Research methodology
Every number on this site comes from one of the 40 sources listed at the bottom of this page, published by 32 bodies. That list is not maintained by hand — it is generated at build time by walking the data files, so it is impossible for us to cite something here that does not appear below, or to publish something below that no page cites.
Which sources do we accept?
In order of preference, and we do not go down a level while a level above has the answer.
- The operating document. For river geometry that is the Corps of Engineers water control manual for the specific dam — the document the pool elevation is actually managed against.
- The regulation itself. For bag limits that is the chapter of administrative code, not a regulations pamphlet summarising it. Chapter and section get cited.
- The agency's own page. For license prices and gauge data, the state department or federal service that sets or measures the thing.
- The published paper. For fish weight equations, the paper that fitted them, with its sample size stated so a reader can judge it.
- The manufacturer's specification. For line diameters, the maker's own table, with the rounding it carries treated as real uncertainty rather than ignored.
How is each source graded?
A source can be current, authoritative and still a poor fit for what we are doing with it. The grade records that separately from freshness.
| Grade | Sources | What it means |
|---|---|---|
| Measured | 37 | Built from published measurements of this species. The underlying study pooled populations from across North America rather than the Upper Mississippi alone, so individual fish still vary. |
| Regional | 2 | Derived from measurements published for nearby waters or the wider species group, so expect a wider spread on the Upper Mississippi. |
| Generic | 1 | A widely used textbook default, not fitted to Upper Mississippi fish. Treat the result as a rough estimate only. |
Where a page draws on several sources of different grades, it displays the weakest, because that is what limits the result. Our fact-checking policy covers the freshness rule that runs alongside the grade.
How are the calculations checked?
Three ways, all of them running on every build. The formula modules are pure functions with unit tests that assert against worked examples computed by hand from the published equation. The astronomy code is cross-checked against independently published sunrise and sunset times, with the tolerance we accept stated in the tests rather than tuned until it passes. And every worked example quoted in page prose is generated by a script that calls the same functions the calculator calls, so the numbers in the text cannot drift from the numbers in the tool.
That last one matters more than it sounds. The most common defect we found in competing tools was prose describing a result the tool no longer produces.
Who publishes the material we rely on?
Sorted by how much of the site rests on each. Concentration is not a bad sign here — it means we are going to the body that owns the data rather than assembling a number from fragments.
| Publisher | Figures cited |
|---|---|
| Wisconsin Department of Natural Resources | 3 |
| Iowa Department of Natural Resources | 2 |
| Minnesota Department of Natural Resources | 2 |
| Ogle, D.H. — FSA WSlit standard-weight database, Northland College | 2 |
| United States Army Corps of Engineers, St. Paul District, Master Water Control Manual appendix, February 2003 | 2 |
| United States Fish and Wildlife Service, Genoa National Fish Hatchery | 2 |
| United States Geological Survey, National Water Information System | 2 |
| Berkley Fishing — Trilene XL product specification table | 1 |
| Brown, Murphy and Springer (1995), Journal of Freshwater Ecology | 1 |
| Iowa Department of Natural Resources, Fish Iowa pool description for Pool 10 | 1 |
| Iowa Department of Natural Resources, Fish Iowa pool description for Pool 9 | 1 |
| Knight, J.A. (1936), Moon Up — Moon Down, as summarised by the Wisconsin Department of Natural Resources | 1 |
| La Crosse County, Wisconsin, Parks and Campgrounds brochure | 1 |
| Minnesota Rules part 6266.0500, effective January 1, 2026 | 1 |
| National Oceanic and Atmospheric Administration, Global Monitoring Laboratory | 1 |
| PowerPro — Spectra braided line product specifications | 1 |
| Region 5 Regional Response Team, Upper Mississippi River Pool 10 overview | 1 |
| Seaguar — InvizX product specification table | 1 |
| United States Army Corps of Engineers, St. Paul District project page for Lock and Dam 10 | 1 |
| United States Army Corps of Engineers, St. Paul District project page for Lock and Dam 7 | 1 |
| United States Army Corps of Engineers, St. Paul District project page for Lock and Dam 8 | 1 |
| United States Army Corps of Engineers, St. Paul District project page for Lock and Dam 9 | 1 |
| United States Army Corps of Engineers, St. Paul District, Blackhawk Park recreation area | 1 |
| United States Fish and Wildlife Service, Upper Mississippi River National Wildlife and Fish Refuge | 1 |
| United States Geological Survey, Upper Midwest Environmental Sciences Center, Pool 7 vegetation study context | 1 |
| United States Naval Observatory, Astronomical Applications Department | 1 |
| Wisconsin Administrative Code chapter NR 22.03 | 1 |
| Wisconsin Department of Natural Resources, Boat and Shore Fishing Access | 1 |
| Wisconsin Department of Natural Resources, Lake Onalaska boat landings inventory | 1 |
| Wisconsin Department of Natural Resources, Mississippi River Pool 7 / Lake Onalaska page | 1 |
| Wisconsin Department of Natural Resources, Wisconsin Administrative Code chapter NR 22, Wisconsin-Iowa boundary waters | 1 |
| Wisconsin Department of Natural Resources, Wisconsin Administrative Code NR 21.015 and NR 22.015, license waiver | 1 |
What are we missing?
Three gaps we know about and have not papered over. There is no working real-time gauge inside Pool 9, so the Pool 9 guide uses the next gauge downstream and says so on the page rather than presenting it as pool stage. There is no published model relating barometric pressure or moon position to catch rates that we would be willing to cite, so theour best fishing time calculator grades the evidence behind each factor instead of producing a percentage. And reel manufacturers do not publish spool geometry, so theline capacity calculator works from the rating printed on the spool rather than from a database of reels we could not source.
Each of those is a place where a competing tool gives you a confident number. We would rather show the gap.
Questions about our sourcing
How many distinct sources does this site use?
40 at the last build, across 32 publishing bodies. That count is generated by walking the data files rather than maintained by hand, so it cannot drift from what the pages actually cite.
Do you cite other fishing websites?
No. Every figure traces to a primary document: an administrative code chapter, a Corps of Engineers water control manual, an agency price page, a manufacturer specification table or a published fisheries paper. Secondary summaries are useful for finding the primary document and are never cited in its place.
What is a standard-weight equation?
A published relationship of the form log10(W) = a + b × log10(L), fitted to measurements of many populations of one species, that gives the weight a fish of that length would be in average condition. It is the basis of the relative weight index fisheries managers use, and it is what the weight calculators on this site run.
Why do you show a range instead of one number?
Because the sources support a range. A standard-weight equation describes a population, not the fish in your hands, and a published line diameter is rounded before it reaches you. Presenting a single figure would be adding precision the data does not contain.
Sources
- Berkley Fishing — Trilene XL product specification table
Berkley publishes these as advertised diameters. Independent micrometer checks of monofilament commonly run a thousandth of an inch over the advertised figure.
- Brown, Murphy and Springer (1995), Journal of Freshwater Ecology
Fitted to 241 channel catfish populations across the species range. The authors state the equation is valid from 70 mm total length upward, replacing an older equation that required 280 mm.
- Iowa Department of Natural Resources
The agency opened public comment in March 2026 on a proposed $1 increase to the resident fishing license, which would take effect December 15 for the 2027 recreation year. The figures here are the prices in force now.
- Iowa Department of Natural Resources
The privilege code sheet lists a $0.50 writing fee alongside each fishing privilege.
- Iowa Department of Natural Resources, Fish Iowa pool description for Pool 10
Iowa DNR describes Pool 10 as 32.8 miles from Lock and Dam 10 at Guttenberg upstream to Lock and Dam 9 at Lynxville. Surface acres are listed as not available on the same page, so this site does not invent an acreage figure.
- Iowa Department of Natural Resources, Fish Iowa pool description for Pool 9
Above that point Pool 9 is Minnesota and Wisconsin water; below it, Iowa and Wisconsin. The two stretches fall under different reciprocity agreements.
- Knight, J.A. (1936), Moon Up — Moon Down, as summarised by the Wisconsin Department of Natural Resources
Solunar theory is included because readers expect it. We have found no controlled study demonstrating a consistent catch-rate effect, so it is capped at one point in the model and labeled as traditional and unproven wherever it appears.
- La Crosse County, Wisconsin, Parks and Campgrounds brochure
The county lists the Goose Island camping season as 15 April to 30 October and takes reservations from the first working business day of the year on 608-788-7018.
- Minnesota Department of Natural Resources
A $5 surcharge is already included in the nonresident figures. Trout and salmon stamp validation is a separate $10 and is not required for Mississippi River pools.
- Minnesota Department of Natural Resources
The agency states the listed price does not include the $1.00 agent fee.
- Minnesota Rules part 6266.0500, effective January 1, 2026
The railroad tracks, not the state line, define where reciprocity applies. Water outside the tracks is ordinary inland water of whichever state it sits in.
- National Oceanic and Atmospheric Administration, Global Monitoring Laboratory
NOAA publishes the spreadsheet equations for solar position, equation of time and sunrise hour angle. Our sunrise and sunset times implement these and agree with published values to within about three minutes, the residual coming from differing atmospheric refraction constants.
- Ogle, D.H. — FSA WSlit standard-weight database, Northland College
Murphy, Brown and Springer (1990) describe a desirable mean relative weight of 100 plus or minus 5 for walleye populations. Individual fish range far wider than a population mean.
- Ogle, D.H. — FSA WSlit standard-weight database, Northland College
Original equation from Murphy, Brown and Springer (1990), developed from 42,487 walleye in 114 populations. A separate equation covers fish of 30-149 mm, which this calculator does not cover.
- PowerPro — Spectra braided line product specifications
Braid is not perfectly round and compresses under tension, so real-world capacity with braid usually beats the geometric estimate by a small margin.
- Region 5 Regional Response Team, Upper Mississippi River Pool 10 overview
Pool 10 also includes refuge closed areas, Effigy Mounds National Monument, Pikes Peak State Park (Iowa) and Wyalusing State Park (Wisconsin).
- Seaguar — InvizX product specification table
Seaguar publishes InvizX diameters in millimetres; the inch column is the manufacturer figure rounded to three decimal places.
- United States Army Corps of Engineers, St. Paul District project page for Lock and Dam 10
Located at Mississippi River mile 615.0. Constructed and placed in operation in 1937. Concrete dam 763 feet long with four roller gates and eight Tainter gates, plus a long earth embankment and a 1,200-foot concrete spillway; lock chamber 110 by 600 feet.
- United States Army Corps of Engineers, St. Paul District project page for Lock and Dam 7
Located at Mississippi River mile 702.5. Constructed and placed in operation in 1935, with major rehabilitation from 1989 through 2002. Concrete structure 940 feet long with five roller gates and eleven Tainter gates; lock chamber 110 by 600 feet.
- United States Army Corps of Engineers, St. Paul District project page for Lock and Dam 8
Placed in operation in 1937 and rehabilitated between 1989 and 2003. The dam is a 934-foot concrete structure with five roller gates and ten Tainter gates; the lock chamber is 110 by 600 feet.
- United States Army Corps of Engineers, St. Paul District project page for Lock and Dam 9
Placed in operation in 1937 and rehabilitated between 1989 and 2006. The dam is an 811-foot concrete structure with five roller gates and eight Tainter gates; the lock chamber is 110 by 600 feet.
- United States Army Corps of Engineers, St. Paul District, Blackhawk Park recreation area
The Corps describes Blackhawk Park as the largest recreation area in Pool 9 and the only Corps-staffed campground on the Upper Mississippi in the St. Paul District, with roughly 150,000 visits a year. Camping reservations go through Recreation.gov.
- United States Army Corps of Engineers, St. Paul District, Master Water Control Manual appendix, February 2003
Measured above the mouth of the Ohio River.
- United States Army Corps of Engineers, St. Paul District, Master Water Control Manual appendix, February 2003
Measured above the mouth of the Ohio River.
- United States Fish and Wildlife Service, Genoa National Fish Hatchery
Authorised under the Upper Mississippi Wildlife and Fish Act of 1924, the same act that created the refuge. Its work now centres on recovering federally endangered aquatic species and supporting tribal and state conservation agencies.
- United States Fish and Wildlife Service, Genoa National Fish Hatchery
Taken from the hatchery’s own published history. Genoa is one of 72 federal hatcheries and now rears more than 15 fish species and 15 mussel species, plus one dragonfly and one salamander.
- United States Fish and Wildlife Service, Upper Mississippi River National Wildlife and Fish Refuge
The refuge stretches 261 river miles from Wabasha, Minnesota to Rock Island, Illinois and protects more than 240,000 acres of floodplain. Pool maps showing closed areas and sanctuaries for Pools 4 through 14 are published on the same site.
- United States Geological Survey, National Water Information System
Brownsville sits in Pool 8 just below Lock and Dam 7. Pool 7 pages use it as a downstream stage reference for the corridor rather than claiming Lake Onalaska pool stage. USGS site 05380590 at Lock and Dam 7 is registered but is not treated as a live Instantaneous Values feed for this build.
- United States Geological Survey, National Water Information System
The gauge at Lock and Dam 9 near Lynxville (site 05388410) is registered but publishes no real-time data, so Pool 9 uses the next gauge downstream. McGregor sits below Lock and Dam 9 in Pool 10, which means it tracks the river’s overall rise and fall but not Pool 9’s own pool stage. Discharge is registered at this site but the Instantaneous Values service last returned a flow reading in 2013, so the build drops it and the page shows stage only.
- United States Geological Survey, Upper Midwest Environmental Sciences Center, Pool 7 vegetation study context
UMESC describes Pool 7 as 19.6 km (12 river miles) from Lock and Dam 6 at Trempealeau, Wisconsin, down to Lock and Dam 7.
- United States Naval Observatory, Astronomical Applications Department
Moon phase is computed from the mean synodic month against a known new moon epoch. This is accurate to within a few hours of the true phase, which is well inside the resolution any fishing decision needs.
- Wisconsin Administrative Code chapter NR 22.03
- Wisconsin Department of Natural Resources
Prices exclude the inland trout stamp ($10) and Great Lakes salmon/trout stamp ($10), neither of which is needed for Mississippi River pools.
- Wisconsin Department of Natural Resources
The agency states residents and nonresidents 16 or older need a license, and that children under 16 do not. Children still follow all length, bag and season limits, and have their own bag limits.
- Wisconsin Department of Natural Resources
- Wisconsin Department of Natural Resources, Boat and Shore Fishing Access
The department warns that launch information may be incomplete and changes without notice, and asks anglers to contact the county, city, village or township listed for a site before relying on it.
- Wisconsin Department of Natural Resources, Lake Onalaska boat landings inventory
The DNR lake page lists multiple Lake Onalaska landings. Confirm fees and condition with the managing town or county before you trailer, and cross-check refuge closed-area maps for Pool 7.
- Wisconsin Department of Natural Resources, Mississippi River Pool 7 / Lake Onalaska page
The Black River discharge into Pool 7 is why Pool 8 now only receives a minimum discharge down the old Black River channel through the Onalaska Dam.
- Wisconsin Department of Natural Resources, Wisconsin Administrative Code chapter NR 22, Wisconsin-Iowa boundary waters
Read from NR 22.04, sport fishing seasons and limits, in the version inserted into the administrative code on 1 July 2026.
- Wisconsin Department of Natural Resources, Wisconsin Administrative Code NR 21.015 and NR 22.015, license waiver
Both chapters carry the same waiver in identical wording. It does not extend to commercial fishing licenses, and it waives the license only, not the rules.