Build a Colorado-focused fishing conditions app that aggregates public government data — USGS stream gauges, CPW stocking reports, weather APIs, and solunar calculations — into a single dashboard that tells anglers: "Where should I fish this weekend, and when will the bite be best?"
The key differentiator from existing apps (BassForecast, Fishbox, onX Fish, etc.) is that yours is Colorado-specific and data-dense — pulling in real USGS water data and CPW stocking info that the generic national apps don't integrate well. Most fishing apps focus on saltwater/bass and treat Colorado as an afterthought. You'd own the niche.
The gap in the market: Existing fishing forecast apps are national, generic, and mostly focused on bass fishing or saltwater. Colorado anglers — primarily targeting trout in rivers and alpine lakes — are underserved. The data that matters most to Colorado anglers (stream flows, water temperature, stocking schedules) exists in scattered government sources that nobody has stitched together well.
Your unfair advantage: You're a data engineer who lives in Colorado Springs and actually fishes these waters. You understand both the data pipeline problem (ingesting, cleaning, joining messy public data) and the domain (what conditions matter for Colorado trout fishing). That combination is rare.
Monetization potential: Fishing apps with premium tiers charge $3–10/month or $30–50/year. Colorado alone has over 1 million licensed anglers. Even capturing a tiny fraction of that market is meaningful side-hustle income. You could also monetize through affiliate links to local fly shops, guide services, or gear.
This is where your data engineering skills shine. Each of these is a separate ingestion pipeline:
What it provides: Real-time and historical streamflow, water temperature, and gage height for hundreds of Colorado monitoring stations.
API endpoint:
https://waterservices.usgs.gov/nwis/iv/?format=json&stateCd=CO¶meterCd=00060,00010&siteStatus=active
Key parameters:
| Code | Parameter | Why It Matters |
|---|---|---|
| 00060 | Streamflow (discharge) in cfs | Too high = dangerous/muddy; too low = fish stressed; just right = prime |
| 00010 | Water temperature (°C) | Trout feed actively in 50–65°F range; above 68°F they stop |
| 00065 | Gage height (ft) | Indicates water level trends |
Data format: JSON (GeoJSON for the new modernized API at api.waterdata.usgs.gov). Updated every 15–60 minutes. Historical data back to 2007.
Pipeline notes:
- ~390 active gauges in Colorado
- Not all gauges measure temperature — you'll need to map which ones do
- The USGS is modernizing their API in 2025–2026, moving from nested JSON to a cleaner GeoJSON format. Build against the new API (
api.waterdata.usgs.gov/ogcapi/v0/) to future-proof.
What it provides: Weekly lists of which waters were stocked with catchable trout (~10 inches), updated every Friday during fishing season.
Current format: HTML table on the CPW website at cpw.state.co.us/fishing/stocking-report. No official API.
Pipeline approach: Web scraping. The stocking report is a simple HTML table — parse it weekly with BeautifulSoup or Scrapy. Store historically to build a stocking pattern database (e.g., "Eleven Mile Reservoir gets stocked in the first week of June most years").
Bonus data: CPW also publishes Fishery Survey Summaries for 127+ waters — PDFs with species composition, access info, and management notes. These could be parsed and indexed to enrich your location profiles.
Why this is valuable: Anglers obsess over stocking reports. Right now they have to manually check the CPW website every Friday. Your app would push notifications: "North Catamount Reservoir was stocked yesterday — conditions look good for Saturday morning."
Options (with free tiers):
| Source | Free Tier | Key Data |
|---|---|---|
| Open-Meteo | Unlimited, no key needed | Hourly forecast, barometric pressure, wind, cloud cover, precipitation |
| NWS (weather.gov) API | Unlimited, no key needed | Official US forecast, alerts, observations |
| Visual Crossing | 1,000 calls/day free | Historical + forecast, clean API |
Key weather variables for fishing:
- Barometric pressure + trend — This is the single biggest weather factor. Falling pressure (pre-storm) triggers aggressive feeding. Stable high pressure means tight bite windows.
- Wind speed and direction — Light wind (5–15 mph) creates surface chop that improves fishing. Heavy wind makes casting difficult.
- Cloud cover — Overcast days often produce better fishing, especially on clear mountain streams.
- Air temperature — Affects water temperature, insect hatches, and angler comfort.
- Precipitation — Light rain can be excellent for fishing; heavy rain muddies water and raises flows dangerously.
What it is: The Solunar Theory predicts fish (and wildlife) feeding activity based on the position of the moon. Major feeding periods occur when the moon is directly overhead or underfoot; minor periods at moonrise and moonset.
Implementation: You can calculate this yourself with the ephem or astropy Python libraries — no API needed. Inputs are latitude, longitude, date, and time.
Key outputs:
- Major and minor feeding windows (times + duration)
- Moon phase (new/full moons correlate with higher activity)
- Moonrise/moonset times
Why it matters: Every serious angler checks solunar tables. Including them makes your app a one-stop shop.
| Source | Data | Use |
|---|---|---|
| SNOTEL (NRCS) | Snowpack & snowmelt data | Predict spring runoff timing — critical for knowing when rivers blow out and when they come back into shape |
| Colorado DWR | Reservoir levels | Lake fishing conditions (full reservoir vs. low pool) |
| USGS Earthquake Hazards | N/A but cool | Just kidding. But the USGS API pattern is the same! |
| Community catch reports | User-submitted | If you build a community feature, crowdsourced data becomes your moat |
┌─────────────────────────────────────────────────────────────────────┐
│ DATA INGESTION LAYER │
├──────────┬──────────┬──────────┬──────────┬────────────────────────┤
│ USGS │ CPW │ Weather │ Solunar │ SNOTEL (stretch) │
│ Water │ Stocking │ API │ Calc │ Snowpack │
│ API │ Scraper │ │ │ │
│ (15 min) │ (weekly) │ (hourly) │ (daily) │ (daily) │
└────┬─────┴────┬─────┴────┬─────┴────┬─────┴────────────┬──────────┘
│ │ │ │ │
▼ ▼ ▼ ▼ ▼
┌─────────────────────────────────────────────────────────────────────┐
│ PROCESSING / STORAGE │
│ │
│ ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ │
│ │ PostgreSQL │ │ Location │ │ Historical │ │
│ │ + PostGIS │ │ Enrichment │ │ Pattern │ │
│ │ (primary DB) │ │ (join gauge │ │ Analysis │ │
│ │ │ │ to waters) │ │ (baselines) │ │
│ └──────────────┘ └──────────────┘ └──────────────┘ │
│ │
└───────────────────────────────┬─────────────────────────────────────┘
│
▼
┌─────────────────────────────────────────────────────────────────────┐
│ SCORING ENGINE │
│ │
│ For each water body, compute a "Fishing Score" (0-100) based on: │
│ • Water temp relative to ideal range for target species │
│ • Flow rate relative to historical median (percentile) │
│ • Barometric pressure trend (falling = bonus) │
│ • Solunar rating for the day │
│ • Recent stocking (big bonus if stocked within 7 days) │
│ • Cloud cover, wind, precipitation │
│ • Season/hatch calendar │
│ │
└───────────────────────────────┬─────────────────────────────────────┘
│
▼
┌─────────────────────────────────────────────────────────────────────┐
│ FRONTEND / DELIVERY │
│ │
│ Phase 1: Streamlit dashboard (fast to build, demo-ready) │
│ Phase 2: Web app (React or similar) │
│ Phase 3: Mobile app (React Native or Flutter) │
│ │
│ Features: │
│ • Map view with color-coded fishing scores │
│ • "Best bets this weekend" ranked list │
│ • Individual water detail page (flow chart, temp, stocking hx) │
│ • Push notifications for stocking events + ideal conditions │
│ • 7-day forecast per water body │
│ │
└─────────────────────────────────────────────────────────────────────┘
This is the core intellectual property — your "secret sauce." Here's a starting framework:
1. Water Temperature Score (0–20)
Species: Rainbow/Brown Trout
Ideal range: 50–62°F
Acceptable: 45–68°F
Shutdown: <40°F or >68°F
Score:
50-62°F → 20 points
45-50°F → 15 points
62-65°F → 15 points
40-45°F → 8 points
65-68°F → 5 points
<40 or >68 → 0 points
No temp data → Use air temp proxy with thermal lag model
2. Flow Score (0–20)
Compare current CFS to historical median for this day-of-year.
Use USGS percentile data.
Score:
25th–75th percentile (normal) → 20 points
10th–25th (low but fishable) → 14 points
75th–90th (high but fishable) → 12 points
<10th (drought/very low) → 5 points
>90th (flood/blowout) → 0 points
Bonus: +3 if flow is trending DOWN from high (clearing/dropping = great)
3. Weather/Pressure Score (0–20)
Barometric pressure trend (last 6 hours):
Falling steadily → 20 points (pre-front = best fishing)
Stable low → 15 points
Stable high → 12 points
Rising steadily → 8 points
Rapidly falling → 5 points (storm imminent, may be unsafe)
Cloud cover modifier:
Overcast → +2
Partly → +1
Clear → +0
Wind modifier:
5-15 mph → +1 (good chop)
>25 mph → -3 (unfishable in many spots)
4. Solunar Score (0–20)
Day rating based on moon phase and major/minor periods:
New/Full moon + major period overlap with dawn/dusk → 20
New/Full moon day → 16
Quarter moon + major period overlap → 12
Quarter moon day → 8
Worst case (last quarter, no overlaps) → 4
5. Stocking Bonus (0–20)
Stocked within last 3 days → 20 points
Stocked within last 7 days → 15 points
Stocked within last 14 days → 8 points
No recent stocking → 5 points (wild fish waters get base 10)
Gold Medal Water designation → +5 bonus (always good fishing)
Each water body gets a composite score (0–100) with a label:
- 80–100: 🔥 Epic — Drop everything and go
- 60–79: ✅ Good — Solid day expected
- 40–59: 🟡 Fair — Catchable but challenging
- 20–39: 🟠 Tough — Low expectations
- 0–19: 🔴 Poor — Save your time
| App | Strengths | Colorado Weakness |
|---|---|---|
| BassForecast | Great pressure/solunar scoring | Bass-only. No trout. No stocking data. |
| onX Fish | Excellent maps, bathymetry | Generic weather overlay. No CO-specific data integration. |
| Fishbox | AI bite predictions, species-specific | National focus, no USGS stream data integration. |
| Fishing Points | Good solunar + weather combo | No water-specific conditions (temp, flow). |
| CPW Fishing Atlas | Official CO data, species info | Static. No forecasting. No scoring. Clunky interface. |
Your differentiator: None of these apps combine USGS real-time water data + CPW stocking reports + weather + solunar into a single score for Colorado waters. You'd be the only app where an angler can see: "Eleven Mile Reservoir: Score 82 — stocked 3 days ago, water temp 56°F, pressure dropping, major solunar period at 6:30 AM."
- Launch as a free Streamlit app or simple web app
- Build an email list with weekly "Best Bets" newsletter
- Share on Colorado fishing forums, Reddit (r/COFishing, r/flyfishing), local Facebook groups
Free tier:
- Top 10 waters with scores
- Current conditions
- Basic 3-day forecast
Premium tier:
- All waters with scores
- 7-day forecast
- Push notifications (stocking alerts, condition alerts)
- Historical patterns ("This lake fishes best in the second week of June")
- Personalized recommendations based on saved favorites and location
- Affiliate partnerships with local fly shops (Anglers Covey in COS, Colorado Angler in Littleton, etc.)
- Guide service referrals — connect anglers with guides when conditions are prime
- Sponsored content from gear brands (tasteful, not spammy)
- Data licensing — conservation orgs, researchers, and CPW itself might want your aggregated dataset
| Layer | Tool | Why |
|---|---|---|
| Ingestion | Python + requests + BeautifulSoup |
USGS API calls + CPW HTML scraping |
| Scheduling | Cron → Prefect or Airflow (later) | USGS every 15 min, weather hourly, stocking weekly |
| Database | PostgreSQL + PostGIS | Spatial queries ("waters near me"), time series storage |
| Scoring Engine | Python | Core algorithm, runs on schedule |
| API | FastAPI | Serve scores to frontend |
| Frontend (Phase 1) | Streamlit | Fastest path to a working demo |
| Frontend (Phase 2) | React + Leaflet/Mapbox | Production web app with interactive map |
| Hosting | Railway, Fly.io, or a small VPS | Cheap to start ($5–20/month) |
| Notifications | Twilio (SMS) or Firebase (push) | Stocking and conditions alerts |
Goal: A working Streamlit dashboard for 10–20 popular Colorado waters.
-
Weekend 1: Data pipelines
- Write USGS API ingestion script (flow + temp for ~20 key stations)
- Write CPW stocking report scraper
- Set up PostgreSQL, define schema
- Store first batch of data
-
Weekend 2: Scoring engine + weather
- Integrate Open-Meteo weather API
- Implement solunar calculations
- Build v1 of the scoring algorithm
- Test against waters you know personally (sanity check: does the score match your experience?)
-
Weekend 3: Frontend
- Build Streamlit dashboard with map view
- Show scores, conditions, and stocking status for each water
- Add individual water detail pages (flow chart, temp trend, etc.)
-
Weekend 4: Polish + Share
- Refine scoring weights based on testing
- Deploy to a public URL
- Share on r/COFishing, local fishing Facebook groups
- Collect feedback
- Expand to 50+ waters
- Add 7-day forecast
- Build email newsletter ("Weekly Best Bets")
- Set up automated scheduling (cron or Prefect)
- Add user accounts and saved favorites
- Implement premium tier
- Add push notifications
- Build production React frontend
- Establish affiliate partnerships
- Apply to local business incubators or outdoor industry programs
Focus your MVP on waters near you and waters that are popular statewide:
| Water | Type | USGS Gauge? | Stocked? |
|---|---|---|---|
| North Catamount Reservoir | Lake | Nearby gauge | Yes |
| South Catamount Reservoir | Lake | Nearby gauge | Yes |
| Fountain Creek | Stream | Yes (07105500) | Occasionally |
| Eleven Mile Reservoir | Lake | Yes (South Platte gauges) | Yes |
| Spinney Mountain Reservoir | Lake | Nearby gauge | Limited |
| Rampart Reservoir | Lake | No | Yes |
| Monument Lake | Lake | No | Yes |
| Water | Type | Why Include |
|---|---|---|
| South Platte (Cheesman Canyon) | River | Gold Medal, iconic |
| Arkansas River (Salida–Buena Vista) | River | Gold Medal, popular |
| Blue River (below Dillon) | River | Gold Medal |
| Frying Pan River | River | Gold Medal, legendary |
| Horsetooth Reservoir | Lake | Front Range, heavily fished |
| Chatfield Reservoir | Lake | Denver metro, heavily stocked |
| Pueblo Reservoir | Lake | Near you, diverse species |
When you talk about this project in a freelance or job context, emphasize:
- Multi-source data integration — Joining USGS, CPW, weather, and astronomical data with different schemas, update frequencies, and reliability characteristics.
- Data quality handling — USGS gauges go offline, report bad values, or have gaps. CPW stocking reports are inconsistently formatted. Weather forecasts are probabilistic. You're building quality checks, fallback logic, and confidence scoring.
- Time-series pipeline — Ingesting, storing, and querying high-frequency sensor data (USGS gauge readings every 15 minutes across hundreds of stations).
- Scoring/feature engineering — Turning raw data into a composite metric that's actionable. This is the same skill as building features for ML models.
- Pipeline orchestration — Multiple ingestion jobs on different schedules, dependencies between them, monitoring for failures.
-
Open a Python shell and hit the USGS API for a local gauge:
https://waterservices.usgs.gov/nwis/iv/?format=json&sites=07105500¶meterCd=00060,00010&period=P7D(That's Fountain Creek near Colorado Springs — flow and temperature for the last 7 days)
-
Parse the JSON and plot the flow over the last week
-
Check the CPW stocking report and manually verify: was any water near you stocked recently? How does the stocking date correlate with what you know about the fishing there?
-
If the answer to "would I use this tool?" is yes — you've got a project worth building.