate to Home Supply Ditch water.
To determine if storing Home Supply water in Boyd Reservoir is feasible, a more
detailed study of the operation of Boyd Reservoir is required.
Reservoir Pump-back
An alternative that would maintain water storage in Mariano Reservoir while reducing or
eliminating sediment load associated with exchange releases would be to install a
reservoir pump-back system, where water would be pumped directly from Mariano and
Lon Hagler reservoirs back into the Home Supply Canal. Assuming the intake at
Mariano would be near the geographical center of the lake, the pump-back system would
need to move water approximately 2/3 of a mile, with an elevation gain of approximately
120 feet.
The gains in water quality from this alternative are heavily dependant on the source of the
entrained sediment. If the sediment originates in the lake itself, then a pump-back would
eliminate the sediment problem. If the sediment originates in the lower reaches of the
ditch, then sediment would be reduced, but storm runoff from neighborhoods that drains
to the ditch would still pick up some sediment.
10
http://cdss.state.co.us/ftp/Div1_Straightline.asp
Hydrosphere Resource Consultants, Inc.
Boulder CO – Socorro, NM
303-443-7839 505-835-2569
Mariano Exchange Ditch Water Operations and Water Rights
Page 9 of 9
October 25 2005
There are several benefits of this alternative, including:
1. It keeps at least some of the sediment out of the Big Thompson River, and
2. The delivery of water from the outfall of the exchange ditch to the Home Supply
Ditch is not dependent on river flows.
Disadvantages are:
1. There would be a capital investment required to install a pump and pipeline, and
2. There would be on- going costs to maintain and run the pump-back system.
5.0 Conclusion
While there are not numerous alternatives to the Mariano exchange that has occurred
historically, there are at least two which may be worth further consideration, the storage
of water in Boyd Lake and pumping water from Mariano Reservoir back to the Home
Supply Ditch. To determine if either of these alternatives is feasible, more detailed study
should be made to determine the availability of storage space in Boyd Lake, and the
probable cost of building and operating a pump-back system from Mariano Reservoir.
Hydrosphere Resource Consultants, Inc.
Boulder CO – Socorro, NM
303-443-7839 505-835-2569
1. 4.0
cf
7.6 78 cfs
cfs s 3.4 7 cfs c
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83
LIC&R Equalizer Lake
eland WWTP
Gaging Station
Big Thompson R at Loveland
son #06741510, avail 1979-2004
Dit
1/1
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863
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186 //
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adj
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8.25 cfs –
54.0 cfs – 11/10/1
45.6 cfs – 10/15/1 861 //
100 9 cfs – 04/15/1 874 // adj 05
.0
/
8
13.0 cfs – 10/06/ 78 // adj 05/ 28/188
10/2 1881 adj 0 28/18 3
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69
16.7
TO FOSSIL
CREEK
RETURNS TO DISTRICT 3
DRAWS INTO
DISTRICT 3
BIGHILCO
GAGE STATION
FIS
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BIGLASCO
ADMIN GAUGE
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DR
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BIGLOVCO
BTPPMCCO
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WINBYPCO
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DIRECTION OF FLOW
BOUBYPCO
BOULARCO
CITY
DITCH NAME
DRY-UP POINTS ON THE RIVER
USGS GAGE STATION
RIVER
DWR GAGE STATION
SPILLING OR MIXING POINT
WATER TREATMENT PLANT
Task 1.4: Site Visits
Mariano Exchange Ditch (MED) System Assessment Project
Task 1.4 - Conduct Site Visits of the MEDS
Site Visit Descriptions
October 10, 2005
A site visit was made by Doug Laiho specifically to observe ditch physical and hydraulic
conditions at the time of a significant rainfall. The MED was expected to be under
conditions where irrigation flows were essentially absent, having been terminated three
weeks earlier and essentially all flow could be attributed to rainfall runoff. The visit
occurred under steady rain conditions from a general storm that had begun almost thirty
hours earlier, with low intensity rain having fallen continuously during the period. This
event was not a high intensity, short duration thunderstorm, which would be more typical
of this time of the year, nor did it have a thunderstorm embedded within it. Such a
thunderstorm event would be expected to have a more dramatic impact on the MED
hydraulic capacity and physical conditions than a general storm. Rain was actively
falling and water was actively running off the ground surface at the time of the visit.
The notable observations which were made include:
•
There was noticeable flow (considerably less than when irrigation water is being
carried) in the MED with a staff gage reading of 0.22’ being made at 12:15 p.m.
•
Pictures in file “MEDPhotos - Site Visit 101005 - Rainfall.zip ” were taken during
the visit.
•
Flow from the MED at the confluence with the Big Thompson River had only
slightly higher visual turbidity than water in the River; most people would
probably consider both flows to be only slightly turbid or essentially clear
•
By observation (versus measurement) approximately ¼ of the flow observed at
the gage originated out of Boedecker Reservoir outlet structure and the remainder
from the Cattail Dam #2 outfall. It is assumed that flow from the Reservoir was
due to gate leakage as irrigation flows had been terminated for the season. Flow
from Boedecker Reservoir was observed to be slightly turbid (green, milky, light
brown in color) and flow from Cattail Dam #2 was essentially clear. There was
no noticeable turbidity change along the length of the MED to the confluence that
would indicate significant sediment was being picked up from the MED bottom or
side slopes.
•
A light wind occurring at the time of the visit (estimated at 20 km/hr) was
producing small waves on the reservoir surface. The reservoir surface level was
shallow, only just covering the outlet, but the waves were probably not large
enough to be picking up sediment by bottom friction. The Reservoir water did
not appear to be turbid at the outlet.
•
Water was flowing into the Reservoir via its inlet channel at a rate estimated to be
approximately 10 cfs. This water had a very obvious dark grey turbidity, typical
of what one would observe as “first flush” runoff from urban streets after a long
period without rainfall runoff. This observation was a surprise and the source of
this colored water was not obvious or further investigated.
October 27, 2005
An opportunistic site visit was made by Doug Laiho when he was in the vicinity for a
different primary purpose, to obtain improved site familiarity and to observe MED
physical conditions approximately a month after the seasonal cessation of exchange water
deliveries. This site visit was expected to be under conditions where the MED should be
essentially dry.
The notable observations which were made include:
•
There was noticeable flow (less than the 10/10/05 visit and considerably less than
when irrigation water is being carried) in the MED with a staff gage reading of
0.16’ being made ad 5:45 p.m.
•
A large block or mass wasting type failure had occurred between structures H11
and H12 (see attached Revised Stormwater Structures Map) since the last site
visit. While bare, erosion prone banks have been observed previously, this was
the first opportunity to examine an incidence of bank erosion. This instance of
bank erosion is probably typical of this area and similar areas dominated by a
cohesive soil material (clay, in this case). This process has been observed on
natural streams (such as Elkhead Creek in Colorado and Nemadji River in
Wisconsin) and results in an essentially perpetually turbid water condition. A
large block of soil had dropped from the right bank along a nearly vertical failure
plane, falling to the channel bed at the toe of the slope. This classic “plane slip”
type mass wasting was probably caused by a combination of hydraulic and
geotechnical factors. It is likely that water flow in the ditch, including secondary
currents, eroded bank edge material from the toe of the failure surface reducing
support for the material above it. Upon cessation of irrigation flows for the
season a portion of this undercut bank edge was left with high residual soil- water
pressure, unsupported by water in the MED. With the underlying sub-soil clay
reduced in volume and unable to drain quickly enough to relieve the pore
pressure, the overburden soil wedge can no longer be supported by the soil below
and fails vertically and slightly ditch-ward into the channel bottom. This can
temporarily stabilize this slope, but deflects the ditch flow against the opposite
bank and the process is repeated. This produces a readily available source of
sediment in the channel bottom which will likely show up as turbidity when
normal flow returns to the ditch.
•
The stream bed upstream of Wilson Avenue has the appearance of a flat poolriffle sequence with 5’ to 20’ long riffles dropping the bed an inch or two,
separated approximately every fifty feet by a flatter gradient run or pool No
channel grade breaks or head-cuts of more than an inch or two were observed in
the channel bottom. This resulting overall flat sloped channel bottom may be
subject to small dynamic changes, but is not likely in a condition of continuing
degradation. Upstream of Wilson Avenue, the channel bottom is bare, unarmored
and the sidewalls are approximately 50% vegetated. Downstream of Wilson
Avenue the channel bottom is bare, unarmored and the sidewalls are more
completely vegetated. Occasional vertical side walls exist primarily on north
facing exposures. The top eight feet of these side walls appears to be fine
material dominated by clay and the lower four feet is primarily clay with some
sand, transitioning to weathered siltstone/claystone. This lower level holds a one
foot capillary fringe of water above the water level. Some stringy algae are
present in the MED bed in the vicinity of First Street.
•
What appears to be an almost free-standing grouted rock energy dissipater exists
opposite an off-channel detention pond outlet at Hydrosphere's structure H12 (see
Revised Stormwater Structures Map and descriptions provided with this
deliverable). The dissipater has been completely eroded behind and on each end,
but is partly supported at its base. This condition, while a severe example, is
typical of structures at locations where off-site flows are discharged to the MED
via structures along the unstable ditch walls.
•
Pictures file “MEDPhotos - Site Visit 102705” were taken during the visit,
including views of bullets one and three preceding.
November 1, 2005
The purpose of this site visit (by Laura Belanger) was to locate and verify stormwater
structures draining to the MED as provided by the City of Loveland (Loveland) on a
stormwater system map. Other possible point and non-point sources were also identified.
Soil samples were collected at Boedecker Reservoir and from the MED bank and channel
bottom in an eroded section of the ditch.
The entire length of the ditch was walked, with the exception of the final northern extent
of the ditch from the location where it emerges from below ground in the vicinity of the
school bus parking lot and recycling center to where it enters the Big Thompson. This
section was not examined due to failing daylight, its minimal extent, and no stormwater
inflows being identified for it on Loveland's map. The lower 60 feet of this section of
ditch was examined during the 9/12/2005 site vis it and no stormwater outfalls were
identified at that time.
Pictures from this field visit can be found in the file:
MEDPhotos - Site Visit 110105.zip
(Note that pictures referenced below are found in this file)
The following is a summary of major findings during the November 2005 site visit.
•
Undocumented Stormwater Inflows to MED: Numerous point source stormwater
inflows were not identified on Loveland's map. It appears that the majoring of
outfalls on the map were those drainage recent developments. There were
numerous unidentified stormwater structures between Boedecker Reservoir and
South Wilson Avenue, with only a few to the east of Wilson (pictures: 034, 035,
036, 037, 038, 040, 041, 042, 043, 047, 048, 049, 050, 051, 057, 058, 076, 077,
078, 109 and 110). Information on unidentified outfalls, along with GPS
coordinates and descriptions, is provided in the attached Revised Stormwater
Structures Map and the Stormwater Structure Descriptions document. Outfalls on
the stormwater map were also found to be inconsistently represented (for
example, some were identified as pipes and others as pipes followed by outfalls,
though the structures were physically the same). Recommended edits are
included in the Stormwater Structure Descriptions document.
•
Block Failures: Large blocks of soil have fallen into the MED at points between
Boedecker Reservoir and South Wilson Avenue (pictures: 030, 053, 054, 055, 062
and 063). Stream banks in the steepest and most eroded sections of the ditch have
visible fractures where it is assumed that additional blocks will eventually break
free. In addition to serving as a source of sedimentation, this situation is
extremely dangerous for anyone walking along these sections of the ditch.
•
Possible Need for Additional Outfall(s): There is ongoing development occurring
along the northern side of the MED to the west of South Wilson Avenue. The
existing but newer neighborhood located here has good drainage along its eastern
and western ends (pictures: 058, 060, 070, 071 and 072). However, the middle
section is not properly drained which has led to the development of natural
drainages eroding the northern bank (pictures: 061, 073 and 074).
•
MED Erosion to East of South Wilson Avenue : Erosion is occurring at points
along the entire MED. To the east of Wilson Avenue, the greatest erosion appears
to be occurring in the vicinity of the Walt Clark Middle School grounds, where
ditch banks are steep (pictures: 083, 084, 085 and 086). Erosion and undercutting
occurs at various points along the entire eastern section of the MED (pictures:
089, 090 and 091). There is also some degradation of the stream channel in two
sections (pictures: 088, 092, 093, 094, 113 and 114).
•
Erosion Due to Older Stormwater Outfalls: Numerous older stormwater outfall
pipes located between Boedecker Reservoir and Wilson Avenue emerge high on
the ditch wall with no grading or other mechanism in place to dissipate energy
from stormwater flows. The most severe erosion has occurred around a pipe
draining an established farm property to the north of the MED along the
westernmost section of ditch (pictures: 034, 035, 036, and 037). It appears that
breaks in this pipe may be causing erosion to occur from within the ditch bank.
In addition, soil has eroded around an older outfall located at the Walt Clark
Middle School (Structure M4 on the Revised Stormwater Structures Map).
Stormwater Structure Descriptions
Stormwater Structures Draining to the Mariano Exchange Ditch (MED)
Task 1.4 - Conduct Site Visits of the MEDS
GPS Coordinates1
Loveland
Hydrosphere Site Stormwater
Visit ID
Structure ID
ResOut
Lat (°N)
40.38474
Long (°W)
-105.13049
Material
H1
40.38472
-105.13042 RipRap/Wetland
H4
H5
H7
40.38453
40.38444
40.38499
H11
H12
M1
M2
M3Wilson
P7810
OF1023
I4084
H14
Diameter
(inches)
NA
Identified on
original
stormwater map
received from
Loveland?
Comments2
Location of outfall structure to the MED at Boedecker Reservoir.
No
NA
No
-105.12827 PVC Pipe
-105.12801 PVC Pipe
-105.12678 Metal
4
8
2
No
No
No
40.38409
40.38352
-105.12331 Overflow Structure?
-105.12137 Corrugated Plastic
4
18
No
No
40.38214
-105.11753 Corrugated Metal (2)
15
Yes
40.38220
40.38244
Concrete w/rubber
-105.11707 backflow preventer
-105.11561
22
NA
Yes
Yes
40.38296
-105.11439 Corrugated Metal
15
No
May not wish to identify as stormwater structure on map. Constructed wetland
draining from Buckingham Ditch (and road?) into MED in riprapped area
between Boedecker outfall and culvert below S. Crestone Drive.
Drains property to north of ditch. There is a lot of erosion occurring
underneath this pipe.
Drains open lands to south of ditch
Drains property to north of ditch.
Cement structure located on south side of ditch. Houses metal pipe workings
with a 4" opening. Small cover reads "Water 125". Is a blowoff valve for
potable water system?
Drains new development on north side of ditch.
There are two 15" pipes side by side at this location. Both drain the reservoir
to their south. Should be "Outfalls" to be consistent with other labeled
structures.
It was a little difficult to measure the diameter of outfall as ends in a rubber
backflow preventer. Need to switch the order of P6816 and OF1023. Pipe
comes first then outfall is adjacent to the Mariano Exchange Ditch.
Culvert routing MED under Wilson.
Drains a few houses, parking lot, maybe part of school grounds on south side
of ditch.
Erosion has left much of pipe exposed, may have leak causing soil around it
to erode.
May not want this on stormwater map. It appears that water from this intake
pipe is used to water the school grounds/fields (sign at school says untreated
water is being applied).
Drains newer development on north side of ditch.
M4
OF1022
40.38325
-105.11431 Corrugated Metal
18
Yes
Intake
M5
OF1003
40.38752
40.38844
-105.11295 Black Plastic Pipe
-105.11021 Corrugated Plastic
1.5
18
No
Yes
H15
M6
OF1006
40.38837
40.38851
-105.10741 Corrugated Metal (3)
-105.10797 Corrugated Plastic
16
18
No
Yes
M7
P3580
40.39018
-105.10845 Corrugated Plastic
18
Yes
M8
M9
M10
P3581
OF1388
OF1387
40.39080
40.39156
40.39226
-105.10902 Corrugated Plastic
-105.10997 Corrugated Plastic
-105.11037 Corrugated Plastic
18
18
18
Yes
Yes
Yes
40.39433
-105.11060
NA
No
There are three 16" metal pipes, side by side, draining older neighborhood to
south of ditch. Discharge onto riprap approximately 10 feet from the ditch.
Drains newer development on north side of ditch.
Should be an "Outfall" (not "Pipe") to be consistent with other labeled
structures. Drains newer development on west side of ditch.
Should be an "Outfall" (not "Pipe") to be consistent with other labeled
structures. Drains newer development on west side of ditch.
Drains newer development on west side of ditch.
Drains newer development on west side of ditch.
Location where the MED goes underground to the north of W 1st Street and
the gaging station (just south of lot where school buses are parked).
No
Natural drainage which has formed along new development to north of MED.
May need additional stormwater structure here.
BusParking
Natural Runoff Area of Potential Concern
H13
40.38273
-105.11970 Natural drainage
1
Stormwater structures, other structures, and sampling locations were first plotted on the Revised Stormwater Structure Map (provided by Hydrosphere) using GPS coordinates obtained during site
visits. The placement of sites on the map was then manually adjusted to corrected for any error in GPS coordinates.
2
In a 11/17/2005 phone conversation with Hydrosphere (Laura Belanger), Shannon Smith (Loveland's GIS staff person) said her understanding was that any structure discharging to the MED,
regardless of material, should be considered an "Outfall". If this is the case, then all structures above, with the exception of "ResOut", "H1", "M3Wilson" and "BusParking" should be given "Outfall"
IDs.
Task 1.5: Soil Evaluation
Mariano Exchange Ditch (MED) System Assessment Project
Task 1.5 - Evaluate MED Soils
The evaluation of soils along the MED involved three components; review of the Larimer
County Soil Survey (USDA 1980), review of information in the Ayres (2004) hydraulic
analysis of the MED and independent soils sampling and testing.
The Soil Survey (1980) shows and describes the soil along the MED as dominantly a
Heldt clay loam which is a clay soil formed from clay shale. This soil is characterized as
deep, well drained, slowly permeable and having high water capacity. On steep slopes,
like the ditch sidewalls, it has high erosion potential.
The geotechnical drilling and sampling conducted for Ayres (2004) confirmed this
material as native clay (CL in accordance with the Unified Soil Classification (USC)
system) with some sand, lying approximately 15’ thick over siltstone/claystone bedrock.
Accordingly, the MED flow line upstream of Wilson would be expected to lie at an
elevation approximately at the same level as weathered bedrock. While called out as
bedrock, this material does not have the appearance of a “rock”; as its name implies, it is
dense clay that weathers rather quickly to fine clay upon exposure to air, water and
freeze/thaw conditions.
Soil samples taken of the MED banks and bed as part of the subject project (collected during
the November 1, 2005 field visit) confirm the presence of this same clay soil type, CL in
accordance with the USC. Soil sample test results are provided in the Terracon Soils Analysis
which is attached. Weathered siltstone/claystone is commonly observed along the MED flow
line in the form of dense, grey colored chips. The desiccated chips crush into very fine
particles when pressured between the fingers. The bank sample and the bed sample both
classify as clay with the bank sample having a much higher proportion of fine material. This
material is available in sufficient quantity as a turbidity source for an indefinitely long time.
Both samples have traces of sand and stone chips that are inadequate in quantity to result in an
armored ditch bed. Accordingly, the stream bed will continue to degrade at a progressively
slower rate, eventually reaching an equilibrium slope of flatter than 0.001. Bed material is
likely the same material as the banks, with a significant amount of the finest material having
been washed away by the flowing water, with weathered bedrock lying immediately below
the loose bed. The settling time of this clay material is measured hours and days, versus
minutes and hours. This means that using detention ponds to settle out enough of this
suspended material from the MED water to have desired impact on water quality would
require a long time period and large volumes. Both samples show a significant amount of the
fine soil remaining in suspension after two days, indicating the possible presence of colloidal
clays, which are not feasible to remove from water by gravitational settling.
The soil sample taken from Boedecker Reservoir bottom is coarser than the soil from
either the MED bed or sidewalls, possibly indicating that the finer sediment in the
Reservoir influent water passes through the Reservoir or is available in smaller quantities
than from the MED downstream. This soil type is also a CL in accordance with the USC.
Confirmation of the primary soil type in the area as a CL is also provided in the
Boedecker Dam rehabilitation report (Tetra Tech, 2003).
Task 1.6: Topographic Surveying
Mariano Exchange Ditch (MED) System Assessment Project
Task 1.6 - Conduct Topographic Surveying
Based on the information gathered as part of Task 1.2 it was concluded that no additional
field surveying was needed at this time. Adequate information was found to be available
through the MED hydraulic analysis completed by Ayres Associates (Ayres, 2004). That
information includes cross section surveys for the full reach at frequent intervals that
adequately define the cross sections themselves as well as the longitudinal gradient of the
MED. One comment on this information is that none of the cross sections show the
several vertical or undercut banks which exist along the middle of the reach between the
dam and Wilson Avenue. It suffices to simply recognize that such features exist even
they do not show up on the survey.
Several important conclusions that can be reached from evaluation of this information.
The first is that the MED upstream of Wilson Avenue exists at a very flat slope (0.002
approximately), similar to other irrigation ditches, such that it is unlikely that significant
vertical degradation is actively occurring. The MED downstream of Wilson Avenue has
a steeper, but still flat slope (0.007 approximately) similar to natural streams in the area,
such that it is likely that in the absence of natural armoring, some vertical degradation is
occurring. This continuing vertical degradation was observed on at least one of the site
inspections. The Ayres (2004) survey and the associated hydraulic analysis also confirms
that the MED channel banks are generally higher than necessary and the channel
conveyance greater than necessary at most locations for transmission of irrigation and
drainage water. The banks exist at much steeper (generally 2:1 or steeper) than normal
(4:1 or flatter) side slopes. The height and side slopes of the MED banks result in
sections of MED which are unstable and have little cover, providing a source of sediment
as described elsewhere. The inconsistency of the MED cross section geometry and high,
steep banks are characteristics of an infrequently maintained and difficult to maintain
ditch.
Task 1.7: Analysis
MEDS Project - Phase 1
Key Initial Findings
Impact of the MED on the Big Thompson River
1
2
3
4
5
6
7
8
9
10
11
On 9/12/05, the MED added approximately 2.7 # TP/day to the Big Thompson River.
According to historical data, there is a significant increase in TP in the river on days when the ditch is running.
On 9/12/05, the MED added approximately 31 # TN/day to the Big Thompson River.
On the one day when TN was measured upstream and downstream of the confluence (7/20/04), TN increased from 380 to 420 ug/l.
On 9/12/05, the MED added approximately 8,500 # TSS/day to the Big Thompson River.
TSS concentrations in the MED (~80-90 mg/l) are approximately twice as high as the river concentrations at M90 (~40 mg/l, 2000-2004 data)
At M130, TSS concentrations are significantly higher than at M90 (mean = 480 mg/l, 2001-2004 data), pointing to other very large sources along the river between M90 and M130.
The temperature of the BT river was warmer downstream of the ditch during the summers of 2002 and 2003.
On the one day when turbidity was measured upstream and downstream of the confluence (8/11/02), the turbidity increased from 10 to 40 NTU.
There is no correlation between turbidity and TSS in the ditch based on 9/12/05 data.
Impacts of the MED to aquatic life, recreation, agriculture, and water supply on the Big Thompson have not been quantified.
Characterization / Sources of These Constituents
1
2
3
4
5
6
7
Boedecker Reservoir is a significant source of turbidity, TP, and TSS to the MED.
Cattail Reservoir appears to be a source of TN to the MED.
There is a large source of TSS in the MED between Wilson Avenue and the mouth (almost doubles the concentration).
Turbidity increases in the MED between Site 4 (~2,000 feet from the reservoir release) and the mouth by 20 NTU.
The TSS in the MED is predominantly inorganic.
The side walls of the ditch are unstable and failing in sections of the ditch.
The grade of the ditch is flatter upstream of Wilson Avenue and little or no bed degradation is apparent. Downstream, particularly
behind the elementary school, the grade increases and more bed degradation occurs.
8 Based on the information analyzed thus far, it appears that both the reservoir and the ditch are contributing
to the turbidity problem at the confluence with the BT River. It is hypothesized that very fine clay material on
the side walls of the ditch slough off and fall to the bottom of the ditch via block failures when the ditch is
not running. These blocks provide a ready source of fine clay to ditch flow, thus increasing the turbidity. The source(s) of
TSS in the ditch between Wilson Ave and the mouth have not been identified. Based on the one sampling
event, it appears that the ditch does not contribute phosphorus or nitrogen. The sources of turbidity and TSS
in the reservoir have not been identified. Release concentrations of TP and TN are not unusual for a reservoir.
Other Key Findings
1 The current condition of the ditch presents a safety issue, both in terms of public safety and potential property damage.
2 Additional testing will be needed to differentiate the reservoir from the ditch and to better characterize the sources.
3 There are potential options to operate the MED system differently to reduce loadings to the BT River.
60
On days when the MED is running, TP
concentrations increase
in the BT River.
Q = 61 cfs
50
Q = 41 cfs
TP (ug/l)
40
30
Q = 38 cfs
Q = 0 cfs
20
10
Q = 0 cfs
VM40 U/S
VM30 D/S
0
1/1/2002
1/1/2003
1/1/2004
12/31/2004
1/1/2006
1600
M90 TSS
M130 TSS
1400
1200
TSS (mg/l)
1000
800
600
400
NOTE:
MED TSS = 90 mg/l
200
0
1/1/2000
12/31/2000
12/31/2001
12/31/2002
1/1/2004
12/31/2004
30
25
Temperature (C)
20
15
July 3 - July 16, 2002
MED Flow = 40-46 cfs
River Flow = 50-95 cfs (M130)
10
5
VM30 D/S
VM40 U/S
0
1
11 21 31 41 51 61 71 81 91 101 111 121 131 141 151 161 171 181 191 201 211 221 231 241 251 261 271 281 291 301 311
September 11, 2003
25
MED
VM30
VM40
Temperature (degrees Celcius)
20
15
Q(MED) = 26 cfs
Q(D/S) = 19 cfs
10
5
0
0
0.1
0.2
0.3
0.4
0.5
Time
0.6
0.7
0.8
0.9
1
September 12, 2003
25
MED
VM30
VM40
Temperature (degrees Celcius)
20
15
Q(MED) = 21 cfs
Q(D/S) = 15 cfs
10
5
0
0
0.1
0.2
0.3
0.4
0.5
Time
0.6
0.7
0.8
0.9
1
September 13, 2003
25
MED
VM30
VM40
Temperature (degrees Celcius)
20
15
Q(MED) = 20 cfs
Q(D/S) = 15 cfs
10
5
0
0
0.1
0.2
0.3
0.4
0.5
Time
0.6
0.7
0.8
0.9
1
September 14, 2003
25
MED
VM30
VM40
Temperature (degrees Celcius)
20
15
Q(MED) = 19 cfs
Q(D/S) = 13 crs
10
5
0
0
0.1
0.2
0.3
0.4
0.5
Time
0.6
0.7
0.8
0.9
1
September 15, 2003
25
MED
VM30
VM40
Temperature (degrees Celcius)
20
15
Q(MED) = 18 cfs
Q(D/S) = 6.5 cfs
10
5
0
0
0.1
0.2
0.3
0.4
0.5
Time
0.6
0.7
0.8
0.9
1
September 16, 2003
25
MED
VM30
VM40
Temperature (degrees Celcius)
20
15
Q(MED) = 5.7 cfs
Q(D/S) = 50 cfs
10
5
0
0
0.1
0.2
0.3
0.4
0.5
Time
0.6
0.7
0.8
0.9
1